David Wallace
speaker
1,940 appearances
2 recordings
1 series
first heard May 2025
last heard 20 Jul
David Wallace’s voice in public audio — every appearance, attributed to the second.
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Appearances
What I mean, I'm putting this slightly figuratively, but where in in slightly more formal ways, how did the symmetry break?
If the if the microscopic physics treats past and future as symmetric, some extra ingredient has to come in.
to break that symmetry and make past and future look different in our emergent physics.
it's part of the story.
Um and and you're right to to pick on that.
I mean at s at some level as a as a matter of logic, if you break the symmetry, you either had to break it by putting some asymmetry into the laws, or you had to break it by putting some asymmetry into the boundary conditions.
And there's very little evidence for asymmetry in the laws, so the boundary conditions look like the way to go.
Um, but that's the beginning of an answer to the question, not the end of an answer.
I mean
One way to think about it is we at some level we seem to understand quite a lot quantitatively
About how to
Derive
large scale physics and small scale physics.
So suppose I want to derive the the kind of viscous flow equations that describe how a sticky liquid flows and I want to dis I want to derive that from the the microscopic physics of that liquid.
We've got a reasonable grip on how to do that.
But notice that the th the the the sticky fluid dynamics and
has asymmetry and time in it, and the microscopic physics doesn't.
And I will guarantee you that if you go to the textbooks that talk about the relation between them, they will not at any point say, and now let's assume the Big Bang was like this.
Um, so the way in which we're actu you it might nonetheless be the case that indirectly things about the Big Bang are what matter.
to getting out that asymmetry, but
Showing 441–460 of 1,940 · page 23 of 97
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