If I understand the big bang theory correctly our whole universe was in a hot dense state. And then suddenly, rapid expansion happened where everything expanded outwards presumably from the singularity. We know for a fact that the universe is expaning and has been expanding since it began. So, theoretically if we go backwards in time things were closer together. The more further back we go, the more closer together things were. We should eventually reach a point where everything was one, or where everything was none (depending on how you look at it). This point should be the center of the universe since everything expanded from it. But after doing a bit of research I have discovered that there is no center to the universe. Please explain to me how this is possible.
Thank you!
In: Physics
The “Big Bang” turns out to be a terrible name. It makes people think of explosions and explosions have a center where everything is moving away from it. That’s not what happened.
If you could “see” the universe far enough back in time it wouldn’t be a single point like some people (most?) imagine. It would be like an insanely dense fog of matter made up of subatomic quarks and gluons called (shockingly enough) quark gluon plasma. This plasma would be more dense than anything that we can currently observe in the universe. Just incredibly incredibly dense. And it would be everywhere. You couldn’t actually exist at this point in time, you couldn’t see even if you could, you couldn’t move either, but in our thought experiment if you could move you’d just find this incredibly dense plasma soup all around you.
When the “Big Bang” occurred what happened was that space everywhere all at once started expanding.
Imagine you are standing in the middle a room, perfectly cube shaped. Each wall, the ceiling, the floors etc is a different color. One of the walls is transparent. Another room identical in size to yours is on the other side of that wall. Your friend is standing in the middle of it. Suddenly you both start shrinking and in an instance you are each 1/10 of your previous size. Relative to each other the distance between you appears to have increased by 10x. After all neither of you physical moved. You didn’t go running in one direction and your friend another.
Ok now what if I told you that instead of shrinking what actually happened is the room you were in grew. And so did the room your friend was in. The effect would look the exact same. The end result would be the same. You’d now have to travel 10x as far to reach your friend. Now imagine an infinite set of rooms in every direction just like yours. Each one with a person in it, each one growing at the same rate. It would look no different than if you all started shrinking at the same time. The number of rooms are infinite so they aren’t expanding into each others space it’s the space itself that is expanding. And it’s expanding everywhere in every direction all at once.
You could pick any room and things would appear more or less the same. The further away a person was from you in the starting room the faster they would seem to be moving away from you as the rooms expanded (or you shrank). And if they looked at you it would appear you were the one moving away. But neither of you moved, nor did anyone else. Again it’s just that the distance between you got ~~smaller~~ larger.
You don’t need a center for this kind of expansion.
So why did space start expanding? We don’t know.
And what was it like BEFORE it started expanding? We also don’t know.
Our current models can’t predict what happened before the Big Bang. Our instruments can’t detect anything that appears to have occurred before the Big Bang. We may never know or understand what it was or why it happened. Scientists and mathematicians will certainly keep looking for explanations and evidence but for now we just have to understand that so far as we can tell the universe doesn’t have any kind of center and it doesn’t even need one.
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