Are Extreme Internal Accelerations Significant in the Inflationary Universe?

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Discussion Overview

The discussion revolves around the significance of extreme internal accelerations in the context of the inflationary universe, particularly focusing on the implications of these accelerations for bound entities and fundamental particles like the Higgs boson. The scope includes theoretical considerations related to cosmology and general relativity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant discusses the development of compressive tidal stresses in bound entities due to accelerations proportional to the Hubble constant in a matter-dominated FRW universe.
  • The same participant suggests that in an inflating universe, the accelerations become significantly larger, potentially leading to dilation pull-apart stresses in any bound entities.
  • Another participant expresses uncertainty about the implications of tidal forces in an exponentially expanding universe, questioning whether these forces would disrupt the formation of Higgs particles.
  • This second participant notes that the expansion of space-time means there is no relativistic velocity between points, which may imply that normal tidal forces do not apply.
  • A third participant acknowledges the existence of real tidal forces that develop as expansion changes, aligning with insights from general relativity experts.
  • Another participant clarifies that tidal forces from a uniform distribution of matter are compressive, while those from a cosmological constant in de Sitter space-time would cause tension.

Areas of Agreement / Disagreement

Participants express differing views on the nature and implications of tidal forces in an inflating universe. There is no consensus on whether extreme internal accelerations have significant consequences for the inflationary scenario or the formation of fundamental particles.

Contextual Notes

The discussion includes assumptions about the applicability of the FRW model in an inflating universe and the nature of forces in such a context, which remain unresolved.

oldman
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Over in the Relativity forum, in the thread "Metrics and Forces", I have been brought (in fact dragged kicking and screaming, by Pervect) to the following view: In the FRW universe with matter, as gravity slows expansion, compressive tidal stresses develop in any entity that is bound by non-gravitational interactions. These stresses are due to accelerations of H ^ 2 per unit separation of the bound entity's elements, where H is the Hubble constant in units of (sec ^ -1).

In a universe with lambda = 0 and where H is about 70 Km/sec/Mpc, or about 10 ^ -19 /sec, these accelerations (and the corresponding compressive stresses they generate in, say, solids bound by electromagnetic interactions) would be entirely imperceptible.

In the inflating early universe, where expansion is exponential, these accelerations are bigger. Much bigger. If one estimates H roughly, from the postulated inflation of the universe by a factor of about 10 ^ 43 in 10 ^ -34 sec,(see Liddle, Intoduction to Modern Cosmology, p. 106), H turns out to be about 10 ^ 77 /sec. The acceleration per unit separation of any bound elements is then very large, about 10 ^ 154 m/sec ^2. The accelerations are due to the speeding up of expansion and would cause dilation pull-apart stresses in any bound entity.

There may not be any bound entities in an inflating universe, which I understand is postulated to be a universe where all the forces of nature are the same and where all the force carriers are massless and travel at c. I don't know whether in such a situation the FRW model is even thought to apply.

But does anyone know if such extreme internal accelerations are thought to have any consequences for the inflationary scenario? Say to disrupt even Higgs particles? Or to prevent them forming?
 
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Ok. First off ill admit I am at a loss as to most of what youre saying, so ill have to guess (this is because I am dumb not because your post sucked :P)

you are asking if the tidal forces, or gravitational forces, of an exponentially expanding universe would rip things appart and prevent your higgs particle? (if this is wrong, ignore the rest :P)

whilst its a good point, its always good to point out when discussing inflation that it is space time expanding. This means that there is no actual relativistic velocity between two points, even though they are 'moving apart'. This, as far as i know, means a.) the universe can expand faster than the speed of light b.) time dilation and other affects don't count

from this i would assume that the normal tidal forces experienced in such a motion also wouldn't apply

not sure tho
 
FunkyDwarf said:
...i would assume that the normal tidal forces experienced in such a motion also wouldn't apply

Yes, this is more or less what I assumed before starting my thread in the relativity forum. But after quite a struggle (while I kicked and screamed), I was in the end persuaded that there are real (compressive/dilational) tidal forces that develop as expansion (slows down/speeds up). Trust the general relativity experts!
 
Just a quick note: the tidal forces due to the gravity of a uniform distribution of matter are compressive (in GR). The tidal forces due to the cosmological constant in a De-sitter space-time are of the opposite sort, i.e. they'd cause tension.

Out of a long thread, the post that most clearly (IMO) computes the value of the tidal forces is

https://www.physicsforums.com/showpost.php?p=1079457&postcount=38
 

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