A Do cosmologists take spontaneous symmetry breaking seriously?

[Chronos]

That is exactly what I said.
We see them in their earlier stages, and we have theories that predict that the galaxies are still around, but we cannot see them in their current state (13.7 Gy after the big bang).You can easily extend that example to matter a few meters behind the particle horizon. Is there matter? Well, probably. It would be extremely odd if the universe would end right at our (Earth) range of causal interaction.

I'm really not seeing your point. Evidence of past causal interaction is as good as it gets. Even light from the sun is causally removed from us by about 8 minutes, and I'm unaware of any doubts about causal connections between the Earth and sun.

 

[Orodruin]

but we cannot see them in their current state (13.7 Gy after the big bang).

This is based on a particular foliation of space-time with cosmological time determining what is "current". The coordinate independent statement is that the object at some point passes a horizon. There is nothing particularly special about your choice of "current".

 

[mfb]

I'm really not seeing your point. Evidence of past causal interaction is as good as it gets. Even light from the sun is causally removed from us by about 8 minutes, and I'm unaware of any doubts about causal connections between the Earth and sun.

We can test the hypothesis "the sun is still there" in 8 minutes from now.

This is based on a particular foliation of space-time with cosmological time determining what is "current".

Yes, and it should be clear from the context what I mean.Edit: I think this is getting off-topic.

 

[Garth]

Again, you're arguing the conclusion rather than considering the models that would lead to the conclusion.

Whether or not there are different regions with different low-energy laws of physics depends upon the underlying physical laws. If there are spontaneous symmetry breaking events, such that the vacuum has either multiple metastable local minima or has a class of degenerate states, then those laws of physics generically give rise to different regions with different low-energy laws of physics.

If, on the other hand, the underlying potential is relatively steep and monatonic, so that we don't have degenerate states or many metastable local minima, and the universe we observe is right at the global minimum of the vacuum energy, then there very likely would not be any other regions of space-time with different low-energy physics.

What you're saying is that until we have evidence to point one way or the other, we should always prefer the second set of models, because it predicts a unique universe. And I'm sorry, but I really don't think that's good science.

What I am saying is that, without evidence, the hypothesis of a multiverse based on the assumption of the characteristics of this universe being determined solely by a stochastic process is not good science.

And I'm not the only one Are Parallel Universes Unscientific Nonsense? Insider Tips for Criticizing the Multiverse (Max Tegmark), Paul Steinhardt Disowns Inflation, the Theory He Helped Create (Paul Steinhardt).

As Paul says, (in the Inflation + Landscape scenario giving rise to Level II parallel universes,) with an enormously flexible Inflation theory and ~10⁵⁰⁰ varieties of String theory one can explain anything and everything - but such theories don't actually explain anything while giving the false impression that they do.

Garth

 

[Dale]

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