Recent content by pervect

If you do an experiment in a small sealed box where you only look at things inside the box, the laws of physics according to special relativity don not allow you to tell whether you are moving or not. If your question is about general relativity, you might be able to detect motion relative to...

I'm on board with this - I regard it as the theory of timelike congruences, which I first stumbled across in Wald, and later read more about in Poisson's "A Relativists Toolkit". Before that, I went with using Fermi Normal coordinates to gain a physical understanding. At that point I couldn't...

I have espoused that idea, and met a lot of resistance in certain instances. When I have the energy, I still do sometimes like to advocate for the idea that the fundamental idea of physics "should be" presented independent of conventions. But that is more from idealism than practicality. I...

I would use much simpler (but also less precise) language to convey a similar thought. I would call "causal diamonds", light clocks. It's just a matter of a different name choice, I am thinking that the idea of a "light clock" might be more familiar for the typical PF reader. I am somewhat...

I'm not sure what the best tools are to treat the relativity of simultaneity. I find space-time diagrams (Minkowskii diagrams) convenient, but I think much of the value lies in learning to draw them, and less in looking at diagrams others have drawn. Looking at diagrams others have drawn can...

Yes - I agree. I suspect that a full classroom environment, with homework and grading of the homework to provide feedback to the audience/students studying the material is a huge help in the success rate of understanding. Some of the pedagogical literature I've seen suggests that the...

MENTOR NOTE: This thread is a continuation of the following thread and focuses on Relativistic Simultaneity and it's effects on time. https://www.physicsforums.com/threads/true-static-equilibrium-and-effects-on-time.1083728/#post-7296784 —- You seem to be stuck on the idea that "time slows...

I would suggest learning about quantities, called invariants, that are independent of the frame of reference. In special relatiavity, his would be, for instance, the Lorentz interval. This would be discussed in textbooks such as "Space time physics" by E.F. Taylor. An older edition is...

That's correct. And in the context of special relativity, neither a material body nor a frame of reference can move at the speed of light. This should not be surprising, since if a frame of reference could move at the speed of light, light would be stationary in said frame of reference. But...

I don't know if this is standard, but I think of a vector, in tensor notation written as ##u^a## as a column vector in matrix notion, represented graphically as a little arrow with magnitude and direction, and a one-form, ##u_a## in tensor notation, as a row vector in matrix notation...

My $.02. Intuition is great, but - it's just not reliable. The only way to know if your intuition is correct or not is to look at the facts. Using your intution to try and guess at the facts is just not going to be reliable. We don't actually have a lot of facts relevant to your questions...

My understanding of quantum mechanics is not good. But I've been under the impression that "ordinary" quantum mechanics is not compatible with special relativity. Specifically, Schrödinger's equation is not compatibility with special relativity, and neither is the idea of instantaneous wave...

I concur with Pallen's observations. MTW goes into the explicit geometric details of how to construct a proper frame of reference. And I agree one can get an inertial proper frame by setting the acaceleration and rotation to zero - Pallen has quoted the relevant section of MTW on this so...

Measuring pressure is certainly possible. Even in Newtonian mechanics, pressure is only as simple as a single number when the pressure is the same in all directions (i.e. isotropic). I could say more about how anisotropic pressures wind up being represented, but I think that would drift off...

You can't move at the speed of light, but it turns out you that relativity depicts what you describe. There's another way of saying this - given a head start, a rocket with a constant acceleration can outrun a light beam. In the case of a rocket accelerating at approximately 1g (the exact...