Chaotic Inflation: Does it Involve Phase Transition?

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Discussion Overview

The discussion revolves around whether chaotic inflation involves a phase transition, specifically in the context of Grand Unified Theory (GUT) symmetry breaking. Participants explore the timing of this phase transition relative to the energy scale of inflation, as well as the implications for particle production and the concept of the "big bang." The scope includes theoretical considerations and speculative reasoning regarding cosmological models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether chaotic inflation involves a phase transition and discuss the timing of GUT symmetry breaking in relation to inflation.
  • It is suggested that if the energy scale of inflation is above the GUT scale, symmetry breaking would occur after inflation, while if it is below, it would likely happen before inflation.
  • There is uncertainty about the energy scale of inflation, with some indicating that current limits suggest it was likely at a lower energy scale, implying GUT symmetry breaking occurred first.
  • Participants inquire whether particle production would commence immediately upon GUT symmetry breaking or only after inflation ends.
  • One participant asserts that the rapid expansion during inflation would mean that any particles from before inflation would not persist, and that observed particles were produced during reheating after inflation.
  • There is a discussion about the nature of the "big bang," with one participant arguing that it is not a real event but rather a term used to describe the early universe, which can refer to various stages including reheating.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between chaotic inflation and phase transitions, as well as the implications for particle production and the concept of the "big bang." The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

The discussion includes assumptions about the energy scale of inflation and its implications for GUT symmetry breaking, as well as the definitions and interpretations of terms like "big bang." These aspects are not fully resolved within the conversation.

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Does chaotic inflation involve phase transition, and if not, when does the phase transition of the breakdown of GUT symmetry occur?
 
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Ranku said:
Does chaotic inflation involve phase transition, and if not, when does the phase transition of the breakdown of GUT symmetry occur?
Not directly, for sure.

As to when, I don't think that's entirely clear. It depends upon what the energy scale of inflation is. If the energy scale of inflation were above the GUT scale, then the symmetry breaking would happen after inflation ended. If the energy scale were below, then it would likely have to happen before inflation began. I think the current limits on the energy scale of inflation show that inflation was probably at a lower energy scale, indicating the GUT symmetry breaking happened first.
 
Chalnoth said:
As to when, I don't think that's entirely clear. It depends upon what the energy scale of inflation is. If the energy scale of inflation were above the GUT scale, then the symmetry breaking would happen after inflation ended. If the energy scale were below, then it would likely have to happen before inflation began. I think the current limits on the energy scale of inflation show that inflation was probably at a lower energy scale, indicating the GUT symmetry breaking happened first.

If GUT symmetry were to break before inflation began, would particle production start as soon as GUT symmetry is broken, or would it have to wait only after inflation ended?
 
Ranku said:
If GUT symmetry were to break before inflation began, would particle production start as soon as GUT symmetry is broken, or would it have to wait only after inflation ended?
The rapid accelerated expansion of inflation ensures that effectively no matter from before inflation began will be around any longer. The particles that we observe today were produced as inflation ended, via the process known as reheating.

So there may have been some particle production as a result of the GUT phase transition, but as long as that transition was before inflation (which seems likely), it doesn't matter.
 
Chalnoth said:
The particles that we observe today were produced as inflation ended, via the process known as reheating.

So is reheating therefore effectively the big bang?
 
Ranku said:
So is reheating therefore effectively the big bang?
The "big bang" isn't a real event. In the Big Bang theory, if you take the matter and radiation budget of the universe and extrapolate back in time, you find that this model predicts a singularity. But that singularity is fiction: the consequences of taking that singularity seriously result in nonsensical predictions. In terms of time, it would have been shortly before reheating, but there would have been no special event that would have actually happened at that time.

Because the "big bang" isn't a real event, when people use the word, they usually aren't talking about any specific event like reheating. They're just talking generically about the very early universe, and could mean anything from the event that started inflation, to reheating, to a span of time shortly after inflation that was still extremely hot, etc.. Precisely what the phrase means will vary somewhat from speaker to speaker.
 
Thank you for your answers.
 

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