J.C.MacSwell

How can a redshift indicate collapse?

...and yet, one loses proportionally more momentum than the other, and the other proportionally more angular momentum. ...and of course, you can't be wrong so... Paradox!

Didn't I already explain this to you next week?

All but the most local are red-shifted. That is evidence they are moving apart from us. From our rest frame it is them moving, from their rest frame it is us moving.

I guess my point was that if the parameter could be adjusted for an acceleration, could it not be adjusted for a deceleration, and since enough deceleration leads to contraction... then how can it be inconsistent with the theory? Having said that, bringing things back to another thread with respect to time frames, if the contraction started everywhere at "once", we would notice a blueshift locally far before waiting for the blueshift from the far reaches of the universe, correct?

If you draw it, you might see the difference and begin to understand. It is not the shape, it's the way the force vector must be applied in each case, to slow down the disc and ring without slipping. They have the same amount of momentum. They have different amounts of angular momentum. This affects the way any force vector must be applied to slow down the disc or ring without slipping. You might then see how it applies in the simplest case of a fixed straight track. If you cannot do this how can you possibly understand the more complicated isolated circuit track. Merged post follows: Consecutive posts merged Thanks BN. The curious thing is, that he offered to do just that, fix any errors or omissions if I pointed them out, but he seems to balk at doing it. From his link in the first post he is obviously capable of drawing, he just needs to slow down and do it. I would be happy if he at least gets this one part right for now, the deceleration of the disc and ring on a fixed straight track. I suspect he will not get it right the first time he tries it, since he thinks they are the same, but it will be a start.

So you can prove this by drawing it on a free body diagram. Draw me a force, that will slow them down as you describe.

70+ posts and no one has mentioned the Nazis, and no one has asked "what can a guy do, when a dog comes on to him". Not bad.

Yes. This is why we let our teenagers drive, instead of relying on sound signals and operating the controls from our house.

In the current model the expansion is accelerating, correct? Is that consistent with GR? Or did they have to add (and start searching for) a factor to make it work?

A force is a vector quantity. You have chosen to model the ring with the same mass as the disc but higher moment of inertia. They have different ratios of mass to moment of inertia. If they roll without slipping while decelerating the decelerating force cannot be applied the same way. Not in the real world and not in an idealized model. You can simplify and say they are approximately the same, but don't point to the difference later and say "Paradox". When forces don't balance or momentums don't balance in an isolated system that is a sign that you have made a mistake, not a sign that there is an exception to a physical law.

It depends on a lot of factors. I was hoping you would draw the force vectors and see the difference between the disc and ring and to see what it meant to have the "same" rolling resistance for decelerating discs or rings. The resultant force vectors cannot have the same magnitude, direction and application point in each case (unless at least one of them is skidding to some extent)

The drawing shows a wheel being pulled with constant velocity against rolling resistance. Deceleration due to rolling resistance will be different from that.

That's basically the idea. Blood alternately rushes to your head or feet but the background doesn't spin. After observing you go back to normal mode.

Draw it and see.

Start with a free body diagram. Draw the forces on ring or disc showing rolling resistance.

If it was shrinking it would be blue-shifted.

Does it come with a tether? Looks like it would make a good counterweight for Sisyphus's idea.

Yes.

You put it and more in on one side of the track, and remove it on the other, along with other "non-extra" inputs and extractions. It just takes more to input to accelerate the ring than the disc, and also more to extract on the other side.

The habitat portion would rotate once per revolution the way you described. All very nice when you don't look out the window. But when you want to observe what is going on outside the background will appear to be rotating, so you apply a counterspin to stop the rotation, making it not rotate, just revolve, and it will look normal. Might feel a little odd while your doing it.

This is not correct. Misleading at best. Correct. Just keep it mind that the force and momentum are vector quantities, unlike energy.

No amount of energy can overcome the law of conservation of momentum. Balance the momentum equations. Balance the energy equations. Just because it has more kinetic energy does not mean it has more momentum. I understand what you think is going on, but it doesn't work that way.

I like that.The habitat could revolve without rotating and allow the inhabitants to observe there surroundings in a normal manner.

If they are at the same velocity there is no difference in translational momentum between objects of equal mass. Neither the ring nor the disc can magically gain any momentum to impart to the track, without taking it from the track, unless an outside force is involved.