According to current theories, the Big Bang happened everywhere at once, so there was no center. One somewhat useful analogy is an inflating balloon; the entire surface of the balloon is expanding, but there's no center to the expansion.
But there should be an approximate center of the “balloon’s” area, right?
(I swear to god I’m not trolling.)
I think I phrased my question wrong. If the universe is expanding and we can see the extreme edges of that expansion, where is the center of that and where we, the Milky Way Galaxy, in relation to it?
The "edge" we see is just the furthest point in the universe that light is able to reach us from. Beyond that the universe is receding too quickly for the light to make it to us. Since the expansion is uniform, we can see an equal distance in all directions and thus we are at the center of our visible universe.
Going with the balloon idea, the universe is the surface of the balloon. A sphere doesn't have a center on the surface.
We could say that the center of the sphere is where the big bang started. The distance to the center of the expansion is 13.7 billion years. It doesn't have a distance in x,y,z coordinates, because those are all on the surface, and it's kind of futile to attempt to understand time as a fourth dimension in this regard. We don't know if the universe is spherical at all. It's just a description used to portray the expansion. The expansion is also happening faster than light, which makes it impossible to convert the age of the universe to a size. The universe is bigger 13.7 billion light years, perhaps even infinite. Infinity doesn't have a center either.
I don't like the balloon analogy because it suggests a center but everything is moving away from everything else. It's more like infinite balloons being blown up at once which only works because the universe is infinite. It's more an expansion than explosion. That's how I've always conceptualized it anyway but happy to be corrected
We don't know if spacetime loops around or is infinite or has an expanding boundary. Best we got for reference is the cosmic background radiation, but it doesn't tell us about any center
I'm not sure if this answers the question, but it might help.
Everything in space is moving, but it's not expanding outward from a central point, like an explosion. Instead, the space between the things is getting bigger.
The balloon analogy gets thrown around a lot, but I find it misleading- It's not about the balloon getting bigger, expanding outward from the center of the sphere. It's more about the surface of that balloon stretching.
The rubber sheet analogy helps. Scatter a bunch of things on a infinite rubber sheet. Now stretch that in all directions - the things get further apart, but are not moving away from a central point.
I believe that's what dark energy is- the shortfall from not violating conservation of energy, given what we know about physics vs what we observe in the universe.
My understanding Quantum field theory says virtual particles can be created out of vacuum fluctuations, which makes me think there will be more energy after expansion. Again, I might be getting it wrong.
I'd say you've more chance of being right than me since I know nothing about it. I mean how can a particle be virtual lol. I thought a vacuum meant no particles.