Was there a maximum speed during Inflation?

[Mordred]

In a sense but that is too simple a picture. The number of E folds is a consequence of the kinetic vs the potential energy terms within the equation of state for the scalar field. As simple as possible for an explanation the high kinetic energy of the particles involves greatly exceeded any binding potential energy of the fields at that time. Which prior to electroweak symmetry breaking were in essence one field as you have no effective weak, strong Em or Higgs field. You wouldn't even have an effective gravitational field. In essence without a mass term you effectively don't have any real binding energy. It is the binding energy of field interactions that lead to the mass terms.

 Any high energy density will trend to a lower energy density unless binding energy prevents it from doing so. Once the volume increases sufficiently to allow temperatures to drop  (temperature is the average kinetic energy in a volume) to allow symmetry breaking resulting in the mass terms the rate of expansion begins the slow roll phase in inflation.

 

45 minutes ago, geordief said:

Did the fact that there were no massive particles  contribute to the speed of inflation?

 

It seems intuitively like it should..

A useful analogy might help think of a very high positive pressure zone. That high pressure zone will want to disperse to a lower pressure state. Much like a balloon when you pop it. Though in the case of the universe there isn't a lower surrounding pressure region like the balloon. There is no outside the universe. However the similarity is there. 

Edited May 11, 2023 by Mordred

[Markus Hanke]

15 hours ago, MigL said:

The problems without inflation are much greater than those introduced by inflation.

Yes, this much is clear - otherwise no one would have bothered to bring up this notion in the first place. And I'm not saying that it doesn't work or that it couldn't have happened - just that it feels really ad-hoc. 

[geordief]

11 hours ago, Mordred said:

useful analogy might help think of a very high positive pressure zone. That high pressure zone will want to disperse to a lower pressure state. Much like a balloon when you pop it. Though in the case of the universe there isn't a lower surrounding pressure region like the balloon. There is no outside the universe. However the similarityis there

Does the inflation model  say what is the rate at which distances increase and if so  are there parameters that this is based on?

[Genady]

2 hours ago, geordief said:

Does the inflation model  say what is the rate at which distances increase and if so  are there parameters that this is based on?

Yes, here it is:

This is snapshot from about minute 35 of this lecture: Lecture 23: Inflation | The Early Universe | Physics | MIT OpenCourseWare.

At about minute 50+ he gives the numerical estimate for the parameters.

I think that in this lecture Guth answers most or all of the questions you've asked about inflation (including, "Here is where inflation stops, and the conventional big bang begins.")

Highly recommend.

 

 

[Mordred]

I always found Guths method for inflationary E-fold related calculations one of the easier methods.

Another method can be found here. Both methods incorporate the equation of state for the scalar field.

https://cds.cern.ch/record/1420368/files/207.pdf

[MigL]

Haven't watched the full lecture yet, Genady; maybe when I have a little more time.
But I definitely liked his explanation of negative pressure.
A lot more elegant than the mess I posted in the 'Testing Creation' thread.
( I'll have to remember gas-filled pistons and forget about springs )

Edited May 11, 2023 by MigL

[Mordred]

I agree negative I've found simpler for others to relate to than potential vs kinetic energy or vacuum. As vacuum is rather misleading with all the different fields that use the vacuum term. Good example being Higgs metastability vacuum