Center of the Universe

[Ramen King Roshi]

So feel free to explain to me if I just don't understand it, but is there a way to determine where the "center" of the universe is? Provided Big Bang rapid expansion type stuff is the correct theory, then there should be a point of origin. And the universe is expanding, and movements of the stars and such are trackable...is there a way to pinpoint where they're all traveling away from, or is it an erratic path?

[VorpalNeko]

No; Big Bang has no center nor any point of origin. It was literally everywhere rather at some specific place.

Suppose the universe is infinite. Imagine you have an infinite line of galaxies the same distance from each other (very idealized, but good enough as an analogy):
..-*--*--*--*--*-... now
As time goes on, the universe expands, by which we mean the galaxies get further and further apart
..-*---*---*---*---*-... later
..-*----*----*----*----*-... later still
and so forth. Things are getting farther an farther apart, and the universe gets less and less dense.

Run this backwards in time instead:
..-*--*--*--*--*-... now
..-*-*-*-*-*-... earlier: things are denser
..*****.. earlier still: things are even denser
but there are still infinitely many galaxies and an infinite amount of space, at every time. But the density increases to infinity as they get squished together: we have a singularity. Everywhere.

That's a toy model to think of a Big Bang with an infinite universe. A finite universe would be a bit different, but there would still be no center, with a metaphorical "explosion" going from everywhere. (Which makes it quite unlike actual explosions, but still.)

[Vannak]

Ramen King Roshi

So feel free to explain to me if I just don't understand it, but is there a way to determine where the "center" of the universe is? Provided Big Bang rapid expansion type stuff is the correct theory, then there should be a point of origin. And the universe is expanding, and movements of the stars and such are trackable...is there a way to pinpoint where they're all traveling away from, or is it an erratic path?

There's a big difference between the big bang and any other kind of explosion.

In a normal explosion you can look at the direction the shrapenel is coming from and trace all the bits back to a single points. However, the big bang isn't an explosion. It's an expansion. Every single point in the universe appears to be the center. If we were home, on the moon, in Andromeda, or on the other side of the observable universe we expect as we look further away, we see greater and greater redshifts regardless of where we actually are.

What seems to be the case isn't that the galaxies are actually moving very fast, but that the spaces between galaxies is increasing itself.

The canon analogy is the inflating of a balloon. Draw points on the surface of a balloon. As you inflate it, each point moves apart similarly to how the galaxies appear to move. Things near by you don't move away very fast, things far away from you move very fast. Note that this doesn't mean that the galaxies are moving relative to their spot on the balloon. There's no one spot on the balloon that all the dots "came from".

Of course, this analogy breaks down because the balloon doesn't start from a single points, like the universe. But if you allow yourself to imagine a balloon that can deflate, in a sort-of-spherical way all the way down to near nothing, you'll get the picture.

[Ramen King Roshi]

Alright, that was actually pretty helpful, thanks biggrin

[Sneaker Pimps]

According to our current scientific knowledge it is immeasurable at this time to find the center of the universe. 'The universe is boundless."

[Dardanos Immortalis]

Even if the universe had a center I don't see how the knowledge of it would be of any practical use to us.

[Xiam]

The Hitchhiker's Guide to the Galaxy

"Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen..."

The Universe is so large that, from our standpoint, the center of it is us. It is so big that the light from the edge of the Universe hasn't yet been able to reach us. Judging by the Red Shift, everything seems to be expanding away from everything else, so - like I said - we see ourselves as the center, and someone in the Andromeda Galaxy would think everything is expanding from them.

Oh, except the Milky Way and the Andromeda Galaxy, which will eventually crash into one another.

Point is, it's really hard to figure out where the Big Bang originated, because there are so many factors against finding the center of the Universe.

[Shokushu]

At the earliest moment of the big bang everything in the observable universe was at the same point.
The tricky bit to understand is that none of it moved away from that point.*

From a center frame of reference you can say that the point itself got bigger (MUCH bigger.) Doesn't make intuitive sense for something like a point to change in size but the fabric of space doesn't really make a lot of intuitive sense anyway.

From about the opposite frame of reference all the stuff at that point shrank a whole lot so that there was lots of emptiness between any two quantums of energy that were formerly squeezed so densely against each other.


*Early on it was basically dense energy in all directions. The tug of gravity was the same in all directions so without gravity or pressure to push stuff around it wouldn't have much reason to move. Fast forward a good bit and you had hydrogen atoms nearly uniform everywhere, but some tiny differences added up and you got gravity sucking the hydrogen into massive stars- and once those start fusion they have solar winds shooting away from them so you push all the gas away in a fairly big area. Big stars also go supernova after long enough and that ejects lots of stuff that gives an even bigger push. Fast forward some more and most of the gas is caught up in galaxies with a whole hell of a lot of empty space between them. At this point there's kind of a lot of gravity in fairly small points- over very long distances it still evens out to basically the same in all directions but the galaxies aren't quite the same distance apart all of the time- so you can get the nearest neighbors drawing each other in, and now that there's all that empty space there's definitely no pressure to fight against them coming together.

[jordan and pablo]

technically, space does not exist outside of our universe so there is no defined end because there is NOTHING to define it
no space, no time
no nothing
because there is no real end, there is no way to determine the edge of the universe and therefore no equidistant point (center) of the universe

*assuming all multiverse theories are incorrect

[Dr Roar]

space has a center, just as all shapes do. its just hard to find and not really important at all.

and the universe is not infinite. to many paradoxes would emerge from an infinite universe.

[Shokushu]

First you've got to confront a common misconception: a lot of people think that the big bang was an explosion.

Ok so now that you know that's wrong, instead try to picture just a single point. We'll call it the center for fun. Everything is at this point. Directions don't really matter, it's not like you could just move forward and leave EVERYTHING for some sort of empty area- there flat out are no areas except where everything is at. Not very easy to picture but keep trying.

So now we'll say the big bang has started. Instead of any of that stuff moving (remember, there's nowhere that isn't the center for it to move to,) the point we've called the center starts to get bigger. A few billion years later and it's bigger than the observable universe.

Ok then, now's the part where I tell you that it wasn't really just one point. Psyche. Things at Cosmological scales don't really make a lot of sense when you try to relate them to everyday scales. What I just made you do is kind of backwards from the frame of reference people usually use but it's not really any better or worse, just different.

[Evil Spagetti]

the earth

[Enchantingly Unexplained]

At some point, all the matter in the universe was at a central point, and existed as some kind of primordial superfluid, a matter-antimatter mixture in which partners annihilated each other upon contact, but somehow the mixture became imbalanced, causing the universe to become lopsided toward having matter.. The superfluid collpapsed under its own weight, and triggered a reaction, the first ultra-mega-supernova, which we call The Big Bang. As the matter As far as we know, the black emptiness of the universe stretches on forever, and the things which fill up this universe are creeping outwards and away from each other. This is directly observable behavior. Rewind the universe, you return to a central point.

[Doubtful Dreamer]

Enchantingly Unexplained

At some point, all the matter in the universe was at a central point, and existed as some kind of primordial superfluid, a matter-antimatter mixture in which partners annihilated each other upon contact, but somehow the mixture became imbalanced, causing the universe to become lopsided toward having matter.. The superfluid collpapsed under its own weight, and triggered a reaction, the first ultra-mega-supernova, which we call The Big Bang. As the matter As far as we know, the black emptiness of the universe stretches on forever, and the things which fill up this universe are creeping outwards and away from each other. This is directly observable behavior. Rewind the universe, you return to a central point.

Er...there is no central point. The big bang is the expansion of space itself, not matter being flung out into space by some explosive process.