The universe as far as we know is all there is
Physics provides no real way for us to ever look anywhere, but within it
We are cocooned from any possible communication from other dimensions or alternate realities
Other dimensions may exist and there may even be a boundary to the cosmos, but so far
We've never observed anything remotely resembling one
On very large scales the universe is actually a pretty simple place
It has been around for a finite amount of time
Roughly 13 and 1/2 billion years it looks pretty much the same everywhere
Galaxies are almost evenly distributed across the cosmos
Everywhere we look we see about the same number of galaxies
It is also big
Very very big and it's getting bigger
The space time between all 100 billion galaxies in the universe is increasing
Like a roiling seething froth new empty space-time is being created as the universe ages
Increasing the distances between the galaxies pushing them apart
Since the universe is expanding it is a natural question to ask what is it expanding into?
When we peer deep into the cosmos we cannot see a boundary so far we have uncovered no evidence that a boundary exists
Space may extend to infinity or it may not, but in Einstein's universe things can be curved
And if things can be curved they can be curved in on themselves
Twisting and bending the shape of the universe and to virtually anything imaginable
General relativity makes it possible to live in an infinite universe with no boundary at all
Because of general relativity
Space-time is not a static entity it is a dynamic and ever-changing fabric within which the locations of all galaxies are woven
Galaxies are not themselves moving very much, but they appear to move to us because of new cosmic real-estate continually injected
Increasing their distance from us it
Is this creation of new space-time and the rate at which it is being created which determines?
How fast a galaxy appears to be moving away from us?
So what is the universe expanding into when new space-time is created into what do the edges go?
The answer depends on whether or not there are edges
If we live in an infinite universe then the answer has to be nothing
adding more fabric to infinity doesn't make more infinity an
Infinite universe would have no edges that expand and the question is meaningless in such a universe there would be no
outside on
The other hand if the universe is finite with a boundary that we have not yet discovered
Then the answer may be that we are expanding into something
If that is true however, then the boundary is so far away that we cannot see it and it can therefore never ever affect us
We have already seen photons that have been traveling since the universe was only 500 million years old
Anything much further away lies beyond our detection forever
Given that the universe is expanding if we cannot see the boundary now
Its expansion guarantees. We never will it will forevermore get further and further away and
It will always lie beyond our detection
Only one hundred years ago. We had no idea there were other galaxies besides our own
It was thought that humanity and the galaxy we inhabit was an island adrift in a universe of a hundred billion stars
We now know that our universe is a vast
dynamic cauldron of activity home to one hundred billion galaxies all
racing away within a boiling ocean of space-time
While we may yet find our universe is just an island we have yet discovered it is much larger than we ever thought