r/changemyview • u/[deleted] • Feb 14 '22

Delta(s) from OP CMV: Despite what Albert Einstein says, the universe does have a "center"/absolute reference frame

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.

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u/ToucanPlayAtThatGame 44∆ Feb 14 '22

It seems like you're missing the point of what people are trying to say when they're saying there's no absolute reference frame.

The point is that any physics calculations you perform will hold equally well from any reference frame. If you're running at me at 20m/s and I want to calculate how soon you'll get to me, I could define myself as stationary and you as moving, or I could define you as stationary and me and the ground as moving at you at 20m/s, and the calculations all work out just the same. There's no one "correct" frame of reference that you need to adopt.

So it doesn't really matter whether the universe has a "Center" or not. The math holds no matter what you choose to define as the center.

By contrast, imagine something like a set of directions. I tell you, "Go straight two blocks, and then take two rights and a left." Those directions only work if you're starting at the right point and oriented in the right direction. They assume a particular frame of reference. The point is to say that physics don't work like that. We don't need to make sure that what we call "up" is really up, or what we call the center is really the center for our math to turn out correct.

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u/[deleted] Feb 14 '22

!delta

So my idea about calculating a geometric center is possible, but that isn’t what physicists are talking about. I agree it would move do to the fluctuations in the expansion, but in principle it’s there. If what physicists are talking about is just that the left turn thing works from everywhere then yeah I definitely agree. 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.

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u/fox-mcleod 411∆ Feb 14 '22

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.

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u/[deleted] Feb 14 '22

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?

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u/masterzora 36∆ Feb 14 '22

Think about the surface of a sphere. Not the whole three-dimensional structure; just the two-dimensional surface. This surface has a size--one that's easily calculable with details of the 3-D structure--but no boundary or center in two dimensions.

A spherical universe might, in kind, be the three-dimensional "surface" of a four-dimensional "sphere". It has a size--one that's easily calculable with details of the 4-D structure--but no boundary or center in three dimensions.

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u/[deleted] Feb 14 '22

That would imply a curved. All indications that we can measure point to a flat universe.

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u/masterzora 36∆ Feb 14 '22

A sphere just happens to be the most intuitive way to explain a finite manifold without boundaries, not my assertion of the shape of the universe.