
Bubble Experiment Finds Universal Laws - Errorcod3
https://www.quantamagazine.org/bubble-experiment-finds-universal-laws-20190731/
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mhxion
I suggest anyone who's super noob to this subject to watch the video inside to
get the abstract idea.
([https://youtu.be/HrtJ3SRQF4E](https://youtu.be/HrtJ3SRQF4E))

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jhoechtl
> What this paper shows nicely is a way that you can restore [universality] by
> applying some confinement,” Burton said.

As a thought experiment this would make me think that : postulate: The
universe must be constrained at least when going to the small. And if it is
constrained when going to the small it has to be confined when going to the
big as well.

Now one brave soul to proof that.

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erikpukinskis
My guess is it’s not really constrained at either end, there actually is no
such thing as big or small, the universe is scale-free and everything is
relative.

Roger Penrose has suggested as the universe spreads out and you get a very
large, boring, empty universe it will eventually become equivalent
mathematically to a very small, dense universe and another “Big Bang” will
occur, not because the universe got small but because the big started looking
the same as the small.

Or something.

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ajmurmann
Can someone explain the significance of the connection to five-dimensional
black holes / "black strings"? To my layman ears that sounds like a entirely
theoretical construct that doesn't actually exist. Does/ might it somehow help
understanding black holes in our universe better?

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BlackFly
The fifth dimension is theoretical, yes. It turns out that you can get
classical electricity and magnetism out of the Einstein equations by adding a
fifth, rotationally symmetric spatial dimension
([https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory](https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory)).
Some people had hopes that quantum mechanics could fall out of the einstein
equations in a similar fashion and this hope sort of lead to string theory,
which needs to add further dimensions beyond the rotationally symmetric U(1)
group of Kaluza-Klein theory to support the SO(3) (I believe) group of the
electro-weak force (so they add 4 more dimensions) then further dimensions for
the strong force symmetries. This latter part isn't my specialty so I am hazy
on the details, but it falls under gauge theory.

So, while the fifth dimension is at the moment largely theoretical, it holds
some interest in the field of gravitational physics due to some elegant
constructions that fall out of it. It may be that the scalar field it predicts
could describe dark matter: [https://arxiv.org/abs/hep-
ph/0207125](https://arxiv.org/abs/hep-ph/0207125).

~~~
pdonis
_> the SO(3) (I believe) group of the electro-weak force (so they add 4 more
dimensions) then further dimensions for the strong force symmetries._

The gauge group of the Standard Model, i.e., including electroweak and strong
interactions, is SU(3) X SU(2) X U(1) (modulo some technicalities that I don't
think matter for this discussion). This is a six-dimensional group, so you
need six compactified dimensions in addition to the four dimensions of
spacetime that we know in order to construct a Kaluza-Klein/string theory type
model that includes all the Standard Model interactions. AFAIK the Calabi-Yau
manifolds that are talked about in string theory are examples of six-
dimensional compactified spaces that can be used in such a model.

~~~
BlackFly
That sounds like the details I was hazy on. Thanks.

