Brian Wecht

speaker

852 appearances 2 recordings 1 series first heard Aug 2026 last heard 5 Sep

Brian Wecht’s voice in public audio — every appearance, attributed to the second.

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Recordings per month over the last 12 months — 2 in all, peaking in Sep 2026 with 1.

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The Skeptics' Guide to the Universe · The Skeptics Guide #1104 - Sep 5 2026 · 5 Sep 2026 podcast

So those pictures that you're showing there on the slide, Steve, those are shapes for what we can do with the extra dimensions.

Those are Calabi-Yau manifolds, which are special shapes of the extra dimensions that allow you to preserve this supersymmetry thing.

So it turns out, unfortunately, there are a very, very large number of such possible shapes for the extra dimensions.

And to this day, we don't know any mechanism for deciding which of those a priori should be correct.

You can say, okay, maybe these give you these particles and these give you these particles, but we don't know which of those would be the right shape for the extra dimensions.

And as far as we can tell, there is no known way to do that within the context of string theory.

So one of the very early hopes for string theory, that we would just follow our noses and find this universe,

appears to I mean there may be people out there who disagree with me on this that appears to definitely not be the case and if you accept string theory that means you accept the possibility of a lot of different possible consistent vacua that is to say universes for these theories yeah I disagree with that Brian okay

Yeah, so people call this different set of shapes for the extra dimensions the landscape of string theory, and right now there's no real known way of deciding which of these would be correct.

so you don't know which, I mean, people, it's a large number.

What that large number is, you can argue about.

But it's 10 to some large number.

And that's even just, if the extra dimensions are something geometric, maybe they could be something weirder, which is also possible with string frameworks.

And so far, we literally don't know any shapes of those extra dimensions that give us the universe we see with the three fundamental non-gravitational forces and the particles we see, et cetera.

So we just don't know how to pick it.

Right.

Is it still just as likely that it could be correct?

I don't know how to judge that.

Like how to say how likely that something is correct is not, I think, that's not really a scientific question.

Is it thrown away?

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