Alex Filippenko: Supernovae, Dark Energy, Aliens & the Expanding Universe | Lex Fridman Podcast #137
the following is a conversation with Alex filipenko an astrophysicist and professor of astronomy from Berkeley he was a member of both the Supernova cosmology project and the high Supernova search team which used observations of the extra Galactic Supernova to discover that the universe is accelerating and that this implies the existence of dark energy this discovery resulted in the 2011 nobba prize for physics outside of his groundbreak can research he is a great science communicator and is one of the most widely admired Educators in the world I really enjoyed this conversation and I'm sure Alex will be back again in the future quick mention of each sponsor followed by some thoughts related to the episode neuro the maker of functional sugar-free gum and mints that I used to give my brain a quick caffeine boost better help and online therapy with a licensed professional Master Class online courses that I enjoy from some of the most amazing humans in history and cash app the app I use to send money to friends please check out these sponsors in the description to get a discount and to support this podcast as a side note let me say that as we talk about in this conversation the objects that populate the universe are both a inspiring and terrifying in their capacity to create and to destroy us solo flares and asteroids lurking in the darkness of space threaten our humble fragile existence here on Earth in the chaos tension conflict and social division of 2020 it's easy to forget just how lucky we humans are to be here and with a bit of hard work maybe one day we'll venture out towards the Stars if you enjoy this thing subscribe on YouTube review it with fast stars on Apple podcast follow on Spotify support on patreon or connect with me on Twitter at Lex fredman and now here's my conversation with Alex filipenko let's start by talking about the biggest possible thing the universe sure will the universe expand forever or collapse on itself well you know that's a great question that's one of the big questions of cosmology and of course we have evidence that the matter density is sufficiently low that the universe will expand forever but not only that there's this weird repulsive effect we call it dark energy for want of a better term and it appears to be accelerating the expansion of the universe so if that continues the universe will expand forever but it need not necessarily continue it could reverse sign in which case the universe could in principle collapse at some point in the Far Far Future so like in terms of investment advice if you were to give me and then to bet all my money on one or the other where did does your intuition currently lie well right now I would say that it would expand forever because I think that the dark energy is likely to be just Quantum fluctuations of the vacuum the vacuum Zero Energy state is not a state of zero energy that is the ground state is a a state of some elevated energy which has a repulsive effect to it and that will never go away because it's not something that changes with time so if the universe is accelerating now it will forever continue to do so and yet I mean you're so effortlessly mentioned Dark Energy do we have any understanding of of what the heck that thing is well not really but we're getting progressively better observational constraints so you know different theories of what it might be predict different sorts of behavior for the evolution of the universe and we've been measuring the evolution of the universe now and the data appear to agree with the predictions of a con density vacuum energy a z Point Energy but one can't prove that that's what it is because one would have to show that the numbers that the measured numbers agree with the predictions to an arbitrary number of decimal places and of course even if you've got 8 9 10 12 decimal places what if in the 13th one the measurements significantly differ from the prediction then the dark energy isn't this vacuum State uh ground state energy of the of the vacuum and so then it could be some sort of a a field some sort of a new energy a little bit like like light like electromagnetism but very different from light that fills space and that type of energy could in principle change in the distant future it could become gravitationally attractive for all we know there is a historical precedent to that and that is that the inflation with which the universe began when the universe was just a tiny blink of an of an eye old a trillionth of a trillionth of a trillionth of a second you know the universe went whoosh it exponentially expanded that dark energy likee substance we call it the inflaton that which inflated the universe later decayed into more or less normal gravitationally attractive matter so the exponential early expansion of the universe did transition to a deceleration which then dominated the universe for about 9 billion years and now this small amount of dark energy started causing an acceleration about five billion years ago and whether that will continue or not is something that we'd like to answer but I don't know that we will anytime soon so there could be this interesting field that we don't yet understand that's morphing over time that's changing the way the universe is is expanding I mean it it's funny that you were thinking through this rigorously like an experimentalist yeah but the what about like the fundamental physics of dark energy is there any understanding of uh what the heck it is or is or is this the kind of uh the the god of the gaps or the field of the gaps uh so like it there must be something there because of what we're observing I'm very much a person who believes that there's all always a cause you know there there are no um miracles of a supernatural nature okay uh so I mean there are two broad categories either it's the vacuum Zero Point Energy or it's some sort of a a new energy field that pervades the Universe the latter could change with time the former the vacuum energy cannot right so if it turns out that it's one of these new fields and there many many possibilities they go by the name of you know quintessence and things like that but there are many categories of those sorts of fields we try with data to rule them out by comparing the actual measurements with the predictions and some have been ruled out but many many others remain to be tested and the data just have to become a lot better before we can rule out most of them and become reasonably convinced that this is a vacuum energy so there is hypotheses for different fields like with names and stuff like that yeah yeah you know generically quintessence like the Aristotelian fifth Essence but there are many many versions of quintessence there's K Essence there's even ideas that you know this isn't something from within this dark energy but rather there are a bunch of say bubble universes surrounding our universe and this whole idea of the Multiverse is not some crazy Mad Men type idea anymore it's you know real card carrying physicists are seriously considering this possibility of a Multiverse and some types of multiverses could have you know a bunch of bubbles on the outside which gravitationally act outward on our bubble because gravity or gravitons the the quantum particle that is thought to carry gravity is is thought to Traverse the bulk the space between these different little bubble membranes and stuff and so it's conceivable that these other verus are pulling outward on us that's not a favored explanation right now but but really nothing has been ruled out no class of models has been ruled out completely certain examples within classes of models have been ruled out but in general I think we still have really a lot to learn about what's causing this observed acceleration of the expansion of the universe be it dark energy or some forces from the outside or or perhaps you know I guess it's conceivable that and sometimes I wake up in the middle of the night screaming the dark energy that which causes the acceleration and dark matter that which causes galaxies and clusters of galaxies to be bound gravitationally even though there's not enough visible matter to do so maybe these are our 20th and 21st century toic epicycles so toy had a geocentric and Aristotelian view of the world everything goes around Earth but in order to explain the backward motion of planets Among the Stars that happens every year or two or sometimes several times a year for Mercury and Venus you needed the planets to go around in little circles called epicycles which themselves then went around Earth yes and in this in this part of the epicycle where the planet is going in the direction opposite to the direction of the overall epicycle it can appear in projection to be going backward Among the Stars socaled retrograde motion and it was a brilliant mathematical scheme in fact he could have added epicycles on top of epicycles and reproduce The observed positions of planets to arbitrary accuracy yeah and this is really the beginning of what we now call forier analysis right any periodic function can be represented by a sum of signs and Co signs of different periods amplitudes and phases so it could have worked arbitrarily well but other data you know show that in fact Earth is going around the Sun um so are dark energy and dark matter just these Band-Aids that we now have to try to explain the data but they're just completely wrong that that's a possibility as well and as a scientist I have to be open to that possibility as an open-minded scientist how do you how do you put yourself in the mindset of somebody that or majority of the scientific Community or majority of people believe that the Earth everything rotates around Earth how do you put yourself in that mindset and then take a leap to uh propose a model that the sun is in fact at the center of this the solar system sure I mean so that puts us back in the shoes of cernus right 500 years ago where he had this philosophical preference for the sun being the dominant body in what we now call the solar system the observational evidence in terms of the measured positions of planets was not better explained by the heliocentric Sun centered system it's just that you know cernus saw that the sun is the source of all our light and heat oh wow and he had you know he he knew from other studies that it's it's far away so the fact that it appears as big as the moon means it's actually way way bigger because even at that time it was known that the sun is much farther away than the moon so um you know he just felt wow it's big it's bright what if it's the central thing but the observed positions of planets at the time in the early to mid 16th century under the heliocentric system was not a better match at least not a significantly better match than tmy system which was quite accurate and lasted 1500 years yeah yeah that's so fascinating to think that the philosophical predispositions that you bring to the table are essent so like you have to have a young person come along that has a weird infatuation with the son yeah that like almost philosophically is like however their upbringing is they're more ready for whatever the more the simpler answer is right oh that's um it's kind of sad it's uh sad from an individual descendant of ape perspective because then that means like me like you as a scientist you're stuck with whatever the heck philosophies you brought to the table you might be almost completely unable to to think outside this particular box you've built right this is why I'm saying that you know as an objective scientist one needs needs to have an open mind to Crazy sounding new ideas and you know even cernus was very much a man of his time and dedicated his work to the pope he still used circular orbits the Sun was a little bit off center it turns out and a slightly off-center Circle looks like a slightly eccentric elliptical orbit so then when Kepler in fact showed that the orbits are actually in general ellipses not circles the reason that you know he needed tuob bra's really great data to show that distinction was that a slightly off-center circle is not much different from a slightly eccentric ellipse and so there wasn't much difference between Kepler's View and uh kernus is View and and Kepler needed the better data uh tuo's toob bra's data and so that's again a great example of of of science and OBS observations and experiments working together with hypotheses and they they kind of bounce off each other they play off of each other and you continually need more observations and it wasn't until Galileo's work uh around 1610 that actual evidence for the heliocentric hypothesis emerged it came in the form of Venus the planet Venus going through all of the possible phases from new to Crescent to to quarter to gibbus to full to waning gibbus third quarter waning crescent and then new again it turns out in the toic system with Venus between Earth and the Sun but always roughly in the direction of the sun you could only get the new and Cresent phases of Venus but the observations showed a full set of phases and moreover when Venus was gibbus or full that meant it was on the far side of the Sun that meant it was farther from Earth than when it's Crescent so it should appear smaller and indeed it did so that was a that was you know the nail and the coffin in a sense and then you know Galileo's other great observation was that Jupiter has moons going around it the four Galilean satellites and even though Jupiter moves through space so too do the moons go with it so first of all Earth is not the only thing that has other things going around it and secondly Earth could be moving as Jupiter does and you know things would move with with it we we wouldn't fly off the surface and our moon wouldn't be left behind and all this kind of stuff so that was a a big breakthrough as well but it wasn't as definitive in my opinion as the phases of Venus perhaps I'm revealing my ignorance but I didn't realize how much data they were working with yeah so there's uh so it wasn't Einstein or Freud thinking in theories it was a lot of data and you're playing with it and seeing how to make sense of it so isn't it it isn't just coming up with completely abstract thought experiments yeah it's looking at the data sure and you Newton's great work right the prinkipia it was based in part on Galileo's observations of balls rolling down inclined planes supposedly fall falling off the Leaning Tower of Pisa but that's probably apocryphal in any case you know um the the the Inquisition actually did or the R Catholic Church uh did did history a favor not that I'm condoning them but they placed Galileo under house arrest yeah and that gave Galileo time to publish to assemble and publish the results of his experiments that he had done decades earlier it's not clear he would have had time to do that you know had he not been under house arrest and so Newton of course Very Much used Galileo's observations let me ask uh the old Russian overly philosophical question about death so we're talking about the expanding Universe sure how do you think human civilization will come to an end if we avoid the uh the near-term issues we're having uh will it be our sun burning out will it be comets okay will it be uh what is it oh do you think we we have a shot at reaching the the heat death of the universe yeah yeah so we're going to leave out the anthropogenic uhle causes of our potential destruction yes which I actually think are greater than the celestial uh causes so um so if we get lucky yeah if we get and intelligent I don't know yeah so no way will we as humans reach the heat death of the Universe I mean it's conceivable that uh machines which I think will be our evolutionary descendants might reach that although even they will have less and less energy with which to work as time progresses because eventually even the lowest mass stars burn out although it takes them trillions of years to do so um so the point is is that certainly on Earth uh there are other Celestial threats existential threats comets exploding Stars the sun burning out so we will definitely need to move away away from our solar system to other solar systems and then you know the question is can they keep on propagating to other planetary systems sufficiently long um in our own solar system the sun burning out is is not the the immediate existential threat um that'll happen in about you know five billion years when it becomes a red giant although I should hasten to add that within the next one or two billion years years the sun will have brightened enough that unless they compensatory atmospheric changes the oceans will will evaporate away you know and and you need much less carbon dioxide for the temperatures to be maintained roughly at their present temperature and plants wouldn't like that very much so you can't lower the carbon dioxide content too much so so within one or two billion years probably the oceans will evaporate away yeah but on a sooner time scale than that I would say an asteroid Collision leading to a potential mass extinction or at least an Extinction of complex beings such as ourselves that require quite special conditions unlike cockroaches and amibas you know to survive um you know one of these civilization changing asteroids is only one kilometer or so in diameter and bigger and a true mass extinction event is 10 kilometers or larger now it's true that we can find and track the orbits of asteroids that might be headed toward Earth and if we find them 50 or 100 years before they impact us then clever applied physicists and Engineers can figure out ways to deflect them but at some point you know some Comet will come in from the deep freeze of the solar system and there we have very little warning months to a to a year what's the Deep Freeze sorry oh the Deep Freeze is sort of out Beyond Neptune there's this thing called the Kyper belt M and it consists of a bunch of you know dirty ice balls or icy dirt balls it's the source of the Comets that occasionally come close to the Sun and then there's a even bigger area called the scattered disc which is sort of a big doughnut surrounding the solar system way out there from which other comets come and then there's the orc Cloud WT after uh Yan ort a Dutch astrophysicist and it's the better part of a lightyear away from the Sun so a good fraction of the distance to the nearest star but that's like a trillion or 10 trillion comet-like objects that occasionally get disturbed by a passing star or whatever and most of them go flying out of the solar system but some go toward the Sun and they they come in with little warning you know by the time we can see them they're only a year or two away from us and moreover not only is it hard to determine their trajectories sufficiently accurately to know whether they'll hit a tiny thing like Earth but outgassing from the comet of um gases you know when the IES sublimate that outgassing can change the trajectory just because of conservation of momentum right it's the rocket effect gases go out in One Direction the object moves in the other direction and so since we can't predict how much outgassing there will be and in exactly what direction because these things are tumbling and rotating and stuff it's hard to predict the trajectory with sufficient accuracy to know that it will hit and you certainly don't want to deflect a comet that would have missed but you thought it was going to hit and end up having it hit that would be like the ultimate Charlie Brown you know goat instead of trying to be the hero right he ended up being the goat what would you uh what would you do if it seemed like in a matter of months that there is some nonzero prob ility maybe a high probability that there will be a collision so from a scientific perspective from an engineering perspective I imagine you would actually be in the room of people deciding what to do what uh yeah philosophically too it's a tough one right because if you only have a few months that's not much time in which to deflect it early detection and and um early action or key because when it's far away you only have to deflect it by a tiny little angle yeah and then by a time it reaches us the perpendicular motion is big enough to you know to to Miss Earth all you need is one radius or or one diameter of the earth right that actually means that all you would need to do is slow it down so it arrives four minutes later or speed it up so it arrives four minutes earlier and Earth will have moved through one radius in in that time so it doesn't take much but you can imagine if a thing is about to hit you you you have to deflect at 90 degrees or more right you know and you don't have much time to do so and you have to slow it down or speed it up a lot if that's what you're trying to do to it and so decades is sufficient time but months is not sufficient time so at that point I would think the the name of the game would be to try to predict where it would hit and if it's in a heavily populated region try to try to start an orderly evacuation perhaps but you know that might cause just so much Panic that I'm how would you do it with New York City or or Los Angeles or something like that right I might have I might have a different opinion a year ago I'm uh a bit U disheartened by you know in the movies the um there's always extreme competence from the government competence yeah competence right but we expect extreme incompetence if anything right yes now so I'm quite disappointed but sort of from a medical perspective I think you're saying there in a scientific one it's almost better to get better and better maybe telescopes and data collection to be able to predict the movement of these things or like come up with totally new technologies like you can imagine actually sending out like probes out there to be able to sort of almost have little finger sensors throughout our solar system to be able to detect stuff well that's right yeah monitoring the asteroid belt is very important and 99% of the so-called neear objects ultimately come from the asteroid belt and so there we can track the trajectories and even if there's you know a close encounter between two asteroids which deflects one of them toward Earth it's unlikely to be on a collision course with Earth in the immediate future it's more like you know tens of years so that gives us time but we would need to improve our ability to detect the objects that come in from a great distance unfortunately those are are much rarer the the Comets come in you know 1% of the collisions perhaps are with comets that come in without any warning hardly and so so that might be more like you know a billion or two billion years before one of those hits us um so maybe we have to worry about the sun getting brighter on that time scale I mean there's the possibility that a star will explode near us in the next couple of billion years but over the course of the history of life on Earth the estimates are that maybe only one of the mass extinctions you know was caused by a star blowing up in particular a special kind called a Gamay burst and the I think it's the oriv I solarian uh saluan or divis saluan Extinction 420 or so 440 million years ago that is speculated to have come from one of these particular types of exploding Stars called Gamay bursts but even there the the evidence is circumstantial so those kinds of existential threats are are reasonably rare the greater danger I think is civilization changing events where it's a much smaller asteroid uh which those are hard harder to detect or or a giant solar flare that shorts out the Grid in all of North America let's say now you know astronomers are monitoring the sun 247 with various satellites and we can tell when there's a a flare or a coronal mass ejection and we can tell that in a day or two a giant bundle of energetic particles will arrive and twang the magnetic field of Earth and send all kinds of currents through long-distance power lines and that's what shorts out the Transformers and Transformers are you know expensive and and hard to replace and hard to transport and all that kind of stuff so if we can warn the power companies and they can shut down the grid before the big bundle of particle hits then we will have mitigated much of this now for a big enough bundle of particles you can get short circuits even over small distance scales so not everything will be saved but at least the whole grid might not go out so again you know astronomers I like to say support your local astronomer they may help someday save Humanity by telling the power companies to shut down the grid finding the asteroid 50 or 100 years before it hits then having clever physicists and Engineers deflect it so many of these Cosmic threats Cosmic existential threats we can actually predict and do something about or observe before they hit and do something about so it's it's terrifying to think that people would listen to this conversation it's like when you listen to Bill Gates talk about pandemics and his Ted Talk a few years ago yeah and realizing we should have supported our local astronomer more well I don't know whether it's more because that's I said I actually think uh human induced threats or things that occur naturally on Earth either a natural pandemic or perhaps you know a bioengineering type pandemic or you know something like a super volcano right um there was one event Toba I think it was 70 plus thousand years ago that that caused a gigantic decrease in temperatures on Earth because it sends up it sent up so much soot that it blocked the sun right it's the nuclear winter type disaster scenario that some people including Carl Sean talked about decades ago but we can see in the history of volcanic eruptions even more recently in the 19th century Tambora and other ones you look at the record and you see rather large dips in temperature associated with massive volcanic eruptions well these super volcanoes one of which by the way exists under Yellowstone you know in the central us I mean it's not just it's not just one or two states it's a it's a gigantic region and there's controversy as to whether it's likely to blow any time in the next 100,000 years or so but that would be perhaps not a mass extinction because you really need to or or perhaps not a complete existential threat because you have to get rid of sort of the very last humans for that but but at least getting rid of um you know killing off so many humans truly billions and billions of humans the one there have been ones tens of thousands of years ago including this one um Toba I think it's called where it's estimated that the human population was down to 10,000 or 5,000 individuals something like that right if you have a 15 degree drop in temperature over quite a short time it's not clear that even with today's advanced technology we would be able to adequately respond at least for the vast majority of people maybe some would be in these underground caves where you'd keep the president and a bunch of other important people you know but the the typical person is not going to be prot protected when when all of Agriculture is is cut off right and when it could be hundreds of millions or billions of people yeah starving to death exactly that's right they don't all die immediately but they use up their supplies or again this electrical grid first toilet paper there you go stash that toilet paper you know um or the electrical grid I mean imagine North America without power for a year right I mean we've become so dependent we're no longer the cave people they would do just fine right what do they care about the electrical grid right what do they care about agriculture they're hunters and gatherers but we now have become so used to our way of life that the only real survivors would be those rugged individualists who live somewhere out in the forest or in a cave somewhere completely independent of anyone else yeah I've recently I recommend it it's totally new to me this kind of survivalist uh folks but there's a a few show there's a lot lot of shows of those but I saw one on Netflix and I started watching them and there's they make a lot of sense they they reveal to you how dependent we are on all aspects of this beautiful systems we human have built right and how fragile they are incredibly fragile and yeah this this whole conversation is making me realize how lucky we are oh we're we're incredibly lucky but we've set ourselves up to be very very fragile and we are intrinsically complex biological creatures that except for the fact that we have brains and Minds with which we can you know try to prevent some of these things or respond to them we as a living organism require quite a narrow set of conditions in order to survive you know we're not cockroaches we're not going to survive a nuclear war so we're kind of there's this beautiful dance between um we've been talking about a astronomy that astronomy the Stars like inspires everybody and at the same time there's this pragmatic aspect that we're talking about and so I see space exploration as the same kind of way that it's uh reaching out to other planets reaching out to the stars is this really beautiful idea but if you listen to somebody like uh Elon Musk he talks about space exploration as very pragmatic like we have to if we we have to be he has this ridiculous way of sounding like an engineer about it which is like it's obvious we need to become a multiplanetary species if we were to survive long term so maybe both philosophically in terms of beauty and in terms of practical what's your thoughts on um space exploration on the challenges of it on how much we should be investing in it and on a personal level like how excited you are about by the possibility of going to Mars colonizing Mars and maybe going outside the solar system yeah you know great question uh there's a lot to unpack there of course you know humans are by their very nature explorers Pioneers they want to go out climb the next Mountain see what's behind it um explore the oan depths explore space this is our destiny to go out there and and of course from a pragmatic perspective yes we need to um plant our seeds elsewhere really because things could go wrong here on Earth now some people say that's that's an excuse to not take care of our planet that well we say we're elsewhere and so we don't have to take good care of our planet no you know we should take the best possible care of our planet we should be cognizant of the potential impact of what we're doing nevertheless it's prudent to have us be elsewhere as well so in that regard I actually agree with Elon uh it'd be good to be on Mars that would be yet another place for us to from which to you know explore further would that be a good Next Step would you say well that's the good it's a good next step I have happen I happen to disagree with him as to how quickly it will happen right I mean I think he's very optimistic now you need Visionary people like Elon to to get people going and to inspire them I mean look at the success he's had with multiple companies uh so maybe he gives this very optimistic timeline in order to be inspirational to those who are who are going out there and certainly his Success With You know the rocket that is reusable because it landed upright and all that I mean you know what that that's a GameChanger sort of like every time you flew from San Francisco to Los Angeles you discard the airplane right I mean that's crazy right so that's a game Cher but nevertheless the time scale over which he thinks that there could be a real thriving colony on Mars I think is far too optimistic what's the biggest challenges to you one is just getting Rockets not Rockets but people out there and two is the colonization like what do you have thoughts about this um challenges of this kind of prospect yeah I haven't thought about it in in great detail uh other than recognizing that Mars is a harsh environment yeah you don't have much of an atmosphere there you've got less than a percent of Earth's atmosphere um so you you to build some sort of a dome right away right and and that that would take time you need to melt the water that's in the permafrost or have canals dug from which you transport it from the from the polar ice caps you know I I was reading recently in terms of like what's the most efficient source of nutrition for humans that were to live on Mars and uh people should look into this but it turns out to be insects insects yeah yeah so you want you want to build GI colony of insects and just be eating insects have a lot of protein right a lot of protein and they're easy to like you can think of them as farming right but it's not going to be easy as easy as growing a whole plot of potatoes like in the movie The Martian you know or something right it's not going to be that easy but you know so there's there's this thin atmosphere it's got the wrong composition it's mostly carbon dioxide there are these violent dust storms the temperatures are generally cold you know you'd need to do a lot of things you need to terraform it basically in order to make it nicely livable without some Dome surrounding you and if you and if you insist on a dome well that's not going to house that many people right you know well so let's look let's look briefly then you know we're looking for a new apartment to move into so let's look outside the solar system do you think you've you've spoken about exoplanets as well do you think there's um possible homes out there for us uh outside of our solar system there are lots and lots of homes possible homes I mean they're there's a planetary system around nearly every Star you see in the sky and one in five of those is thought to have a roughly earth like Planet you know and that's a relatively new yeah it's a new discovery I mean that the Kepler satellite which was flying around uh above Earth's atmosphere was able to monitor the brightness of stars with exquisite detail and they could detect planets crossing the line of sight between us and the star thereby dimming its light for a short time ever so slightly and it's it's amazing so there are now thousands and thousands of these exoplanet candidates of which something like 90% are probably genuine exoplanets and you have to remember that only about 1% of stars have their planetary system oriented Edge on to your line of sight which is what you need for this Transit method to work right some arbitrary angle won't work and certainly perpendicular uh to your line of sight that is in the plane of the sky won't work because the the the planet is orbiting the star and never crossing your line of sight so the fact that um you know they found planets orbiting about 1% of the stars that they looked at in this field of 150 plus thousand stars they found planets around 1% you then multiply by the inverse of 1% which is you know right 1% is about how many what the fraction of the of the stars that have their planetary system oriented the right way and that already back of the envelope calculation tells you that of order 50 to 100% of all stars have planets okay and then they've been finding these earthlike planets etc etc so there are many potential homes the problem is getting there okay so then a typical bright star serus uh the brightest star in the sky maybe not a typical bright star but it's 8.7 light years away okay so uh that's that means the light took 8.7 years to reach us we're seeing it as it was about nine years ago okay so then you know you ask how long would a rocket take to get there at Earth's escape speed which is 11 kilometers per second okay and it turns out it's about a quarter of a million years okay now that's 10,000 Generations okay let's say a generation of humans is 25 years right so you need this colony of people that is able to sustain itself all their food all their waste disposal all their water all their recycling of everything for 10,000 Generations they have to commit themselves to living on this vehicle right I just see it happening what I see potentially happening if we avoid self-destruction intentional or unintentional here on Earth is that machines will do it robots that can essentially hibernate they don't need to do much of anything for a long long time as they're traveling and moreover if some energetic charged particle some Cosmic gray hits the circuitry it fixes itself right machines can do this uh I mean it it's a form of artificial intelligence you just tell the thing fix yourself basically and then when you land on the on the planet start producing copies of yourself initially from materials that perhaps sent or you just have a bunch of copies there and then they set up you know factories with which to do this I mean this is very very futuristic but it's much more feasible I think than sending Flesh and Blood over Interstellar distances a quarter of a million years to even the nearest Stars you're subject to all kinds of charged particles and radiation you have to you know Shield yourself really well that's by the way one of the problems of going to Mars is that it's not a three-day Journey like going to the Moon you're out there for the better part of a year or two and you're exposed to lots of radiation you know which typically doesn't do well with living tissue right or living tissue doesn't do well with the radiation okay and and the hope is that the robots that AI systems might be able to carry the carry the the fire of Consciousness whatever makes us humans yeah like a little drop of whatever makes us humans so special not to be too poetic about it but no but I I like being poetic about it because it's a it's an amazing question you know is there something Beyond just the bits the ones and zeros to us you know it's an interesting question um I like to think that there there isn't anything and that how beautiful it is that our thoughts our emotions our feelings our compassion all come from these ones and zeros right that to me actually is a a beautiful thought and the idea that machines silicon based life effectively could be our natural evolutionary descendants not from a DNA perspective but they are our creations and they then carry on that to me is a a beautiful thought in some ways but others find it to be a horrific thought right exciting to you I it is exciting to me as well yeah because to me from a purely an engineering perspective it's I believe it's impossible to create like whatever systems we create that take over the world it's impossible for me to imagine that those systems will not carry some aspect of what makes humans beautiful yeah so like that a lot of people have these kind of paperclip ideas that will we bring will'll build machines that are cold inside or philosophers call them zombies you know they're they're that naturally the systems that will out compete us on this Earth will be cold and non nonconscious not capable of all the human emotions and empathy compassion and love and hate every the the beautiful uh mix of uh what makes us human but to me intelligence requires all of that so in order order to outcompete humans you better be good at the full picture right so artificial general intelligence in my view encompasses a lot of these attributes that you just talked about yeah curiosity inquisitiveness you know right it might look very different than us humans but you have some of the magic but it'll but it'll also be much more able to survive the onslaught of existential threats that either we bring upon ourselves or don't anticipate here on Earth or that occasionally come from Beyond and there's nothing much we can do about a supernova explosion that just suddenly you know goes off and and and really if we want to move to other planets outside our solar system I think realistically that's a much better option than thinking that humans will actually make these gigantic Journeys and you know then I do this calculation from my class you know Einstein's special theory of relativity says that you can do it in a short amount of time in your own frame of reference if you go close to the speed of light but then you bring in eal mc^2 and you figure out how much energy it takes to get you accelerated to close enough to the speed of light to make the time scales short in your own frame of reference and the amount of energy is just unfathomable right we can do it at the large hron collider with with protons you know we can accelerate them to 99.9999% of this speat of light but that's just a proton we're gazillions of protons okay and that doesn't even count the rocket that would carry us the payload and you would need to either store the fuel in the rocket which then requires even more mass for the rocket or collect fuel along the way which you know is difficult and so getting close to the speed of light I think is not an option either other than for a little tiny thing like you know Yuri Milner and others are thinking about this this star shot project where they'll a little tiny camera to Alpha centuri 4.2 light years away they'll zip past it take a picture of the exoplanets that we know orbit that three or more star system and uh say hello real quick say hello real quickly and then send the images back to us okay yeah so that that's a tiny little thing right maybe you can accelerate that to they're hoping 20% of the speed of light with a whole bunch of high-powered lasers aimed at it it's now clear that other countries will allow us to do that by the way but that's a very forward looking thought I mean I very much support the idea but there's a big difference between sending a little tiny camera and sending a payload of people with equipment that could then mine the um the resources on the exoplanet that they reach and and then go forth and multiply right well let's let's talk about the big Galactic things and how we might be able to leverage them to travel fast I know this is a little bit science fiction but you know know uh ideas of wormholes and yeah the ideas at the edge of black holes that reveal to us that this fabric of SpaceTime is uh could be messed with yeah perhaps is that at all an interesting thing for you uh I mean in in your in looking out at the universe and studying it as you have is that also a possible like a dream for you that we might be able to find Clues how we can actually use it to improve our transportation it's an interesting thought I'm certainly excited by the potential physics that suggest this kind of faster than light travel effectively or you know cutting the distance to make it very very short through a wormhole or something like that possible no well you know col me not very imaginative but based on today's knowledge of physics which I realize you know people have gone down that rabbit hole you know aury ago Lord Kelvin one of the greatest physicists of all time said that all of fundamental physics is done the rest is just engineering and guess what then came special relativity quantum physics general relativity how wrong he was so let me not be another L Lord Kelvin on the other hand I think we know a lot more now about what we know and what we don't know and what the physical limitations are and to me most of these schemes if not all of them seem very far-fetched if not impossible so travel through wormholes for example you know it appears that for a non-rotating black hole that's just a complete no-o because the The Singularity is a point-like singularity and you have to reach it to Traverse the Wormhole and you get squished by The Singularity okay now for a rotating black hole it turns out there is a way to pass through the Event Horizon the boundary of the black hole and avoid the singularity and go out the other side or even Traverse the the doughnut hole like singularity in the case of a rotating black hole it's a ring Singularity so there's actually two theoretical ways you could get through a rotating black hole or a Charged black hole not that we expect charged black holes to exist in nature because they would quickly bring in the opposite charge so as to neutralize themselves but rotating black holes definitely reality we we now have good evidence for them do they have Travers ible wormholes probably not because it's still the case that when you go in you go in with so much energy that it it it either squeezes the Wormhole shut or you encounter a whole bunch of incoming and outgoing energy that vaporizes you it's called the mass inflation instability and it just sort of vaporizes you nevertheless you know you could imagine well you're in some vapor form but if you make it through maybe you could you know re form or something so it's still information yeah it's still information it's scrambled information but there's a way maybe of bringing it back right but then the thing that really bothers me is that as soon as you have this possibility of traversal of a wormhole you have to come to grips with a fundamental problem and that is that you could come back to your Universe At A Time prior to your leaving and you could essentially prevent your grandparents from meeting this is called the grandfather Paradox right and if they never met and if your parents were never born and if you were never born how would you have made the journey to prevent the history from allowing you to exist right it's it's a it's a causal it's a violation of causality of cause and effect now physicists such as myself take causality violation very very seriously we've never seen it you took a stand yeah I mean you know I mean it's one of these right Back to the Future type movies right and you have to work things out in such a way that you don't mess things up right some people say that well you come back to the universe but you come back in such a way that you cannot affect your journey um but then I mean that that seems kind of uh contrived to me or some say that you end up in a different universe and this also goes into the the many different types of the Multiverse hypoth esis and the many worlds interpretation and all that but again then it's not the universe from which you left right and you don't come back to the universe from which you left and so you're not really going back in time to the same universe and you're not even going forward in time necessarily then to the same universe right you're ending up in some other universe so so you've you what have you achieved right you you've traveled you traveled you uh you ended up in a different place than you started in more ways than one yeah and then then there's this idea um the aluer drive where you warp space time in front of you so as to greatly reduce the distance and you can expand the space time behind you so you're sort of riding a wave through SpaceTime but the problem I see with that beyond the Practical difficulties and the energy requirements and by the way how do you get out of this bubble through which you're you know riding this wave of space time miguelier acknowledged all these things he said this is purely theoretical fanciful and all that but a fundamental problem I see is that you'd have to get to those places in front of you so as to change the shape of SpaceTime so as to make the journey quickly but but to get there you you got there in the normal way at a speed considerably less than that of light so in a sense you you haven't saved any time right you might as well have just taken that journey and and gotten to where you were going yeah there's a right you what have you done you it's not like you snap your fingers and say okay let that space there be compressed and then I'll make it over to Alpha centuri in the next month you can't snap your fingers and do that yeah and but yeah we're sort of assuming that we can fix all the biological stuff that requires for humans to persist uh uh persist through that whole process because ultimately it might boil down to just extending the life of the of the human in some form whether it's through the robot through the digital form or through or actually just figuring out genetically how to live forever CU that Journey that you mentioned the long journey might be different if somehow our understanding of genetics of our understanding of our own biology all that kind of stuff would uh that's another trajectory if you could put us into some sort of suspended animation you know hibernation or something and greatly increase the lifetime and so these 10,000 Generations I talked about what do they care it's just one generation and they're asleep okay long nap so then you can do it it's still not easy right because you got some big old huge colony and that just through E equals MC squ right that's a lot of mass that's a lot of stuff to um to accelerate the Newtonian kinetic energy is gigantic right so you're still not home free but at least you're not trying to do it in a short amount of clock time right which if you look at eal mc^2 requires truly unfathomable amounts of energy because the energy is sort of it's it's your rest mass m c^2 divided by the square root of 1us v^2 over c^2 and if your listeners want to just sort of stick into their pocket calculator as V over C approaches one that one over the root of 1us v^2 over c^2 approaches Infinity MH so if you wanted to do it in zero time you'd need an infinite amount of energy that's basically why you can't reach let alone exceed the speed of light for a particle moving through a pre-existing space it's that it takes an infinite amount of energy to do so so that's talking about us going somewhere what about one of the things that inspires a lot of folks including myself is the possibility that there's other that this this conversation is happening and another planet in different forms with uh intelligent life forms well first we could start as a cosmologist what's your intuition about whether there is or isn't intelligent life out there outside of our own yeah I would say I'm one of the pessimists in that I I don't necessarily think that we're the only ones in the observable universe which goes out you know roughly 14 billion years in light travel time and more like you know 46 billion years when you take into account the expansion of space so the diameter of our observable universe is something like you know 90 992 billion Lighty years that encompasses you know 100 billion to a trillion galaxies with um you know 100 billion stars each so now you're talking about something like 10 to the 22nd 10 to the 23rd power stars and roughly an equal number of earthlike planets and so on um so there there there may well be uh other intelligent life but your your sense is our Galaxy's not teaming with life yeah our galaxy our Milky Way galaxy with several hundred billion stars and and potentially habitable planets is not teeming with intelligent life intelligent yeah I wouldn't well I'll get to the Primitive life the bacteria in a moment but um you know we we may well be the only ones in our Milky Way galaxy at most a handful I'd say but I'd probably side with the school of thought that suggests we're the only ones in our own Galaxy just because I don't see human intelligence as being a a natural evolutionary path for life um I mean there's a there's a number of arguments first of all there's been more than 10 billion species of life on Earth in its history yes uh nothing has approached our level of intelligence and mechanical ability and curiosity you know whales and dolphins appear to be reasonably intelligent but there's no evidence that they can think abstract thoughts that they're curious about the world they certainly can't build machines with which to study the world um so that's one argument secondly we came about as early hominids only four or five million years ago and as H Homo sapiens only about a quarter of a million years ago so for the vast majority of the history of life on Earth an intelligent alien zipping by Earth would have said there's nothing particularly intelligent or mechanically able on Earth okay yeah thirdly it's not clear that our intelligence is a long-term evolutionary Advantage now it's clear that in the last 100 years 200 years we've improved the lives of millions hundreds of millions of people but at the risk of potentially destroying ourselves either intentionally or unintentionally or through neglect as we discussed before that's a really interesting point which is it's possible that their huge amount of intelligent civilizations have been born even through our galaxy but they live very briefly and they die flash bulbs in theight Flight that brings me to the fourth the fourth issue and that is the you know the fairy Paradox if they're common where the hell are they you know yeah not withstanding the various UFO reports in Roswell and all that they just don't don't meet the bar they don't clear the bar of scientific scientific evidence in my opinion okay so you know there's there's no clear evidence that they've ever visited us on Earth here so and you know SEI has been now the search for extraterrestrial intelligence has been scanning the skies and true we've only looked a couple hundred light years out and that's a tiny fraction of the whole galaxy a tiny fraction of these 100 billion plus Stars nevertheless you know I if if the if the Galaxy were teaming with life especially intelligent life you'd expect some of it to have been far more advanced than ours okay there's no special nothing special about when the Industrial Revolution started on earth right the chemical evolution of our galaxy was such that billions of years ago nuclear processing and stars had built up clouds of gas after their explosion that were Rich enough in heavy elements to have formed earthlike planets even billions of years ago so there could be civiliz that are billions of years ahead of ours and if you look at the exponential growth of Technology among Homo sapiens in the last couple 100 years and you just project that forward I mean there's no telling what they could have achieved even in 1,000 or 10,000 years let alone a million or 10 million or a billion years and if they reach this capability of interstellar travel and colonization then you can show that within 10 million years or certainly a 100 million years you can populate the whole galaxy all right and they you know so then you don't have to have tried to detect them Beyond 100 or a thousand Lighty years they would already be here do you think as a thought experiment do you think it it's possible that they are already here but we humans are so human Centric that we're just not like our conception of what intelligent life looks like yeah is is um we don't want to acknowledge it like what what if trees right right right like okay I guess the in a form of a question do you think we'll actually detect intelligent life if it came to visit us yeah I mean it's like you know you're an ant crawling around on a sidewalk somewhere and do you notice the humans wandering around exactly and and the Empire State Building and you know rocket ships flying to the moon and all that kind of stuff right it's conceivable that um we haven't detected it and that we're so primitive compared to them that we're just not able to do so like if you look at dark energy Maybe we call it as a field it's just that my own feeling is that in science now through observations and experiments we've measured so many things and basically we understand a lot of stuff okay fabric of reality yeah the fabric of reality we understand quite well and there are a few little things like dark matter and dark energy that may be some sign of some super intelligence but I doubt it okay you know why would some super intelligence be holding clusters of galaxies together why would they be responsible for accelerating the expansion of the universe so the point is is that through science and applied science and engineering we understand so much now that I'm not saying we know everything but but we know a hell of a lot okay and so there's it's not like there are lots of mysteries flying around there that are completely outside our level of um of of exploration or understanding yeah from a I would say from from uh the mystery perspective it seems like the mystery of our own like cognition and Consciousness is much grander than like the degrees of freedom of possible explanations for what the heck is going on is much greater there than in the in the physics of the absor how the brain works how did life arise yeah that's big big questions but they to me don't indicate uh the existence of of of an alien or something I mean unless we are the aliens you know we we could have been contamination from some rocket ship that that hit here a long long time ago and all evidence of it has been destroyed but again that alien would have started out somewhere they're not they're not here watching us right now right they're not among us and so though there are exp potential explanations for the fmy Paradox and one of them that I kind of like is that the truly intelligent creature are those that decided not to colonize the whole galaxy cuz they'd quickly run out of room there CU it's exponential right you send a probe to a planet it makes two copies they go out they make two copies each and it's an exponential right they quickly colonize the whole galaxy but then the distance to the next galaxy the next big one like Andromeda that's two and a half million light years yeah that's a much grander scale now right and so it it also could be that the reason they surv this long is that they got over this tendency that may well exist among sufficiently intelligent creatures this tendency for aggression and self-destruction right if they bypass that and that may be one of the great filters if there are more than one right then they may not be a type of creature that feels the need to go and say oh there's a nice looking planet um and there's a bunch of you know ants on it let's go squish him and colonize it no it could even be the kind of Star Trek like prime directive where you go and explore worlds but you don't interfere in any way right and and also we call it exploration is beautiful and everything but there is underlying this desire to explore is a desire to conquer yeah I I mean if we're just being really honest about right now for us it is right and you're saying it's possible to separate but I would venture to say that you wouldn't that those are coupled so I could I could imagine a civilization that lives on for billions of years that just stays on its like figures out the minimal effort way of just peacefully existing it's like a monastery yeah and it limits itself yeah it limits itself you know it's it's planted its seeds in a number of places so it's not vulnerable to a single point failure right Supernova going off near one of these s or something or an asteroid or a comet coming in from the arc Cloud equivalent of that planetary system and without warning you know thrashing them to bits so they've got their seeds in a bunch of places but they chose not to colon colonize the Galaxy and they also choose not to interfere with this incredibly priv primitive organism Homo sapiens right um or or they uh this is like a they enjoy this like a TV show for them yeah could a TV show right so they just tuned in right so those are possible explanations yet I I think that to me the most likely explanation for the FME Paradox is that they really are very very rare and you know Carl Sean estimated a 100,000 of them if there's that many some of them would have been way ahead of us and and I think we would have seen them by now if there were a handful maybe they're there but at that point you're right on this dividing line between being a pessimist and an optimist yeah and and what are the odds for that right if you look at all the things that had to go right for us yeah and the then you know getting back to something you said earlier let's discuss you know primitive life yeah that could be the thing that's difficult to achieve just getting the random molecules together to a point where they start self-replicating and evolving and becoming better and all that that that's an inordinately difficult thing I think though I'm not you know some molecular cell biologist but just it's it's it's the usual argument you know you're wandering around in the Sahara Desert and you stumble across a watch is your is your initial response oh you know a bunch of sand grains just came together randomly and formed this watch no you you think that something formed it or it came from some simpler structure that then became you know more complex all right it didn't just form well even the simplest life is is a very very complex structure even the even the simplest procaryotic cells not to mention eukaryotic cells although that transition may have been this so-called great filter as well maybe the cells without a nucleus are relatively easy to form and then the big next step is where you have a nucleus which then provides a lot of energy which allows the cell to become much much more complex and so on interestingly going from eukaryotic cells single cells to multicellular organisms does not appear to be at least on Earth one of these great filters because there's evidence that it happened dozens of times independently on Earth so by by a really great filter something that happens very very rarely I mean that we had to get through um an obstacle that is just incredibly rare to get through and one of the really exciting scientific things is that that particular Point U is something that we might be able to discover Even in our lifetimes that find life elsewhere like Europa or yeah be able to see that would be bad news right because if we find lots of pretty Advanced life yeah that would suggest and and especially if we found some you know defunct you know fossilized civilization or something somewhere else that would be you mean of like what's that defunct civilization of like I'm sorry I switched gear there if we if we found some intelligent or rather you know even even trilobites right and stuff you know elsewhere that would be bad news for us because that would mean that the great filter is ahead of us you know right because it would mean that lots of lots of things have gotten roughly to our level yeah but but given the fmy Paradox if you accept that the fmy Paradox means that there's no one else out there you don't necessarily have to accept that but if you accept that it means that no one else is out there and yet there are lots of things we found that are at or roughly at our level that means that the great filter is ahead of us and that bodess poorly for our long-term future you know it's funny you said uh you started by saying you're a little bit on the pessimistic side but it's funny because we're doing this kind of dance between pessimism and optimism because I'm not sure if us being alone in the observable universe as intelligent beings is pessimistic well it's good news in a sense for us because means that we made it through oh right see if we're the only ones and there are such great filters maybe more than one formation of life might be one of them formation of eukaryotic that is with the nucleus cells be another development of humanlike intelligence might be another right there might be several such filters and we were the lucky ones and you know then people say well then that means you're putting yourself into a special perspective and every time we've done that we've been wrong and yeah yeah I know all those arguments but it still could be the case that there's one of us at least per Galaxy or per 10 or 100 or a thousand galaxies and we're sitting here having this conversation because we exist and so there's a there's an observational selection effect there right just because we're special doesn't mean that we shouldn't have these conversations about whether or not we're special right yeah so that's that's exciting that's optimistic so that's the that's the optimistic part that if we don't find other intelligent life there it might mean that we're the ones that made it uh and and in general outside the great filter and so on you know it's not obvious that uh the Stephen Hawkin thing which is it's not obvious that life out there is is going to be kind to us oh yeah so you know I knew Hawking and I greatly respect his his scientific work and in particular the early work on the unification of general theory of relativity and quantum physics to two great pillars of modern physics you know Hawking radiation and all that fantastic work you know if he were alive he should have been a recipient of this year's physics Nobel Prize which was for the discovery of black holes and also uh by Roger Penrose for the theoretical work showing that given a star that's massive enough you you basically can't avoid having a black hole anyway Hawking fantastic I I tip my hat to him may he rest in peace that would have been a heck of a Nobel Prize black holes heck of a good group but but but going back to what he said that we shouldn't be um broadcasting our presence to others there I actually disagree with him respectfully because first of all we've been unintentionally broadcasting our presence for a 100 years since the develop velopment of radio and TV okay um secondly any alien that has the capability of coming here and squashing us uh either already knows about us and you know doesn't care because we're just like little ants and when they're ants in your kitchen you tend to squash them but if they're ants on the sidewalk and you're walking by do you feel some great conviction that you have to squash any of them no you you generally don't right we're irrelevant to them all they need to do is keep an eye on on us to see whether we're approaching the kind of technological capability and know about them and have intentions of attacking them and then they can squash us right um they you know they could have done it long ago yeah they'll do it if they want to whether we advertise our presence or not is is irrelevant so I really think that that's not a huge existential threat so this is a good place to bring up a difficult topic you mentioned um they're they might they would be paying attention to us to see if we come up with any crazy technology there's folks who have uh reported UFO sightings there's actually I've recently found out there's uh websites that track this the D the data of these reportings and there's millions of them in the past uh several decades so seven decades and so on that they've been recorded and the yist community as they refer to themselves you know one of the ideas that I find compelling from an alien perspective that they kind of started showing up ever since we figured out how to build nuclear weapons MH that we should what a coincidence yeah uh so I mean you know if I was an alien I would start showing up then as well just well why not just observe us from afar no I know right I would figure out but that's why I'm always uh keeping a distance and staying blurry right but very pixelated very pixelated you know there there is a something in the human condition that a cognition that wants to see wants to believe beautiful things and uh some are terrifying some are exciting uh goats Bigfoot is a big Fascination for folks yeah and uh UFO sightings I think falls into that there's people that look at lights in the night sky and I mean there's it's kind of a downer to think in a skeptical sense to think that that's just a light yeah you want to feel like there's something magical there sure uh I mean I felt that first when my dad my dad's a physicist when he first told me about ball lightning yeah when I was like a little kid very weird very like weird physical phenomena and you said his intuition was telling me this as a little kid uh like I really like math his intuition was whoever figures out ball lightning will get a Nobel Prize mhm like he I think that was a side comment he gave me and I I decided there when I was like 5 years old or whatever that I'm going to win a Nobel Prize for figuring out B that was like one of the first sort of Sparks of the scientific mindset those Mysteries they capture your imagination I I think when I speak to people that report UFOs that's that fire that's what I see that excitement yeah I understand that MH but what what do we do with that because there's hundreds of thousands if not millions and then the scientific Community you're like the perfect person you you have an awesome Einstein sure I what what do we do with those reports it's uh most of the scientific Community kind of rolls their eyes and dismisses it is it is it possible that a Time % of those folks saw something that's worth deeply investigating sure we should investigate it it's just one of these things where you know they've not brought us a hunk of kryptonite or something like that right they haven't brought us actual tangible physical evidence with which experiments can be done in Laboratories right it's it's anecdotal evidence the photographs are um in some cases in most cases I would say quite ambiguous I don't know what to think about so David fraver is the first person he's a Navy pilot Commander yeah and there's a bunch of them but he's sort of one of the most legit pilots in people I've ever met right the fact that he saw something weird he doesn't know what the heck it is yeah he saw something weird I mean I don't know what to do with that and one on the psych psychological side so I'm pretty confident he saw what he says he saw which he's not Prov he's saying it's something weird right one of the interesting psychological things that worries me is that everybody in the Navy everybody in the US government everybody in the scientific Community just kind of like uh pretended that nothing happened mhm that kind of instinct that's what makes me believe if aliens show up we would all like just ignore their presence that's what bothered me that you don't you don't investigate it more carefully and use this opportunity to inspire the world like so in terms of kryptonite I think the conspiracy theory folks say that whenever there is some good hard evidence that scientists would be excited about the U there's this kind of conspiracy that I don't like cuz it's ultimately negative that the US government will somehow hide the good evidence yeah uh to uh to protect it of course there's some legitimacy to it cuz you want to protect military uh Secrets all that kind of stuff but yeah I I don't know I don't know what to do with this beautiful mess because um I think think millions of people are inspired by UFOs right and it feels like an opportunity to inspire people about science so I would say you know as Carl hean used to say extraordinary claims require extraordinary evidence right I've quoted him a number of times uh we would we would welcome such evidence uh on the other hand you know a lot of the things that are seen or perhaps even hidden from us you could imagine for military purposes surveillance purposes the US government doesn't want us to know or maybe some of these Pilots saw Soviet or Israeli or whatever uh satellites right a lot of the or some of the crashes that have occurred were later found to be you know weather balloons or whatever you know when there are more conventional explanations science tends to stay away from the um from The Sensational ones right and so it may be that someone else's calling in life is to investigate these phenomena and I welcome that as a scientist I I don't categorically actually deny the possibility that ships of some sort could have visited us because as I said earlier at slow speeds there's no problem in reaching other stars in fact our Voyager and Pioneer spacecraft in a few million years are going to be in the vicinity of different Stars we can even calculate which ones they're going to be in the vicinity of right uh so there's nothing that breaks any laws of physics if you do it slowly but that's different you know just having Voyager or Pioneer fly by some star that's different from having active aliens altering the trajectory of their vehicle in real time spying on us and then either zipping back to their home planet or sending signals that tell them about us because they are likely many years many light years away and they're not going to have broken that barrier as well okay right so so I I just you know go ahead study them great I you know for some young kid who wants to do it it might be their calling and that's how they might find meaning in their lives is to be the scientist who really explores these things I chose not to because at a very young age I found the evidence to the degree that I investigated it to be really quite unconvincing and I had other things that I wanted to do but I don't categorically deny the possibility and I think it should be investigated yep I mean this is uh this is one of those phenomena that um 99.9% of people are almost definitely there's conventional explanations and then there's like mysterious things that probably have explanations that are a little bit more complicated yeah it's but there's not enough to work with I tend to believe that if aliens showed up there will be plenty of evidence uh for scientists to study that like it exactly U as you said a voyager type of spacecraft I could see sort of um some kind of kind of a dumb thing almost like a sensor to like probing like statistically speaking flying by maybe lands maybe there's some kind of robot type of thingies that just like move around and so on yeah like in ways that we don't understand but but I feel like well I feel like there'll be plenty of hard hard to dismiss evidence and I also especially this year believe that the US government is not sufficiently competent given the huge amount of evidence that would be revealed from this kind of thing to conceal all of it right uh at least in modern times you can say maybe decades ago but in modern times but you know I uh the the people I speak to and the reason I bring it up is because so many people write to me they're inspired by it by the way I wanted to comment on something you said earlier um yeah I had said that I'm sort of an a pessimist in that I think there are very few other intelligent mechanically able creatures out there but then I said yes in a sense I'm an optimist as you pointed out because it means that we made it through the great filter right I I meant originally that I'm a pessimist in that I'm pessimistic about the possibility that there are many many of us out there you mathematically speaking in the Drake equation exactly right right but but it may mean a good thing for our ultimate survival right so I'm glad you caught me on that yeah I I definitely agree with you I it is ultimately an optimistic statement but anyway I think you know UFO research is is interesting and I guess one of the reasons I've not been terribly convinced is that I think there are some scientists who are investigating this and they've not found any clear evidence now I must admit I have not looked through the literature to convince myself that there are many scientists doing systematic studies of these various reports so I can't say for sure that there's a critical mass of them it's just that you you never get these reports from Hardcore scientists that's other thing and astronomers you know what do we do we spend our time studying the heavens and you'd think we'd be the ones that are most likely aside from Pilots perhaps at seeing weird things in the sky and we just never do of the unexplained UFO type nature yeah I definitely I I try to keep an open mind but for people who listen um it's actually really difficult for a scientist like I get probably like this year I probably gotten over probably maybe maybe over a thousand emails on on the topic of AGI mhm it's very difficult to uh you know people write to me it's like how can you ignore this in AI side like this model this is obviously the model that's going to achieve general intelligence how can you IGN know it I'm giving you the answer here's my document and there always just these large writeups the problem is it's very difficult to we weed through a bunch of BS right it's it's very possible that you had actually saw the UFO but you have to acknowledge by UFO I mean an extr terrestrial life right you have to acknowledge the hundreds of thousands of people who are a little bit if not a lot full of BS and from a scientist perspective it just it's really hard work and it's um when there's amazing stuff out there it's like why investigate Bigfoot when evolution in all of its richness is beautiful who cares about a monkey that walks on two feet like there's a zillion decoys right at observatories true fact we get lots and lots of phone calls when Venus the evening star but just really a a bright Planet happens to be close to the Crescent Moon because it's such a striking pair this happens once in a while so we get these phone calls oh there's a UFO next to the moon and no it's Venus and so they're just and I'm not saying the the best UFO reports are of that nature no there are some much more convincing cases and I've seen some of the footage and blah blah blah um but it's just there's so many decoys right so much so much noise that you have to filter out Y and there's only so many scientists so it's there's so there's only so much time as well and you have to choose what problems you work on you know this might be a fun question asked to kind of explore the idea of the expanding Universe yeah so the the radius of the observable universe is 45.7 billion light years yeah and the age of the universe is 13.7 yeah billion years MH mhm that's less right than the radius of the universe yeah how's that possible so that's a great question so the and I meant to bring a little a little prop I have with pingpong balls on a rubber hose a rubber band I I use it in many of the lectures that one can find of me online but you have in an expanding Universe the space itself between galaxies or more correctly clusters of galaxies expanding so imagine light going from one cluster to another it traverses some distance and then while it's traversing the rest that part that it already traveled through continues to expand now 13.7 billion years might have gone by since the light that we are say seeing from the early stages the so-called Cosmic microwave background radiation which is the the Afterglow of the Big Bang or the echo of the big Bang Yeah 13.7 billion years have gone by that's how long it's taken that light to reach us but while it's been traveling that distance the parts that it already traveled continue to expand MH so it's like you're walking on at an airport you know on one of these walkways and you're walking along because you're trying to get to your terminal but the walkway is continuing as well you end up traveling a greater distance or the same distance faster is another way of putting it right that's why you get on one of these traveling walkways but so you get a roughly a roughly a factor of Pi you know but it's more like 3.2 I think but when you work it all out you multiply the number of years the universe has been in existence by you know three and a quarter or so and that's how you get this 46 billion Lightyear radius but how is that let me ask some nice dumb questions uh how is that not traveling faster than the speed of light yeah it's not traveling faster than the speed of light because locally at any point if you were to measure the light the photon zipping past it would not be exceeding the speed of light the speed of light is a locally measured quantity after light has traversed some distance if the rubber band keeps on stretching then yes it looks like the light traveled a greater distance than it would have had the space not been expanding but locally it never was exceeding the speed of light it's just that the distance through which it already traveled then went off and expanded on its own some more and if you give the light credit so to speak for having traversed that distance well then it looks like it's going faster than the speed of light but but that's not that's not how spe that's happen right that's not how Speed Works speed and in relativity also the other thing um that is interesting is that you know if you take two ping-pong balls that are sufficiently far apart especially in an accelerating universe you can easily have them moving apart from one another faster than the speed of light so you know take two pingpong balls that were originally 400,000 kilometers from each other and let every centimeter in your rubber band expand to two in one second then suddenly this 400,000 kilometer distance is 800,000 km it went out by 400,000 km in 1 second that exceeds the 300,000 kilom perss speed of light but that light limit that that particle limit in special relativity applies to objects moving through a pre-existing space there's nothing in either special or general relativity that prevents space itself from expanding faster than the speed of light that's no problem Einstein wouldn't have had a problem with with a with an with a universe and observed Now by cosmologists yeah I um I'm not sure I'm yet ready to deal emotionally with expanding space it's like that to me is one of the most a inspiring things you know starting from the Big Bang it's definit abstract it space itself is expanding right could you can we talk about the big bang a little bit sure yeah yeah what uh so like the entirety of it the universe yeah was very small right but it was not a point it was not a point because if if we live in what's called a closed Universe now a sphere or the three-dimensional version of that would be a hypersphere you know then regardless of how far back in time you go it was always that topological shape you can't turn a point suddenly into a shell okay it always had to be a a shell yeah so when when people say well the universe started out as a point that that's being kind of flippant kind of glib it didn't really it just started out a at a very high density and we don't know actually whether it was finite or infinite I think personally that it was finite at the time but it expanded very very quickly indeed if it exponentiated and continued in some places to exponentiate then it could in fact be infinite right now and most cosmologists think that it is infinite wait yeah sorry what uh infinite which dimension MTH si infite in space infinite in space and by that I mean that if you were trying to meure use light to measure its size You' you'd never be able to measure its size because it would always be bigger than the distance light can travel that's what you get in a universe that's accelerating in its expansion okay but if a thing was a hypersphere it's very small not a point yeah how can that thing be infinite well it it expands exponentially that's what the inflation theory is all about indeed at your home institution Alan Guth is one of The Originators of the whole inflationary Universe idea along with Andre Lind at at Stanford University here in the Bay Area and others Alexis stabinsky and others had similar sorts of ideas but in an exponentially expanding Universe if you actually try to make this measurement you you send light out to try to see it curve back around and and hit you in the back of the head if next exponentially expanding Universe the amount of space remaining to be traversed is always a bigger and bigger quantity so you'll never get there from here you'll never you you'll never reach the back of your head so observationally or operationally it can be thought of as being infl INF that's one of the best definitions of infinity by the way that's what's that that's one of the best sort of uh physical manifestations of infinity that yeah yeah because you have to ask how would you actually measure it now sometimes say to my cosmology theoretical friends well if I took if I were God and I were outside this whole thing and I took a Godlike slice in time wouldn't it be finite no matter how big it is and they object and they say Alex you you can't be outside and take a Godlike slice of time you know because there's nothing outside well I'm not you know or also you know what slice of time you're taking depends on your motion and that's true even in special relativity that slices of time get tilted in a sense if you're moving quickly the axes x and t actually become tilted not not perpendicular to one another um and you know you can look at Brian Green's books and lectures and other things where he he imagines taking a loaf loaf of bread and slicing it in units of time as you progress forward but then if you're zipping along relative to that loaf of bread the slices of time actually become tilted and so it's not even clear what slices of time mean but I I'm an observational astronomer I know which end of the telescope to look through and the way I understand the infinity is as I just told you that operationally or observationally there no there'd be no way of seeing that it's a finite Universe of measuring a finite universe and so in that sense it's it's infinite even if it started out as a finite little dot well you know not a DOT I'm sorry a finite little hypersphere but it didn't really start out there cuz what what what what happened before that well we don't know so this is where it gets into a lot of speculation and let's go I mean let's go there okay sure so you know nobody can prove wrong the idea right what happened before T equals z and whether there are other universes out there I like to say that these are sort of on the bound boundaries of science they're not just ideas that we wake up at 3 in the morning to go to the bathroom and say oh well let's think about what happened before the Big Bang or let there be a multiplicity of universes in other words we have real testable physics that we can use to draw certain conclusions that are plausibility arguments based on what we know now admittedly there are not really direct tests of these hypotheses that's why I call them hypotheses they're they're not really elevated to a theory because a theory in science is really something that has a lot of experimental or observational support behind it so they're they're hypotheses but they're they're not unreasonable hypotheses based on what we know about general relativity and quantum physics okay and they may have indirect tests in that if you adopt this hypothesis then there might be a bunch of things you expect of the universe and lo and behold that's what we measure but we're not actually measuring anything at T less than zero or we're not actually measuring the presence of Another Universe in this Multiverse and yet there are these indirect ideas that stem forth so it's hard to prove uniqueness and it's hard to completely convince oneself that a certain hypothesis must be true but you know the more and more tests you have that it satisfies let's say there are 50 predictions it makes and 49 of them are in are are things that you can measure and then the 50th one is the one where you you want to measure the actual existence of that other universe or what happened before T equals z and you can't do that but but you've satisfied 49 of the other testable predictions and so that's science right now A a conventional condensed matter physicist or someone who deals with real data in the laboratory might say oh you cosmologists you know that's not really science because it's not directly testable but I would say it's sort of testable but but it's not completely testable and so it's at the boundary but it's not like we're coming up with these crazy ideas among them Quantum fluctuations out of nothing and then inflating into a universe with you might say well you created a giant amount of energy but in fact this Quantum fluctuation out of nothing you know in a Quantum way violates the conservation of energy but you know who cares that was a classical law anyway and then an inflating Universe maintains whatever energy it had be it zero or some infinites amount in a sense the stuff of the universe has a positive energy but there's a negative gravitational energy associated with it it's like I drop an apple I got kinetic energy energy of motion out of that but I did work on it to bring it to that height mhm so by going down and gaining energy of motion positive 1 2 3 4 5 units of kinetic energy it's also gaining or losing depending on one how you want to think of it negative 1 2 3 four five units of potential energy so the total energy Remains the Same an inflating Universe can can do that or other physicists say that energy isn't conserved in general relativity that's another way out of creating a universe out of nothing you know but the point is that this is all based on reasonably well tested physics and although these these extrapolations seem kind of outrageous at first they're not completely outrageous they're they're within the realm of what we call science already and maybe some Y young whipper snapper will be able to figure out a way to directly test what happened before T equals z or to test for the presence of these other universes but right now we don't have a way of doing that so speaking of uh young whipper snappers Roger Penrose yeah uh so he kind of has a you know idea that we there may be some information that travels from whatever the heck happened before the Big Bang yeah maybe I kind of doubt it so do you think it's possible to detect some like actually experimentally be able to detect some I don't know what it is radiation some some sort of yeah and the cosmic microwave background radiation there may be ways of doing that is but is it is it philosophically or practically possible to detect signs that this was before the Big Bang or is it or is it what you said which is like everything we observe will as we currently understand will have to be a creation of this particular observable universe yeah I mean you know if you it's very difficult to answer right now because we don't have a single verified fully self-consistent experimentally tested quantum theory of gravity right and of course the beginning of the universe is a large amount of stuff in a very small space so you need both quantum mechanics and general relativity same thing if our universe Recaps and then bounces back to another big bang you know there's also ideas there that some of the information leaks through or survives I don't know that we can answer that question right now because we don't have a quantum theory of gravity that most physicists uh believe in and belief is perhaps the wrong word that most physicists trust because the experimental evidence favors it yeah right you know there are various forms of string theory there's Quantum Loop gravity there are various ideas but which if any will be the one that survives the test of time and more importantly within that the test of experiment and observation yeah so my own feeling is probably these things don't survive I don't think we've seen any evidence in the cosmic microwave background radiation of of information leaking through similarly um the one way or one of the few ways in which we might test for the presence of other universes is if they were to collide with ours that would leave a a pattern a temperature signature in the cosmic microwave background radiation some astrophysicists claim to have found it but in my opinion it's not statistically significant to the level that would be necessary to have such a an amazing claim right you know it's just a 5% chance that the microwave background had that distribution just by chance yeah five % isn't very long odds if you're claiming that instead that you're that you're finding you know evidence from Another Universe I mean it's like if the Large Hadron Collider people had claimed after gathering enough data to show the higs particle when there was a 5% chance it could be just a statistical fluctuation in their data no they they required five Sigma five stand deviations which is roughly One Chance in 2 million that this is a statistical fluctuation of no physical greater significance you know extraordinary claims require extraordinary go it all boils down to that and the and the greater your claim the greater is the evidence that is needed and the more evidence you need from independent ways of measuring or of coming to that deduction you know a good example was the the accelerating universe you know when we found it evidence for it in 1998 with supern noi with exploding Stars it was great that there were two teams that lent some credibility to the Discovery but it was not until other astrophysicists used not only that technique but more importantly other independent techniques that had their own potential sources of systematic error or whatever but they all came to the same conclusion and that started giving a much more complete picture of what was going on in a picture in which most astrophysicists quickly gained confidence that's why that idea caught on so quickly is that there were other physicists and astronomers doing observations completely independent of supern noi that seemed to indicate the same thing yeah that period of uh of your life that work with a incredible team of people that um won the Nobel Prize is just fascinating work oh gosh you know never in my wildest dreams as a kid did I think that I would be involved much less so heavily involved in a discovery that's so revolutionary I mean you know as a kid as a scientist if you're realistic once you learn a little bit more about how science is done and you're not going to win a Nobel Prize and be the next Newton or Einstein or whatever you just hope that you'll contribute something to humankind's understanding of how nature works and you'll be satis ified with that you know but here I was in the right place at the right time a lot of luck a lot of hard work um and there it was you know we discovered something that was really amazing and that that was the the greatest thrill right I couldn't have asked for anything more uh than being involved in that Discovery so one so the the couple of teams of supernova cosmology project and the high Supernova search team so the what was the Nobel Prize given for it was given for the discovery of the expansion of the universe not for the elucidation of what dark energy is or what causes that expansion uh that acceleration be it universes on the outside or whatever it was only for the observational fact so first of all what is the accelerating universe so the accelerating universe is simply that if we look at the galaxies moving away from us right now we would expect them to be moving away more slowly than they were billions of years ago and because Galaxies have visible matter which is gravitationally attractive and dark matter of an unknown sort that holds galaxies together and holds clusters of galaxies together and of course they then pull on one another and they would tend to the expansion of the universe just as when I toss an apple up you know even ignoring air resistance the mutual gravitational attraction between Earth and the Apple slows the Apple down and if that attraction is great enough then the Apple will they stop and even come back the Big Crunch you could call it or the gnab Gibb which is Big Bang backwards right that's what could have happened to the universe but even if the universe's original expansion energy was so great that it avoids the Big Crunch that's like an apple thrown at Earth's escape speed it's like that the the the the rockets that go to Mars someday right you know uh with people even then you'd expect the universe to be slowing down with time but we looked back through through the history of the universe by looking at progressively more distant galaxies and by seeing that the evolution of this expansion rate is that in the first N9 billion years yeah it was slowing down but in the last five billion years it's been speeding up so who asked for that right you know um I think it's interesting to talk about a little bit of the human story of the Nobel Prize sure which is I mean fascinating it's a really first of all the prize itself it's kind of fascinating in the psychological level that uh prizes uh I know we kind of think that prizes don't matter but somehow they kind of focus the mind about some of the most special things we have ACC the recognition the funding you know but and also inspiration for like I said when I was a little kid they get The Nobel Prize like I I didn't you know it inspires millions of young scientists at the same time there's a sadness to it a little bit that uh especially in the field like depending on the field but experimental fields that involve teams of I don't know sometimes hundreds I mean of brilliant people the Nobel Prize is only given to just a handful I that's right is it Ma Max a three yeah yeah and it's not even written in Alfred nobel's will it turns out one of our teammates looked into it in a museum in Stockholm when we went there for Nobel week in 2011 the the leaders who got the prize formally knew that without the rest of us working hard in the trenches the result would not have you know been discovered so they invited us to participate in Nobel week and so one of the team members looked in the will and it's not there it's just tradition that's but it's archaic you know that's the way science used to be done and it's not the way a lot of science is done now and you look at gravitational wave discovery which was you know recognized with the Nobel Prize in 2017 Ray weet MIT got it and Kip Thorne and um and um Barry beish at Caltech and Ron DAV one of the masterminds had passed away earlier in the year so again one of the rules of Nobel is that it's not given pusle yeah or at least the one exception might be if they've made their decision and they're busy making their press releases right before October the first week in October or whatever and then the person passes away I think they don't change their minds then but yeah you know it it it doesn't square with today's reality that a lot of science is done by big teams in that case a team of a thousand people in our case it was two teams consisting of about 50 people and we used techniques that were arguably developed in part by people who astrophysicists who weren't even on those two papers I mean some of them were but other papers were written by by other people you know know and so it's like we're standing on the shoulders of giants and none of those people was officially recognized and to me it was okay you know again it was the thrill of doing the work and ultimately the work the discovery was recognized with the prize and you know we got to participate in Nobel week and you know it's okay with me I I've known other physicists whose lives were ruined because they did not get the Nobel Prize and they felt strongly that they should have Ralph alfer um of the alfha beta gamma you know paper predicting the microwave background radiation he should have gotten it his adviser gamov was dead by that point but um you know penus and Wilson got it for the discovery and and alfur apparently from colleagues who knew him well I've talked to them his life was ruined by this he just it just nod at his inard so much it's uh very possible that uh and a small handful of people even three that you would be one of the Nobel one of the winners of the Nobel Prize that doesn't weigh heavy on you well you know there were the two team leaders Saul pearlmutter and Brian Schmidt and usually it's the team leaders that are recognized and then Adam Reese was my postto um first first author I guess yeah first author I was second author of that paper yeah uh so I was his direct Mentor at the time although he was you know one of these people who just you know runs with things he was an MIT undergraduate by the way um Harvard graduate student and then a postto as a so-called Miller fellow for basic research in science at Berkeley something that I was back in ' 84 to 86 but you're you're you know you're largely a free agent but he worked quite closely with me and he came to Burkle to work with me and on Schmidt's team he was charged with analyzing the data and he measured the brightnesses of these distant supern noi showing that they're fainter and thus more distant than anticipated and that led to this conclusion that the Universe had to have accelerated in order to push them out to such great distances and I was shocked when he showed me the data the results of his calculations and measurements um but it's very you know so he deserved it but and on Sal G gon g gold hobber deserved it but he died I think a year earlier in 2010 but that would have been four and so and me well I was on both teams but you know was I number four five six seven I don't know well it's it's also very so if I were to it's possible that you're I mean I I could make a very good case for you're in in the three and does thaty kind you know so but is that psychologically I mean listen it weighs on me a little bit because I yeah I I don't know what to do with that it it U perhaps it should motivate uh the rethinking like Time magazine started doing like you know person of the year yeah and like they they would start doing like Concepts and almost like the black hole gets the Nobel Prize or Universe gets the Nobel Prize and here's the list of people so like ult or like the Oscar that you could say yeah because it it's a team effort now you know and it should be redone and the Breakthrough prize in fundamental physics which was started by Yuri Milner and Zuckerberg is involved and others as well you know uh they recogniz a larger team yeah they they recognized teams and so in fact both teams in the accelerating universe were recognized with the Breakthrough prize in 2015 nevertheless the same three people reys pearlmutter and Schmidt got the red carpet rolled out for them and were at the big ceremony and shared half of the prize money and the rest of us roughly 50 shared the other half and didn't get to go to the ceremony so but I I I feel for them I mean for the gravitational waves it was a thous people what are they going to do invite everyone for the higs particle it was 6 to 8,000 physicists and engineers in fact because of the whole issue of who gets it experimentally that Discovery still has not been recognized right the theoretical work by Peter higs and uh angir got recognized but there was a troa of other people who WR perhaps wrote the most complete paper and they were they were left out and um another guy died you know and yeah it's heart it's all of it's heartbreaking some people argue that the Nobel Prize has been deluded to because if you look at Roger Penrose you can make an argument that he should get the prize by himself like it's she separate those like could have and should have perhaps he should have perhaps gotten it with Hawking before Hawking's death right the problem was Hawking radiation had not been detected but you could argue that Hawking made enough other fundamental contributions to the theoretical study of black holes and The observed data were already good enough at the time of before Hawking's death okay I mean the latest results by Reinhardt gel's group is that they see the time dilation effect of a star that's passing very close to the black hole in the middle of our galaxy that's cool but and it adds additional evidence but hardly anyone doubted the existence of the super massive black hole and Andrea gz's group I believe hadn't yet shown that relativistic effect and yet she got part of the prize as well so clearly it was given for the the original evidence that was really good and that evidence is at least a decade old you know so one could make the case for for Hawking um one could make the case that in 2016 when mayor and Kao won the Nobel Prize for the discovery of the first exoplanet um 51b pegasi well there was a fellow at Penn State Alex walon who in 1992 three years preceding 1995 found a a p a planet orbiting a pulsar a very weird kind of star a neutron star and that wouldn't have been a normal Planet sure and so the Nobel committee you know they gave it for the discovery of planets around normal sunlike stars but but hell you know Wan found a planet so they could have given it to him as the third person instead of to Jim Peebles for the development of what's called physical cosmology he's at Princeton he deserved it but they could have given Nobel for the development of physical cosmology to pees and I would claim some other people were pretty important in that development as well you know and they could have given it some other year um so there's there's a lot of controversy I try not to dwell on it was I number three probably not you know Adam Reese did the work um you know I helped bounce ideas off of him but it we wouldn't have had the result without him yeah and I was on both teams for reasons I mean you know I the the St of the first team the Supernova cosmology project didn't match mine they came largely from experimental high energy particle physic physics where there's these hierarchical teams and stuff and it's hard for the little guy to to have a say at least that's what I kind of thought whereas the team of astronomers led by Brian Schmidt was first of all a bunch of my friends and they grew up as astronomers making contributions on little teams and we decided to band together but all of us had our voices heard so it was sort of a a culture a style that I preferred really but let me tell you a story at the Nobel banquet okay I'm sitting there between two physicists who are who are members of the committee of the Swedish National Academy of Sciences you know and I strategically kept you know offering them wine and stuff during this long drawn out Nobel ceremony right and I got them to be pretty talkative and then in a in a polite diplomatic way I started asking them pointed questions m M and basically they admitted that if there are four or more people M equally deserving they wait for one of them to die or they just don't give the prize at all when it's unclear who the three are at least unclear to them but unclear to them it's they're not even right part of the time I mean Joselyn Bell discovered pulsars MH with a radio antenna a set of radio antennas that her adviser Anthony hsh conceived and built so he deserves some credit but but he didn't discover the Pulsar she did and his initial reaction to the data that she showed him was a condescending rubbish my dear yeah I'm not kidding now I know JN Bell and she did not let this destroy her life yeah she won every other prize Under the Sun okay um Vera ruin arguably one of the discoverers of Dark Matter although there if you look at the history there were a number of people that was the issue I think there were a number of people four or more who had similar data and similar ideas at about the same time Ruben won every prize Under the Sun the new big large scale survey telescope being built in Chile is being renamed the Vera rubben telescope because she passed away in December of 2015 I think um you know it'll conduct this survey large scale survey with the Reuben telescope so she's been recognized but never with the Nobel Prize and I would say that to her credit she did not let that consume her life either and perhaps it was a bit easier because there had been no no Bell given for the discovery of Dark Matter whereas in the case of pulsars and Joselyn Bell there was a prize given for the discovery of the freaking pulsar and she didn't get it what I mean what a Trav of justice so I I also think as a fan of fiction as a fan of stories that the the the travesty and the tragedy and the unfairness and the tension of it is what makes the prize and similar prize is beautiful the the decisions of other humans that result in dreams being broken and you know like I that's why we love the Olympics as so so many you know people athletes give their whole life for this particular moment and and then there's referee decisions and like little slips of here and there like the little misfortunes that destroy entire dreams and that's it's it's weird to say but it feels like that makes the entirety of it even more special yeah if it was perfect it wouldn't be interesting well humans like competition and they like Heroes and unfortunately it gives the impression to youngsters today that science is still done by by white men with gray beards wearing white lab coats and I'm very pleased to see that this year you know Andrea gz the fourth woman in the history of the physics prize to have received it and then uh two women one at Berkeley uh one elsewhere won the Nobel Prize in chemistry without any male co-recipient and so that's sending a message I think to girls that they can do science and they have um Role Models I think uh the Breakthrough prize and other such prizes show that teams get recognized as well and and if you pay attention to the newspapers you know most of the good authors like you know Dennis Overby of the New York Times and others said that these were teams of people and they they emphasized that and you know they all played a role um and you know maybe if some grad student hadn't soldered some circuit maybe the whole thing wouldn't have worked you know um but still you know Ray Weiss Kip Thorne was the theoretical uh you know impetus for the whole search for gravitational waves Barry bearish brought the MIT and Caltech teams together to get them to cooperate at a time when the project was nearly dead from what I understand and contributed greatly to the experimental setup as well he's a great experimental physicist but he was really good at bringing these two teams together instead of having them duke it out in blows and leaving both of them bleeding and dying you know that National Science Foundation was going to cut the funding from what I understand you know so so there's human drama involved in this whole thing and the Olympics yeah you know a runner a swimmer a rummer runner you know they they slip just at the moment that they were taking off from the first thing and that costs them some fraction of a second and that's it they didn't win you know and in that case I mean the the coaches the families which I've met a lot of Olympic athletes and the coaches and the families of the athletes are really the winners of the medals I mean but they don't get the medal and it's it's you know credit assignment is a fascinating thing I mean that's the full human story we have yeah we have and and uh outside of prizes it's fascinating I mean uh just to be in the middle of it for artificial intelligence there's a field of deep learning that's really exciting and people have been there's a yet another award uh the touring award given for deep learning to to three folks who are very much responsible for the field but so are a lot of others that's right and there's a few there's uh uh there's a fellow by the name of Schmid Huber who uh sort of symbolizes the the Forgotten folks in in the Deep Learning Community but you know that's that's the unfortunate set thing we remember we remember Isaac Newton we remember uh these these these special figures and the ones that flew close to them uh we forget well that's right and you know often the breakthroughs are made based on the body of knowledge that had been assimilated prior to that but you know again people like to worship Heroes you you mentioned the Oscars earlier and you know you look at the direct I mean well I mean okay directors and stuff sometimes get Awards and stuff but um you know you look at even something like I don't know songwriters musicians Elton John or something right Bernie topin right wrote many of the words or he's not as well known or or the Beatles or something like that I was heartbroken to learn that Elvis didn't write most of his songs yeah Elvis That's right there there you go but he was the King right and he had such a personality and and he it was such a performer right but it's the unsung heroes in many cases yeah so maybe taking a step back we talked about the Nobel Prize for the accelerating universe but uh your work and the ideas uh around Supernova were important uh in detecting this accelerating universe can we go to the very basics of what is this uh beautiful mysterious object of a supernova right so a supernova is an exploding star most stars die a relatively quiet death our our own sun will despite the fact that it'll become a red giant and incinerate Earth it'll do that reasonably slowly but there's a small minority of stars that end their lives in a Titanic explosion and that's not only exciting to watch from afar but it's critical to our existence because it is in these explosions that the heavy elements synthesize through nuclear reactions during the normal course of the Stars Evolution and during the explosion itself get ejected into the cosmos making them available as raw material for new stars planets and ultimately life you know and that's just a great story um the best in in some ways so you know we like to study these things and and our Origins but it turns out these are incredibly useful beacons as well because if you know how powerful uh an exploding star really is by measuring the apparent brightness at its peak in galaxies whose distances we already know through having made other measurements and you can thus calibrate how powerful the thing really is and then you find ones that are much more distant then you can use their observed brightness compared with their true intrinsic power or Luminosity to judge their distance and hence the distance of the Galaxy in which they're located so okay it's like looking at if you'll uh let me just give this one analogy you know you judge the distance of an oncoming car at Night by looking at how bright its headlights appear to be and you've calibrated how bright the headlights are of a car that's two or three meters away of known distance and you go who that's a a faint headlight and so that's pretty far away you also use the apparent angular separation between the two headlights as a consistency check in your brain but that's what your brain is doing so we can do that for cars we can do that for stars nice I like that but you know with cars the headlights are all there's some variation there's but but uh they're somewhat similar so you can make those kinds of conclusions what uh how much uh variation is there between Supernova that you can yeah that in can you detect them right so first of all there are several different ways that stars can explode and it depends on their mass and whether they're in a binary system and things like that and the ones that we used for these cosmological purposes studying the expansion of the history history of the universe are the so-called type Roman numeral one lowercase a type 1 a super noi they come from a weird type of a star called a white dwarf our own son will turn into a white dwarf in about 7 billion years it'll have about half its present Mass compressed into a volume just the size of Earth so that's an inordinate density okay it's incredibly dense and the matter is what's called by Quantum physic degenerate matter not because it's morally reprehensible or anything like that but this is just the name no judgments here yeah Quantum physicists give to electrons that are squeezed into a very tight space the electrons take on a motion due to Heisenberg uncertain Heisenberg's uncertainty principle and also due to the poly exclusion principle that electrons don't like to be in the same place they like to avoid each other so those two things mean that a lot of electrons are moving very rapidly which gives the star an extra pressure far above the thermal pressure associated with just the random motions of particles inside the star so it's a weird type of star but normally it wouldn't explode and our sun won't explode except that if such a white dwarf is in a pair with another more or less normal star it can steal material from that nor normal star until it gets to an unstable limit rough roughly 1 and a half times the mass of our sun 1. four or so this is known as the chandar CH Chandra sear limit after subber Manan Chandra sear an Indian astrophysicist who figured this out when he was about 20 years old on a voyage from India to England where he was to be educated and then he did this and then 50 years later he won the Nobel Prize in physics in 1984 largely for this work okay that he did as a youngster who was on his way to be educated you know oh and his advisor the great AR Edington in England who had done a lot of great things and was a great astrophysicist nevertheless he too was human and had his faults he ridiculed chandra's scientific work at a conference in England and you know most of us have we had been Chandra would have just given up astrophysics at that time you know when the Great Arthur Edington you know ridicules our our work and that's another inspirational story for the youngster you know just just keep going you know but anyway your advisor yeah no matter what your advisor says right so or don't always pay attention to your advisor right don't don't be uh don't lose hope if you really think you're on to something that doesn't mean never listen to your adviser they may have Sage advice as well yeah but anyway um you know when a white dwarf grows to a certain Mass it becomes unstable and one of the ways it can end its life is to go through a thermonuclear runaway so basically the carbon nuclei and inside the white dwarf starts start fusing together to form heavier nuclei and the energy that those Fusion reactions emit emits doesn't go into um you know being dissipated out of the star or you know whatever U or expanding it the way you know if you take a blowtorch to the middle of the sun you heat up its gases the gases would expand and cool but this degenerate star can't expand and cool so the energy pumped in through these Fusion reactions goes into making the nuclei move faster and that gets more of them sufficiently close together that they can undergo nuclear fusion thereby releasing more energy that goes into speeding up more nuclei and thus you have a a runaway a bomb an uncontrolled nuclear fusion reactor right instead of the controlled Fusion which is what our sun does okay our sun is a marvelous controlled Fusion reactor this is what we need here on Earth Fusion Energy to solve our energy crisis right uh but the sun holds the stuff in you know through gravity and you need a big Mass to do that so this uncon uncontrolled fusion reaction blows up a star that's pretty much the same in all cases and you measure it to be almost the same in all cases but the devil is in the details and in fact we observe them to not be all the same and theoretically they might not be all the same because the rate of the fusion reactions might depend on the amount of Trace heavier elements in the white dwarf and that could depend on how old it is when it was you know whether it was born billions of years ago when there weren't many heavier elements or whether it's a relatively young white dwarf and all kinds of other things and part of my work was to show that indeed not all the type 1as are the same you have to be careful when you use them you have to calibrate them they're not standard candles the way it just if all headlights or all candles were the same lumens or whatever you'd say they're standard and it would be standard candles is an awesome term okay standard candles is what astronomers like to say I don't like that term because there aren't any standard candles but there are standardizable candles and by looking at these yeah you calibratable standardizable calibratable you look at enough of them in nearby galaxies whose distances you know independently and what you can tell is that you know uh this is something that a colleague of mine Mark Phillips did who was on Schmidt's team and arguably one of the was one of the people who deserved the Nobel Prize but he showed that the intrinsically more powerful type 1as um decline in brightness and it turns out rise in brightness as well more slowly than the less luminous onea and so if you calibrate this by measuring a whole bunch of nearby ones and then you look at a distance one instead of saying well it's a 100 watt type 1 a supernova they're much more powerful than that by the way plus or minus 50 you can say no it's it's 112 plus or minus 15 or it's or it's 84 plus or minus 17 it it tells you where it is in the power scale and it greatly decreases the uncertainties and that's what makes these things cosmologically useful I showed that if you spread the light out into a spectrum you can tell spectroscopically that these things are different as well and in 1991 I happened to study two of the extreme peculiar ones the low Luminosity ones and the high Luminosity ones 1991 BG and 1991t this showed that not all the 1 A's are the same and indeed at the time of 1991 I was a little bit skeptical that we could use type 1a's because of this diversity that I was observing but in 1993 Mark Phillips wrote a paper that showed this correlation between the light curve the brightness versus time and the peak luminosity and once gives you enough information to calibrate yeah then they become calibratable and that was a game changer how many type 1 a are out there oh gosh to use for data now there are thousands of them but at the time the high Z team had 16 and the um Supernova cosmology project had 40 but the 16 were better measured than the 40 and so our statistical uncertainties were comparable if you look at the two papers that were published how's that make you uh feel that there's these gigantic explosions just sprinkled out there is that well I certainly don't want one to be very nearby and it would have to be within something like 10 light years to be an existential threat so they can happen in our uh Galaxy oh yeah you uh in most cases we'd be okay because our galaxy is 100,000 light years across and you'd need one of these things to be within about 10 light years to be an existential threat and it gives birth to a bunch of other um stars I guess yeah it gives birth to expanding gases that are chemically enriched and those expanding gases mix with other chemically enriched expanding gases or primordial clouds of hydrogen and helium I mean th this is um in a sense the The Greatest Story Ever Told right I try to I teach this introductory astronomy course at at Berkeley and I tell them there's only five or six things that I I want them to really understand and remember and I'm going to come to their deathbed and I'm going to ask them about this and if they get it wrong I will retroactively fail their whole career will have been shot that and they don't observe a total solar eclipse and yet they had the opportunity to do so I will retroactively fail them but one of them is you know where did we come from where did the elements in our DNA come from the carbon in our cells the oxygen that we breathe the calcium in our bones the iron in our red blood cells those elements the phosphorus in our DNA they they all came from stars from nuclear reactions in stars and they were ejected into the cosmos and in some cases like iron made during the explosions and those gases drifted out mixed with other clouds made a new star or a star cluster some of whose members then evolved and exploded thus enriching the gases in the Galaxy progressively more with time until finally 4 and a half billion years ago from one of these chemically enriched clouds our solar system formed with a rocky earthlike planet and somewhere somehow these self-replicating evolving molecules bacteria formed and evolved D through paramia and amibas and slugs and and apes and and us and here we are sensient beings that can ask these questions about our very Origins and with our intellect and with the machines we make come to a reasonable understanding of our Origins what a beautiful Story I mean if that does not put you at least in awe if not in love with science and its power of deduction I don't know what will right it's it's one of the greatest stories if not the greatest story obviously that's you know personality dependent and all that it's it's a subjective opinion but it's perhaps The Greatest Story over ever told I mean you could link it to the big bang and go even farther right to make an even more complete story but as as a subset that's even in some ways a greater story than than even the existence of the universe in some ways cuz you could end up you could just imagine some really boring universe that never leads to sensient creatures such as ourselves and is this Supernova usually the the introduction to that story so are are they usually the thing that launches the is there other engines of creation well the Supernova is the one I mean I I I touch upon the subject earlier in my course in fact right about now in my lectures because I talk about how our sun right now is fusing hydrogen to form helium nuclei and later it'll form carbon and oxygen nuclei but that's where the process will stop for our sun it's not massive enough some Stars can that are more massive can go somewhat beyond that so that's the beginning of right this idea of the birth of the heavy elements since they couldn't have been born at the time of the Big Bang conditions of temperature and pressure weren't sufficient to make any significant quantities of the heavier elements and so so that's the beginning but then you need some of these stars to explode right because if those heavy elements remained forever trapped in the cores of stars then they would not be available for the production of new stars planets and ultimately life so indeed the Supernova my main area of Interest plays a a leading role in this whole story I saw that you got a chance uh to call Richard Fineman a mentor of yours when you were at Caltech yeah uh do you have any fond memories of Fineman any lessons that stick with you oh yeah he was quite a character uh and one of the deepest thinkers of all time probably and at least in my life the physicist who had the single most intuitive understanding of how nature works of anyone I've met uh he I I learned a number of things from he was not my thesis adviser I worked with Wallace Sergeant at galtech on what are called active galaxies big black holes in the centers of galaxies that are accreting or swallowing material a little bit like the stuff of of this year's Nobel Prize in physics 2020 uh but Fineman I had for for two courses one was general theory of relativity at The Graduate level and one was applications of quantum physics to all kinds of interesting things and he you know he had this very intuitive way of of looking at things that he tried to that he tried to bring to his students and he felt that if you can't explain something in a reasonably simple way to a non scientist or at least a you know someone who is versed a little bit with science but is not a professional scientist then you probably don't understand it very well yourself very thoroughly so that in me um you know made a desire to to to be able to explain science to the to the general public and I've often found that in explaining things yeah there's a certain part that I didn't really understand myself that's one reason I like to teach the introductory courses to the lay public is that I sometimes find that my explanations are lacking in my own mind you know so he did that for me is there uh if I could just pause for a second you said he had one of the most intuitive understanding of nature what if you could break apart what intuitive means like it is it on a philosophical level no sort of physical how do you draw a mental picture or a picture on paper of what's going on and he's perhaps most famous in this regard for his Fineman diagrams which in what's called Quantum electrodynamics a Quantum field theory of electricity and magnetism what you have are actually you know an exchange of photons between charged particles and they might even be virtual photons if the particles are at rest relative to one another and there are ways of doing calculations that are brute force that take pages on pages and pages of calculations and Julian schwinger uh developed some of the mathematics for that and won the Nobel Prize for it but feineman had these diagrams that he made and he had a set of rules of what to do at the vertex you know you have two particles coming together and then a particle going out and then two particles coming out again and he'd have these rules Associated when there were vertices and when there were particles splitting off from one another and all that and it looked a little bit like a bunch of a hodgepodge at first but to those who learned the rules and understood them he you know they they saw that you could do these complex calculations in a much simpler way and indeed in some ways Freeman Dyson had an even better knck for explaining really what Quantum electrodynamics actually was but I didn't know Freeman Dyson I I knew Fineman maybe he did have a more intuitive view of the world than Fineman did but of the people I knew finean was the most intuitive most sort of is there a picture is there a simple way you can understand this and in in um in the path that a particle follows even you know you can figure out the you can get the classical path at least you know for a baseball or something like that by using quantum physics if you want but you know in a sense the baseball sniffs out all possible paths it goes out to Andromeda galaxy and then goes to the to the batter but the probability of doing that is very very small because tiny little paths next door to Any Given path cancel out that path and the ones that all add together they they are the ones that are more likely to be followed and this actually ties in with font's principle of least action and their ideas and Optics that go into this as well and and it just sort of beautifully brings everything together but the particle sniffs out all possible paths what a crazy idea but if you do the mathematics associated with that it ends at being actually useful a useful way of looking at the world so you're also I mean you you're widely acknowledges I mean outside of your science work is being one of the greatest Educators in the world and Fineman is famous yeah for for being that is there something about being a teacher that you've well it's it's very very rewarding when you have students who are really into it and you know going back to Fineman at Caltech I was taking these graduate courses and there were two of us myself and Jeff richond who's now a professor of physics at University of California Santa Barbara who asked lots of questions and a lot of the Caltech students are nervous about asking questions they they want to save face they seem to think that if they ask a question their peers might think it's a stupid question well I didn't really care what people thought and Jeff Richmond didn't either and we ask all these questions and in fact in many cases they were quite good questions and Fineman said well the rest of you should be having questions like this and I remember one time in particular when he said you know he said to the rest of the class why is it always these two aren't you aren't the rest of you curious about what I'm saying do you really understand it all that well if so why aren't you asking the next most logical question no you guys are too scared to ask these questions that these two are asking so he actually invited us to lunch a couple of times where just the three of us sat and had lunch with one of the greatest thinkers of 20th century physics and so yeah he he rubbed off on me and so you encourage questions as well I encourage questions you know and uh yeah you know definitely I mean you know I encourage questions I I like it when students ask questions I tell them that they shouldn't feel shy about asking a question question probably half the students in the class would have that same question if they even understood the material enough to ask that question yeah curiosity is the first step of um absolutely of seeing the beauty of something so yeah and the question is the ultimate form of curiosity yeah let me ask uh what is the meaning of life the meaning of life you know from a cosmologist perspective or from a human perspective or from my personal you know life is what you make of it really right it's um each of us has to have our own meaning and it doesn't have to be well I I think that in many cases meaning is is to some degree associated with goals you set some goals or expectations for yourself things you want to accomplish things you want to do U things you want to experience and to the degree that you experience those and do those things it can give you meaning you don't have to change the world the way Newton or Michelangelo or Da Vinci did I mean people often say don't change the world but look come on there's seven and a half close to eight billion of us now most of us are not going to change the world and does that mean that most of us are leading meaningful lives no it it just has to be something that gives you meaning that gives you satisfaction that gives you a good feeling about what you did and and often based on nature which can be very good and also very bad but often it's the things that help others that give us meaning and a feeling of satisfaction you taught someone to read you cared for someone who was terminally ill you brought up a a nice family you brought up your kids um you did a good job you you put your heart and soul into it you read a lot of books if that's what you wanted to do had a lot of perspectives on life you you traveled the world if that's what you wanted to do um but if some of these things are not within reach you're in a socioeconomic position where you can't travel the world or whatever you find other forms of of meaning uh it doesn't it it doesn't have to be some profound I'm going to change the world I'm going to be the one who everyone remembers type thing right in the context of The Greatest Story Ever Told like the fact that we came from stars and now we're two Apes asking about the meaning of life yeah how does that fit together does that make any sense you know it does it does and this is sort of what I I was referring to that it's a beautiful universe that allows us to come into creation right it's a way that the Universe found of knowing of understanding itself because I don't think that you know inanimate rocks and stars and black holes and things have any real capability of of abstract thoughts and of learning about the rest of the universe or or even their Origins I mean they're just they're just a pile of atoms that's that's has no conscience has no ability to think has no ability to explore and we do and you know I'm not saying we're the epitome of all life forever but at least for life on Earth so far the evidence suggests that we are the epitome in terms of the richness of our thoughts the degree to which we can explore the universe do experiments build machines understand our Origins and I just hope that we use science for good not evil and that we don't end up destroying ourselves I mean the whales and dolphins are plenty intelligent they're they don't ask abstract questions they don't read books but on the other hand they're not in any danger of destroying themselves and everything else as well and so maybe maybe that's a better form of intelligence but at least in terms of our ability to explore and make use of our minds I mean to me it it's this it it's this that gives me um the potential for meaning yeah right the fact that I can understand and explore it's kind of fascinating to think that the universe created us and eventually we've built telescopes to look back at it to look back at its Origins and to wonder how the heck the thing works it's magnificent needn't have been that way right and this is one of the you know the Multiverse sort of things you know you can alter the laws of physics or or even the constants of nature seemingly inconsequential things like the mass ratio of the proton and the neutron you know wake me up when it's over right what could be more boring but it turns out you play with things a little bit like the ratio of the mass of the neutron to the proton and you generally get boring universes only hydrogen or only helium or only iron you don't even get the rich periodic table let alone bacteria paramia slugs and humans okay I'm not even anthropomorph an anthropos centz this to the degree that I could even a rich periodic table mhm wouldn't be possible if if certain constants weren't this way but but they are and that to me leads to the idea of of a Multiverse that you know that the dice were thrown many many times and there's this Cosmic archipelago where most the universes are are boring and some might be more interesting but we are in The Rare Breed that's really quite darn interesting and if there were only one and maybe there is only one well then that's that's truly amazing we're lucky we're lucky but I actually think there are lots and loss just like there are lots of planets Earth isn't special for any particular reason there are lots of planets in our solar system and especially around other stars and occasionally they're going to be ones that are conducive to the development of complexity culminating in Life as we know it and that's a beautiful story I don't think there's a better way to end it Alex it's a huge honor one of my favorite conversations I've had in this podcast thank you thank so much for talking for for the honor of of having been asked to do this thanks for listening to this conversation with Alex filipenko and thank you to our sponsors neuro the maker of functional sugar-free gum and mints that I used to give my brain a quick caffeine boost better help online therapy with a licensed professional master class online courses that I enjoy from some of the most amazing humans in history and cash app the app I use to send money to friends please check out these sponsors in the description to get a discount and to support this podcast if you enjoy this thing subscribe on YouTube review it with five stars and apple podcast follow on Spotify support on patreon or connect with me on Twitter at Lex fredman and now let me leave you with some words from Carl Sean the nitrogen in our DNA the calcium in our teeth the iron in our blood the carbon in our apple pies were made in the Interiors of collapsing Stars we are made of star stuff thank you for listening and hope to see you next time