If the universe is forever expanding and forever accelerating. Then there would be a point at which the velocity of the expansion of the universe would surpass the speed of light; at that point the arrow of time would be reversed. Would the Universe then retract???

Under current models... no.

 

There is no current model that has the universe's expansion accelerating then stopping.

But the universe is accelerating with its expansion. right?

Yeah

Then wouldn't the universe's rate of expansion eventually surpass the speed of light?

Originally posted by Physics5000

Then wouldn't the universe's rate of expansion eventually surpass the speed of light?

 

Yes, however spacetime expanding at C is not a problem. Relativity is only violated when objects move through spacetime as fast or faster than light. Kinda like leaves floating on a flowing stream. The stream is flowing fast, but the leaves aren't actually moving through the water (generally speaking).

Originally posted by Physics5000

Then wouldn't the universe's rate of expansion eventually surpass the speed of light?

 

It has done in the past, 'superinflationary stage' or somesuch

There is no current model that has the universe's expansion accelerating then stopping.

 

The topic posting is the contention of a new model.

 

Then wouldn't the universe's rate of expansion eventually surpass the speed of light?

 

Effectively it already has, within its own environment. The farthest so far observed astronomical object is a quasar which is 27 billion light-years distant. Yet the universe is only roughly 15 billion years old.

Ultimately what this means is this quasar is moving away from Earth at faster than the speed of light.

The only manner in which to account for this is a degree of redshift occuring due to the expansion of the universe. Thus it is possible due to the expansion of the universe for objects within the universe to move away from each other at speeds faster than light.

 

Yes, however spacetime expanding at C is not a problem. Relativity is only violated when objects move through spacetime as fast or faster than light. Kinda like leaves floating on a flowing stream. The stream is flowing fast, but the leaves aren't actually moving through the water (generally speaking).

 

As has been mentioned however, this does not violate relativity.