= 27d567bc2d48d9f40e9ccc20ea370b15)
The_Duck comments on What are your contrarian views? - Less Wrong
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (806)
You don't need GR for a rotating disk; you only need GR when there is gravity.
Rotation drags spacetime.
Only if the rotating object is sufficiently massive.
Only if the rotating object has any mass at all.
For a rotating object of sufficiently small mass, the mass can be ignored, and reasonably accurate results can be found with special relativity.
I don't disagree. This discussion was philosophical in the pejorative sense, being about absolutely exact results, not reasonable approximations.
The OP was claiming that special relativity was incoherent, not just that it wasn't absolutely exact.
If you want absolutely exact results, you'll need a theory of everything. There are quantum effects messing with spacetime.
Right. Well I'd agree that special relativity is incoherent for accelerating rotating frames -- it gives different experimental predictions depending on your choice of reference frame. It may be unusual to use accelerating reference frames, but they work just fine in classical physics. But they don't in special relativity.
It's not a very meaningful or contrarian statement though. Special relativity was known to be incoherent with regard to accelerating reference frames from day one. "Special" as in "special case", which it is. I guess my objection here is thta the OP listed it as a contrarian viewpoint, but as far as I can tell it is the standard view taught in Physics 103.
No they don't. From an accelerating reference frame, an object with no force on it will accelerate. You can only get it to work if you add a fictitious force.
I don't think it's accurate to call it incoherent for accelerating reference frames. If you try to alter the coordinate system so that something that was accelerating is at rest, and you try to predict what happens with the normal laws of physics, you'll get the wrong answer. But it never says you should get the right answer. There's symmetries in the laws of physics that cause them to be preserved by Lorentz transformations. Since a transformation can be found to make an arbitrary object be at rest at the origin and in a given orientation, it's often useful to use the transformation so that you can do the math with the object being at rest. Special relativity simply does not have such a symmetry to allow an accelerating object to be changed to an object at rest.
The fact that you can't use arbitrary "reference frames" doesn't mean that special relativity only works for a special case any more than using the (x,t) |-> (-t,x) transformation on Newtonian physics not working means that Newtonian physics only works in special cases and is incoherent.
The reason special relativity is a special case is that it only applies to flat spacetime, when no mass is involved.