Question about Inflation Theory.

[iloveknowledge]

In cosmological physics, and accordingly to inflation theory, what caused the field to expand ? I can understand the concept of quantum fluctuactions but i don't really understand how did the process of expansion started : "He found that if the universe contained a field in a positive-energy false vacuum state, then according to general relativity it would generate an exponential expansion of space."(Wikipedia). 

And why the expansion wasn't immediate but gave time to the Universe to become isotropic as shown in MWB ?

 

[beecee]

1 hour ago, iloveknowledge said:

In cosmological physics, and accordingly to inflation theory, what caused the field to expand ? I can understand the concept of quantum fluctuactions but i don't really understand how did the process of expansion started : "He found that if the universe contained a field in a positive-energy false vacuum state, then according to general relativity it would generate an exponential expansion of space."(Wikipedia). 

And why the expansion wasn't immediate but gave time to the Universe to become isotropic as shown in MWB ?

 

 

We don;t know what caused Inflation, or the BB for that matter. Inflation explains the flatness and horizon problem as well as the homogeneity and isotropy observations, and as such is generally accepted as part of the BB. 

[iloveknowledge]

27 minutes ago, beecee said:

We don;t know what caused Inflation, or the BB for that matter. Inflation explains the flatness and horizon problem as well as the homogeneity and isotropy observations, and as such is generally accepted as part of the BB. 

I just read that Inflation was caused by rupulsive-gravity and negative pressure. I am so confused.

Edited April 7, 2019 by iloveknowledge

[Strange]

10 minutes ago, iloveknowledge said:

I just read that Inflation was caused by rupulsive-gravity and negative pressure. I am so confused.

Not negative gravity, but the pressure of the energy in the "inflaton field". But the only reason for suggesting the existence of this filed is to explain what we observe. We don't know if any such field existed, what it was or why.

[MigL]

If Mordred was still around, he could probably explain the concept of a false low vacuum energy state a lot better than me.
He would probably explain in terms of a 'Mexican hat' potential, or a bowl with a raised 'hump' in the middle.
I, however, prefer a much simpler example/analogy.

Consider dropping a pencil onto a tabletop.
It is extremely unlikely, but the pencil could land on its tip.
This is a perfectly symmetric outcome, as you can rotate around it and see exactly the same thing.
And you might think the pencil is in its lowest energy state; but it is not.
It is an unstable false low energy state.

A simple tipping of the pencil will take it off this false low energy hump, and drop it onto its side to the real low energy state.
You will also find that the real low energy state is no longer symmetric; the pencil on its side is now pointing in a specific direction.
It has undergone a symmetry break.

It is the gradual drop, from the false low energy state, to the ( possibly ) real lowest energy state which provide the impetus for inflation, and this was outlined in A Guth's original theory in the 80s. There are now many more proposed models than A Guth's original.
The last symmetry break involved the Electroweak symmetry break, which separated Electromagnetism and the Weak force, but prior symmetry breaks may have resulted in the break from the Color ( strong ) force, and even from gravity. This may mean that inflation wasn't smooth but proceeded at differing speeds during each 'roll down' to the next false low energy state.
For a more in-depth explanation of Symmetry groups in GUTs look at the Wiki entry for Grand Unified Theory.
I believe the most promising ( and Mordred's favorite ) is SO(10) Lie group

[iloveknowledge]

7 hours ago, MigL said:

If Mordred was still around, he could probably explain the concept of a false low vacuum energy state a lot better than me.
He would probably explain in terms of a 'Mexican hat' potential, or a bowl with a raised 'hump' in the middle.
I, however, prefer a much simpler example/analogy.

Consider dropping a pencil onto a tabletop.
It is extremely unlikely, but the pencil could land on its tip.
This is a perfectly symmetric outcome, as you can rotate around it and see exactly the same thing.
And you might think the pencil is in its lowest energy state; but it is not.
It is an unstable false low energy state.

A simple tipping of the pencil will take it off this false low energy hump, and drop it onto its side to the real low energy state.
You will also find that the real low energy state is no longer symmetric; the pencil on its side is now pointing in a specific direction.
It has undergone a symmetry break.

It is the gradual drop, from the false low energy state, to the ( possibly ) real lowest energy state which provide the impetus for inflation, and this was outlined in A Guth's original theory in the 80s. There are now many more proposed models than A Guth's original.
The last symmetry break involved the Electroweak symmetry break, which separated Electromagnetism and the Weak force, but prior symmetry breaks may have resulted in the break from the Color ( strong ) force, and even from gravity. This may mean that inflation wasn't smooth but proceeded at differing speeds during each 'roll down' to the next false low energy state.
For a more in-depth explanation of Symmetry groups in GUTs look at the Wiki entry for Grand Unified Theory.
I believe the most promising ( and Mordred's favorite ) is SO(10) Lie group

Thank you so much, this was very clear.

[StringJunky]

9 hours ago, MigL said:

If Mordred was still around, he could probably explain the concept of a false low vacuum energy state a lot better than me.
He would probably explain in terms of a 'Mexican hat' potential, or a bowl with a raised 'hump' in the middle.
I, however, prefer a much simpler example/analogy.

Consider dropping a pencil onto a tabletop.
It is extremely unlikely, but the pencil could land on its tip.
This is a perfectly symmetric outcome, as you can rotate around it and see exactly the same thing.
And you might think the pencil is in its lowest energy state; but it is not.
It is an unstable false low energy state.

A simple tipping of the pencil will take it off this false low energy hump, and drop it onto its side to the real low energy state.
You will also find that the real low energy state is no longer symmetric; the pencil on its side is now pointing in a specific direction.
It has undergone a symmetry break.

It is the gradual drop, from the false low energy state, to the ( possibly ) real lowest energy state which provide the impetus for inflation, and this was outlined in A Guth's original theory in the 80s. There are now many more proposed models than A Guth's original.
The last symmetry break involved the Electroweak symmetry break, which separated Electromagnetism and the Weak force, but prior symmetry breaks may have resulted in the break from the Color ( strong ) force, and even from gravity. This may mean that inflation wasn't smooth but proceeded at differing speeds during each 'roll down' to the next false low energy state.
For a more in-depth explanation of Symmetry groups in GUTs look at the Wiki entry for Grand Unified Theory.
I believe the most promising ( and Mordred's favorite ) is SO(10) Lie group

In the natural state, was the electroweak force only a primordial force; existing  only in the early stages of the universe?

[swansont]

10 minutes ago, StringJunky said:

In the natural state, was the electroweak force only a primordial force; existing  only in the early stages of the universe?

Yes

https://en.wikipedia.org/wiki/Electroweak_epoch

[StringJunky]

6 minutes ago, swansont said:

Yes

https://en.wikipedia.org/wiki/Electroweak_epoch

Cheers. It's slowly dawning on me what the particle physicists are doing in particle colliders.

Edited April 8, 2019 by StringJunky