Loved the interview as layman but curious about the subject! <br><br>(On life outside of earth, I wanted to check how the numbers play out. So, voyager 1 has travelled less than a mpc (0.7 milliparsecs), whereas visible universe is 29 Gpc - our space exploration has covered ~10^(-14) of what's out there, not sure if I'd call that exhaustive. The distance it's covered is ~5*10^(-4) times the distance to nearest observed liveable-like planet (Proxima Centauri b according to google). <br><br>Also, there's only been an intelligent (enough to eventually go to space) species around for ~10^(-4) of the total time since life was born (and ~10^(-5) of the total time universe's been here). <br>Both of those numbers give kinda small windows of opportunity for mingling. Let's say that e.g. smart species extinct themselves often, or that the time it takes to develop smart life in the first place has large variance, I could see how the cases where species find each other might be rare. <br><br>Some of the better odds include Earth's lifetime, which is ~0.3 of the Universe's lifetime (4.5 By compared to 13.8 By) - so other planets should be around (closest perceivably liveable planet seems to be around 1 pc away, not sure about density of such stars but seems like we only had to look to the nearest star system to us to find one so probably not rare. Btw it's around the same age as Earth as well); and life being born during a planet's lifetime (it's been around for ~0.8 of earth's lifetime) - which makes me think life of some sort should be around on those liveable planets.<br><br>But it's not us that has to be exhaustive, but the other species. Since there have been stars since forever, some lifeforms from the earliest ones could have had time to shape up in their space comms for over almost 10 By by now. In the last hundred years, where we've actually understood something about light, as long as they're 30 pc away (within 10^{-9} of visible universe size, 10^{-3} of Milky Way size), they could've reached us with light. Milky Way is 30kpc large, with ~3200 stars, oldest of which are over 13 By, and some of them are within 30 pc. Which indeed would point towards loneliness : ( )<br>Show less