Big bounce theory in light of the closed Universe finding

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Discussion Overview

The discussion centers on the implications of recent Planck evidence suggesting a closed Universe and its potential support for the Big Bounce hypothesis. Participants explore the consequences of this evidence for cosmological models, particularly regarding cyclic Big Bangs and the nature of the universe's expansion.

Discussion Character

  • Debate/contested
  • Exploratory

Main Points Raised

  • Some participants suggest that if the closed Universe finding is confirmed, it could revitalize the Big Bounce hypothesis, leading to cyclic Big Bangs rather than a permanently accelerating expansion.
  • There is curiosity about which model may best fit the Big Bounce scenario, specifically whether it would lead to eternal return or differentiated Big Bangs.
  • Some participants express skepticism about the current state of evidence, noting that there is no observational data to clearly distinguish between competing theories.
  • One participant mentions that alternative models, including the Big Bounce, are being actively investigated as potential solutions to longstanding cosmological problems, such as the horizon problem.
  • Concerns are raised regarding the premature conclusions drawn from the Planck evidence, with a suggestion that the findings may not imply what some believe they do.

Areas of Agreement / Disagreement

Participants generally express uncertainty about the implications of the Planck evidence, with multiple competing views on the viability of the Big Bounce hypothesis and its models. The discussion remains unresolved, with no consensus on the interpretations of the findings.

Contextual Notes

Participants note that the current state of the field is in flux, and the Planck evidence is still under review, which may affect interpretations and conclusions drawn from it.

user30
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TL;DR
The Big Bounce theory has seen a resurgence in light of the Plank evidence of a closed universe. Which type of cyclic universe would it most likely point to?
As you all know:

Planck evidence for a closed Universe and a possible crisis for cosmology

https://www.nature.com/articles/s41550-019-0906-9

If confirmed, it would bring back the Big Bounce as a possible hypothesis for the evolution of the universe. This has long-term consequences being that the Big Bounce results in cyclic Big Bangs, since the expansion of the universe is not permanently accelerating, as once thought.

What I'm curious about is, which model would best fit the model - eternal return or differentiated Bing Bangs? That is to say same histories or different?

Here is some overview of the Big Bounce hypothesis.
https://en.wikipedia.org/wiki/Big_Bounce
 
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I'll add: This is from a threadmaker who has been speaking of the Big Bounce and the cyclic universe in opposition to the status quo and accelerating universe, not at all convinced our data is all that meets the eye. As you all can imagine, I am more than excited by these findings. :smile:

Let's see if it sticks, too...
 
It's all guesswork at this time. There doesn't seem to be any observational evidence to distinguish theories.
 
mathman said:
It's all guesswork at this time. There doesn't seem to be any observational evidence to distinguish theories.

Then the field is dead by your estimation. Science withour falsification is pretty meaningless.
 
FWIW

"Alternative pictures including a Big Bounce may provide a predictive and falsifiable possible solution to the horizon problem, and are under active investigation as of 2017.[1]"
 
user30 said:
are under active investigation

Yes. But it is too early to tell how all this will turn out. The Planck evidence itself is still being reviewed and might turn out not to imply what some are saying it implies.

In short, this area is in too much flux right now for us to say anything definitive. Thread closed.
 

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