This is of course false, the Terrell effect is just as present, you can't "wish it away".

No, the Terrell Penrose effect will still be present

*but* it won't as precisely affect the shape of the track as a perfectly circular wheel does. AlphaNumeric as well as the videos show that when the spinning (not rolling) wheel is in the plane of the monitor

__it will not appear distorted__. This will not be the case for the tank tread because of its non-symmetrical shape.

In other words, there is no proof.

Not if they aren't backed up by solid math. There isn't any backing up this claim.

Tach, if there is no meaning to proofs made of words, then what is the point of talking? If we cannot make sense of anything said without mathematical symbols, then how can we even begin to have a discussion on relativity? If you're correct then we have been spouting gibberish for the past 160 posts!

So, what gravitational effects will it have on a moving observer?

If the observer is moving at the same speed as the wheel's tangential velocity, the wheel will still look distorted.

Actually , the wheel looks distorted, I even gave you the precise equation, it is a family of ellipses moving at speed $$V$$. What is still in debate, it the form of distortion of the spokes, my equations clearly differe from **Pete's**. I think that I pointed out the source of error in Pete's equations.

Actually the movies show the distortion, all of them.

Yes, but they look differently distorted from different angles! Pete has pointed this out in a later post, quoted here at the end.

Maybe 60 years ago this view was valid, not today.

Hmmmmmmmm.. I don't even know enough about it to make a statement. The way I understand, it is now something like an 'electron cloud' ... too bad, because orbiting electrons would provide a possibility to test this experimentally.

The tank is not a practical example either, as excellerating the entire tank to c - (1 m/s) is itself problematic..., beyond our current technology.

Particle accellerators should be a good alternative, relativistic velocities are attainable, in that case. But I don' see how it fits the current hypothetical.

Particle accelerators accellerate particles and ions, bare nuclei.

Has there been any test involving whole atoms at relativistic velocities? Something like the LHC would likely strip the electrons away. Would seem to have had to happen in a linear accelerator. Even then I would expect the atom to become unstable, torn apart by the EM fields of the accelerator.

I suppose if there were relativistic tanks I would have known already.

I know that accelerators have to work with ions because they use strong electric fields to force these to move. Do they use completely bare nuclei? (and I am too sleepy now to check) Also, isn't it possible that a hydrogen atom with an electron attached will form when particles smash together? This would still conserve charge.

Can you show a fixed wheel which rotates in the plane of the monitor screen?

The animations given earlier are the best I can provide, but these not only account length contraction but other effects such as terrell rotation and ray tracing. This wheel looks 100% normal.

most of its mass is actually concentrated in the top half

I can disprove the redlined sentence , before I do it, I am asking you to provide your proof. This is the claim that you made in post 52 that it is at the origin of our disagreement. Provide your proof (since you made the claim) and I will provide my counter-proof.

How can you disprove it? We agree that visually, at least, most of the spokes will be above a line drawn in the rest frame. Mass will intuitively be found in the same place.

No, I've seen it before. For example, it was mentioned in [post=2385907]DRZion's first Sciforums thread[/post] in 2009.

My point is that you are now disagreeing with the same material you used to support your argument a year ago.

Yep, and this is why I started this thread too.

Chinglu brought up an objection which was just too much like my earlier objection - that there will be no way to determine the course of events using relativity. Minds work alike, and they can fail alike as well. I still have to make up my mind about it.

There isn't "more mass", The raytraced image of the spokes makes them look curved as in the picture.

A simple test proves this: place a strip of paper between the wheel and the light source or between the wheel and the eye and you'll see only half the spokes. No spokes have "wandered" in the half of the wheel peeking over the fence.

Even so, if only 4 spokes are present above the edge of the paper, they will still be bunched up!

I still don't see a contradiction.

- The videos are rendering
*visual effects*, they are showing what a camera would actually record (except for light intensity changes and doppler shift color changes).
- In the camera rest frame the rolling wheel spokes are distorted while the spinning wheel spokes are straight..
- Remember Teller-Penrose - at a distance, the light-delay shape distortion of an approaching object is approximately opposite to the length-contraction shape distortion.
- With the spinning wheel in the video, there is no length contraction distortion, only light-delay distortion.

Did you notice that the spinning wheel distortion is reversed when looking at it from the other side?

This adds even more complexity to the issue. Because now the spokes will be shifting around as the observer moves around. Hence, no force is acting on the spinning wheel, but as the observer moves around the spokes will appear to migrate from one portion of the wheel to another, and quite likely shift the center mass of the wheel.

There are three questions:

1) How does the y-axis mass-energy distribution of the rolling wheel depend on our reference frame?

2) What frame-dependent gravitational effects are implied by the answer to 1)?

3) Does the answer to 2) imply any contradictory outcomes?

Question 1) is being thrashed out.

Tach says the answer should be no, but the calculations so far suggest (to me at least) that the answer is yes, that in the ground frame there is more mass-energy above the fence than below.

The second and third questions haven't been addressed with any kind of formalism.

I think that the reason Tach is disagreeing with przyk, RJBeery, and myself about the first question is that he thinks that would imply that the answer to the third question is yes.

But I'm sure we can all agree that if the answer to the third question turns out to be 'yes', then we're doing something wrong.

These are good questions! I am too tired to think clearly today, I will try tomorrow though.