David Kipping is an astronomer at Columbia University, director of the Cool Worlds Lab, and host of the Cool Worlds YouTube channel. Please support this podcast by checking out our sponsors: - SimpliSafe: https://simplisafe.com/lex - Shopify: https://shopify.com/lex to get free trial - ExpressVPN: https://expressvpn.com/lexpod to get 3 months free EPISODE LINKS: David's Twitter: https://twitter.com/david_kipping David's YouTube: https://youtube.com/@CoolWorldsLab Cool Worlds Lab: https://coolworldslab.com/ PODCAST INFO: Podcast website: https://lexfridman.com/podcast Apple Podcasts: https://apple.co/2lwqZIr Spotify: https://spoti.fi/2nEwCF8 RSS: https://lexfridman.com/feed/podcast/ YouTube Full Episodes: https://youtube.com/lexfridman YouTube Clips: https://youtube.com/lexclips SUPPORT & CONNECT: - Check out the sponsors above, it's the best way to support this podcast - Support on Patreon: https://www.patreon.com/lexfridman - Twitter: https://twitter.com/lexfridman - Instagram: https://www.instagram.com/lexfridman - LinkedIn: https://www.linkedin.com/in/lexfridman - Facebook: https://www.facebook.com/lexfridman - Medium: https://medium.com/@lexfridman OUTLINE: Here's the timestamps for the episode. On some podcast players you should be able to click the timestamp to jump to that time. (00:00) - Introduction (05:10) - Habitable exoplanets (15:30) - Alien life in our Solar System (27:20) - Starship (31:28) - James Webb Space Telescope (44:47) - Binary planets (55:04) - Exomoons and Kepler-1625b (1:08:34) - Discoveries of alien life (1:22:15) - Aliens (2:08:43) - Oort clouds (2:19:30) - Future of astronomy (2:32:45) - Alpha Centauri (2:45:03) - Kardashev scale (2:56:41) - AI and space exploration (3:13:37) - Great Filter (3:24:51) - Colonization of Mars (3:31:35) - Simulation hypothesis (3:43:48) - Advice for young people (3:48:06) - Meaning of life
Chapter 1: What is discussed at the start of this section?
The following is a conversation with David Kipping, an astronomer and astrophysicist at Columbia University, director of the Cool Worlds Lab, and he's an amazing educator about the most fascinating scientific phenomena in our universe. I highly recommend you check out his videos on the Cool Worlds YouTube channel. David quickly became one of my favorite human beings.
I hope to talk to him many more times in the future. And now a quick few second mention of each sponsor.
Chapter 2: How does the concept of habitable exoplanets emerge?
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Chapter 3: What challenges are faced in detecting Earth-like planets?
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Chapter 4: How do moons influence the habitability of planets?
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Your research at Columbia is in part focused on what you call cool worlds or worlds outside our solar system where temperature is sufficiently cool to allow for moons, rings and life to form and for us humans to observe it. So can you tell me more about this idea, this place of cool worlds?
Yeah, the history of discovering planets outside our solar system was really dominated by these hot planets. And that's just because of the fact they're easier to find. When the very first methods came online, these were primarily the Doppler spectroscopy method, looking for wobbling stars, and also the transit method.
And these two both have a really strong bias towards finding these hot planets. Now, Hot planets are interesting. The chemistry in their atmosphere is fascinating. It's very alien. An example of one that's particularly close to my heart is TRACE-2b, whose atmosphere is so dark, it's less reflective than coal.
And so they have really bizarre photometric properties, yet at the same time, they resemble nothing like our own home. And so it said there's two types of astrophysicists. The astrophysicists who care about how the universe works. They want to understand the mechanics of the machinery of this universe. Why did the Big Bang happen? Why is the universe expanding? How are galaxies formed?
And there's another type of astrophysicist which perhaps speaks to me a little bit more. It whispers into your ear, and that is why we hear Are we alone? Are there others out there? And ultimately, along this journey, the hot plants aren't going to get us there.
When we're looking for life in the universe, it seems to make perfect sense that there should be plants like our own out there, maybe even moons like our own planet around gas giants that could be habitable. And so my research has been driven by trying to find these more terrestrial globes that might resemble our own planet.
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Chapter 5: What are the challenges of faster-than-light travel?
It could be any faster-than-light system. As long as it travels superluminarily, it will violate causality. Presumably, that will be observable with LIGO.
potentially yeah potentially depends on i think you know the properties of whatever the spacecraft is um i mean one one problem with warp drives is there's all sorts of problems with warp drives but when like the start of that sentence one problem yeah there's just this one minor problem that we have to get around but uh when it arrives at its destination it basically collects this vast uh
It has an event horizon almost at the front of it, and so it collects all this radiation at the front as it goes. And when it arrives, all that radiation gets dumped on its destination and would basically completely exterminate the planet it arrives at. That radiation is also incident within the shell itself. There's Hawking radiation occurring within the shell, which is pretty dangerous.
Chapter 6: How do warp drives impact the Fermi paradox?
And then it raises all sorts of exacerbations of the Fermi paradox, of course, as well. So you might be able to explain why we don't see a galactic empire. I mean, even here it's hard. You might be able to explain why we don't see a galactic empire if everybody's limited to Voyager 2 rocket speeds of like 20 kilometers per second or something.
But it's a lot harder to explain why we don't see the stars populated by galactic empires when warp drive is eminently possible because it makes expansion so much more trivial that it makes our life harder. There's some wonderful simulation work being done out of Rochester where they actually simulate all the stars in the galaxy,
or a fraction of them, and they spawn a civilization on one of them, and they let it spread out at sublight speeds. And actually the very mixing of the stars themselves, because the stars are not static, they're in orbit of the galactic center and they have crossing paths with each other,
if you just have a range of even like five light years and your speed is of order of a few percent, the speed of light is the maximum you can muster, you can populate the entire galaxy within something like 100,000, about a million years or so. So a fraction of the lifetime of the galaxy itself. And so this raises some fairly serious problems because
if any civilization in the entire history of the galaxy decided to do that, then either we shouldn't be here or we happen to live in this kind of rare pocket where they chose not to populate to. And so this is sometimes called fact A, Hart's fact A. The fact A is that a civilization is not here now. An alien civilization is not in present occupation of the Earth. And that's difficult to
resolve with the apparent ease at which even a small extrapolation of our own technology could potentially populate a galaxy in far faster than galactic history so to me by the way yeah the firm paradox is truly a paradox for me but i suspect that if alien visit earth
I suspect if they are everywhere, I think they're already here and we're too dumb to see it. But leaving that aside, I think we should be able to, in that case, have very strong,
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Chapter 7: What future technologies could aid in space exploration?
when we look up at the stars, at the emanation of energy required. We would see some weirdness that like where these are these kinds of stars and these are these kinds of stars that are being messed with, like leveraging the nuclear fusion of stars to do something useful.
Like the fact that we don't really see that, like maybe you can correct me, wouldn't we be able to, if there is like alien civilizations running galaxies, Wouldn't we see weirdnesses from an astronomy perspective with the way the stars are behaving?
Yeah, it depends exactly what they're doing. But the Dyson sphere example is one that we already discussed where a survey of 100,000 nearby galaxies find that they have all been transformed into Dyson sphere collectors. You could also imagine them doing things like, we wrote a paper about this recently, of starlifting where you can extend the life of your star by scooping mass off the star.
So you'd be doing stellar engineering essentially. space. If you're doing a huge amount of asteroid mining, you would have a spectral signature because you're basically filling the solar system with dust. By doing that, there'd be debris from that activity. And so there are some limits on this. Certainly we don't see
bright flashes which would be one of the consequences of warp drives as I said is as they decelerate they produce these bright flashes of light we don't seem to see evidence of those kind of things we don't see anything obvious around the nearby stars or the stars that we've surveyed in detail beyond that that indicate any kind of artificial civilization.
The closest maybe we had was Boyajian star that there was a lot of interest in. There was a star that was just very peculiarly dipping in and out its brightness.
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Chapter 8: How do we define the meaning of life and our existence?
And it was hypothesized for a time that that may indeed be some kind of Dyson-like structure, so maybe a Dyson sphere that's half-built. And so as it comes in and out, it's blocking out huge swaths of the star. It was very difficult to explain really with any kind of planet model at the time.
But an easier hypothesis that was proposed was it could just be a large number of comets or dust or something, or maybe a planet that had broken apart, and as its fragments orbit around, it blocks out starlight.
And it turned out with subsequent observations of that star, which especially the amateur astronomy community made a big contribution to as well, that the dips were chromatic, which was a real important clue that that probably wasn't a solid structure then that was going around it. It was more likely to be dust. Dust is chromatic. By chromatic, I mean it looks different in different colors.
So it blocks out more red light than blue light. If it was a solid structure, shouldn't do that. It should be opaque, a solid metal structure or something. So that was one of the clear indications. And the behavior of the way the light changed or the dips changed across wavelength was fully consistent with the expectations of what small particulates would do. And so that's very hard.
The real problem with alien hunting The technical term. This is the real problem. The one problem.
The one problem with the warp drive and the one problem with alien hunting, yes.
Actually, I'd say there's three big problems for me with any search for life, which includes UFOs or the way to fossils on Mars. is that aliens have three unique properties as a hypothesis. One is they have essentially unbounded explanatory capability. So there's almost no phenomena I can show you that you couldn't explain with aliens to some degree.
You could say, well, the aliens just have some super high-tech way of creating that illusion. But The second one would be unbounded avoidance capacity. So I might see a UFO tomorrow and then the next day and then the next day and then predict I should see it on Thursday at the end of the week, but then I don't see it.
But I could always get out of that and say, well, that's just because they chose not to come here. They can always avoid future observations fairly easily. If you survey an exoplanet for biosignatures and you don't see oxygen, you don't see methane, that doesn't mean there's no one living there. They could always be either tricking their atmosphere, engineering it.
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