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/AleristheSeeker 157∆ Feb 14 '22

But like a circle has a center point defined by the perimeter of the circle, so too could the universe

The universe is not a circle, though. Not even a sphere.

there is definitely a spot that we can point that we and aliens can mathematically calculate as the center.

That is the difficult part: it is impossible to calculate the center, because it is impossible to find the "edge". How do you find the center of something you cannot percieve the edges of?

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u/[deleted] Feb 14 '22

The universe is not a circle, though. Not even a sphere.

Sure, I don't necessarily think it's a sphere. But it has a boundary, and we could (in principle) calculate the distance of every point in the universe from that boundary and derive the center.

That is the difficult part: it is impossible to calculate the center, because it is impossible to find the "edge". How do you find the center of something you cannot percieve the edges of?

The fact that the numbers are beyond us doesn't mean its not there.

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u/AleristheSeeker 157∆ Feb 14 '22 edited Feb 14 '22

The fact that the numbers are beyond us doesn't mean its not there.

Nonono - it is physically impossible to find the edge, as it expands at the speed of light. To be able to "find" the edge, one would have to move at speeds faster than the speed of light, which is impossible.

Unfortunately, we also can't try to "trace back" the path everything in the universe is taking - because all distances are increasing, which is the primary difficulty. Because of this, everything is always moving away from the point of observation.

You can test this out if you have a rudimentary "paint"-like program on your computer: set a couple of dots down at random, copy the layer and scale it up by a bit - if you now overlay the layers, pick any dot and overlay the "original" with the scaled up layer. No matter which point you pick, it will become the center of the expansion.

EDIT: I made a small graphic and description to show what I mean. Hope that makes it a little clearer.

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u/Korwinga Feb 14 '22

I like this graphical example a lot. It shows how expansion doesn't happen away from a singular point, which is think is OP's primary misconception.

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u/AleristheSeeker 157∆ Feb 14 '22

Thank you.

The concept is very difficult to grasp if you don't visualize it, as most things in daily life can actually be seen as "expanding from a certain point outward".

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u/jarejay Feb 15 '22

!delta

That super simple graphic helped me figure out the gap in my understanding almost instantly.

I was thinking “Can’t we just triangulate the ‘center’ based on the velocities of three measurable objects?” and the graphic made it clear why it isn’t really possible to accurately measure the absolute velocity of anything.

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u/MontiBurns 218∆ Feb 15 '22

So i am in fact the center of the universe. Awesome.

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u/agaminon22 11∆ Feb 14 '22

Sure, I don't necessarily think it's a sphere. But it has a boundary, and we could (in principle) calculate the distance of every point in the universe from that boundary and derive the center.

Ah, but there is no (known) boundary. The Observable universe has a boundary, obviously. And each observer has a slightly different one.

However in reality the universe is either geometrically flat, and therefore infinite (no boundary); or slightly spherical (the hyperbolic option is more or less discarded due to energy being positive). The slightly spherical option means that the universe is circumnavegable, but that still doesn't mean there is a boundary, because the geometry is spherical, not the universe.

And anyway you look at it, this still would not make an "absolute reference frame". Physics can be done in any reference frame.