Is the Expansion of the Universe Leading to Heat Death?

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Discussion Overview

The discussion revolves around the implications of the universe's expansion on the concept of Heat Death and related phenomena such as the Big Rip. Participants explore the nature of entropy, the closed or open status of the universe, and the effects of dark energy on cosmic evolution. The conversation touches on theoretical frameworks and interpretations within cosmology.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question the assumption that all matter will eventually be ripped apart, noting that atoms currently cluster in galaxies.
  • There is a distinction made between Heat Death, which relates to increasing entropy in a closed system, and the Big Rip, which is contingent on specific properties of dark energy.
  • One participant argues that the observable universe is not a closed system due to the continual entry of matter into the observable horizon, while another suggests that it is effectively closed based on causal connections established during the inflationary epoch.
  • Concerns are raised about the implications of dark energy, with uncertainty about its nature and potential future behavior affecting predictions about the universe's fate.
  • Some participants propose that the cosmological event horizon may limit the entropy of the observable universe, drawing parallels to black hole event horizons.
  • There is acknowledgment of differing opinions regarding the causal connections and horizon issues, particularly in relation to black holes.

Areas of Agreement / Disagreement

Participants express differing views on whether the observable universe is a closed system and the implications of dark energy. There is no consensus on the fate of the universe or the validity of the cosmological principle as it applies to the observable universe.

Contextual Notes

The discussion highlights limitations in understanding the nature of dark energy and its effects, as well as the assumptions underlying the cosmological principle and entropy considerations. The implications of these factors remain unresolved.

  • #61
Gold Barz said:
They said quantum fluctuations are the reason for these universes, is it the same type of quantum fluctuations that happen normally in our universe or is it different? do these virtual particles "inflate"? the same virtual particles we see near black holes?
Quantum fluctuations in what?
Some pre-existent quantum foam has to be assumed, can we observe such or unambiguously test for it? I think not.
It is not like the Hawking radiation around a BH because there was no BH, the BH Hawking radiation is based on the spherically symmetric Schwarzschild solution embedded in a flat space-time, but there is no space-time 'outside' any 'yet-to-be-created' universes.

Just a thought.

Garth
 
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  • #62
I object to the notion of inflation forcing acceptance of multiverses - albeit less strenuously than say, a week ago. Recent discussions with more qualified experts give me pause to reexamine my position... i.e., I might be wrong. Shocking.
 
  • #63
Gold Barz said:
They said quantum fluctuations are the reason for these universes, is it the same type of quantum fluctuations that happen normally in our universe or is it different? do these virtual particles "inflate"?
As far as I know they are the same, at least in that framework. In my opinion there is, however, an important difference in the theoretical treatment of the subject. When treating quantum fluctuations of any field in any classical background, no backreaction of the fluctuations on the background spacetime is considered. For eternal inflation to work, the backreaction of the fluctuations on the metric has to be considered: some of the fluctuations of the field responsible for inflation can start to inflate space as they have the properties to do so. However, in order to successfully explain the quantum effects of matter on spacetime one should consider the fluctuations of the metric itself (the quantum effects of spacetime). This is not possible without going into wild speculations, as there is no successful quantum gravity yet. The model of eternal inflation (leading to separated universes or bubbles) relies on this heuristic argument which seams not to be completely rigorous. This is just my personal opinion.
 
  • #64
That's a bit wordy for my taste, hellfire, but I like the way you think. My only concern is we might need to relax our parameters when it comes to the fluctuation thing. Your objection on the basis of back-reactions is well founded [there have been numerous papers to that effect]. But I have nagging doubts if it works all the way back to the quantum level. But, hell, I have nagging doubts about everything on that level. So don't let it stop you, just fear what happens in between. I know it scares me.
 
  • #65
Garth said:
Quantum fluctuations in what?
Some pre-existent quantum foam has to be assumed, can we observe such or unambiguously test for it? I think not.

I'm going to agree with Garth on this one. We should try to obtain a more complete understanding of our own universe before indulging in wild speculation about multiverses. If it's possible to test for them, then I'm sure it's many, many years off.
 
  • #66
But the current inflation theory seems to suggest the existence of other "bubbles"...like I said before the creator of the theory said it himself that inflation forces the idea of multiple universes or bubbles on us, but as ST and Garth said there is no way we can test this and we do not even know if it is possible to test for it, and there will be NO communication between bubbles, so when its all said and done it might as well be only one universe, even if there are others.

Also, I have read many times that most scientists do not doubt inflation, is this really true?
 
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  • #67
Gold Barz said:
Also, I have read many times that most scientists do not doubt inflation, is this really true?

Eh, it's true that most astronomers/physicists favor inflation over all competing theories, but I wouldn't go as far as to say they don't doubt it. If we detect B-mode polarization of the CMB at the predicted levels, then it may attain the status of "beyond reasonable doubt" in the minds of most scientists, but we still lack direct evidence.
 
  • #68
So in the most current inflationary theory, these pocket universes are suggested right?
 
  • #69
I yield to the graduate student.. but still disagree... much fun!
 
  • #70
Who's the graduate student?, disagree with what point?...I'm lost lol
 
  • #71
Heat death simply means that entropy or total chaos/disorder has reached its ultimate conclusion and every part of the entire Universe/Cosmos has the same temperature as every other part.
Without a difference in temperature, no work can be extracted nor energy generated from any system. Even if every part of the Cosmos = 100C, it would make no difference.
Matter is frozen energy and unless it can be heated or accelerated to a higher state it will remain frozen. This cannot happen once entropy has reached its maximum effect.

www.physlink.com/Education/AskExperts/ae181.cfm
 

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