James Web Telescope

[iNow]

13 minutes ago, John John said:

I never thought of that

I’m sure the list of things you’ve never thought of is nearly as large as the universe itself 

Edited August 22 by iNow

[Mordred]

46 minutes ago, John John said:

That is what Newton said about the apple but it pulls the Earth up just a little bit.

Yes towards the common barycenter though which is the effective center of mass. However the universe has no center of mass. Mass is uniformly distributed at sufficient large volumes 100 Mpc.

 

[Airbrush]

With eternal inflation, cosmic inflation continues indefinitely in some regions, creating a "multiverse" of bubble universes.  In this framework, each "bubble" universe could have its own center and edges, but the entire multiverse doesn’t have a center or edges.

Edited August 25 by Airbrush

[MigL]

9 minutes ago, Airbrush said:

creating a "multiverse" of bubble universes.  In this framework, each "bubble" universe could have its own center and edges

Please explain what you 'see' when you get to the 'edge' of one of these bubble universes.

[Airbrush]

On 8/24/2024 at 5:35 PM, MigL said:

Please explain what you 'see' when you get to the 'edge' of one of these bubble universes.

Good question.  Anyone know this? 

My guess is:  what you would see depends on what is further from you, the observable edge of the bubble OR the actual edge of the bubble.

Edited August 27 by Airbrush

[MigL]

No, what do you suppose you would see when you get to the actual edge of the bubble ?

If no answer makes any physical sense, then there might not be an actual edge.

[Mordred]

2 hours ago, Airbrush said:

Good question.  Anyone know this? 

My guess is:  what you would see depends on what is further from you, the observable edge of the bubble OR the actual edge of the bubble.

You wouldn't see an edge, in the case of bubble universes or Hubble bubbles due to eternal inflation. What you will have is regions of differing expansion rates.

[Airbrush]

On 8/27/2024 at 9:15 AM, Mordred said:

You wouldn't see an edge, in the case of bubble universes or Hubble bubbles due to eternal inflation. What you will have are regions of differing expansion rates.

• "Eternal inflation" suggests that our universe is just one of many "bubble universes" that form in an ever-expanding multiverse.   These bubbles can be thought of as branching off from the inflating space-time of a previous universe, leading to a potentially infinite number of universes within the multiverse.  The multiverse is the entire collection of these bubble universes. The multiverse could contain universes with different physical laws, different dimensions, and varying properties."

Have you seen those Youtube animations showing bubble universes branching off from a previous universe?  It seems like bubbles have centers and edges.  When you get to the edge of one of these bubbles, your most powerful telescopes won't see any galaxies beyond the edge, because that region is still inflating out of range and is well beyond your visual horizon.

 

Edited August 29 by Airbrush

[Mordred]

Yeah they make universes look like soap bubbles which is extremely unrealistic. The math and relevant equations of state for the boundary conditions tell a completely different story.

 The boundary conditions are determined as a region where the expansion rate can be reasonably described by a specific value of Hubbles constant value using the FLRW metric 

 Just as those bubbles universes are formed by anistropic expansion rates there is no physical surface.

For analogy think of a river flowing into an ocean. You have water of a certain salinity separated by water of a different salinity. The boundary is the region where mixing occurs. There is no surface.

Now apply that analogy using the equations of state for a scalar field as per inflation. You have one region with a different inflationary expansion as opposed to another region. This leads to differing phase transitions at differing times involving electroweak symmetry breaking and is described by false vacuum to true vacuum phase transitions.

 If it's easier one can think of it as region of different blackbody temperature as the blackbody  temperature of our universe evolves in proportion to the inverse of the scale factor. However that wouldn't provide any detail on what causes the differing inflationary rates

 

 

Edited August 29 by Mordred

[MigL]

IIRC, these regions of differential expansion/inflation are the result of symmetry breaking for that region, and, from A Guth's original paper on inflation, the boundary of the region would be a source of magnetic monopoles.

None have ever been detected, and most question their existence.

[Mordred]

1 hour ago, MigL said:

IIRC, these regions of differential expansion/inflation are the result of symmetry breaking for that region, and, from A Guth's original paper on inflation, the boundary of the region would be a source of magnetic monopoles.

None have ever been detected, and most question their existence.

Yes however I will note most papers involving bubble universes in terms of bubble nucleation ignore don't add any terms for magnetic monopoles. Primarily for the reason of none ever being detected.