Recent content by harrylin

Hi Greg! Wow that's a long time ago. Regretfully I didn't find more insight on that topic. In fact, the whole Bell theorem issue remains one of the greatest riddles to me - and I had forgotten about that subtle point. Thanks for reminding me of it! :-)

What is derived are the Lorentz transformations, and those are defined relative to inertial frames - exactly as the "Galilean transformations" of classical mechanics. Very likely your question is therefore more basic, and belongs in the classical physics forum. Can you answer the question what...

It says that there is no way to tell. And note that there are different definitions of "inertial frame"; I suspect that your definition differs from that of those who replied before me.

Exactly - but it seems that you missed the point that I made. Length, volume and mass are usually measured at 1 bar at room temperature and in rest and locally. There is no reason to treat "mass" differently from "volume" and the issue is effortlessly taken care of by the merchants.

However, that's exactly what most merchants do - already length and volume depend on temperature - and even on speed and location. In real life one has to work with "standard" conditions. Why would a merchant prefer a convention rule for "mass" that is not consistent with that for "volume"?

That's a misunderstanding of what I said. Thus, maybe it's just a matter of semantics. You and jbriggs ignored my clarification that physically it is different if the car changes velocity or if you change velocity. According to you, the kinetic energy of a system changes (and thus is not...

I was talking about invalid physics, not history...

Once more, that's a misapplication of the laws of physics - they are not valid between reference systems. Newton's first law, energy conservation etc. all don't work, it's just nonsense.

I'm not sure what you try to argue there, but it's simply wrong, due to a misapplication of the laws of physics. Physically it's not the same if you accelerate or if that body accelerates. The velocity and kinetic energy of a fast particle cannot change due to your relative speed to it - that...

It's not difficult to find Definition no.1 of the Principia - https://en.wikisource.org/wiki/The_Mathematical_Principles_of_Natural_Philosophy_(1846)/Definitions

It's sometimes better to read the physics FAQ about such topics: http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html

There is a variant of that experiment which may be easier to follow: https://en.wikipedia.org/wiki/Relativity_of_simultaneity#The_train-and-platform_thought_experiment Here you start with a single source in the middle of the train, and analyse what will happen with the detection, as nicely...

Summary with last pictures here: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Mission_complete_Rosetta_s_journey_ends_in_daring_descent_to_comet

No, we don't generally see them were they were when they sent their light; your question suggests to me that you did not understand the animation that you posted in post #19; t may be useful to have another look at it. And maybe, just maybe, the issue that is puzzling you (or part of it) is...

Maybe it's useful to phrase what others already said in again other words. A tennis ball that is thrown straight upward relative to the train, is thrown at an angle relative to the tracks. And just the same, a light ray that is emitted straight upwards relative to the train, is emitted at an...