Dark Energy & Expanding Universe: Newtonian Perspective

[darkside00]

A very simple way to explain the observable universe expanding:
Perhaps there is just a bunch of matter surrounding the observable universe and all the observable stars/galaxies are moving per the gravitational field created by matter outside that we have not yet seen. Thoughts?

 

[jtbell]

A uniform spherical shell of matter exerts a net gravitational force of zero on any object inside it:

https://www.physicsforums.com/showthread.php?t=121120

Considering that, how would you distribute your "outside" matter so as to produce a net outward force on all the "inside" matter?

 

[darkside00]

The outside matter could be distributed to pull the star/galaxies away as we see it. Just cause we haven't seen all matter yet, we can't get zero

 

[phyzguy]

A uniform spherical shell of matter exerts a net gravitational force of zero on any object inside it:

https://www.physicsforums.com/showthread.php?t=121120

Considering that, how would you distribute your "outside" matter so as to produce a net outward force on all the "inside" matter?

It's clear this is true of Newtonian gravity. Is it clear that this still holds in an expanding universe that obeys general relativity?

 

[Ich]

Is it clear that this still holds in an expanding universe that obeys general relativity?

Yes, that's proven.

 

[Slyce034]

It's clear this is true of Newtonian gravity. Is it clear that this still holds in an expanding universe that obeys general relativity?

Yes, that's proven.

On the other hand, how do we know that the area outside the observable universe obeys general relativity?

 

[Ich]

On the other hand, how do we know that the area outside the observable universe obeys general relativity?

That was not the question.

 

[darkside00]

yeah, the question is does this outside matter affect our universe(if it exists without us seeing), off course it does

 

[darkside00]

Or are we certain we've seen all matter? to make the net zero.
perhaps matter outside 'not our observable" is moving opposite direction

 

[Chronos]

Er, no. jtbell already explained why this does not work. Furthermore, we see distant galaxies [the ones receeding the 'fastest'] as they were billions of years ago, so it us, not them, that is closest to this hypothetical unseen matter surrounding the observable universe. Apparently no one notified the Andromeda galaxy because it is on a collision course with the Milky Way.

 

[Slyce034]

Could the outside matter's distribution be determined by where matter would most likely agglomerate in multiverses? I assume we have not seen all matter since any dark matter outside our line of sight to another observable galaxy/object would be difficult to detect.

 

[Joshua.B]

A very simple way to explain the observable universe expanding:
Perhaps there is just a bunch of matter surrounding the observable universe and all the observable stars/galaxies are moving per the gravitational field created by matter outside that we have not yet seen. Thoughts?

but if there is already matter outside the observable universe that means tha the Universe is not expanding only the amount of the Universe we can actually see is increasing. also does that mean that there is a finite point to which te Universe can expand??