korrents

korrents · Lex Fridman Podcast · #468

Janna Levin: Black Holes, Wormholes, Aliens, Paradoxes & Extra Dimensions | Lex Fridman Podcast #468

Janna Levin · 3h 00m · youtube.com ↗

24 korrents from this recording

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Janna Levin did not write this page.

Every claim below is a statement made in this recording, quoted word for word and linked to the second it was said, so you can hear it rather than take our word for it. The wording comes from the transcript published alongside the recording; the sentence above each quote is our reading of the claim, not their wording.

  1. 0:04:13 · watch on youtube.com↗

    Our reading

    Black holes are not the same thing as dead stars; they are a more general and more fundamental phenomenon than the end state of a star.

    Their wordsBut then I think that there’s a confusion that dead stars, these very, very massive stars that die, are synonymous with the phenomenon of black hole. And it’s really not the case. Black holes are more general and more fundamental than just the death state of a star.
    Interesting
  2. 3 min later

  3. 0:07:01 · watch on youtube.com↗

    Our reading

    A black hole is its event horizon, not the matter crushed to a point at the centre.

    Their wordsThe black hole is not the mass crushed to a point. The black hole is the event horizon. And the event horizon is really just a point in spacetime or a region at spacetime.
    Interesting
  4. 9 min later

  5. 0:16:14 · watch on youtube.com↗

    Our reading

    Science is agnostic about what it is used for: the same physics that explained why stars shine also built the bomb.

    Their wordsAnd that’s what I mean by science is agnostic. Right? It’s the same technology overcoming a critical mass, igniting thermonuclear fusion.
    Interesting
  6. 10 min later

  7. 0:26:29 · watch on youtube.com↗

    Our reading

    The world's scientists came to America because it was intellectually free, and they will stop coming if that freedom goes.

    Their wordsAbsolutely. The world flocked here. And that won’t be the case if we no longer have intellectual freedom.
    Interesting
  8. 6 min later

  9. 0:32:01 · watch on youtube.com↗

    Our reading

    Inside a black hole the singularity is not a place you could steer around; it is a moment in your future you can no more avoid than time itself.

    Their wordsIn other words, the singularity ends up in their future and they can no more avoid the singularity than they can avoid time coming their way. There’s no shenanigans you can do once you’re inside the black hole to try to skirt it.
    Interesting
  10. 6 min later

  11. 0:37:56 · watch on youtube.com↗

    Our reading

    The bigger the black hole, the less you would notice crossing its horizon, because curvature is harder to feel the larger it gets.

    Their wordsThat might surprise people. The bigger it is, the less noticeable it is that you’ve crossed the event horizon. One way to think about it is curvature is less noticeable the bigger it is.
    Interesting
  12. 4 min later

  13. 0:41:56 · watch on youtube.com↗

    Our reading

    Supermassive black holes did not grow by merging smaller ones — there has not been enough time — they collapsed directly out of primordial matter.

    Their wordsWe don’t think that the universe has had enough time to make them from stars that just merge. We know that two black holes can merge and make a bigger black hole and then those can merge and make a bigger black hole. We don’t think there’s been enough time for that.
    Interesting
  14. 14 min later

  15. 0:55:32 · watch on youtube.com↗

    Our reading

    Weightlessness, not weight, is the purest experience of gravity — what you feel sitting in a chair is atoms interfering.

    Their wordsTo be falling. That is the purest experience of gravity. The experience of gravity, unfettered, uninterrupted by atoms is weightlessness.
    Interesting
  16. 10 min later

  17. 1:05:03 · watch on youtube.com↗

    Our reading

    The best scientists ask the simplest questions, because they never lie to themselves that they understand something they do not.

    Their wordsThe best scientists I know often ask the simplest questions. First of all, there’s probably some confidence there, but also they’re never going to lie to themselves that they understand something that they don’t understand.
    Interesting
  18. 2 min later

  19. 1:06:53 · watch on youtube.com↗

    Our reading

    A black hole is featureless in the way a fundamental particle is: charge, mass and spin are the whole of it, and no two differ in anything else.

    Their wordsSo they’re flawless in the sense that you can completely understand a black hole by looking at just its electric charge, its mass and its spin. And every black hole with that charge mass and spin is identical to every other black hole.
    Interesting
  20. 11 min later

  21. 1:17:29 · watch on youtube.com↗

    Our reading

    Information is not lost in a black hole; the paradox is a crisis handing us clues, not a sign that quantum mechanics fails.

    Their wordsI’m unhappy with that. I would not be happy with information loss. I love that it’s telling us that there’s this crisis because I do think it’s giving us the clues, and we have to take them seriously.
    Interesting
  22. 5 min later

  23. 1:22:45 · watch on youtube.com↗

    Our reading

    There is a hard ceiling on how much information a volume can hold: try to exceed what fits on its surface and you simply make a black hole.

    Their wordsIf I tried to pack a lot of information into a volume, more information than I could pack, let’s say, on the surface of a black hole, I would simply make a black hole and I would find out, oh, I can’t have more information than I can fit on the surface.
    Interesting
  24. 6 min later

  25. 1:28:39 · watch on youtube.com↗

    Our reading

    Nobody really believes there is a firewall at the event horizon, but the firewall papers were what stopped the field from stalling.

    Their wordsI don’t think anyone really believes that at the event horizon you’ll find a firewall. But it did lead to things like the entangled wormholes embroidering a black hole, which was born out of an attempt to address the concerns that AMPS raised. So it did lead to progress.
    Interesting
  26. 1 min later

  27. 1:29:52 · watch on youtube.com↗

    Our reading

    The thing to give up in the information paradox is locality: keep the empty event horizon, and let things be connected non-locally by wormholes.

    Their wordsI’m going back to the vacuum. The empty space, the beautiful event horizon I’ll give up locality, meaning that I will allow things to be connected non-locally by a wormhole.
    Interesting
  28. 3 min later

  29. 1:33:20 · watch on youtube.com↗

    Our reading

    There may be no theory of quantum gravity to find, because gravity is not fundamental — it emerges at large scales out of quantum phenomena.

    Their wordsI think that this is suggesting that there might not be a theory of quantum gravity, that gravity will emerge at a macroscopic level, out of quantum phenomena. Now, we don’t know how to do that yet, but these are all hints.
    Interesting
  30. 11 min later

  31. 1:43:57 · watch on youtube.com↗

    Our reading

    With more planets than stars in the Milky Way, it has become impossible to believe life was not sparked somewhere else, possibly within a few hundred light years of us.

    Their wordsIt becomes impossible to imagine that life was not sparked somewhere else, in our Milky Way galaxy, and maybe even in our local neighborhood of the Milky Way galaxy, maybe within a few hundred light years of our solar system.
    Interesting
  32. 5 min later

  33. 1:48:39 · watch on youtube.com↗

    Our reading

    Looking for aliens who build things is a failure of imagination: the long-lived species we know of do not manipulate their environment at all.

    Their wordsSo I think we’re very attached to imagining creatures like us, that manipulate technology, and I think we have to be way more imaginative if we’re going to really take seriously life in the universe.
    Interesting
  34. 4 min later

  35. 1:52:54 · watch on youtube.com↗

    Our reading

    The hardest step on the road from chemistry to us was multicellularity, and it was strictly a problem of energetics.

    Their wordsI would say, multicellularity which is strictly an energy problem, I think. Again, it’s just like can electrons flow the right way. And is it energetically favorable for multicellularity to exist because if it’s energetically expensive, it’s not going to succeed.
    Interesting
  36. 6 min later

  37. 1:58:34 · watch on youtube.com↗

    Our reading

    Wormholes are not yet an engineering problem, but they sit entirely within the realm of plausible physics.

    Their wordsThat’s going to be really telling. So I’m not saying it’s simply an engineering problem, but it’s all within the realm of plausible physics, I think.
    Interesting
  38. 12 min later

  39. 2:10:50 · watch on youtube.com↗

    Our reading

    Calling dark matter and dark energy invented names for physicists' ignorance gets it exactly backwards: only extraordinary precision let us see that they are missing.

    Their wordsAnd so I would say, yes, we are just giving proxy names to things we don’t understand, but to dismiss that as some kind of, “Oh, they just don’t know…” It is actually quite the opposite.
    Interesting
  40. 8 min later

  41. 2:18:26 · watch on youtube.com↗

    Our reading

    Gravitational waves should be mapped as sound rather than pictured: they ring spacetime in the range a human ear could hear.

    Their wordsSo the idea is that they’re closer to something that you would want to map as a sound, than it’s something as a picture.
    Interesting
  42. 21 min later

  43. 2:39:18 · watch on youtube.com↗

    Our reading

    A discovery you can see your way through to is impossible to abandon, even out of a real fear that it will be misused.

    Their wordsI would find it impossible to not pursue a discovery that I could imagine my way through, if I can really see how to get there. I cannot imagine abandoning it for some other reason, fear that it would be misused, which is a real fear.
    Interesting
  44. 2 min later

  45. 2:40:53 · watch on youtube.com↗

    Our reading

    A self-respecting theoretical physicist kills most of their own ideas rather than waiting for somebody else to do it.

    Their wordsI totally agree. Sometimes I take too long to come to that conclusion, but I will proudly say, as most theoretical physicists should, that I kill most of my ideas myself.
    Interesting
  46. 18 min later

  47. 2:59:06 · watch on youtube.com↗

    Our reading

    Everything we build — every proof, every Nobel Prize, every idea, even the AI — will eventually be erased, which is why the near term matters.

    Their wordsEventually, I think it’s kind of hard to imagine, but yes, all of these Nobel Prizes, all of these mathematical proofs, all of these conversations, all of these ideas, all the influence we have on each other, even the AI, eventually will expire.
    Interesting