Martin Rees: Black Holes, Alien Life, Dark Matter, and the Big Bang | Lex Fridman Podcast #305
there's no reason to think that the ocean ends just beyond your Horizon and likewise there's no reason to think that the aftermath of our big bang um ends just at the boundary of what we can see indeed there are quite strong arguments um that it probably goes on about 100 times further it may even go on so much further that uh all comori are replicated and uh there's another set of people like us sitting in in a room like this the following is a conversation with Lord Martin reee ameritus professor of cosmology and astrophysics at Cambridge University and co-founder of the center for the study of existential risk this is the Lex Freedman podcast to support it please check out our sponsors in the description and now dear friends here's Martin reys in your 2020 Scientific American article you write that quote today we know that the universe is far bigger and Stranger than anyone suspected so what do you think are the strangest maybe the most beautiful or maybe even the most terrifying things lurking out there in the cosmos well of course we're still groping for any detailed understanding of the remote parts of the universe but of course what we've leared in the last few decades is really two things first we've understood that the Universe Had An Origin about 13.8 billion years ago in a so-called big bang a hot Den state whose very Beginnings are still shrouded in mystery and also we've learned more about the extreme things in it black holes neutron stars explosions of various kinds and one of the most potentially exciting discoveries in the last 20 years mainly in the last 10 has been the realization that most of the stars in the sky are orbited by resu of planets just as the sun is orbited by the Earth the other familiar planets and this of course makes the night sky far more interesting what you see up there aren't just points of light but they're plany systems and that raises the question could there be life out there and so that is an exciting problem for the 21st century so when you see all those lights out there you immediately imagine all the planetary worlds that are around them and they potentially have all kinds of different lives living organisms life for forms or his that we don't know at all we know that these planets are there we know that they have masses and um orbits rather like the planets of our solar system but we don't know at all if there's any life on any of them I mean it's entirely logically possible that life is unique to this earth doesn't exist anywhere on the other hand uh it could be that the origin of life is something which happens routinely given conditions like the young Earth in which case there could be literally billions of places in our galaxy where some sort of biosphere has evolved and settling um where the truth lies between those two extremes is a challenge for the coming decades so certainly we're either lucky to be here or very very very lucky to be here I guess that's the difference uh where do you fall your own estimate your own guess on this question are we alone in the universe do you think I think it would be foolish to give any firm estimate because we just don't know and that's just a example of how we are depending on greater observations and also incidentally in the case of Life we've got to take account of the fact that uh as I always say to my scientific colleagues biology is a much harder subject than physics and most of the um Universe we know about could be understood by physics but uh we've got to remember that even the smallest living organism an insect is far more complicated with layer on complexity uh than uh the most complicated star or Galaxy you know that's the funny thing of about physics and biology the dream of physicist in the 20th century and maybe this century is to discover the theory of everything and there's a sense by that once you discover that theory you will understand everything if we unlock the mysteries of how the universe works would we be able to understand how life emerges from that fabric of the universe that we understand I think the phrase Theory of Everything is very misleading because it's used to describe a theory which unifies the um three laws of microphysics electrity magnetism and the weak interaction with gravity so it's important step forward for particle physicists but the lack of such a theory doesn't hold up any other scientists anyone doing biology or most of physics is not held up at all through not understanding subnuclear physics they're held up because they're dealing with things that are very complicated and that's especially true of anything biological so what's holding up biologists is not a lack of a so-called Theory of Everything uh it's the inability to understand things which are very complicated what do you think we'll understand first how the Universe works or how the human body works deeply like from a fundamental deep level well I think um perhap we can come back to it later that there are only limited prospects of ever being able to understand with un AG's human brains the most fundamental theories linking together all the forces of nature I think that may be a limitation of the human brains um but I also uh think that um we can perhaps aided by computer simulations um understand a bit more of the complexity of nature but uh even understanding a simple organism from the atom up is very very difficult and I think extreme reductionists have a very misleading perception they tend to think that um in a sense we're all solutions of thring equation Etc um but that isn't the way we'll ever understand anything uh it may be true that we our reductions in the sense if we believe that that's the case we don't believe in any special life force in living things but nonetheless no one thinks that we can understand a living thing by solving sh's equation to take an example which isn't as complicated lots of people study the flow of fluids like water why waves break why flows go turbulent things like that this is a serious branch of Applied Mathematics and engineering and in doing this have concepts of viscosity turbulence and things like that now you can understand quite a lot about how water behaves and how waves break in terms of those Concepts but the fact that any breaking wave is a solution of tring's equation for 10 of 30 particles even if you could solve that which you clearly can't would not give you any insight so the important thing is that every science has its own reducible Concepts in which you get the best explanation uh so it may be in chemistry it's things like veence um in biology the concept in cell biology um and in the ecology there are Concepts like imprinting Etc and in Psychology there are other Concepts so in a sense The Sciences are like a tall building where you have basic physics the most fundamental then the rest of physics then chemistry then cell biology Etc all the way up to the I guess Economist in the penthouse and all that um and we have that um and that's true in a sense but it's not true that it's like a building in that it's made unstable by an unstable base because if you're chemist biologist or Economist you're facing challenging problems but they're not made any worse by uncertainty about subnuclear physics and at every level just because you understand the rules of the game or have a some understanding of the rules of the game doesn't uh mean you know what kind of beautiful things that game creates right so if you're interested in um birds and how they fly uh then things like uh um imprinting the baby on the mother and all that and uh things like that are what you need to understand um you couldn't even in principle solve this vertical equation how an albatross wanders for thousands of miles of the Southern Ocean and comes back and then coughs up food for its young uh that that's something we can understand in a sense and uh predict the behavior but it's not because we can solve it on the atomic scale you mentioned that there might be some fundamental limitation to the human brain yes that limits our ability to understand understand some aspect of how the universe works that's really interesting that's sad actually if if if to the degree it's true it's sad so what do you mean by that I would simply say that just as um a monkey can't understand quantum theory even Newtonian physics um there's no particular reason why the human brain should have evolved to be well matched to understanding a deepest aspect of reality and I suspect that there may be aspects that we not even aware of and couldn't really fully comprehend um but as an intermediate step towards that one thing which I think is very interesting possibility is the extent to which AI can help us I mean I think uh if you take the example of uh So-Cal theories of everything one of which is string theory um String Theory involves very complicated geometry and structures in 10 dimensions and it's certainly in my view on the cards that the physics of 10 Dimensions they very complicated geometry um may be too hard for a human being to work through but could be worked through by an AI um with the advantage of the huge processing power which enables them to learn World Championship chest within a few hours just by watching games so there's every reason to expect that these um machines could help us to solve these problems and of course if that's the way we came to understand where the string theory was right um it would be in a sense frustrating because you wouldn't get the sort of aha Insight which is the greatest satisfaction from doing science but on the other hand if um a machine CHS away a 10-dimensional geometry figuring out all the possible origami in wound up in extra Dimensions if it comes out at the end spews out the correct mass of the electron the fact that there are three kinds of neutrinos something like that you would know that there was some truth in the theory and so we may have a theory which we come to trust because it does predict things that we can observe and check but we may never really understand the full workings of it to the extent that we do more or less understand um how um most phenomena can be explained in a f Way of course in case of quantum theory many people would say understandably there's still some Mysteries you don't quite understand why it works but there could be deeper Mysteries when we get to these unified theories where there's a big gap between um what a computer can print out for us at the end and what we can actually grasp and think through in our heads yeah it's interesting that the idea that there could be things a computer could tell us that is true and maybe you can even help us understand why it's true a little bit y But ultimately it's still a long journey to really deeply understand the wise of it uh yes and that's the limitation of our brain we we can try to sneak up to it in different ways given the limitations of our brain have you I've gotten a chance to spend the day a deep mind talk to Demis habis his big dream is to apply AI to the questions of science certainly to the questions of physics have you gotten a chance to interact with them well I know him quite well I've uh he's one of my heroes certainly and and I remember I'm sure he would say the same and I remember the the first time I met him he said that he was like me he wanted to understand the universe but he thought the best thing to do was to try and develop Ai and then with the help of AI he'd stand more chance of understanding the universe yeah and I think he's right about that so and of course um although we're familiar with the way his computers played go and chess um he's already made contribution to science through uh uh understanding protein folding better than the best human chemists and so already he's on the path to showing ways in which computers have the power to learn and do things by having ability to analyze enormous samples in a short time uh to do better than humans and so um I think he would resonate for what I've just said that it may be that uh in these other fundamental questions the computers will play a crucial role yeah and there also doing uh quantum mechanical simulation of electrons they're doing uh control of uh high temperature plasma Fusion reactors yes that's a new thing which is very interesting they can suppress the instabilities in these toac um better than any other way yeah and it just the march of progress by AIS and science is is is making uh big strides do you think an AI system will win a Nobel Prize in the century what do you think and does that make you sad if I can digress and put in a plug for my next book yes it has a chapter saying why Nobel prizes do more harm than good yes so on a quite separate subject I I think Nobel prizes do great of damage to the perception of the way science is done of course if you ask who or what deserves the credit for any scientific discovery it maybe often someone has an idea a team of people who work a big experiment Etc um and of course it's the quality of the equipment which is um crucial and certainly in the subjects I do in astronomy um the huge advances we've had uh come not from us being more intelligent than Aristotle was but through us having far far better uh data um from powerful telescopes on the ground and in space and also incidentally uh we benefited hugely in astronomy uh from um Compu simulations because um if you are a subatomic physicist then of course you crash together the particles in a big accelerator like the one at CERN and see what happens but um I can't crash together to galaxies or two stars and see what happens but in the virtal world of a computer one can do simulations like that and the power of computers is such that these simulations uh can um yield um a phenomena and insights which we wouldn't have guessed beforehand and the way we can feel we're making progress in trying to understand some of these phenomena why galaxies have the size and shape they do and all that is because we can do simulations um tweaking different initial conditions and seeing which gives the best fit to what we actually observe and so that's a way in which we've made progress in using computers and incidentally uh we also now need them to analyze data because one thinks of astronomy as being traditionally rather data poor subjects but the um European satellite called Gaia has just put on line the um speeds and colors and properties of nearly two billion stars in the Milky Way and which you can do fantastic analysis of and that of course could not be done at all without just the number crcy capacit computers and the the new methods of machine learning actually love of raw data the kind that astronomy provides organized structured raw data yeah well indeed because the reason they really have a benefit over us is that they can learn and think so much faster that's how they can learn to play chess and go that's how they can learn to diagnose lung cancer better than a radiologist because they can look at 100,000 scans in a in a few days whereas no human radiologist sees that many in a lifetime well there's still magic to the human intelligence to the intuition to the common sense reasoning uh well we hope so for now what what what is the new book that you mentioned the book I me it's called if science is to save us it's coming out in September um and it's on the um well the big challenges of science um you um climate dealing with the bio bios safety and dealing with cyber safety and also it's got chapters on the um way science is organized universities andies Etc and and the the ethics of Science and um and perhaps the limit and the limits yes yeah well let me actually just stroll around the the beautiful and the strange of the universe uh over 20 years ago you hypothesized that we would solve the mystery of dark matter by now so unfortunately we didn't quite yet MH uh first what is dark matter and why has it been so tough to figure out well I mean we we learned that galaxies and other large scale structures which are moving around but uh um preventive flying apart by G by gravity um would be flying apart if they only contain the stuff we see if everything in them was shining and to understand how Galax is formed and why they do remain confined the same size uh one has to infer that is about five times as much stuff producing gravitational forces than the total amount of stuff in the gas and stars that we see and that stuff is called Dark Matter um that's his leading name it's not dark it's just transparent Etc um and the uh most likely interpretation is that it's a swarm of uh microscopic particles which have no electric charge and the very small crosssections are hitting each other and hitting anything else so they swarm around and we we can detect their Collective effects and when we do computer simulations of how galaxies form and evolve and how they emerge from The Big Bang then uh we get a nice consistent picture if we put in five times as much mass in the form of these mysterious dark particles and for instance it works better if we think they're non- interacting particles than if you think they're a gas which would have shock waves and things so we know something about the properties of these but we don't know what they are and um the disappointment compared to my guess 20 years ago um is that particles answering this description have not yet been found it was thought that the big accelerator the lar handro collider at Ser which is the world's biggest might have found a new class of particles which would have been the obvious candidates and it hasn't and uh um some people say well Dark Matter can't be there Etc but what I would argue is that there's a huge amount of parameter space that hasn't been explored um there are other kinds of particles called Axion which behave slightly differently which are a good candidate um and um there's a factor of 10 power of 10 between the heaviest particles that could be created by the large hydron cider and the heaviest particles which on theoretical grounds could exist without turning into black holes so there's a huge amount of possible particles which could be out there as remnants of the Big Bang but which we wouldn't be able to te so easily so um the fact that we've got new constraints on what the Dark Matter could be doesn't diminish my belief that it's there in the form of particles because we've only explored a small fraction of parameter space so there's this search you're literally upon unintended are searching in the dark here in this giant parameter space of possible particles you're searching for I mean there could be all kinds of particles could be and there's some which may be very very hard to detect but I think we can hope for um some new theoretical ideas because um one point which perhaps you'd like to discuss more is about the very early stage of the Big Bang um and uh the situation now is that we have a outlined picture for How the Universe has evolved um from the time when was expanding in just a nanc well up to the present and we could do that because after nanc the physics of the material is in the same range that we can test in the lab after a nanc the particle is moving around like those in the L hat collider if you wait for for one second they're rather like in the centers of the hottest stars and nuclear reactions produce hydrogen helium Etc which fit today so so we can with confidence extrapolate back to when the universe was a n second old inde I think we can do it with as much confidence as anything a geologist tells you about the early history of the earth and that's huge progress in the last 50 years but any progress puts in sharper Focus uh new Mysteries and of course the new mystes in this context are why is the universe expand the way it is why does it contain this mixture of atoms and dark matter and radiation and why does it have the properties which allow Galaxy to form being fairly smooth but not completely smooth and the answer to those questions are generally believed to lie in a much much earlier stage of the universe when conditions were much more extreme and therefore far beyond the stage when we had the foot told in experiments very theoretical and so um we don't have a convincing Theory we just have ideas until we have something like string theory or some other Clues to the ultra early Universe uh that's going to remain speculative so um there's a big gap and to say how big the Gap is um if we take the observable universe out to bit more than 10 billion life years um then when the universe was a nanc old that would have been squeezed down to the size of of our solar system or compressed into that that volume but the times we're talking about when the Key properties of the universe were first imprinted were times when that entire universe was squeezed down to the size of a tennis ball or baseball if you prefer and to emerge from something microscopic so it's a huge extrapolation and it's not surprising that since it's so far from our experimental range of detectability uh we are still groping for ideas but you think first Theory will reach into that place and then experiment will perhaps one day catch up well I think simulation in a sense it's combination I think what what we hope for is that um uh there'll be a theory which applies to the early universe but which also has consequences which we can test in our present day Universe um like um discovering why neutros exist or things like that and that's the thing which as I mentioned we may perhaps need a bit of AI to help us to calculate but but I think um the the hope would be that we will have a theory which applies under the very very extreme early stages of the universe but which gains credibility and gains confidence because it also manages to account for otherwise unexplained features of um the low energy world and what people call a standard model of particle physics where there lots of undetermined numbers so it may help with that so we're dancing between physics and philosophy a little bit but what do you think what do you think happened before the Big Bang so this seems this feels like something that's out of the reach of science it's out of the reach of present science because science develops and as the front is Advance uh then new problems come into Focus that couldn't even been postulated before I mean if I think of my own career when I was a student the evidence for the Big Bang was pretty weak whereas now it's extremely strong um but we are now thinking about the reason why the universe is the way it is and all that um so uh I I would put all these things we've just mentioned in the category of speculative science um and I don't see a bicationic um but of course to answer your question if we do want to understand the very early Universe then we've got to realize that it may involve even more counterintuitive Concepts than quantum theory does because it's a condition even further away from everyday world than quantum theory is and remember our lives our brains evolved um and haven't changed much since an Our Ancestors roam the African Savannah and looked at the everyday World um and uh it's rather amazing that we've been able to make some sense of the quantum microw world and of the cosmos but uh uh there may be some things which are Beyond us and certainly as you implied there are things that we don't yet understand at all and of course one concept we might have to jettison is the idea of three dimensions of space and time just ticking away there lots of ideas I mean I think stepen Hawking had an idea that talking about what's what hasn't before the big bang it's like asking what happens if you go north from the North Pole you know it somehow closes off that's just one idea um I don't like that idea but that's a possible one um and uh and so we just don't know um what's happened at the very beginning of the Big Bang were there many Big Bangs rather than one Etc um and those are issues which um we may be able to get some foothold on from some new Theory um but even then um we won't be able to directly test the theories but I think um it's a heresy to think you have to be able to test every prediction of a theory let me give another example um we take seriously what Einstein's theory says about the inside of black holes even though we can't observe them because that theory has been Vindicated in many other places in cosmology and black holes gravitational waves and all those things um likewise if we had a a theory which um explains some things about the early history of our big bang in the present Universe then we would take seriously the inference if it predicted many Big Bangs not one even though we can't predict the other ones so the example is that we can take seriously a prediction if it's the consequence of a theory that we believe on other grounds we don't need to be able to uh detect another big bang in order to take it seriously it may not be a proof but it's a good indication that uh this is the direction where the truth lies yeah if the theory is gained confidence in other ways yes what do you sense do you think there's other universes besides our own those are sort of well- defined theories which make assumptions about the physics at the relevant time and this time incidentally is 10 the^ 36 seconds um or earlier than that so this tiny sliver of time and um the some theories uh famous One du to Andre lindai um the Russian cosmologist now at Stanford called Eternal inflation um which did predict um an eternal production of new Big Bangs as it were and uh that's based on specific assumptions about the physics but those assumptions of course are just hypotheses which aren't Vindicated but there are other theories which only predict one big bang so I think uh we should be open-minded and not dogmatic about these these options until we do understand the relevant physics but there are these different scenarios of very different ideas about about this but I think all of them have the feature that physical reality is a lot more extensive than what we can see through our telescope I think even the most conservative astronomers would say that because we can see out with our telescopes to a sort of horizon which is about depending on how you measure it maybe 15 billion light years away or something like that but that Horizon of our observations is no more physical reality than the Horizon around you if you're in the ocean and look looking out at your horizon there's no reason to think that the ocean ends just beyond your Horizon and likewise there's no reason to think that the aftermath of our big bang um ends just at the boundary of what we can see indeed they're quite strong arguments um that it probably goes on about 100 times further it may even go on so much further that uh all combinatorial are replicated and uh there's another set of people like us sitting in in a room like this every possible combination of yeah that that could happen that's not logically impossible um but but I think I think many people would accept that it does go on um and contain um probably a million times as much stuff as what we can see within the Horizon the reason for that incidentally is that if we look as far as we can in One Direction and in the opposite direction then the conditions don't differ by more than one pass in 100 thousand so that means that if we're part of some finite structure the gradient across the part we can see is very small and so that suggests that it probably does go on a lot further and the best estimates say it must go at least 20 times further is that exciting or terrifying to you just the spans of it all the wide everything that lies Beyond the Horizon that that example doesn't even hold for Earth so it goes way way farther and on top of that just to take your metaphor further with the on the ocean yeah while we're on top of this ocean not only can we not see beyond on the horizon we also don't know much about the depth of the ocean that's right nor the actual mechanism of observation that's in our head yes no I think the r and is all those points you make yes yes but but I think um uh even even the solar system is pretty vast by human standards and so uh I don't think the perception of this utterly vast Cosmos um need have any deeper impact on us than just realizing that we are very small on the scale of the external world yeah it's humbling though it's it's humbling in uh depending where your ego is it's humbling in well if you start very unhumble indeed it may make a difference but for most of us I don't think it make much much difference and uh well there's a more general question of course about uh um whether um the human race as such is something which is very special or if on the other hand um it's just one of many such species elsewhere in the universe or indeed existing at different times in our universe it to me it feels uh almost obvious that the Universe should be full of alien life perhaps dead alien civilizations but just the the vastness of space and yes it just feels wrong to think of Earth as somehow special it sure as heck doesn't look that special when you the more we learn the less special it seems well I mean I don't agree with that as far as life is concerned because uh remember that we don't understand how life began here on Earth yes we don't understand although we know that in evolution from simple life to complex life we don't understand uh what caused the transition between complex chemistry and the first um replicating metabolizing entity we call alive yes that's a mystery um and uh serious physicists are now and chemists are now thinking about it but we we don't know so we therefore can't say was it a rare fluke yeah which would not have happened anywhere else or was it something which uh involves a process would have happened in any other planet where conditions were like they were on the young Earth um so we can't say that now um I think well many of us would indeed bet that probably some kind of Life exists elsewhere but even if um you accept that then um there many contingencies going from simple life to um uh present day life and and some biologists like Stephen J Gould thought that if you reran Evolution you'd end up with something quite different and maybe nothing with intelligent species so the contingencies in evolution um May militate against the emergence of intelligence even if life gets started in lots of places so I think these are still completely open questions and that's why it's such an exciting time now that we are starting to be able to address these I mean I mentioned the uh the fact that the origin of life is a question that we may be able to understand um and serious people are working on it it used to be put in the sort of twoo difficult box everyone knew was important but they didn't know how to tackle it or what exp expon to do but it's not like that now and um that's partly because of clever experiments but I think most importantly because um we are aware that we can look for life in other places other places in our solar system and of course on the exoplanets around other stars and uh within 10 or 20 years I think two things could happen which would be really really important we might with the next big T scope be able to image some of the earthlike planets around other stars image like get a picture well actually let me caveat that it take 50 years to get a resolved image but but but but actually detect the light because now of course these exoplant are detected by their effect on the parent star they either cause their parent star to dim slightly when they Transit across in front of it and so we see the dips or their gravitational the pole makes the star wobble a bit so so most of the the 5,000 plus planets that have been found around other stars they've been found indirectly by their effect yes in one of those two ways on the par you can still do a pretty good job of estimating size all those kinds of things size and the size and the mass you can estimate um but uh um but detecting the the actual light from one of these EXO planets hasn't really been done yet except one of two very very very bright big planet so maybe like James Webb Telescope would be well James web may do this but even better will be the European groundbased telescope called unimaginative the extremely large telescope which has a 39 M diameter mirror 39 M mic of 800 sheet of glass and that will collect enough light from one of these exoplanets around a nearby star um to be able to um separate out its light from that of the star which is a millions of times brighter and get the spectrum of the planet and see if it's got oxygen or chlorophyll and things in it so that that that will come um J James web may may make some some steps there um but I think we can look forward to learning quite a bit um in the next 20 years because I like to say um supposing that aliens looking at the solar system then they'd see the Sun as an ordinary star they'd see the Earth as in Carl sega's eyes phrase a pale blue dot lying very close in the sky to its star our sun and much much much fainter but if they could observe that dot they could learn quite a bit they could perhaps get the spect of the light and find the atmosphere they'd find the shade of blue is slightly different depending on whether the Pacific Ocean or the land mass of Asia was facing them so they could infer the length of the day and the oceans and continents and maybe something about the seasons and the climate and uh that's the kind of calculation calculation and inference we might be able to draw within the next 10 or 20 years about other exoplanets and um and evidence of some sort of biosphere on one of them would of course be crucial and it would rule out the uh still logical possibility that life is unique but there's another way in which this may happen in the next 20 years people think there could be something swimming under the ice of Europa and Enceladus and probes are being sent to maybe not quite go under the ice but detect the spray coming coming out to see if there's evidence for Organics in that and if we found any evidence for an origin of life that happened in either of those places that would immediately be important because if life has originated twice independently in one planed system the solar system that would tell us straight away it wasn't a rare accident and must have happened billions of times in the Galaxy at the moment we can't rule out it being unique and incidentally if we found life on Mars then that would still be ambiguous because uh um people have realized that this early life could have got from Mars to Earth or vice versa on meteorites so um if you found life on Mars then some Skeptics could still say if it's a single origin um but I think but europa's far that's far enough away statistically so so that's why that would be especially it's always the Skeptics that ruin a good party but but we need them of course we need them at the party we need some Skeptics at the party um but boy would that be so exciting to find life on one of the moons yeah because it means that just be any kind of vegetation or life um the question of the um aliens of Science Fiction is a different matter intelligent aliens yeah but if if you have a good indication that there's life elsewhere in the solar system that means life is everywhere Y and that y That's I don't know if that's terrifying or what that is because if life is everywhere why is intelligent life not everywhere why I mean you've talked about that most likely alien civilizations if they are out there they would likely be far ahead of us the ones that would actually communicate with us yes and that um again one of those things that is both exciting and terrifying you you've mentioned that they're likely not to be of biological nature well I think that's important of course again it's a speculation but uh uh in speculating about um intelligent life and I I take the search seriously in fact I chair the uh committee that the um Russian American investor Yuri Milner supports looking for intelligent life he's putting 10 million dollars a year into better equipment and getting time on telescopes to do this and so I think it's worthwhile even though I I don't hold my breath for Success it's it's very exciting but but that does lead me to wonder what might be detected and um I think well we don't know we've got to be open minded about anything we have no idea what it will be and so any anomalous object or even some strange shiny object in the solar system or anything we've got to keep our eyes open for but I think um if we ask what about a um Planet like the Earth where Evolution had taken more of the same track then as you say it wouldn't be synchronized um if it had lagged behind then of course it would not have got to Advanced life uh but it may have had a Stars it may have formed on a planet around an older star okay but then let's ask what we would see um it's taken nearly four billion years from the first life to us and we've now got this technological civilization which uh um could make itself detectable um to any alien live aliens out there um but I think most people would say that this civilization of Flesh and Blood creatures in the collective civilization may not last more than a few hundred years more I think that the that people may some people would say it it it will um kill itself off um but I'm more optimistic and I would say that um what we're going to have in future is um no longer the slow darwinian selection but we're going to have what I call secular intell design which will be um humans designing um uh their progeny to be better adapted to where they are and uh if they go to Mars or some somewhere they're badly adapted they want to adapt a lot and so uh they will adapt um but there may be some limits to what could be done with flesh and blood and so they may become largely electronic um download their brains and have and be electronic entities and if they're electronic then what's important is that they're near Immortal and also they won't necessarily want to be on a planet with an atmosphere or gravity they may go off into the blue yonder and they and if they're near Immortal they won't be daunted by Interstellar travel taking a long time and so um uh if if we looked at what would happen on the earth in the next millions of years then there may be these electronic entities which have been sent out and are now far away from the Earth but still sort of burping away in some in some fashion to be detected um and so uh this um this therefore leads me to think that um if there was another planet which had evolved like the Earth and was ahead of us uh it wouldn't be synchronized so we wouldn't see a flesh and blood civilization but we would see these electronic progeny as it were um and and then this raes another question because um there's the famous argument against there being um lots of aliens out there which is that they would um come and invade us and eat us or something like that you know that's a common idea U so fairy is attributed to have been the first to say um and I think there's a um es scape Clause to that because these um entities yeah would be say they evolve by secular andt design designed by their predecessors and then designed by us um and uh um whereas darwinian selection requires two things it requires aggression and intelligence this future intelligence design um May favor intelligence because that's what they were designed for but it may not favor aggression and so these future entities they they may be um sitting Deep Thoughts thinking Deep Thoughts um and and not being a tall expansionist so they could be out there yeah and we can't refute their existence in the way the fair Paradox is supposed to refute their existence because these would not be aggressive or expansionist well maybe Evolution requires competition not aggression and I wonder if competition can take forms that are non- expansionary so you can still have fun competing yeah in the space of ideas which maybe primarily the philosophers perhaps yeah in in a way right it's a it's an intellectual exercise versus a sort of violent exercise so what does this civilization on Mars look like so do you think we would more and more you know maybe start with some genetic modification and then move to basically cyborgs increasing integration of electronic systems computational systems into our bodies and brains this is a theme of um uh my other new book out this year which is called the end of astronauts and end of asona co-written with my um uh old friend and colleague from Berkeley Don Goldsmith and uh it's really about um the the role of human space flight versus sort of robotic space flight and um just to summarize what it says um it argues that the um practical case for sending humans into space is getting getting weaker all the time as robots get better more capable robots 50 years ago couldn't do anything very much but now they could assemble big structures on space or on in space or on the moon and they could probably do exploration well present ones uh on Mars um can't actually um do the geology but future AI will be able to do the geology and already they can dig on Mars and so if you want to do exploration of Mars and of course even more of um encel or Europa where you could never send humans we depend on robots and they're far far cheaper because to send a human to Mars requires feeding them for 200 days on the journey there and bringing them back and neither of those are necessary for robots so the Practical case for humans is getting very very weak and if humans go it's only as an adventure really and so the line in our book is that um uh human space flight should not be pursued by nasau or Public Funding agencies um because it has no practical purpose but also because it's specially expensive if they do it because they would have to be risk averse in launching civilians into space I can illustrate that by noting that the shuttle was launched 135 times and it had two spectacular failures which each kill the seven people in the crew um and uh it had been mistakenly presented as safe for civilians and there was a woman school teacher killed in one of them it was a big National trauma and they tried to make it safer still um but if you launch into space just the kind of people prepared to accept that sort of risk and of course test p and people who go hangliding and go to the South Pole Etc are prepared to accept a 2% risk at least for a big challenge then of course you do it more cheaply and that's why um uh I think um human space f should be left to the billionaires um and their sponsors um because then the taxpayers aren't paying and they can launch simply those people who are prepared to accept risks space adventure not space tourism yeah and and we should cheer them on um and um as regards where they would go then um lowth orbit I suspect can be done quite cheaply in future but going to Mars which is very very expensive and dangerous for humans um the only people who would go would be um these um adventurers um maybe on one way trip like some of the early polish explorers and mellan and people like that you know and we would share them on um and I expect and I very much hope that by the end of a century there will be a small community of such people on Mars um living very uncomfortably far less comfortably than at the South Pole or the bottom of the ocean or top of Everest but they will be there uh um and they won't have certain ticket um but they they'll be there um incidentally I think it's a dangerous delusion to think as uh Elon Musk has said that we can have mass immigration from the Earth to Mars to escape the Earth's problems um it's a dangerous illusion because it's far easier to deal with climate change on Earth than to terraform Mars to make it properly habitable to humans so there's no Planet be for a risk averse people but for these crazy adventurers uh then you could imagine that they would be trying to live on Mars as um as great pioneers and by the end of the century then there will be huge advances compared to the present in two things first in in the understanding genetics so as to genetically redesign one's Offspring and secondly to use cybor techniques to um implant some something in our brain or indeed think about downloading Etc and those techniques will will one hopes be heavily regulated on Earth on credentials and ethical grounds and of course we are pretty well adapted to the Earth so we don't have the incentive to do these things in the way they were there so um our argument is that um it'll be those crazy Pioneers on Mars using all these scientific advances which will be controlled here away from The Regulators they will transition into a new posthuman species MH and so um if they do that and if they transition into something which is electronic eventually because there may be some limits to the capacity of Flesh and Blood brains anyways um then um those electronic entities um may not want to stay on a planet like Mars they may want to go go away and so they'll be the precursors of the future um evolution of life and Intelligence coming from the earth um and of course there's one point which perhaps astronomers are more aware of than most people most people are aware that we are the outcome of four billion years of evolution most of them nonetheless probably think that we humans are somehow the culmination the top of the tree but yes no astronomers can believe that because astronomers know that the Earth is 4 and a half billion years old the sun's been shining for length of time but the sun has got six billion years more to go before it flares up and engulfs the inner planet so the sun is less than halfway through his life um and the expanding Universe goes on far longer still maybe forever and I quote Woody Allen who said eternity is very long especially towards the end so uh so we shouldn't think of ourselves as maybe even a halfway stage in the emergence of cosmic complexity and so these entities who are post cursors they will go beyond the solar system and of course even if there's nothing else out there already then they could uh populate the the rest of the the Galaxy and maybe eventually meet the others who are out there expanding as well yeah expanding and populating with expanded uh capacity for life and intelligence all those kinds of things well they might um but um uh again all better off because can't see what they'd be like um they won't they won't be uh um green green men and women with eyes on stalks you know they' be something quite different um we we just don't know um but there is an interesting question actually which comes up when I've sometimes spoken to audiences about this topic but the question of Consciousness and self-awareness because you going back to philosophical questions I mean it's whether an electronic robot would uh be a zombie or would it be conscious and self aware and um um I think there's no way of answering this empirically um and um some people think that Consciousness and self-awareness is an emerging property in any sufficiently complicated Network that they would be others say well maybe it's something special to the flesh and blood that we're made of we don't know um and in a sense this may not matter um to the way people things behave because we they could be zombies and still behave as though they were intelligent but uh I remember after one of my talks someone came up and said wouldn't it be sad if these future entities which were the main intelligence in the universe um had no self-awareness so there was nothing which could appreciate the Wonder and mystery of the universe and the beauty of the universe in the way that we do um and so it does perhaps affect one's perspective of whether you welcome or deploy for this possible future scenario depending whether you think the the future posthuman entities are conscious and have an aesthetic sense or whether they're just zombies and uh of course you have to be humble to realize that self-awareness may not be the highest form of being that humans have a very strong ego and a very strong sense of identity like personal identity connected to this particular brain yeah yeah uh it's not so obvious to me that that is somehow the the highest achievement of a life form that maybe this kind of you think something Collective would be it's possible that uh well I think from an alien perspective when you look at Earth it's not so obvious to me that individual humans are the atoms of intelligence it could be the entire organism together the collective intelligence and so we humans think of ourselves as individuals we dress up we Wear Ties and suits and we give each other prizes but in reality the intelligence the things we create that are beautiful emerges from our interaction with each other and that may be where the intelligence is ideas jumping from one person to another over Generations yes but we have experiences where we uh can appreciate yes Beauty and wonder and all that and uh uh a zombie may not have those experiences yeah or it may have a very different we have a very black and white harsh description of Z like a philosophical zombie zombie that could be just a very different way to experience uh and you know in terms of the explorers that colonized Mars I um I mean there there's several things I want to mention one it's just at a high level to me that's one of the most inspiring things humans can do is reach out into the unknown that's in the space of ideas in the space of science but also the Explorers yes no I agree with that and and that inspires people here on Earth more uh I mean it did in their you know when going to the moon or going out to space in the 20th century that inspired a generation of scientists I think that also could be used to inspire a generation of new scientists in the 21st century by reaching out towards Mars so in that sense I think what Elon Musk and others are doing is actually quite inspiring it's not no I agree it's not a recreational thing it's actually has a deep humanitarian purpose of really inspiring the world and then on the other one to push back on your thought you know I don't think Elon says we want to escape Earth's problems it's more that we should allocate some small percentage of resources to have a backup plan and because yes you yourself have spoken about and written about all the ways we clever humans could destroy ourselves yes and I'm not sure it does seem when you look at the long Arc of human history it seems almost obvious that we need to become a multiplanetary species over a period if we are to survive many centuries it seems that as we get clever and clever with the ways we can destroy ourselves Earth is going to become less and less safe um so in that sense this is one of the things you know people talk about climate change and then we need to respond to climate change and that's a long-term investment we need to make but it's not really longterm it's a a span of decades I think what Elon is doing is a really long-term investment we should be working on multiplanetary colonization now if we were to have it ready five centuries from now and so taking those early steps and then also there's something happens when you're when you go into the unknown and do this really difficult thing you discover something very new you discover something about robotics or materials engineering or nutrition or Neuroscience or human relations or political systems that actually work well with humans you discover all those things and so it's it's worthy effort to go out there and uh try to become cyborgs yeah no I agree with that I think the only different point I'd make is that um this is going to be very expensive if it's done in a risk averse way and that's why I think we should be grateful to uh the billionaires if they're going to sort of foster um uh these opportunities uh for uh thrill seeking uh Risk Takers who we can all admire yeah but anyway I should push back on the billionaires because there's sometimes a negative connotation to the word billionaire it's not a billionaire it's a company versus government because governments are billionaires and trillionaires yeah it's not it's not the wealth it's the the capitalist uh imperative so uh which I think deserves a lot more praise than people are giving it I'm I'm troubled by the sort of criticism like it's billionaires playing with toys for their own pleasure I think what some of these companies like SpaceX and blue origin are doing is some of the most inspiring engineering and even scientific work ever done in human history no no I agree I think the people whove made the greatest are people who've really been Mega benefactors I mean I think you know some of them some of them yeah yes some of them but but but those who who' founded um Google and all that and and even Amazon they they their beneficiaries they're in a quite different category in my view from those who just Shuffle around money um or or or or or um or crypto coins and things like that who are now you're really talking trash yes but but but but but I think if they use their money in these ways that's fine but but I think um it's true that the far more money is owned by us collectively as taxpayers but I think the fact is that in a democracy um there be big resistance to exposing human beings to very high risks if in a sense we share responsibility for it yeah I don't know that's that's the reason I think it could be done much more cheaply by by by these private funders that's an interesting hypothesis but I have to push back it I don't know if it's obvious why NASA spends so much money and takes such a long time to develop the things he was doing so before Elam musk came along because I would love I would love to live in a world where government actually uses taxpayer money to get some of the best engineers and scientists in the world and actually work across governments Russia China United States the European Union together to do these these big project it's strange that Elon is able to do this much cheaper much faster it could have to be do with risk aversion you're right but I I think it's it's it's the um it's that it's that he had all the um the whole assembly within this one building as it were rather than depending on a supply chain um but I think it's also uh that he um had a Silicon Valley culture and had younger people whereas um the the big Aerospace company companies Boeing and locked Martin um they had people who were left over from the Apollo program in some cases and and and so they weren't quite quite so Lively and indeed um quite apart from the controversial issues of the future of human space flight um in terms of the uh next generation of big Rockets then the one that musk is going to launch for the first time this year um the huge one um is going to be far far cheaper than the one that NASA has been working on U at the same time um and that's because it will have a reusable first stage and it's going to be be great it can launch over a 100 tons into Earth orbit and inent that's going to be make it feasible to do things that I used to think were crazy like having solar energy from space that's no longer so crazy if you can do that um and also for science because um its nose cone could contain within it something uh as big as the entire unfurled James web telescope mirror and therefore you could have a big telescope much more cheaply if you can launch it all in one piece and so it's going to be hugely beneficial to science and to any practical use of space to have these cheaper rockets that are far more completely reusable than any was NASA had so I think mosks are a tremendous service to the space exploration and the h space technology through these Rockets certainly plus it's some big sexy rocket it's just great engineering of course yeah it's like looking at a beautiful big bridge that humans are capable us descendants of apes are capable to do something so Majestic yes and also the way they land coming down on this bar that's amazing it's both controls engineering it's um increasing sort of intelligence in these Rockets but also great propulsion materials uh entrepreneurship and it just inspires it just inspires so many people no I'm entirely with you on that so would it be exciting to you to see a human being step foot on Mars in your lifetime yes I think it's unlikely in my lifetime since I I'm so ancient but uh but I think this this Century it's going to happen and I think that that will indeed be exciting and the I hope there will be a small community by the end of a century but as as I say I think they they may go with oneway tickets or accepting the risk of a of a of of no return and so they've got to be people like that and uh I still think it's going to be hard to persuade the public to send people when you say straight out that they may never come back um but uh of course the Apollo Astronauts they took a high risk and in fact in in my um previous book I I quote the speech that been written for Nixon to be read out if Neil Armstrong got stuck on the moon and and it was um written by one of his um his advisers um and very eloquent speech you know about um how they would have come to a noble end Etc um but of course there was a genuine risk at that time um but of but that may have been accepted but um clearly the crashing of the sh shuttle were not acceptable to the American public even when they were told that this was only a 2% risk given how often they launched it and so so that's what leads me to think that um it's got to be left to the kind of um people who are prepared to take these risks and and I think um think of American Avengers there a guy called Steve foset who was a um Aviator did all kinds of crazy things you know and and then a guy who fell um supersonically um with with the parachute from very altitude all these people we all cheer them on they extend the bounds of humanity um but uh I don't think the public will be so happy to fund them and I mean I disagree with that I think if we change the narrative we should change the story you think so I think I think there's a lot of people because the the the the public is happy to fund uh folks in other domains that take bold giant risks first of all military for example military in military obviously yes yes um I think this is in the name of science especially if it's sold correctly I sure a would go up there with a risk with I would I would take a 40% chance risk of death for something that's can I would I might want to be even older than I am now but then I would go I guess what I'm trying to communicate is there's all there's a lot of people on Earth that's the nice feature and I'm sure there's going to be a significant percentage or some percentage of people that are they take on the risk for the adventure so and I I particularly love that that risk of Adventure when taking on inspires people and just the ripple effect it has across the generation especially among the young minds is uh perhaps immeasurable but you're thinking um that sending humans should be something we do less and less sending humans to space that it should be primarily an effort the the work of space exploration should be done primarily by robots well I think it it can be done much more cheaply obviously on on Mars and uh no one's thinking of sending humans to Enceladus or Europa the outer planets um and uh uh and the point is we'll have much better robots because um uh to take an example um You' seen these pictures of um uh the moons of Saturn and the picture of Pluto and the comet taken by probes and Cassini spent 13 years going around Saturn and its moons after seven year vo and those are all based on 199 technology and if you think of how smartphones have advanced in the 20 years since then do think how much better one could do instrumenting some very small sophisticated probe and could send dozens of them to explore the outer planets and that's the way to do that because no one thinks you could send humans that far um and but I would apply the same argument to to Mars and if you want to assemble big structures like um for instance radio astronomers would like to have a big radio telescope on The Far Side of the Moon so it's away from the uh Earth's um background artificial radio waves um and uh that could be done by assembling it using robots without people so on the moon and on Mars um I think everything that's useful can be done by machines much more cheap than by humans do you know the movie 2001 of Space Odyssey of course yes you must be too young to have SE that when he came out obviously H yeah I remember see when it came out you saw it when he came out yeah years ago 60 when was it 60 uh it was in the 60s yeah that's right still a classic it's still probably for me the greatest AI movie ever made yes yes I agree one of the great space movies ever made yes so well let me ask you a philosophical question since we're talking about robots exploring space do you think H 9000 is good or bad so for people who haven't watched this computer system makes a decision to uh uh basically prioritize the mission that the ship is on over the humans that are part yes of the mission um do you think Hal is good or evil if you ask probably in that context it was probably good but I think you're raising what is of course very much uh active issue in everyday life about the extent to which we should um entrust any important decision uh to machine and there again I'm very worried because I I think um if you are recommended for an operation or not given Paro from prison or even denied credit by your bank you feel you should be entitled to an explanation it's not enough to be told that the machine has a more reliable record um on the whole and humans have of making these decisions you think you should be given reasons you could understand and and that's why I think uh the present societal Trend to um uh take away the humans and leave us um in the hands of decisions that we can't contest uh is a very dangerous one I think we've got to be very careful of the extent to which AI which can handle lots of information actually makes the decisions without oversight and I think um we can use them as a supplement but to take the case of um uh radiology and cancer um I mean it's true that the rad radiologist hasn't seen as many uh X-rays of cancer lungs as the machine so the machine could certainly help but you want the human to make the final decision and I think that's true in most of of these instances but if we turn a bit to the shortterm concerns with the robotics I think the big worry of course is the uh effect it has on um people's self-respect and their labor market and I think um my solution would be that we should um arrange to tax more heavily than big International conglomerates which uh use the robots um and um use that tax to uh fund decently paid dignified posts of the kind where being a human being is important above all carers for old people teachers assistance for young gers in public parks and things like that and if the people who are now working in mind-numbing jobs in Amazon warehouses or in telephone call centers are automated but those same people are given jobs where being a human is an asset um then that's a Plus+ situation and so that's way I think that we should benefit from these these Technologies um take over the Mind numbing jobs um and uh you use machines to make them more efficient but um enable um the people so displaced to do jobs where we do want a human being I mean most people when they're when they're old um they rich people if they have the choice they want human carers and all that don't they they may want robots to help with some things empty the bed pans and things like that but but but they they want real people and uh uh and certainly in this country I think even worse in America um the the care of old people is completely inadequate and it needs just more human beings to help them cope with everyday life and look after them when they're sick and um uh and so um that seems to me the way in which the money raised in tax from these big companies should be deployed so that's in the short term but if you actually just look the fact that is where we are today to long-term future in 100 years it does seem that there is some significant chance that the human species is coming to an end in its pure biological form there's going to be greater and greater integration through genetic modification than cyborg type of creatures and so you have to think all right well we're going to have to get from here to there and that process is going to be painful and uh that you know how there's so many different trajectories that take us from one place to another it does seem that we need to deeply respect humanness and Humanity basic human rights human welfare like happiness and all that kind of stuff no absolutely and then that's why I think we ought to try and slow down the application of these human enhancement techniques and Cyborg techniques for humans for just that reason I mean uh that's why I want to lead into the people on Mars let them do it but but for just that reason but there are people too okay people on Mars are people too I I tend to you know but they are very poorly adapted to where they are right that's why they need this modification whereas we're adapted to to the Earth quite well so we don't need these modifications we're we're happy to be humans living in in the environment where our ancestors lived so we don't have the same same motive so I think there's a difference but I agree we we don't want drastic changes probably in in our our lifestyle um and that indeed is a worry because some things are changing so fast um but I think um I'd like to inject a note of caution um if you think of the way uh progress in one technology goes um it goes in a sort of spur it goes up very fast and then it levels off um let me give you two examples well one we've had already human space flight um at the time of the Apollo program which was only 12 years after Sputnik 1 um I I was alive then and I thought it would only be 10 or 20 years further before the were footprint Mars but as we know for reasons we could all understand um that was and Still Remains the high point of human space exploration um that's because it was funded for reason of superp power rivalry at huge public expense um but uh let me give you another case um civil aviation um if you think of the change between 1919 when that was oock and Brown's first transatlantic fight to 1979 the First Flight of the jumbo jet was a big change but it's more than 50 years since 1969 and we still have jumbo jet more or less the same so that's an example of something which developed fast and over and to take another analogy um we've had huge developments in uh mobile phones but uh I suspect the ibone the iPhone 24 may not be too different from the iPhone 13 and you know they they uh develop but then they saturate and then maybe some new innovation takes over in stimulating economic growth yeah so it's that uh we have to be cautious about being too optimistic and we have to be cautious about being too cynical I think that is the optimistic is begging the question I mean do do we want this R rapid change right so first of all there's some degree to which technological advancement is is something is a force that can't be stopped and so the question is about directing it versus stopping it or slow it can be sort of slopped or slow well take human space flight there could be have been uh footprints on Mars if if America had gone on spending 4% of the federal budget on the project after yes Apollo the reason so there were very good reasons but um and we could we could have had supersonic flight but Concord came and went during the 50 years during which but the reason it didn't progress is not because we realize it's not good for Human Society the reason it didn't progress is because it it couldn't make uh sort of from a capitalist perspective it couldn't make uh there there was no short-term or long-term way for it to make money so for M but is but that's the same mistake it's not good for society I don't think everything that makes money is good for society and everything that doesn't make money is bad for society right that's a that's a difficult that's a difficult thing we're always contending with when we look at social networks it's not obvious even though they make a tremendous amount of money that they're good for society especially how they're currently implemented with advertisement and engagement maximization so that's the constant struggle of oh you know I agree with you many Innovations are damaging yes yeah yes uh well but I would have thought that supersonic flight was uh something that would benefit only a tiny Elite sure huge expense and environmental damage that was obviously something which they're very glad not to have in my opinion yeah but perhaps there was a way to do it where it could benefit the general populace if you were to think about airplanes wouldn't you think that in the early days airplanes would have been seen as something that can surely only benefit 1% at most of the population as opposed to a much larger percentage there there's there's another aspect of capital a system that's able to drive down cost once you get the thing kind of going so the you know we get together maybe with taxpayer money and get the thing going at first and once it gets going companies step up and drive down the cost and actually make it so that uh blue collar folks can actually start using the stuff sometimes that does happen that's good yeah so it's that's again the the double- edge sword of uh human civilization that some technology hurts us some benefits us and we don't know ahead of time we could just do our best and there's a gap between what could be done and what we collectively decide to do yes in in the term you could push forward some developments um faster than do let me ask you in your book on the future prospects for Humanity you imagine a time machine that allows you to send a tweet length message to scientists in the past like to Newton yes um what tweet would you send it's an interesting thought experiment what message would you send to Newton about what we know today well I think he'd love to know that there were planet around other stars um he he'd like to know that uh that would really blow his mind he everything was made of atoms uh he'd like to know that if he looked a bit more carefully through his prisms um uh and uh looked at light not just from the Sun but from from some Flames he might get the idea that uh different substances emitted light of different different colors and he might have been twigged to discover some things that had to wait two or 3 hundred years could have given him those Clues I think it's kind of kind of it's fascinating to think to look back at how little he understood people at that time understood about our world yes and and certainly about the cosmos because of course well if we think about astronomy um then until about 1850 um U astronomy was a matter of um um uh the positions of how the stars and the planets moved around Etc of course that goes back a long way but Newton understood why the planets moved around in ellipses but uh he didn't understand um why the solar system was all in a plane what we call the ecliptic and uh he didn't understand it no one did till the mid 19th century what the stars are made of I mean they we thought they made of some fifth Essence not earth a and water like everything else you know um and it was only after 1850 when um people did use prisms more precisely to get to get Spectra that they realized that the the sun was made of the same stuff as the earth and the needed the stars were and uh it wasn't until um 1930 that people knew about nuclear energy and knew what kept the sun shining for for so long so it was quite late that some of these key ideas came in you know which would completely transform newon views and of course the entire scale of the Solus of the G Galaxy and than the rest of the Universe imagine came later what he would have thought about the Big Bang or even just general relativity gravity just just him and Einstein talking for for a couple weeks yeah would he be able to make sense of SpaceTime and the curvature of SpaceTime and well I think given a quick course I mean he was sort of uh if one looks back he he was really a unique intellect in a way you know and uh uh he said that he thought better than everything everyone else by thinking on things continually and thinking very deep thoughts and um so he he was a utterly remarkable intellect obviously but of course scientists aren't all like that I think it's very one thing interesting me having spent a life among scientists is what a variety of uh mindsets and mental Styles they have yes um and um um well just to contrast Newton and Darwin um Darwin uh said uh and he probably correct that he that he thought he just had a um as much sort of Common Sense and reasoning power as the average lawyer and that's probably true because his his ability was to sort of collect data and think through things deeply um that's a quite different kind of thinking from what was involved in in Newton or someone doing abstract mathematics I think in the 20th Century the coolest well there's the theory but from a astronomy perspective black holes is one of the most fascinating entities to have been through Theory and through experiment to have emerged from obviously I agree it's an amazing story that uh um well of course what's interesting is Einstein's reaction because of course although as you know we now accept this is one of the most REM predictions of Einstein's theory he never took it seriously even believed it yeah um although it was a consequence of uh solution of his equations which someone discovered just a year after his theory SW Shield um but he he never took it seriously and others did um but then of course um uh well this is something that I've been involved in actually find any evidence for black holes and that's come in the last 50 years and um so now there's pretty compelling evidence that they exist um as the remnants of stars or big ones in the centers of galaxies and we we understand uh what's the what's going on we have ideas vaguely on how how they form and of course uh gravitation waves have been detected and that's an amazing piece of technology ligo is one of the most incredible engineering efforts of all time that's an example where the engineers deserve the most of the credit because the Precision is well as they said it's like measuring the thickness of a hair at the distance of alpha centu yeah it's incredible 10us 21 so maybe actually if we step back what are black holes what do we humans understand about black holes and what's still unknown Einstein's theory extended by people like Roger Penrose tells us that um black holes are in a sense rather simple things basically because they are um um Solutions of Einstein's equation um and the thing that was shown in the 1960s by Roger Penrose in particular um and by a few other people was that um a black hole when it forms and settles down is defined just by two quantities its mass and its spin so they're actually very standardized objects it's amazing that objects as standardized as that um can be so big and can lur in the vessel solar system and so that's the situation for a ready formed black ho but the way they form obviously is very messy and complicated um and uh uh one of the things that I've worked on a lot is um what the phenomena are which are best attributed to black holes and what they lead to them and all that and um uh which can you explain to that so what what what are the different phenomena the Leo black ho let's let's talk about it this is so so cool so yes okay okay well I mean I think one thing that only became understood really in the 1950s I suppose and Beyond was um uh how Stars evolve differently depending on how heavy they are yeah this the sun um Burns H into helium and then when it's run out of that it contracts to be a white dwarf and we know how long that will take take about 10 billion years altogether for its lifetime um but big stars burn up their fuel more quickly and more interesting because when they've turned hydrogen to helium they then get even hotter so they can fuse helium into carbon and go up the periodic table and then they eventually explode when they have an En crisis and they blow out that process material which as a digression is crucially important because um all the atoms inside our bodies were synthesized inside a star a star that lived and died more than 5 billion years ago before Asos formed and so we each have inside us atoms made in thousands of different stars all over the Milky Way and that's an amazing idea and my predecessor Fred Hy in 1946 was the first person to suggest that idea and that's been born out that's a wonderful idea um so um that's how massive stars explode and they leave behind something which is very exotic and of two kinds one possibility of neutron star and these were first discovered in 1967 68 um these are Stars a bit heavier than the sun uh which are compressed to an amazing density so the whole mass of more than the Sun's mass is in something about 10 miles across so um they're extraordinary dense the Exotic physics um and they they've be they've been studied in immense detail and they've been real Laboratories because the good thing about astronomy apart from exploring what's out there is to use the fact that the cosmos has provided us with a lab with far more extreme conditions than we could ever simulate and so we learn lots of basic physics from looking at these objects um and that's been true Neutron but for black holes that's even more true because the um uh bigger stars um when they collapse they leave something behind in the center which is too big to be a stable by two or four neutron star becomes a black hole and we know that there are lots of black holes weighing about 10 up to 50 times as much as the sun which are the remnants of of stars they were detected first 50 years ago when a black hole was orbiting around another star and grabbing material from the other star which swirled into it and gave us x-ray so the x-rays astronomers found these um uh objects orbiting around an ordinary star and emitting x-ray radiation very intensely varying on a very short time scale so something very small and dense was giving that radiation that was the first evidence for black holes um but then the other thing that happened was realizing that there was a different class of monster black holes in the centers of galaxies and um these are respon for what's called quazars which is when um something in the center of a galaxy is grabbing some fuel and outshines all the 100 billion stars or so in the rest of the Galaxy giant beam yeah light and in many cases it's be it's a be it's a beam is that that's got to be the most epic thing the universe produces is quazars um well it's a it's a debate of what's most epic but qu quazars maybe or maybe gam burst or something but but they they are remarkable and they were a mystery for a long time and they're one of the things I worked on in my younger days so even though they're so bright they're still a mystery and but you can only see I think they're less of a mystery now I think we do understand basically what's going on how how were quers discovered well they were discovered when astronomers found things that looked like stars and that they were small enough to be a point like not resolved by a telescope but uh uh out sha an entire galaxy yeah and uh that's suspicious yes but um but then they they realized that what they were they were um uh object which you now know are black holes and they were um black holes were capturing gas and that gas was getting very hot but it was producing um far more energy than all the stars added together and it was the energy of the uh black hole that was um lighting up all the gas in the Galaxy so you've got a spectrum of it there so so this was something which was realized from the 1970s onwards um and and uh as you say the other thing we've learned is that they often do produce these Jets squirting out um which could be detected in in all wave bands so um picture black hole generating Jets of light at the center of most galaxies right do we know do we have a sense if every galaxy has one of these big big boys well black holes most Galaxies have big black holes they vary in size the one in our galactic center do we know much about ours we do yes we um we know um it weighs about as much as 4 Million Suns Which is less than some which are several billion in other galaxies um and but we know this um one our Center isn't very bright or conspicuous and that's because not much is falling into it at the moment if if a black hole is isolated then of course it doesn't radiate it only all that radiates is gas swirling into it which is very hot or has magnetic it's only radiating the thing it's murdering or consuming however you put it yeah that's right and so so um it's thought that our galaxy may have been bright bright at sometime in the past but now and that's when the black hole formed or grew um but but now it's uh not um capturing very much gas and so it's it's rather it's rather faint and only detected indirectly and by fairly we radio Mission and uh and so I think the answer to your question is that um we suspect that most Galaxies have a black hole in them so that means at some stage in their lives or maybe one or more stages they went through a phase of being like a quazar where that black hole um captured gas and became very very bright but for the rest of the the lives the black holes are fairly quiescent because there's not much gas falling into them and so this universe of ours is sprinkled a bunch of galaxies and giant black holes with like very large number of stars uh orbiting these black holes and then planets orbiting likely it seems like planets orbiting almost every one of those stars and just this beautiful Universe of ours what happens when galaxies Collide when these two big black holes Collide is that is well um what would happen is that uh well and I should say that um this is going to happen near us one day but not for four billion years because the Andromeda galaxy which is the biggest galaxy near to us which is about nearly three million life years away which is Big disc Galaxy with the black hole his Hub rather like our Milky Way and um that's uh um in Falling Towards us because they're both in a common gravitational potential well and um that will collide with our galaxy in about 4 billion years but it'll be it'll be maybe it'll be less a collision and more of a dance because there'll be like a swirling situation swirling but eventually there'll be to be a merger they'll go through each other and then merge in fact uh um the nice movies to be made of this you know computer simulations and it it'll go through um and um and then um the there's a black hole in the sense of Ander and our galaxy and the Galax the black holes will uh settle towards the center yes then they will orbit around each other very fast and then they will eventually merge and that'll produce a big burst of gravitational waves yes um a very big burst that an alien civilization with a Lego leg detector will be able to detect yes well in fact well but we can detect these with um they lower frequencies than the ways that have been detected by ligo so there's a space aerometer which can detect these they're about it's about one cycle per hour rather than about 100 cycles per second the ones detected um but that that would happen but um uh thinking back to what will happen in four billion years to any of our descendants they'll be okay because the um the two disc galaxies will merge it end up as a sort of amorphous ellip IAL Galaxy but um the Stars won't be much closer together they are now it it'll still be just twice as many stars in the structure almost as big and so um the chance of another star colliding with our sun would still be very small because there's actually a lot of space between indeed stars and planets and yes the chance of a star getting close enough to affect our Solar System's orbit is small and it won't change that very much so you could be reassured a heck of a Starry Sky though what would that look like well it won't make much difference even to that actually it'll just be um wouldn't that look kind of beautiful when you're swirling or is oh cuz it's swirling so slowly yeah but they're far away so be be twice as many stars in the sky yeah and but the pattern changes pattern will change a bit and uh there won't be the Milky Way because the Milky Way uh across the sky is because we are looking in the disc of our galaxy and uh you lose that because the um the dis will be so disrupted and uh it'll be a more sort of spherical distribution and of course many Gs are like that um and that's probably because they have been through merges of this kind if we survive 4 billion years we would likely be able to survive beyond that oh yeah what what's the other thing on the horizon for humans uh in terms of the sun burning out all those kinds of interesting cosmological threats to our civilization well I think on the cosmological time scale because it won't be humans because something even Evolutions go no faster than darwinian and I would argue it will be faster than darwinian in the future uh then um we're thinking about six billion years before the Sun dies so any entities watching the death of the sun if they're still around they be different much as we are from slime mold or something you know and far more different still if they become electronic so on that time scale we just can't predict anything but I think going back to um uh to to the human time scale um then um we've talked about whether there'll be people on Mars by the end of a century and uh even in these long perspectives then indeed this century is very special because it may see the transition between purely Flesh and Blood entities to those which are sort of cyborgs and that'll be a an important transition in um um in in biology and complexity in this Century but of course the other importance and this has been the theme of A couple of my older books is that um this is the first century when one species namely our species has the future of the planet in his hands and that's because of uh um two types of uh concerns one is that there are more of us where more demanding of energy and resources and therefore we are for the first time uh changing the whole planet through um um climate change loss of biodiversity and all those issues this has never happened in the past because haven't been enough humans hav't been much in so this is a um an effect that's obviously is high on everyone's agenda now and rightly so because um we've got to ensure that we leave a Heritage that isn't eroded or damaged to Future Generations um and so so that's one class of threats but there's another thing that worries me perhaps more than many people seem to worry and that's the uh threat of misuse of technology and so this is particularly because um Technologies Empower even small groups of of uh malevolent people or indeed in careless people to create some effect which could cas globally and um um to take an example um a uh a dangerous pathogen or pandemic um I mean my worst nightmare is that um there could be um some small group that uh can engineer a virus to make it more varant or more transmissible than a natural virus this is soal gain of function experiments which were done on the flu virus 10 years ago and can be done for others um and of of course we now know from covid-19 uh that um uh our world is so interconnected that a disaster in one part of the world can't be confined to that part and was spread globally so it's possible for a few dissidents with expertise in biotech could create a global catastrophe of that kind and also I think um uh we need to worry about Bay large scale disruption by cyber attacks in fact um I quote in one of my books a 2012 report from the uh American Pentagon uh about the um possibility of a state level Cyber attack on the electricity Grid in the eastern United States which is it could happen and it says at at the end of this chapter that this would Merit a nuclear respon MH it's a pretty scary possibility that was 10 years ago and I think now what would have needed a state actor then could be done perhaps by a small group empowered by Ai and so there's obviously been a um an arms raised between the uh um the Cyber criminals and the cyber security people not clear which side is winning but the main point is that as we become more dependent on more Integrated Systems then uh we get more vulnerable and uh um and so we have the knowledge then the misuse of that knowledge becomes um uh more and more of a threat and and i' say bio and cyber are the two biggest concerns um and uh if we depend too much on AI and complex systems then um just breakdowns it may be that they they break down and um um even if it's innocent breakdown then it may pretty hard to mend it and just think how much worse the pandemic would have been if we'd lost the internet in the middle of it we be depended more than ever for communication and everything else on on on the internet and zooms and all that um and if that that had broken down that would have made things far worse and those are the kinds of threats that we I think need to be more energized and politicians need to be more energized um to uh minimize and um one of the things I've been doing the last year um through being a member of our part of our Parliament is sort of a um I help to instigate a committee to think more on better preparedness for um extreme technological risks and things like that so they're a big concern in my my mind that uh we've got to make sure that we um can benefit from these um uh advances um but safely because um the stakes are getting higher you the benefits are getting great as we know huge benefits from from computers but but also huge downsides as well and one of the things this war in Ukraine has shown of the most terrifying things outside of the humanitarian crisis is that at least for me I realized that the human capacity to initiate nuclear war is greater than I thought I thought the lessons of the past have been learned it seems that we hang on the brink of nuclear war with this conflict like every single day we just just one mistake or bad actor or the actual leaders of the particular Nations launching a nuclear strike and all hell broke breaks loose so then adding to that picture cyber attacks and so on that can lead to to confusion and chaos and then out of that confusion um calculations are made such that uh a nuclear launch is a nuclear weapon is launched and it's and then you're talking about I I mean I don't the directs probably 60 70% of humans on Earth are dead instantly and then the rest I mean it's uh basically 99% of the human population is wiped out in the period of well it years that bad be devastating for civilization of course and of course you're quite right that this could happen very quickly um because of uh um information coming in and there's a there's hardly enough time for human um collected and careful thought and there have been uh recorded cases of false alarms there several where um where they've been suspected um attacks from the other side and uh um fortunately they've been realized to be false alarm soon enough but but this could happen and there's a new class of threats actually which in in our Center in Cambridge people are thinking about which is that um um the uh Commander control system of the nuclear weapons and the submarine Fleet and all that um is now more automated and uh could be subject to cyber attacks and that's a new threat which didn't exist 30 years ago and so um I think indeed it it's it's we're in a sort of scary world I think um and uh it's because things happen faster and human beings aren't in such direct and immediate control because so much is delegated to machines um and also because the world is so much more interconnected uh than uh some um local event can Cascade globally in a way it never could in the past and much faster yeah it's a double Ed sword because the inter interconnectedness brings um um brings a higher quality of life across a lot of metrics yeah it can do but of course there again I mean if you think of Supply chains where we get stuff from around the world then um one lesson we've leared is that there's a trade-off between resilience and efficiency and is resilient uh to have um an inventory in stock and to depend on local supplies where it's more efficient to have um long Supply chains but the risk there is that a a break in one Link in one chain can screw up car production this has already happened in the pandemic so so there's a tradeoff and there are other examples I mean for instance the other thing we learned was that uh uh it may be efficient to have 95% of your hospital intensive care beds occupied all the time which has been the UK situation whereas to do what the Germans do and always keep 20% of them free for an emergency is really a sensible precaution and so I think um we've probably learned a lot of lessons from covid-19 and they would include um rebalancing the tradeoff between resilience um and efficiency boy the the fact that co9 a pandemic that could have been a lot a lot worse brought the world to its knees anyway it could be far worse in terms of its fatality rate or something fality rate so the fact that that I I mean it revealed so many flaws in our human institutions yeah yeah and then I I think you I'm rather pessimistic because um uh I do worry about the uh the B bad actor or the small group who can produce catastrophe um and um uh if you imagine someone with access to the kind of equipment it's available in University Labs or industrial labs and they could create some dangerous p pen um then even one such person is too many and how can we stop that because uh it's true that you can uh have regulations I mean academies are having meetings Etc about how to regulate these new biological experiments Etc make them safe but even if you have all these regulations then enforcing regulations is yeah pretty hopeless we can't enforce the tax laws globally we can't enforce the drug laws globally and so similarly we can't readily enforce the um laws against people doing these dangerous experiments even if all all the governments say they should be prohibited and so my my line on this is that uh all nations are going to face a big trade-off between three things we value um Freedom security and privacy and I think uh um different nations will uh make that choice differently um the Chinese would give up privacy and have more certainly more security if not more Liberty um but I think uh um in in our countries um I think we're going to have to give up more privacy in the same way that's a really interesting tradeoff um but there's also something about human nature here where I personally believe that all humans are capable of Good and Evil and there's some aspect to which we can fight this by encouraging people incentivizing people towards uh the better angels of their nature so uh in order for a small group of people to create to engineer deadly pathogens you have to have people that for whatever trajectory took them in life wanting to do that kind of thing and if we can aggress ly work on a world that sort of sees the beauty in everybody and encourages the flourishing of everybody in terms of mental health in terms of meaning in terms of all those kinds of things that's one way to fight the development of um uh of weapons that can lead to atrocities yes and I completely agree with that and to reduce the reason why people feel embittered yes um um but of course we've got a long way to go to do that because uh if you look at the present World um nearly everyone in Africa has reason to feel imited because um their economic development is lagging behind most of the rest of the world and the prospect of getting out of the poverty trap is uh is rather Bleak especially if the population grows because for instance um they can't develop like Eastern tigers by Cheap manufacturing because robots are taking that over uh so that they were naturally feel embittered um uh by the inequality and of course um what we need to have is some sort of mega version of the Marshall Plan that helped Europe in the post World War II era um to enable Africa to develop that would be um not just an altruistic thing for Europe to do but in our own interest because otherwise um uh those in Africa will feel massively disaffected um and indeed um it's a manifest ation of the excessive inequalities the fact that the 2,000 richest people in the world have enough money to double the income of the bottom billion and uh that's um you know an indictment of the ethics of the world and this is where I've I my friend Steven Pinker and I have had some contact we wrote joint articles on bio threats and all that um but um um he writes these books being very optimistic about quoting figures about how uh um life expectancy has gone up infant morality has gone down literacy has gone up and all those things and he's quite right about that um and so he says the world's getting getting better and do you disagree with your friend Steph Pinker well I mean I I agree with those facts okay but but I think he misses our he misses our part of the picture um because um there's a new class of of FRS which uh um hang over us now which didn't hang over us in the past and I would also question whether we have collectively improved our ethics at all because um uh let's think back to the Middle Ages it's true that as Pinker says the average person was uh in a more miserable State than they are today on average um for all the reasons he quantifies that's that's fine um but in the Middle Ages there wasn't very much that could have been done to improve people's lot in life because of lack of knowledge and lack of science Etc and so the gap between the way the world was which is pretty miserable and the way the world could have been which wasn't that much better was fairly narrow whereas now the gap between the way the world is and the way the world could be is far far wider and therefore I think we are ethically um more uh um at fault uh in allowing this Gap to get wider than it was in medieval times and so I I would very much question and dispute the idea that we are ethically um in advance of our predecessors that's a lot of interesting hypotheses in there and I don't there it's a it's a fascinating question of how much is the size of that gap between the way the world is in the way the world could be is a reflection of our ethics or maybe sometimes it's just a reflection of a very large number of people uh like maybe it's a a technical challenge too it's not just well of our political systems systems like how many and we're trying to figure this thing out like there's 20th century tried this thing that sounded really good on paper of collective the communism type of things and it's like turned out at least the way it was done there that leads to atrocities and the suffering and the murder of tens of millions of people okay so that didn't work let's try democracy and that seems to have a lot of flaws but it seems to be the best thing we got so far so we're trying to figure this out out as our Technologies become more and more powerful have the capacity to do a lot of good to the world but also unfortunately have the capacity to destroy the entirety of the human civilization and I think it's social media generally uh which uh um makes it harder to get a a sort of moderate consensus because in the old days when people got their news filtered through responsible journalists in this country the BBC and they made newspapers Etc and they would muffled the crazy extremes whereas now of course um they're on the internet and if you click on them you get to this still more extreme and so I think we are seeing a sort of dangerous polarization which I think is going to make all countries harder to govern and that something we find pessimistic about so to push back it is true that brilliant people like you highlighting the limitations of social media is making you realize the the stakes and the failings of social media but at the same time they're revealing the division it's not like they're creating it they're revealing it in part and so that puts a lot of uh that puts the responsibility in into the hands of social media and the opportunity in the hands of social media to alleviate some of that division so it could in the long Arc of human history result so bringing some of those uh divisions and the anger and the hatred to the surface so that we can talk about it and as opposed to uh disproportionately promoting it actually just surfacing it so we can get over well you're assuming that the uh the fat cats are more public spirited than the politicians and I'm not sure about that I think there's a lot of money to be made in being publicly spirited I think there's a lot of money to be made in increasing the amount of love in the world despite the sort of public perception that all the social media companies heads are interested in doing as making money I think that may be true but I just personally believe people being happy is a hell of a good business model and so making as many people happy helping them flourish in a long-term way that's a lot of way to make people that's a good way to make well I think on the other I think guilt and shame are good motives to make you behave better in the future okay so that's my my experience in the political perspective certainly certainly is the case but it does make sense now that we can destroy ourselves with nuclear weapons with engineered pandemics and so on that the aliens would show up that like if I was the um you know had a leadership position maybe as a scientist or otherwise in an alien civilization and I would come upon Earth I would try to watch from a distance to not interfere yeah and I would start interfering when these life forms start becoming quite that have the capacity to be destructive and so I mean it's it is an interesting question when people talk about uos sightings on all those kinds of things that at least these are benign aliens you're thinking benign yes I mean they benign almost curious almost um partially as with all curiosity partially selfish to try to observe is there something interesting about this particular evolutionary system because I'm sure even to aliens Earth is a curiosity y but it's in this very special stage you know speci perhaps centy is very special among the 45 million centuries the Earth experienced already so it is a very special time where they should be specially interested but um I think going back to the um the politics um the other problem is uh getting people who have short-term concerns to care about the long term by the long term I now mean just looking 30 30 years or so ahead you I know people who've been scientific advisers to governments and things and they may make these points but of course they don't have much traction because as we know very well any politician has an urgent agenda of very worrying things to deal with and so um they aren't going to prioritize these issues which are um longer longer term andless immediate and don't just concern their constituency they concern dist parts of the world um and so I think I think um what what we have to do is to um um uh enlist charismatic individuals to convert the public because if the if the politicians know the public care about something climate change as an example um then then uh they they will make decisions which um uh take cognizance of that um and I think for that to happen uh then we do need some um public individuals who are respected by everyone um and to have a high profile and in the climate context I I would say that I mentioned four very desperate people who've had such a big effect in the last few years one is Pope Francis the other's David atenor the other's Bill Gates and the other's greater thorberg and those four people have certainly had a big shift in public opinion um and uh uh and even change the rhetoric of business although how deep that is I don't know and so but but politicians um can't let these issues drop down off the agenda um if if there's a public clamor and it needs people like that to keep the public climate going to push back a little bit so those four are very interesting and I have deep respect for them they have except David Andor uh David Andor is really I mean everybody loves him I mean I can't say but the you know with Bill Gates and Greta there's that that also has created a lot of division oh sure yeah yeah and this is a big problem so it's not just charismatic I I put that responsibility actually on the scientific community and Pope does too yeah yep uh and the politicians so we need the charismatic leaders and they're rare yeah yeah when you look at human history those are the ones that make a difference those are the ones that um not deride they they Inspire the populace to think long term the JFK we do we go to the moon in this decade not because it's easy but because it is hard there's no discuss about like um shortterm political gains or any of that kind of stuff uh in in the vision of going to the Moon yeah or going to Mars or taking on gigantic uh uh projects or taking on world hunger or taking on climate change or uh the education system all those things that require long-term significant investment that that requires but it's hard to find those people and and incidentally I think another problem is which is a downside of social media is that um uh of younger people I know um the number who would contemplate a political career has gone down because of the the pressures on them and their family from social media um it's a hell of a job now um and so I think we are all losers because the quality of people who choose that uh path is um is is really dropping and as we see by the quality of those who are in these composition that said I think uh the Silver Lining there is the quality of the competition actually is inspiring because it's it's it shows to you that there's a dire need of leaders which I think would be inspiring to young people to step into the fold I mean great leaders are not afraid of a little bit of a little bit of uh fire on social media so if you have you have a 20-year-old kid now 25-year-old kid is seeing how the world respond responded to the pandemic seeing the geopolitical division over the war in Ukraine seeing the Brewing war between the west and China we need great leaders and there's a hunger for them and the time will come when when when they step up I I I I believe that but also to add to your list of four he doesn't get enough credit I've been defending him in this conversation Elon Musk in terms of the fight in climate change uh but he also has led to a lot of division but we we need more David en yeah no no I mean I'm a fan I'm definitely I mean I've heard him described as a 21st century Brunell for his Innovation and that that's true but uh um whe whether he's a an ethical inspiration I don't know yeah he has a a lot of fun on Twitter well let me ask you to put on your wise Sage hat what advice would you give to young people today maybe they're teenagers in high school maybe early college uh what advice would you give to a career or have a life they can be proud of yes well I'd be very diffident really um about offering any any wisdom but uh I think I think they they should they should realize that um um the choices they make at that time are um important and um from experience of I've had with many friends um many people don't realize that opportunities open until it's too late they somehow think that some opportunities are only open to a few privileged people and they don't even try and and they could succeed um but um if I focus on people working in um some profession I know about like science I would say pick an area to work in where new things are happening uh where uh you can uh do something that the old guys never had a chance to think about um don't go into a field that's fairly stagnant because then um there won't be much to do or you'll be trying to tackle the problems that the old guys got stuck on and so I think in science um I can give people good advice that they should um pick a subject where there are exciting new developments and also of course something which uh suits their style because even within science which is just one profession um there's a big range of style between the sort of solitary thinker the person who does field work the person who works in a big team Etc and whether you like Computing or mathematical thought Etc so pick some subject that suits your style and where things are happening fast um and uh be prepared to be flexible that's what what I'd say really keep your eyes open for the opportunity throughout like you said go to a new field go to a field where new cool stuff is happening just keep your eyes open yes that's pudus but I think most of us and I include myself in this didn't realize this sort of thing is too late yeah I think this applies Way Beyond science um what do you make of this finiteness of our life do you think about death do you think about mortality do you think about your mortality and are you afraid of death well I mean I'm not afraid because I I think I'm lucky I feel lucky to have L as long as I have um and uh and to have been fairly Lucky in um in my life in many respects compared to to most people so I feel very fortunate um uh this reminds me of this current uh um emphasis on uh living much longer than these So-Cal alos Laboratories um which have been set up by billionaires um there's one in San Francisco one in uh La Hoya I think and one in Cambridge and uh that they're funded by um these guys who when young wanted to be rich and now they're rich they want to be young again they won't find that quite so easy and do we want this I don't know if if there was um some Elite that was able to live much longer than others that would be a really fundamental kind of inequality and um I think um if it happened to everyone then that might be an improvement it's not so obvious um but uh uh I think um for my my part I think to have lived as as long as most people um and had a fortunate life is all I can expect and a lot to be grateful for those are all platitudes well I am incredibly honored that you sit down with me today I thank you so much for life of exploring some of the deepest mysteries of our universe and um of our humanity and thinking about our future with existential risks that are before us um it's it's a huge honor Martin that you sit with me and I really enjoyed it and well thank you Lex I thought we couldn't go on for as long as this but we could have gone on much longer I think exactly thank you so much thank you for listening to this conversation with Martin reee to support this podcast please check out our sponsors in the description and now let me leave you with some words from Martin Ree himself I'd like to widen people's awareness of the tremendous time span lying ahead for our planet and for life itself most educated people are aware that were the outcome of nearly 4 billion years of darwinian selection but many tend to think that humans are somehow the culmination our son however is less than halfway through its lifespan it will not be humans who watch the sun's demise 6 billion years from now any creatures that then exist will be as different from us as we are from bacteria or amoeba thank you for listening and hope to see you next time