The Milky Way as seen over Japan. (This is for you Star Trek and Star Wars nerds out there.)

No matter where you are in the universe it's expansion is relative to your position. It is also expanding faster than the speed of light. Therefore, a., we really don't know how big it is, and b., it's impossible to tell.

Happy Relativity Monday!

if the state of our information on size and speed is limited by the speed of light, how could we ever know that it's expanding faster than the speed of light?

The best we can do is measure the speed of other galaxies and make a best guess based on that. Think of the blueberry pancake analogy.

right, but the apparent speed of ANY galaxy relative to ours can't be faster than the speed of light (and I've never seen a paper that claimed a speed anywhere close to that). and if the speed of light is an absolute limit, think of the pancake coming up against the edge of the pan. if we believe in c as an absolute limit, our estimate of the speed of even the fastest moving galaxies should approach c as a limit. i do agree that we have no idea how big the universe really is (since we can't see farther away than our current best telescopes can show, and the indirect evidence is controversial). as to whether it's impossible to tell, well, i don't like to assume that anything is impossible. it discourages outrageous new ideas!

All good points

I have long questions whether or not C is the actual speed limit, or if it's just the best that we can come up with. Maybe it's the fastest thing that we can wrap our heads around. As for the edge of the universe, we THINK that it's around 14.3 billion years old, but how can we know for sure? If we could somehow travel to the farthest star that we can see and set up a telescope we may see another 14 billion years into the past. Then we move again and see another 14. The reality is that we just don't know for sure but we make some pretty cool guesses.

I don't believe in absorb, I think there is more going on than we can comprehend with our instruments and limited understanding. It's like watching an ant hill from a mile away, we can see a little bit of activity but we also miss a lot.

Don't forget: what we know about is just about 5% of what is really there. Lot's of stuff to discover! (I repeat my connet here, so that you see it in your notifications).

That is very true. I hope I live long enough to see the next big discovery.

very good, then. perhaps you're right and a Son of Hubble telescope will show us major mass beyond 14 billion years ago. then we'll struggle to decide whether our original estimate of the universe age was a little low, or is our big bang model a little tiny? i too hope to see the next level of discovery, and i think it will be that 'dark matter' is outside the 14 bill range, but close enough to draw those peripheral galaxies outward in an accelerating way. ( :

I think you are correct. We know that dark matter has mass, hence the name "matter." And since gravity and mass are closely related it seems that this would be the driving force behind the big stretch. The next big question is what happens next...will everything that we consider real simply move so far apart that gravity cannot holt it together and it becomes a bunch of wandering subatomic particles...or will the big rubber band snap back and compress all matter in the universe, creating another big bang and therefore, another universe? These are the questions that keep me up at night.

let us not hold our breath!

Don't forget: what we know about is just about 5% of what is really there. Lot's of stuff to discover!