PeterDonis's latest activity

Hm. This congruence would be irrotational, but I don't think its orthogonal hypersurfaces would be flat. So it would not meet the...

Ok, that is fine. However, what is true includes that, in an invariant sense, you can't place the rockets in the new locations at the...

I think the intent was to have the same physical threads in the second case--that you would take the structure built in flat spacetime...

Perhaps a slightly different experiment might help. Consider a flock of small rockets. Initially they are at rest far from a black hole...

But what does that relaxed proper length depend on? You seem to be saying that, if I build two beams of the exact same material, one in...

I will make a self correction which implies we were both right/wrong in a sense. Again, I think the correct analog to a well understood...

In my view, this is not a sensible approach. What you have is a collection of independent rockets, not a body. In a body, in any normal...

No, that's not correct. What is correct is that the lightning strike events have a particular relationship in spacetime, and in any...

All of our experiments done to date over more than a century indicate that reality is accurately described by special relativity on a...

Note that the figures you've reproduced show two different experiments. In figure 2-1 the strikes are simultaneous in S, and if that...

In a generic curved spacetime, yes, because the two types of rigid motions allowed by the H-N theorem each depend on the spacetime...

Yes, agreed. But... They're not orthogonal to the static congruence (the Killing congruence), yes. They are orthogonal to the...

I'll see if I can find any references in the previous threads we had here. At least one of them, IIRC, dealt with a scenario in...

Note that this implies a comparison with the corresponding accelerated object in flat spacetime--in the case under discussion in this...

The only such stresses on a rigid object, whatever its history, are those of tidal gravity.