To stir the pot Post inflationary period

  • Context: Graduate 
  • Thread starter Thread starter spark802
  • Start date Start date
  • Tags Tags
    Period
Click For Summary

Discussion Overview

The discussion revolves around the nature of the early universe and the mechanisms that allowed for its expansion, particularly focusing on the inflationary period. Participants explore various models and theories related to inflation, including the concept of vacuum states and the challenges faced by different inflationary models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions what material or matter existed to facilitate the expansion of the early universe, suggesting a vacuum state with lower or negative values outside the expansion.
  • Another participant asserts that ordinary radiation and non-relativistic matter are sufficient to explain an expanding universe, emphasizing that there is no "outside the expansion."
  • Discussion includes the false vacuum model proposed by A. Guth, which involves a transition from a false vacuum to a true vacuum with virtual particle production, and notes that many later models build on this concept.
  • Several inflationary models are mentioned, including slow roll inflation, chaotic inflation, chaotic eternal inflation, natural inflation, and hill inflation, with some models addressing historical problems such as the flatness problem, horizon problem, and monopole problem.
  • Participants note that Guth's original model faced issues like runaway inflation, which lacked a mechanism to halt it, while later models provide various solutions.
  • Some models incorporate the inflaton field, while others do not, and the Higgs field is referenced in relation to certain inflationary models.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the early universe and the mechanisms of inflation. There is no consensus on the existence of an "outside" to the expansion or the adequacy of various models to explain the observed phenomena.

Contextual Notes

Participants reference several historical problems associated with inflationary models and the need for solutions, indicating that the discussion is complex and involves unresolved aspects of theoretical physics.

spark802
Messages
47
Reaction score
12
My question is what sort of material/matter existed to allow an expansion of the early universe?

It had to be some sort of vacuum state...and it had to be lower/negative values outside of the expansion?
 
Space news on Phys.org
Nope. Ordinary radiation and non-relativistic matter lead to an expanding universe.

There was no "outside the expansion". You might want to familiarize yourself with how to understand the expanding universe: the balloon analogy might help: http://www.phinds.com/balloonanalogy/
 
To expand on this,

All models that describe a possible mechanism that caused the inflationary era (specifically) are from effects within our own universe. The original inflationary mechanism commonly called false vacuum by A.Guth involves a false vacuum to a true vacuum with virtual particle production. Many later models use a similar methodology. False vacuum is your minimal vacuum state, true vacuum the state its now in. Google false vacuum for more detail.
 
Thanks for the info, from both members. I will look into both links.

That's a killer line regarding the deodorant...

Dave
 
Lol yeah I laughed my head off the first time I saw that line.

The false vacuum model is niw commonly referrred to as old inflation. It had several problems pointed out by Guth himself. You have to give him credit its rare to see the inventor of a model point out its own problems.
The probkem he pointed out is called runaway inflation. There was no mechanism to stop it. Later models provided a vareity of mechanisms. So I will pointed out a few key ones.
Although in some of the good fit models they take adviantage of the runaway.


Slow roll inflation.
Chaotic inflation
chaotic eternal inflation
natural inflation
hill inflation.

The above is a short list compared to the number of models. However they are all considered good fits to observationsal evidence.

The slow roll approximation is often used a a comparision model. So its of particular interest.
Other historical inflation problems include the following.

Flatness problem
horizon problem
monopole problem

Later inflationary models provide solutions to these problems. I mention them as you will encounter them in your studies
 
Forgot to mention you will come across the term inflaton field. Some models use this. Sone however don't. The Higgs field is also in some models such as false vacuum and later models.
I have a technical review paper if your interested but its pretty advanced.
 
Mordred said:
Other historical inflation problems include the following.

Flatness problem
horizon problem
monopole problem

Later inflationary models provide solutions to these problems. I mention them as you will encounter them in your studies
All successful inflation models -- not just later ones -- should provide solutions to these problems (it's what makes them successful). As you mention, Guth's original "old inflation" is perhaps the one exception -- it failed to solve them due the failure of nucleated bubbles of true vacuum to coalesce efficiently and delicately enough. But other "older" models are successful, like Linde's "new" inflation and chaotic polynomial inflation.
 
bapowell said:
Nope. Ordinary radiation and non-relativistic matter lead to an expanding universe.

There was no "outside the expansion". You might want to familiarize yourself with how to understand the expanding universe: the balloon analogy might help: http://www.phinds.com/balloonanalogy/

I've sort of had a grasp on the balloon model, some one told me think of painting dark spots on a half inflated balloon and watch the spots increase distance from one another as you inflate the balloon more.

I like any simple sort of analogy along those lines...
 
Mordred said:
Lol yeah I laughed my head off the first time I saw that line.

The false vacuum model is niw commonly referrred to as old inflation. It had several problems pointed out by Guth himself. You have to give him credit its rare to see the inventor of a model point out its own problems.
The probkem he pointed out is called runaway inflation. There was no mechanism to stop it. Later models provided a vareity of mechanisms. So I will pointed out a few key ones.
Although in some of the good fit models they take adviantage of the runaway.


Slow roll inflation.
Chaotic inflation
chaotic eternal inflation
natural inflation
hill inflation.

The above is a short list compared to the number of models. However they are all considered good fits to observationsal evidence.

The slow roll approximation is often used a a comparision model. So its of particular interest.
Other historical inflation problems include the following.

Flatness problem
horizon problem
monopole problem

Later inflationary models provide solutions to these problems. I mention them as you will encounter them in your studies

Thank you again, I will look into these as well...
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
Replies
18
Views
2K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 20 ·
Replies
20
Views
4K
  • · Replies 16 ·
Replies
16
Views
3K