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Comment by tsegratis | Hacker News Reader

Thanks. Is red-shift average the same in all directions?

If there were a big-bang, and we were at the edge, different parts would accelerate away from us at different speeds

That would give a measurable center...??

Otherwise, I suppose universe is a sheet of elastic stretched everywhere equally

I learnt stuff from the link, it suggests universe wraps like a balloon does in 2D, but with a higher dimension. So center is not visible. They conclude no center, but equally say no evidence for higher dimensions... Of course balloons have centers just need to express them in the right dimensions

So I think they defeat their own argument?? (4D objects still have centers -- just expressed 4D)

But anyway, was mainly trying to find if there is an infinity within reality; or just stupendous immeasurablility?

-- That would be more crazy than being at the center, imho

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>If there were a big-bang, and we were at the edge, different parts would accelerate away from us at different speeds

You're operating on a very outdated understanding of what the big bang was - for half a century now we've understood that there was no single point at which the big bang occurred, so there's no center to the universe everything is spreading out from. The big bang happened everywhere at once, and space has continued expanding everywhere at once ever since.

https://physics.stackexchange.com/questions/136860/did-the-b... is a well written explanation, so I won't try to poorly rephrase it here.

Thanks that was super helpful

A 3D obj stretched everywhere equally -- I suppose this is the same as the 2D balloon -- as it is also stretched everywhere equally

One says everywhere is equi-distant from the origin in a 4th dimension. The other also says everywhere equi-distant but from zero, but adds a topolgy with no edges

A 3D topology with no edges ofcourse requires a 4th dimension though

So I think these are really two ways of saying the same thing?

In any case, it really helped answer some other Qs for me

In a simplistic sense the differences in the Hubble constant, are of course a dimension. So adding dimensions as in string theory is a fancy way of explaining nothing. But I wondered... Is there a correlation between Hubble constant differences and 3D space?

If so, it would (in my unremmitingly small brain) show an interaction with dark energy a.k.a. this 4th dimension

A clearer way to say that: the skin of the balloon has a thickness, and differences in the Hubble constant are measuring that thickness

-- Your answer was awesome and super helpful -- Can you do it a second time? :)

Your questions are answered at:

1. https://www.youtube.com/watch?v=aPStj2ZuXug&t

2. https://www.youtube.com/watch?v=blSTTFS8Uco

And more such videos at PBS SpaceTime. A fair warning though that that is a rabbit hole and likely to consume a lot of your hours/days to get through.

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