Past eternal universe in inflationary models

In summary, there is a disagreement among scientists regarding the concept of inflation and its potential for being past eternal. While one paper claims that inflation cannot be past eternal, another paper argues that it can be made to be past eternal. The discrepancy in opinions is due to different assumptions made by each group of scientists. However, there is no consensus among cosmologists on this matter.
  • #1
skydivephil
474
9
Assuming inflation is true, we have this paper by Guth, Valenkin and Borde:
http://cdsweb.cern.ch/record/521154
which says that inflation can't be past eternal

and then we have this paper saying it can be made past eternal:
http://arxiv.org/abs/gr-qc/0301042

Can anyone explain to me the discrepancy in layman terms?
 
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  • #2
Difference of opinon among respectable scientists. The eternal bounce scenario is not appealing because it inadequately explains how energy is recovered between cycles, imo.
 
  • #3
Thanks for that Chronos, can you describe in layman terms what are the different assumptions that lead them to the different conclusions? is there a consensus on this question amonst other comsologists?
 

Related to Past eternal universe in inflationary models

1. What is the concept of a past eternal universe in inflationary models?

The idea of a past eternal universe in inflationary models is that the universe has always existed and has gone through an infinite number of expansion and contraction cycles. Inflationary models propose that the universe underwent a rapid period of exponential expansion in its early stages, leading to the current observable universe.

2. How does the concept of a past eternal universe fit into the Big Bang theory?

The past eternal universe concept challenges the traditional Big Bang theory, which states that the universe had a definite beginning. Inflationary models propose that the universe has always existed, thus providing a different explanation for the origin of the universe.

3. What evidence supports the idea of a past eternal universe in inflationary models?

One of the main pieces of evidence supporting the concept of a past eternal universe in inflationary models is the observed flatness of the universe. This suggests that the universe has been expanding at a constant rate for an extremely long time. Additionally, observations of the cosmic microwave background radiation also support the idea of inflation and a past eternal universe.

4. How does the concept of a past eternal universe affect our understanding of the beginning of time?

The concept of a past eternal universe challenges our traditional understanding of the beginning of time. It suggests that time may not have had a definite beginning and that the universe has always existed in some form. This idea raises questions about the nature of time and the concept of a "beginning" in cosmology.

5. Are there any alternative theories to the concept of a past eternal universe in inflationary models?

Yes, there are alternative theories that propose different explanations for the origin and evolution of the universe. Some theories suggest that the universe had a definite beginning, while others propose a cyclical model with a series of expansions and contractions. These alternative theories are still being studied and debated in the scientific community.

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