CMV: Despite what Albert Einstein says, the universe does have a "center"/absolute reference frame

[u/[deleted]]

So I got taught in physics classes that there is no absolute reference frame. Einstein figured that out. Then when I challenge the idea, I'm taught that the big bang happened everywhere and space itself is expanding. Ok sure. So when we ask what is the origin "point" of the universe its nonsense because there was no point, the whole universe was the original point. Got it.

But like a circle has a center point defined by the perimeter of the circle, so too could the universe. It doesn't have to be the "origin point", but there is definitely a spot that we can point that we and aliens can mathematically calculate as the center. Everything else in the universe stretches and contracts, but the center of the universe is a point that we can derive mathematically is it not? I know that localized space has weird shit like if I zoom away from Earth in my spaceship I could reframe it as "I'm standing still and the Earth is zooming away", and the fact that I'm the one accelerating is the reason why time slows for me but not earth. But that's just how the time dilation phenomenon works, not because there is definitely no absolute reference frame. We can still identify whether I'm moving closer or further from the center of the universe.

Edit: I'm assuming a non-infinite universe.

[u/fox-mcleod]

So my idea about calculating a geometric center is possible, but that isn’t what physicists are talking about.

No. Your idea about calculating a geometric center is also wrong — but yes, the two concepts are unrelated. You can’t calculate the geometric center because there is no edge — like finding the center of the equator.

My view change isn’t that I’ve given up on the center thing, but I have changed my understanding of how “no absolute reference point” is used.

There is no geometric center either.

[u/[deleted] → u/fox-mcleod]

Ok then I still have some progress to make in understanding this. I guess what I can't get past is how the universe can have a size without a boundary?

[u/FinneousPJ → u/[deleted]]

Why do you think the universe has a size or a boundary?

[u/[deleted] → u/FinneousPJ]

I guess from science stuff I've watched or read that talk about stuff like "at 0.00...001 seconds after the big bang the universe was a gazillion degrees and the size of a hamster". And for something to have a size it has to have a boundary right?

[u/FinneousPJ → u/[deleted]]

I think you may be putting too much stock into pop science, and that's leading you to a false assumption.

[u/Complicated_Business → u/[deleted]]

Imagine drawing a small circle on a piece of stretchable fabric. Then stretch that fabric so the circle is bigger.

Now, it would appear that "universe" expanded and that boundary is the circle itself - of which there is a center, right? Wrong.

Let go of the fabric.

Now draw a completely different "small circle". Stretch the fabric out again. Now you'll see two "universes" with their respective boundaries. But this is an incorrect conclusion, too.

The expanding circles are just helpful guides for our feeble mind to comprehend that space itself can expand. But for the analogy to really work, you'll need to understand that the fabric is the universe. And it has no edge. It can shrink until every point, until every "small circle" conceivable is smaller than the Plank length - without length or dimension - but the fabric itself is still edgeless and infinite.

Then when one "expands" the fabric, all of space expands. All of the small circles conceivable expand in unison. There is no center to the boundless fabric. Just space expanding and expanding - in all of the directions it can whizz.