Relativity revisited once more still again

If it were infinite yes but some of us seriously doubt it is.

assuming that somehow when we three meet for the first time that you and I are passing by A (I'd supposed in opposite directions) when we're all three still 20, regardless where you and I came from. It's at that instant you fire your retros so that both of you then watch me pass, nearly at c, though apparently motionless

The q is, Ora, assuming a finite Universe whether or not at my return I'm still 20 at our second meeting

Admittedly I'm simplifying; though it's the "same spot" of course you and A (as well as Earth probably) are long gone by millions or maybe billions of generations

The pattern in the Cosmic Microwave Background Radiation is strong evidence that the universe is truly infinite.

why?

There is really no evidence for relativity!
Or can someone show me some?

When atomic clocks are subjected to differing gravitational loads, they run at different speeds.

Already considered invalid.

Quote:

Not if I travelled for some time near the speed of light. In this case, A might be much older, depending on the particulars.

I'm assuming you and A are both 20 at the instant you fire your retros, at which moment all three of us are of course still 20

Perhaps owing to the curvature of space, my movement slowly resumes, reversing at the "halfway" mark, in which case upon my return we're all three the same old age. Just wild speculation

That is incorrect. It is considered a valid proof of the theory.

Now, only Special Relativity is considered absolutely true for all time. Everyone acknowledges that one day General Relativity will be superseded by a successful unified field theory.

But until someone comes up with that successful unified field theory, General Relativity is pretty darn good.

In your hypothetical, do the two travelers start out at rest with respect to the rest of the universe, and then accelerate up to light speed when they begin their journey towards each other?

...then accelerate up to light speed...

This doesn't resolve your q's at all; you might be right in your implication that how we achieved that starting speed might be a critical issue but I'm just not smart enough to address it

….the universe is truly infinite

You are smarter than what you give yourself credit for!

It is all non-sense, but you think you are the wrong one! YOU ARE NOT!

By whom?

It really is very incorrect.

There already IS a unified field theory.

Why is General Relativity 'pretty darn' good?

Ora that's really a good q. However Ora since all motion is presumably relative anyway I am wondering whether it matters

But incidentally perhaps you can now grasp how the idea of a fixed reference" keeps poking in its unwanted nose

This doesn't resolve your q's at all; you might be right in your implication that how we achieved that starting speed might be a critical issue but I'm just not smart enough to address it

In your hypothetical, do the two travelers start out at rest with respect to the rest of the universe, and then accelerate up to light speed when they begin their journey towards each other?

Or were the two travelers traveling at light speed all along, never before having been at rest relative to the rest of the universe?

There is no such thing as "at rest with respect to the rest of the universe." Things in the universe are moving at lots of different speeds.

Brandon9000 wrote:

There is no such thing as "at rest with respect to the rest of the universe." Things in the universe are moving at lots of different speeds.

Chalk it up to sloppy language. I'm referring to the condition of "not traveling anywhere near the speed of light".

I was asking if he was envisioning these travelers accelerating to light speed, or whether he was envisioning them already traveling at light speed from the start.

I think I might propose my own hypothetical tomorrow or sometime. I think I know the question he is trying to answer, and there is probably a better way to construct a hypothetical to explore his question.

By the scientists of the world.

It predicts the results of experiments accurately.

Not one that has succeeded in displacing General Relativity.

Because it models the universe with a high degree of accuracy.