/sci/ - Science & Math

Try Brian Greene's "The Fabric of the Cosmos" or similar.
Whether there's a micro-structure is unknown. Some (including Greene) think it does. But if it does and you could distinguish one point in empty space from another, then you could count them going by as you moved and measure an "absolute velocity". This violates Relativity.
Also, if there is a "minimum length" such as the Planck Length, how can this shrink further as you accelerate?

There's no "zero coordinate" and the orthogonal axes won't _stay_ straight or orthogonal. That's equivalent to saying space isn't Euclidian. Einstein needed to learn Riemannian geometry before he could formulate General Relativity.
I believe the velocities in Overwatch are too low to make these effects matter though.

>>9318263
Thanks anon, I'll give it a read.

I've read a bit online about people debating whether space-time is discrete; is that in the same ballpark?

And, what do you think anon? How come?

>>9318263
Can't you already measure an absolute velocity by measuring the CMB? The CMB in front of you will be blue-shifted, behind you will be red-shifted.

>>9318203
>Does space-time have a scientifically recognized structure?
Spacetime is a four-dimensional hyperboloid.

>>9318203
>what is space-time?
A quintuple [math] \left(M,\mathcal{O},\mathcal{A}, \nabla ,<\cdot , \cdot >\right) [/math] where M is a 4-dimensional smooth manifold, equipped with a topology [math]\mathcal{O}[/math] , a smooth atlas [math]\mathcal{A}[/math], a covariant derivative [math]\nabla[/math] and an inner product [math]<\cdot , \cdot >[/math].

>>9318315
And such a shift HAS been measured.
But that's residual motion relative to the "local" expansion.
Usually explained by the galaxies-are-dots-on-the-surface-of-an-expanding-balloon analogy. The surface _is_ the entire universe. The interior doesn't exist.
As the balloon inflates adjacent dots move apart, proportional to their initial separations.
You have to imagine the galaxies are little stickers on the surface. The galaxies themselves don't enlarge. Gravity overcomes the expansive force.
Finally, you have to envision some of the dots getting un-stuck and drifting a little (very little) relative to the rubber surface. That's what the CMB asymmetry show.

>>9318294
As I understand it, yes. Micro-structure is equivalent to discrete (or quantized) space-time.

Now, maybe the original questioner was asking about the _overall_ shape of space. Does it have curvature? Today's best measurements say "no". Greene discusses that too. One of the problems Inflation was intended to address was the so-called Flatness Problem. Curvature grows with time. Like a pencil balanced point-down, unless the balance is PERFECT it's going to teeter one way or another. The Flatness at Time Zero + 10e-30 seconds or so must have been incredibly (and unlikely) precise if we don't see any signs of it today. Inflation is supposed to have steamrollered over everything as the cosmos stretched.