"Quick" Question About the Universe :P

[LSJ]

This just popped into my mind from another thread;

Let's say that the universe really is affected by cycles of contraction to a singularity, and then expansion. Every time the universe expands, does matter and/or energy on the outermost reaches escape the contraction?

If a particle is released on the very edge of the farthest galaxy directed away from the centre of the universe at a speed great enough to escape the gravitational force of that galaxy, then it is going into an endless vacuum. Let's say it is a photon - once it escapes the gravitational force of the galaxy, it has nothing to stop it, or at least nothing to pull it back.

Every time the universe expands, it loses some of itself. A lot of itself, considering all the energy that is probably wasted out into space. So the universe would be constantly shrinking. Does this happen? And if so, how would this affect future cycles?

I am just a curious person today. Thanks for any responses, even if it is "I dunno".

[Elfdude]

No, the big crunch occurs because the gravitational power of the singularity literally pulls all matter, space, and time into a single point. The edges of the singularity are literally the edges of the universe. There is no 'place' for said particle to be.

[LSJ]

But if the forward momentum is enough to escape the gravitational forces of the farthest reaches of the universe, what would eventually stop it and pull it back after traveling in a near total vacuum for billions to trillions of years?

Basically, how would the contraction pull all particles, no matter how far away, into the singularity?

[PacSubCom]

But if the forward momentum is enough to escape the gravitational forces of the farthest reaches of the universe, what would eventually stop it and pull it back

Nothing. Because ... the forward momentum is enough!

[Elfdude]

But if the forward momentum is enough to escape the gravitational forces of the farthest reaches of the universe, what would eventually stop it and pull it back after traveling in a near total vacuum for billions to trillions of years?

This can't happen for the same reason a square can't be a circle. The edges of the singularity are literally the edges of the universe. There exists no space outside of the big bang singularity. Thus no particles can move beyond the big bang singularity (at least in 4 dimensional space). For this reason it has been postulated that our universe is actually the inside of a white hole. Basically you can approach the event horizon of a white hole but you can never cross it.

Basically, how would the contraction pull all particles, no matter how far away, into the singularity?

Gravity collapses space and time itself. If we imagine our universe as a giant balloon the inside edge represents the event horizon of our universe. No matter how long we attempt to cross it we can never do so at least in 4 dimensional space. In a hypothetical big crunch gravity pulls the edges of the balloon closer and closer together pulling everything in between together as well. Particles aren't moving, the space between them gets smaller.