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
There’s a few fundamental traps that are hard to intuitively grasp about the big bang as a “starting point”.
1 – the big bang is everything, everywhere. It didn’t “happen and then now we’re after that”, we are currently experiencing it, the expansion of space is still happening, and that’s our primary evidence for its occurrence. “the big bang” describes the entirety of the *present* existence of the universe, not an event that kicked it off.
2 – The big bang is the start of *space* existing as we know it. Not just matter. This can be hard to intuit because we think of it as “all the matter was closer together in empty space, then moved away from each other, occupying different space”, which is only kind of true. But the big bang describes *space itself* expanding, meaning the objects didn’t necessarily “move into other space” (there wasn’t space to move into), but in many cases could be thought of as the *space between objects growing*, while the objects didn’t really move. This one is really hard to explain, and even harder to understand because it’s just entirely unintuitive and runs contrary to our thinking about every day scale and the movement of objects.
3 – In many current models of understanding, “spacetime” is one thing, and includes space and time dimensions. This is how relativity is modeled, why things “experience time differently” in gravity wells or at high speeds etc etc. What this *means*, is that the big bang is the starting point for *time* as well as matter and space. Effectively, as you “travel back toward the big bang”, and the universe gets more dense… the time distance to the “beginning” also increases. Time is weird and hard to really grasp (and hard to model), but ultimately what this means is that getting to “time = 0” at the big bang would take infinite amounts of time. I find it helpful to think of it like a mathematical graphic asymptote, where reaching T=0 is impossible, and things get infinite and unintuitive the closer you get.
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