Sean Carroll
speaker
26,727 appearances
49 recordings
4 series
first heard Apr 2024
last heard 21 Sep
Sean Carroll’s voice in public audio — every appearance, attributed to the second.
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recordings per month · last 12 monthsRecordings per month over the last 12 months — 29 in all, peaking in Jun 2026 with 6.
Appearances
An observer like you would definitely exist without a multiverse, or equivalently, if there were many regions but they all allowed for the existence of life, those theories seem finely tuned and have low priors, right?
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So I can just invent a theory where the cosmological constant is small and go, boom, I'm done.
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I've invented a theory.
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The problem is if I didn't know the value of the cosmological constant, I would have put a small prior on those theories.
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And if I have a multiple
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multiverse with different values of the cosmological constant everywhere, I have no reason to put a small prior on that, there's no fine tuning there.
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Like it's just random stuff happening and still allows for the existence of life.
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So you have to take the priors into consideration when you do this sort of comparison.
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The other thing is, um there is something which I I'm not sure I don't think it is in Neil's original paper, but it is in the paper that Isaac Wilkins and I are working on ourselves, which is sort of a saturation effect, um, where we don't ask we don't
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update your priors by how many observers are like you.
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We update our priors by the probability there would be at least one.
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Observer like you in this universe.
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So if your universe is relatively tiny, that does get penalized compared to a universe which is very big and has more places for you for observers to appear.
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That is something that we accept, and we actually think that that is a perfectly reasonable way to go.
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There's something called the presumptuous philosopher problem in anthropic reasoning, which the traditional
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saturation, which just puts the prior proportional to the number of observers like you
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That has the huge problem that there's there's an infinite preference for infinitely big universes, right?
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Even if the universe is big enough but finite, big enough there should be many, many observers like you.
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That's nothing compared to the infinite number of observers like you in an infinitely big universe.
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So you just say, without looking out the window, you go, all right, I know I'm not in the finite-sized universe.
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Showing 821–840 of 26,727 · page 42 of 1337
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