Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens | Lex Fridman Podcast #428

Sean Carroll · 2h 35m · youtube.com ↗

20 korrents from this recording

Sean Carroll 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.

0:04:37 · watch on youtube.com↗

Our reading
The story that Einstein could not keep up with quantum mechanics is almost exactly backwards: his philosophical objections were correct and should have been taken far more seriously.

Their wordsI think that that story about the latter part is completely wrong, almost 180 degrees wrong. I think that Einstein understood quantum mechanics as well as anyone, at least up through the 1930s. I think that his philosophical objections to it are correct. He should actually have been taken much more seriously about that.

Interesting
19 min later
0:23:46 · watch on youtube.com↗

Our reading
The simplest explanation for why we have never noticed an alien civilization is that there are none out there.

Their wordsBut I think your intuition is right that it would’ve been easy for there to be lots of civilizations then we would’ve noticed them already and we haven’t. Absolutely the simplest explanation for why we haven’t is that they’re not there.

Interesting
2 min later
0:26:10 · watch on youtube.com↗

Our reading
A great filter is a weak explanation for the silence, because it would have to work every single time — one civilization with self-replicating probes could fill the galaxy.

Their wordsThat is absolutely possible. I’m actually putting less credence on that one just because you need to happen every single time. If even one, I mean, this goes back to John von Neumann pointed out that you don’t need to send the aliens around the galaxy. You can build self-reproducing probes and send them around the galaxy.

Interesting
2 min later
0:27:55 · watch on youtube.com↗

Our reading
Listening for alien radio is the wrong search: a probe that sits and waits beats a signal that passes you by, so an artifact in our solar system is likelier than a message.

Their wordsThis is the 2001 monolith hypothesis. I would be less surprised to find a quiescent alien artifact in our solar system than I would to catch a radio signal from an intelligent civilization.

Interesting
12 min later
0:39:51 · watch on youtube.com↗

Our reading
The singularity of a black hole is not a place at its centre but a moment in your future: falling in, you run out of time rather than out of room.

Their wordsRemember space and time are parts of one unified space-time, the location of the singularity in the black hole is not the middle of space, but our future. It is a moment of time. It is like a big crunch.

Interesting
30 min later
1:09:33 · watch on youtube.com↗

Our reading
Physicists did not invent dark matter and dark energy to rescue their theories — they would much rather the answer were something cooler, and the data will not allow it.

Their wordsI tear my hair out when people who are not physicists accuse physicists, like you say, of losing the plot because they need dark matter and dark energy. I don’t want dark matter and dark energy; I want something much cooler than that. I’ve tried. But you got to listen to the equations and to the data.

Interesting
2 min later
1:11:52 · watch on youtube.com↗

Our reading
The Copenhagen interpretation taught to physics students is a God-awful mess; many-worlds is beautiful because it needs fewer ingredients and one equation.

Their wordsIf you think about how we teach quantum mechanics to our students, the Copenhagen interpretation, it’s a God-awful mess. No one’s going to accuse that of being very beautiful. I’m a fan of the many-worlds interpretation of quantum mechanics, and that is very beautiful in the sense that fewer ingredients, just one equation, and it could cover everything in the world.

Interesting
11 min later
1:22:55 · watch on youtube.com↗

Our reading
Declining many-worlds because it extrapolates past what we can observe is methodologically respectable and still a failure of nerve.

Their wordsAnd if you just wanted to be methodologically conservative and say, “That’s a step too far; I don’t want to buy it,” I’m sympathetic to that. I think that you’re just wimping out, I think that you should have more courage, but I get the impulse.

Interesting
8 min later
1:30:37 · watch on youtube.com↗

Our reading
Assuming you are a typical observer in the universe is not humility but a hilariously presumptuous claim that typical observers are like you.

Their wordsBut then you draw some conclusions from this, and what you end up realizing is you’ve been hilariously presumptuous because by saying, “I’m a typical observer in the universe,” you’re saying, “Typical observers in the universe are like me,” and that is completely unjustified by anything.

Interesting
2 min later
1:32:17 · watch on youtube.com↗

Our reading
"Why is there something rather than nothing?" cannot have the kind of answer why-questions usually get, because the universe is not embedded in anything bigger — it can just be.

Their wordsI think that specifically the question why is there something rather than nothing? does not have the kind of answer that we would ordinarily attribute to why questions because typical why questions are embedded in the universe. And when we answer them, we take advantage of the features of the universe that we know and love. But the universe itself, as far as we know, is not embedded in anything bigger or stronger, and therefore it can just be.

Interesting
1 min later
1:33:30 · watch on youtube.com↗

Our reading
There is no philosophical knockout objection to the simulation hypothesis, and also no reason whatsoever to take it seriously.

Their wordsI don’t think that there’s any philosophical knockout objection to the simulation hypothesis. I also think that there’s absolutely no reason to take it seriously.

Interesting
3 min later
1:36:00 · watch on youtube.com↗

Our reading
Judging an AI by how close it is to a human is the mistake: appreciating what it can actually do is both more accurate and better protection against its dangers.

Their wordsAnd rather than trying to ask, how close is it to being a human-like intelligent, we should appreciate it for what its capabilities are, and that will both be more accurate and help us put it to work and protect us from the dangers better rather than always anthropomorphizing it.

Interesting
1 min later
1:37:02 · watch on youtube.com↗

Our reading
A language model's apparent mind is mostly our own bias: it predicts text, and leverages our evolved habit of attributing intentionality to anything that acts human.

Their wordsWhat a large language model is trying to do is to predict text. That’s what it does. And it is leveraging the fact that we human beings for very good evolutionary biology reasons, attribute intentionality and intelligence and agency to things that act like human beings.

Interesting
9 min later
1:46:02 · watch on youtube.com↗

Our reading
The largest contribution physics can make to AI is energy efficiency: computers waste heat hilariously worse than brains do, and nobody has seriously tried to fix it.

Their wordsI think this is one of the biggest things that physics can help with, and it’s an obvious kind of low-hanging fruit situation where the heat generation, the inefficiency, the waste of existing high-level computers is nowhere near the efficiency of our brains. It’s hilariously worse, and we haven’t tried to optimize that hard on that frontier.

Interesting
9 min later
1:54:46 · watch on youtube.com↗

Our reading
Life is not fighting the second law of thermodynamics; it surfs increasing entropy and depends on it to hold itself together.

Their wordsSometimes people think that complexity or life or whatever is fighting against the second law of thermodynamics, fighting against the increase of entropy. That is precisely the wrong way to think about it. We are surfers riding the wave of increasing entropy. We rely on increasing entropy to survive.

Interesting
11 min later
2:06:15 · watch on youtube.com↗

Our reading
Consciousness and free will are not illusions: being emergent and non-fundamental is exactly as real as a table is.

Their wordsThat’s different than something being emergent or non-fundamental, but also real. This table is real, even though I know it’s made of atoms, that doesn’t remove the realness from the table. I think that consciousness and free will and things like that are just as real in tables and chairs.

Interesting
10 min later
2:16:16 · watch on youtube.com↗

Our reading
Science can tell you how to reach your goals but never which goals are right — and it will help just as happily if your goals are horrible.

Their wordsBut there’s an instrumentalist view here, you have to first decide what your goals are and then science can help you achieve those goals. If your goals are horrible, science has no problem helping you achieve them, science is happy to help out.

Interesting
11 min later
2:27:40 · watch on youtube.com↗

Our reading
When somebody accuses you of being arrogant about an idea, almost all they ever mean is that they disagree with you.

Their wordsYeah, it is interesting because, when people react against you by saying you are being arrogant about this, 99.999% of the time, all they mean is I disagree. That’s all they really mean, right?

Interesting
3 min later
2:30:30 · watch on youtube.com↗

Our reading
Einstein's equation is much smarter than Einstein was: it knew about black holes, gravitational waves and the Big Bang while he did not.

Their wordsAnd the punchline is the equation is much smarter than Albert Einstein because Albert Einstein did not know about the Big Bang, he didn’t know about gravitational waves, he didn’t know about black holes but his equation did.

Interesting
3 min later
2:33:17 · watch on youtube.com↗

Our reading
The Nobel Prize is probably a net good for the world and a net negative for science, because it makes scientists want to win a Nobel Prize.

Their wordsI think that Nobel Prize has enormous problems. I think it’s probably a net good for the world because it brings attention to good science. I think it’s probably a net negative for science because it makes people want to win the Nobel Prize.

Interesting