DeSitter cosmological horizon stability?

In summary, the conversation discusses the possibility of the universe reaching a DeSitter spacetime where there would be a cosmological horizon that would radiate similar to a black hole. However, there is uncertainty about whether this horizon would eventually evaporate due to the cosmological constant diluting. The validity of this speculation is also questioned, as it cannot be tested by experiments currently or in the foreseeable future. There is also a discussion about whether the radiation from the horizon would eventually be reabsorbed, but the model in question does not seem to suggest this. Overall, the conversation presents a speculative model with uncertainties about its validity and implications for the stability of the cosmological horizon.
  • #1
Suekdccia
351
27
TL;DR Summary
DeSitter cosmological horizon stability?
If the universe keeps expanding at an accelerated rate (given by the cosmological constant) then the universe would approach a DeSitter spacetime where there would be a cosmological horizon that would radiate just as the event horizon of a black hole radiates Hawking radiation

I thought that once this state is reached, the universe would stay like that, but I recently discovered that this horizon could evaporate just like a black hole and the cosmological constant would dilute (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6560872).

Is this true? Even if that happened and the expansion would stop being accelerated by a cosmological constanr, what would happen then after?
 
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  • #2
Suekdccia said:
Is this true?
It's a speculative model which we have no way of testing by experiment now or in the foreseeable future.
 
  • #3
PeterDonis said:
It's a speculative model which we have no way of testing by experiment now or in the foreseeable future.
Even if this model was right and the horizon tends to evaporate, wouldn't the radiation eventually be reabsorbed by the cosmological horizon (balancing the process and keeping the horizon stable after all)?
 
  • #4
Suekdccia said:
Even if this model was right and the horizon tends to evaporate, wouldn't the radiation eventually be reabsorbed by the cosmological horizon (balancing the process and keeping the horizon stable after all)?
The model in the paper does not appear to be saying that (it appears to be saying that the ultimate limit of the process is flat spacetime), but I'm not sure how valid the model in the paper is. As I said, it's speculative, and many speculative models turn out to have inconsistencies in them that aren't obvious at first glance.
 

FAQ: DeSitter cosmological horizon stability?

What is a DeSitter cosmological horizon?

A DeSitter cosmological horizon is a boundary in DeSitter space, which is a solution to Einstein's field equations with a positive cosmological constant. This horizon represents the maximum distance from which light emitted now can ever reach an observer in the future, due to the accelerated expansion of the universe.

Why is the stability of the DeSitter cosmological horizon important?

The stability of the DeSitter cosmological horizon is crucial because it affects the behavior of perturbations in the universe. If the horizon is unstable, small perturbations could grow over time, leading to significant changes in the structure and evolution of the universe. Stability ensures a predictable and uniform expansion, which is essential for our understanding of cosmological models.

What factors influence the stability of the DeSitter cosmological horizon?

The stability of the DeSitter cosmological horizon is influenced by several factors, including the nature of the cosmological constant, the presence of matter and energy perturbations, and the overall geometry of the universe. Quantum effects and the behavior of scalar fields can also play a significant role in determining the stability.

How do scientists test the stability of the DeSitter cosmological horizon?

Scientists test the stability of the DeSitter cosmological horizon through a combination of analytical methods and numerical simulations. They study the behavior of perturbations in the DeSitter space by solving the relevant equations governing the dynamics of the universe. Observational data from the cosmic microwave background and large-scale structure surveys also provide empirical tests of these theoretical predictions.

What are the implications of an unstable DeSitter cosmological horizon for cosmology?

If the DeSitter cosmological horizon were found to be unstable, it would have profound implications for our understanding of the universe's fate. An unstable horizon could lead to scenarios where the universe experiences significant inhomogeneities or even collapse in certain regions. This would challenge the current cosmological models and necessitate new theories to explain the dynamics of the universe.

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