I mean if I drop a rock into a lake, its makes circles and the outermost circles are the oldest. Or if I blow something up, the furthest debris is the oldest.
In: Physics
On a number line, where is the “center” of infinity? 0? Maybe. But -59264920.5849201 is just as valid as the “center”.
We cannot speak with any definition about anything beyond the observable universe. We can speculate, but due to an increasing expansion of the universe things are constantly falling out of our observable universe. And technically *you* are the center of *your* observable universe. Someone down the street or in the galaxy over would be their own center of the universe.
The analogy doesn’t work though, because *space* expands from the big bang. Every point traces back to the same, and depending on your frame of reference, everything is moving away from you just as fast according to distance.
It would be like you are in the center of an explosion, but when you move a very far distance out into one side of the explosion, you look around and note you are *still* seemingly in the center, with everything exploding away from you just as evenly as your last viewpoint.
With no edge, and every far off point expanding away equally, there is no true “center”. Every point is just as “center” as every other point in space.
EDIT to continue: To leave the furthest edge of the explosion, or to travel beyond the furthest ripple in the ocean, is to step outside of space itself, which isn’t possible. Space was once contracted to a single point, but “where that point is” isn’t a question that makes sense, because ALL space of the universe was only there, and there was nothing beyond, because “beyond” implies… well, space.
It’s hard to wrap your head around and others will explain it better but…in your example the lake existed before the stone was thrown. What makes the big bang so hard to comprehend is that it wasn’t an explosion in space, it was an explosion of space and time. There was no before because there isn’t time without the big bang. There’s no center because there is no space without the big bang. One day, about 13.6 billion years ago, space and time started existing. As far as we know there was already infinite space from the beginning, the bang part is that there’s even more now so things that were close back then have more space between them now.
Imagine a hollow rubber ball. Or a tennis ball, except it’s smooth.
Imagine yourself walking on the surface of the ball.
How would you find the center of the surface of the ball?
Ohm it’s rather easy, just imagine an infinite space, with no edge, shrunk down to infinite small space. Now every point in that infinite space is basically the same point, meaning every point is the centre. Now, how did it expand? By adding more space between every point of space. Continue to do this till you get the size that it’s now at.
Let’s imagine the universe is a giant balloon, and we put little dots on it while it’s deflated. When we blow up the balloon, all of the little dots we drew on it move farther from one another as the balloon gets bigger. Now if you were a tiny person standing on one of these dots, you would see all of the other dots move away from you. But here’s the thing: no matter which of these dots you’re standing on, it would always look as if you’re in the center, and that all of the other dots are moving away from you. The universe is kind of like this. Instead of a special spot in the middle of the universe where everything started, it’s expanding everywhere at the same time. So, no matter where you are in the universe, it would seem as if everything else is moving away from you, similar to the balloon.
When you drop something in a lake or blow something up, it starts from one point and spreads out. But the universe isn’t like that. It isn’t expanding from one point and into empty space; instead it’s the space itself that’s expanding. That’s why there isn’t a single center—everything is spreading out together.
It is a common misconception that the Big Bang occurred at a single point and everything spread out from that. The Big Bang wasn’t explosion. It wasn’t a small bomb that sent shrapnel everywhere from a central point.
The Big Bang happened everywhere all at once. It’s hard to comprehend, we aren’t used to thinking in infinities but to the best of our knowledge that’s ehat happened. It also happened incomprehensibly fast. During the Inflationary Epoch, which lasted a fraction of a fraction of a fraction of a second the universe expanded by a linear factor of at least 10^26, possibly more.
Imagine if in less than a blink of an eye you had a one nanometer string that suddenly was 10 light years long. That’s how fast it happened.
And it happened everywhere.
Imagine you have a sheet of graph paper where you each square is 1cm by 1cm. Now imagine that graph paper is infinite. You can move up or down, left or right, it doesn’t matter. Every where it’s the same. Endless 1cm^2 squares. Now, imagine positioning yourself above a square, right above the center. Let’s zoom in on that square so it appears the square is 1 m by 1 m. From your perspective it seems like everything moved away from you right? The square to your left was 1cm away now it’s 1m away. Same on your right or above or below. So you are at the center and everything else moved right? Nope. If you were to have started at any other square and done the same thing, you would have seen the same result, everything would have appeared to move away from you there too.
That’s what happened (and continues to happen) for the universe. Space itself is expanding. Not the stuff in space, the thing that stuff is in.
But all the evidence so far tells us there is no center.
The Big Bang isn’t exploding “outwards”, it spreads at each point in all directions. This is pretty much why we have no center.
Your lake analogy doesn’t work, because in the case of the Big Bang there was no “lake” to drop the rock in.
It’s more like you dropped the rock and a tiny, tiny lake appeared exactly where you dropped it and started growing. Where in the lake did you drop the rock? Everywhere, because the whole lake was all exactly where you dropped it. And there wasn’t even a lake until you dropped it.
Only it’s still wrong, because a lake has an edge, and the universe doesn’t. So the nearest analogy we can get would be to make the expanding lake the surface of a sphere, like a soap bubble, that starts incredibly small, exactly where you dropped the rock (whatever that means now), and expands bigger and bigger. Again – where in the surface of the bubble did you drop the rock? Everywhere, because, again, the whole surface was all exactly in the place where you dropped it. The bubble wasn’t even there before that. There’s no special “centre” anywhere in the surface bubble.
And that’s STILL not good enough, because the spherical bubble is a two-dimensional surface embedded in three dimensional space, and it has an inside and an outside. Whereas the universe is three dimensions of space and one of time, and it’s not necessarily embedded in anything else – it just “IS” .
And frankly, if your mind didn’t give up at that point, I’m amazed, because mine certainly does; you just have to accept the basic ideas and fall back on the mathematics to work out what that means for a 4 dimensional universe. But the question and answer are still the same: where in the universe did ~~you drop the rock~~ the Big Bang happen? Everywhere. The whole of the universe was all packed up together incredibly small, not “in” anything else – and it all grew. There’s no special centre of the universe. And – as far as we currently know – there wasn’t even a universe “before” that. “Before” in quotes, because even time only started at the Big Bang.
No, my mind won’t do that either. The “no space or time before the Big Bang” picture is only one of several. The problem is that the maths that describes the universe basically breaks down at the Big Bang. That may or may not always be the case; the jury is still out. For now, it’s the best description we have.
Where is the centre of the surface of a sphere? Alternately, which country contains the centre of the planet?
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