Weird little questions for this here group

[eccoblackfin]

How large is the known universe? Or, put in a different light, do 'we' have any clue as to where the universal center might be, or what it looks like in theory or otherwise? Finally, what's the object, be it galaxy, star, restaurant, etc., furthest away from us?

Comments

[timeprojectile]

The "known universe" is, sort of, about 14 billion light years in radius, which would mean 28 billion in diameter. We can only see the distance the light has been able to travel in the 14 billion years since (this episode of?) the Universe began. But space has expanded since the light set out from these galaxies, so technically I think that would make them farther away today than what their light-travel time would infer. And furthermore, we think the Universe is even larger still, beyond what we can ever see due to the Universe's finite age and increasing expansion, because the best way we have to explain why the cosmic microwave background looks more or less the same even on opposite sides of the sky (which are twice as far away from one another as light has had time to travel) is that it was all once in contact with each other long ago, but an ultra-powerful expansion of space immeasurable fractions of a second after the Big Bang, known as Inflation, blew these similar regions apart

[eccoblackfin]

Thanks, that answered a lot of questions. It also raised a hell of a lot more though.

Ah, don't you just love astronomy?

[timeprojectile]

That's what science always does. Raise more questions than it answers. Which can be frustrating if you're in one of those moods when you want answers...but wonderful if you're in one of those moods where you want to feel like you're part of something magical and mysterious and beautiful.

[eccoblackfin]

So, with that theory/analogy, we're basicaly just skimming along the surface of a bubble? Does that mean that sometime in the next trillion years or so we'll do a full circle and be smashed together in a new big bang?
Or maybe, we're already being pulled into the next one, the so-called 'dark flow', by the rest of the universe that we don't know about yet o.O

[timeprojectile]

I don't think we know yet, and I'm not sure we CAN know, what the ultimate fate of the Universe will be. Like I said, I think I was told that we can't really think of the curvature of the Universe being in an extra dimension...the sphere thing is not to be taken literally, it's a matter of visualizing how geometry in "curved" space works

[umbran]

Does that mean that sometime in the next trillion years or so we'll do a full circle and be smashed together in a new big bang?

No. The "everything is moving away from everything else" phenomenon is not due to our moving around on the surface of the bubble, but because the bubble is expanding. So long as the bubble continues to expand, things'll continue to move apart.

If there's enough mass in the Universe, eventually the bubble stops expanding, and starts shrinking. Then, things will start oving together, and we head for a Big Crunch or Big Bounce, depending on your favorite theory.

[cultureofdoubt]

Superb answer. And right about "But space has expanded since the light set out from these galaxies, so technically I think that would make them farther away today than what their light-travel time would infer"
The radius is about 46 billion light years "comoving radial distance" - which is basically the distance with the expansion factored out to today's scale (there's other ways of measuring distance you'll sometimes come across which are more practical to measure but give very different values - I think this one is most meaningful here though)