Can Our Universe Expand Forever Or Expand Then Contract Later Just So It Could Die?

From Einstein E=mc^2 to the conservation of energy theory, these concepts agree that energy cannot be created nor destroyed — after all these energies existed since singularity (even before the big bang).  Thus, if I agree with these concepts, it means everything within this universe can be deconstructed into the smallest of the smallest possible units, and each of these smallest units could be counted individually in a way that if they’re to be reunited they could be constructed into the whole universe again.  The question is if this is the case, is our universe static in quantity?

I surmise there is another possibility!  What if the first scenario is true but there is one exception!  The exception is that outside of the singularity there is a bigger container that could feed more energy into the already constructed universe which we’re living in.  This could mean the quantity of our constructed universe could be changed according to the limitation of the larger container which contains our universe.  If this is the case it could mean that our universe could be shrunk in size and quantity by somehow shredding off existing energy and feeding the lost energy back to the larger container.

Relatively then, from within our universe, it could be that our universe is infinite since it could be expanded forever or be shrunk forever depending on the situation.  We don’t know the limitation of the larger container so we could only see the direction of our universe as an infinite expansion or infinite contraction relatively!  There’s a saying that nothing could last forever, and so we know that even the sun and anything else that exists within our universe got an expiration date.  I suspect that our universe could be expanded forever until the larger container stops feeding energy to our existing universe which would then allow this universe to contract and die off eventually!