I DeSitter cosmological horizon stability?

AI Thread Summary
The discussion revolves around the stability of the DeSitter cosmological horizon in an expanding universe influenced by the cosmological constant. It is suggested that, unlike a static state, the horizon could evaporate similarly to a black hole, leading to a dilution of the cosmological constant. Questions arise regarding the implications of this evaporation and whether the emitted radiation could be reabsorbed, potentially stabilizing the horizon. The validity of the speculative model being referenced is questioned, highlighting the challenges in testing such theories experimentally. Ultimately, the conversation emphasizes the uncertainties and inconsistencies inherent in speculative cosmological models.
Suekdccia
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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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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.
 
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)?
 
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.
 
https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
Why was the Hubble constant assumed to be decreasing and slowing down (decelerating) the expansion rate of the Universe, while at the same time Dark Energy is presumably accelerating the expansion? And to thicken the plot. recent news from NASA indicates that the Hubble constant is now increasing. Can you clarify this enigma? Also., if the Hubble constant eventually decreases, why is there a lower limit to its value?
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