Are Extreme Internal Accelerations Significant in the Inflationary Universe?

In summary, the conversation discusses the development of compressive tidal forces in a FRW universe with matter as gravity slows expansion. These forces are due to accelerations of H ^ 2 per unit separation of bound entities. In a universe with a cosmological constant of 0 and a Hubble constant of 70 Km/sec/Mpc, these forces are imperceptible. However, in the early universe with exponential expansion, the accelerations are much larger and could potentially disrupt Higgs particles or prevent them from forming. The conversation also notes that these tidal forces are compressive in a uniform distribution of matter, but would be of the opposite type in a De-sitter space-time due to the cosmological constant.
  • #1
oldman
633
5
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?
 
Last edited:
Space news on Phys.org
  • #2
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 becuase 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
 
  • #3
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!
 
  • #4
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
 

FAQ: Are Extreme Internal Accelerations Significant in the Inflationary Universe?

What is the concept of tidal stresses during inflation?

Tidal stresses during inflation refer to the changes in gravitational forces on a planet or celestial body during its expansion in the early universe. These stresses are caused by the varying strength of gravitational pull from neighboring objects as the body expands.

How do tidal stresses affect the shape and size of celestial bodies during inflation?

Tidal stresses can cause irregularities in the shape and size of celestial bodies, as the varying gravitational forces can stretch and compress different regions of the body. This can lead to the formation of tidal bulges and distortions in the body's overall shape.

What is the significance of studying tidal stresses during inflation?

Understanding tidal stresses during inflation can provide insights into the formation and evolution of celestial bodies. It can also help explain the distribution and movement of matter in the early universe.

What are some methods used to study tidal stresses during inflation?

Scientists use various mathematical and computational models to study tidal stresses during inflation. They also analyze data from satellite observations and simulations to understand the effects of these stresses on celestial bodies.

Are tidal stresses during inflation still relevant in the present-day universe?

While the effects of tidal stresses during inflation may have diminished over time, they are still relevant in the current universe. These stresses can still play a role in the formation and evolution of celestial bodies, particularly in systems with multiple objects interacting through gravity.

Similar threads

Replies
0
Views
1K
Replies
4
Views
3K
Replies
10
Views
3K
Replies
16
Views
4K
Replies
1
Views
1K
Replies
1
Views
2K
Back
Top