IS the Theory of Relativity now proved or not?

[hellas1]

Hey all,

Is Einstein's T.O.R. proved yet?

I ask this because I'm interested in Cosmological Topology and new developments within it which state the Universe is a square, while some physicists state it is a Mobius strip, of sorts.

Comments?
hellas1

[ajm317]

http://en.wikipedia.org/wiki/Tests_o...ral_relativity

[Sphere]

I know that both the bending of light under gravity, and time dilation have been proven by experiment (many decades ago). Time dilation is actually essential to GPS satellites because they measure distance using time, and they travel so fast their internal atomic clocks are significantly off from those on Earth.

[Djûn]

If we're trying to be REALLY pedantic here, we could say that nothing can be proven, only heaps of evidence supporting theories. The Theory of Relativity happens to be one of these theories as far as I'm aware.

[eventhorizen]

As far as I am aware the Theories of Relativity have been proven to be slightly inaccurate in certain circumstances.

[ajm317]

As far as I am aware the Theories of Relativity have been proven to be slightly inaccurate in certain circumstances.

What circumstances?

[Big War Bird]

What circumstances?

Black holes for one. Its kinda hard to make sense of what's going on inside one when all your calculations go to infinity or zero.

[Portuguese Rebel]

If we're trying to be REALLY pedantic here, we could say that nothing can be proven, only heaps of evidence supporting theories. The Theory of Relativity happens to be one of these theories as far as I'm aware.

I'm with this guy...

[MaximiIian]

I was under the impression that it had been proven, as well as any scientific theory can be proven, for decades now.

[Simetrical]

The theory of general relativity has been more or less proven since 1919. Since then, evidence has only accumulated in its favor. It's only at very small scales that it's known to be incorrect, where quantum mechanics dominates.

[ajm317]

Black holes for one. Its kinda hard to make sense of what's going on inside one when all your calculations go to infinity or zero.

Black holes aren't really a problem in the context of relativity. Things go to infinity or zero yes, but it is entirely possible that is in fact what they do. From the point of view of relativity, there's not necessarily anything interesting going on in a black hole. It's a point with finite mass and infinite density that leads to an infinite curvature in spacetime.

And there's not really anything wrong with that in relativity. The problem comes when you attempt to add what you know from quantum theory to the picture, one of them has to give so to speak, but we don't know that it's relativity that does so.

The theory of general relativity has been more or less proven since 1919. Since then, evidence has only accumulated in its favor. It's only at very small scales that it's known to be incorrect, where quantum mechanics dominates.

Relativity isn't "known to be incorrect" at small scales. For one it's never been tested at those scales. What is known is that it conflicts with quantum theory at those scales, and that one or both of them must be wrong.

[Simetrical]

Relativity isn't "known to be incorrect" at small scales. For one it's never been tested at those scales. What is known is that it conflicts with quantum theory at those scales, and that one or both of them must be wrong.

Relativity is a purely continuous theory, isn't it? It doesn't agree with the quantization of all sorts of physical quantities at small scales. Wouldn't it would predict continuously varying phenomena where observation shows discrete ones? The field equations assume continuous time, for instance (right?), which AFAIK isn't an accurate model at very small timescales.

[ajm317]

Relativity is a purely continuous theory, isn't it? It doesn't agree with the quantization of all sorts of physical quantities at small scales.

Well yes. One would assume that given what we know about the other forces, there must be some way to quantize gravity. Evidently you can actually get quite far with this by treating gravity as an effective field theory, although you still can't get reasonable predictions at Planck length.

That said though, you can't actually test any of the predictions that arise from this yet. It is reasonable to assume general relativity must be quantized, but we just can't observe the effects. I suppose it's nitpicking, but I would say we believe general relativity to be wrong, but we haven't done an experiment that proves it.

Wouldn't it would predict continuously varying phenomena where observation shows discrete ones? The field equations assume continuous time, for instance (right?), which AFAIK isn't an accurate model at very small timescales.

It's been a while since I opened my quantum field theory book, but I don't think time is ever quantized by anyone, save some of the more exotic quantum gravity candidates. The big difference between GR and, say, quantum electrodynamics is that in QED the field becomes an operator which acts on a quantum state.

[Simetrical]

Well yes. One would assume that given what we know about the other forces, there must be some way to quantize gravity. Evidently you can actually get quite far with this by treating gravity as an effective field theory, although you still can't get reasonable predictions at Planck length.

That said though, you can't actually test any of the predictions that arise from this yet. It is reasonable to assume general relativity must be quantized, but we just can't observe the effects. I suppose it's nitpicking, but I would say we believe general relativity to be wrong, but we haven't done an experiment that proves it.

I see. So basically, we're pretty sure it must be wrong. But at the scales at which QM starts to become important, GR predicts near-zero forces anyway, and we can't tell whether the observed forces are those predicted by GR or some other near-zero forces. Something like that?

Of course, you still have all sorts of weird phenomena that GR doesn't cover. All the quantum stuff, like entanglement and virtual particles and heaven knows what. But I take it you'd say that doesn't show GR to be wrong, either, because those phenomena are just outside the scope of the theory.

It's been a while since I opened my quantum field theory book, but I don't think time is ever quantized by anyone, save some of the more exotic quantum gravity candidates. The big difference between GR and, say, quantum electrodynamics is that in QED the field becomes an operator which acts on a quantum state.

Since you mention it, of course, the Schroedinger equation is a differential equation with respect to time, so I guess it must treat time as continuous. (Not that I know what most of the quantities in the Schroedinger equation actually mean, but I can figure out the t.) Maybe I was getting confused with the fact that there's no measurable time interval smaller than the Planck time ― I guess you could still have 1.5 Planck times, so that doesn't mean it's quantized.

[Playfishpaste]

Dude, gravity hasn't even been proven. Laws are laws because they are repeatable and without a doubt true. Relativity can't be because we haven't confirmed all the variables and likely never will in the near future.

[Simetrical]

Gravity is proven to within the standards of science. While saying that nothing is verifiable is all very good and well in principle, practically speaking it's absurd. Things are verifiable, just not absolutely and irrefutable (outside of math).

[Playfishpaste]

Well of course, but that's all circumstantial, we should all consider gravity and relativity as true for the vast amounts of evidence for them, they just aren't laws because there is no solid 100 percent proof, like there are for Newton's and Thermodynamics.

[Simetrical]

What? Thermodynamics and Newton's laws have no more evidence in their favor than gravity.

[Sphere]

"Newtons Laws" are actually not correct, even at the macroscale. For instance they do not accurately predict the orbit of Mercury. Relatavistic ideas and equations are needed to account for these inaccuracies.

And the Laws of thermodynamics are completely inadequate for explaining nuclear reactions.

[Simetrical]

Newton's laws are still accurate within certain bounds. Inaccuracy may approach a few percent near an object as large as the Sun, but that doesn't make the laws entirely wrong, just imprecise in some contexts.