I The Einstein Clock aka Light Clock

[Dale]

Do we agree that there is a problem?

Yes, there is a problem. The problem is here:

The source of radiation is the point of space with its respective coordinates, and it has nothing to do with the fact whether the material device is at rest in this point or not.

That is false.

The source of light is current and charge densities, as described by Maxwell’s equations. Those are material. And, importantly, the charge density $\rho$ and current density $\vec j$ together transform as a four-vector $(\rho,\vec j)$, called the four-current density. In particular for this conversation, the direction that $\vec j’$ points is not generally the same direction that $\vec j$ points.

in either frame in this scenario to have the speed c we will need to measure the distance between the wave front and the ORIGIN OF THE COORDINATES. This is so even for O' where at the moment of the measurement will be no material lamp.

This is true, but does not imply that the material lamp is not the source. The source of the wave front is the material lamp at the retarded time. The fact that the source has moved between the retarded time and the measurement time is irrelevant. At the retarded time the lamp was at the origin and the material lamp physically emitted the wavefront at the origin. The lamp is the source.

How do we choose which sheet to pull at speed v?
If the shots are not identical, on what grounds we choose one of the trajectories to be inclined?

By applying Maxwell’s equations in each frame, properly transforming the material sources in each frame.

 

[Ibix]

Will we agree upon that?

Idealising the emission to a single event, that event is independent of the state of motion of the source (note that this is an idealisation). However, how the radiation is distributed very much depends on the state of motion of the physical object that is the source. Dale argues this based on the physics of light emission in #31, PeroK shows it based on aberration in #29, and I showed it based on conservation of four-momentum in #27.

You are using an inconsistent physical model of light, and that is why you are finding contradictions. My guess is, it is because you are simply inserting radiation by hand because you don't want to think about the physics of emission, and you are doing the insertion twice (once in each of the two frames). That wouldn't be a problem except that you are doing it inconsistently. If you apply SR correctly, the contradictions you find will go away.

 

[Herman Trivilino]

In the Einstein original paper,

What is the reason you are studying this paper? Are you trying to understand the physics? Or are you trying to understand the physics and the paper at the same time?

If the latter you've taken on a task few if any educators would have their students pursue. That paper was written in 1905 for an audience of physicists already proficient in 19th century physics. You are neither.

A far better approach would be to start studying a text written for modern students who are trying to learn special relativity. Then if you're still interested in the 1905 paper you'd be better prepared to take that on.

For this reason, I'll venture that the "help" you're getting in this thread is not at all helpful to you.

 

[PAllen]

Ladies and gentlemen, I thank you all.

I still think you do not understand my difficulty. I hope you will see this is not filibuster for just wasting your time. Most of you are explaining to me the basics of SR, and that's very much preaching to the choir. What I'm trying to speak of is the basics of these basics.

Well, you have claimed counterfactual things (e.g., that aberration does not apply) multiple times in this thread, so we do need to explain basics.

The closest to the point are those who are talking about the motion of the source of light. Although I never had problems with which lightbulb is moving (I'm not that dumb, believe me), I do have issues with how we define the source of light. Some of you are confusing the actual material device that emitted light and the notion of the source of light in SR. These are NOT the same, whence all my difficulties.

I will once again give it different wording.

1. Let's forget about the sphere of light for a moment. Let there be two lamps each emitting two photons in opposite directions. We place these two lamps in the origins of the coordinate systems the moment they coincide, each lamp motionless in its respective frame. At the same moment, the two lamps emit four photons, two per lamp, two going in the direction of the motion of O', two in the opposite direction.

And these 4 photons, if emitted by the same physical process, will have different energies. All observers will agree that the 4 photons do not have the same energy/frequencly.

Now, the fronts of the radiation will coincide for both directions for both lamps, no matter moving or not moving. One lamp is therefore surplus;

How do you conclude that? The photons have different energies.

this system can be reduced to only one lamp attached to no matter which frame. Let it be attached to O. The distance measured from the point of origin of light over time will be equal to c for both O and O'.

True, but the detection events in O' will be at completely different location/time from the detection events in O. System O will say its detection events are simultaneous and equidistant, while those of O' are at different distances and different times (both from each other and from O s detections). Meanwhile, O' will claim the reverse. Both O and O' will measure two photons of different energy at each of their different detection events. (Pretending you can non-destructively measure a photon ...)

This is quite elementary, but I needed to say this to demonstrate that in either frame in this scenario to have the speed c we will need to measure the distance between the wave front and the ORIGIN OF THE COORDINATES. This is so even for O' where at the moment of the measurement will be no material lamp.

That's why I maintain that within the context of SR the material light emitter and the source of light ARE NOT THE SAME THING. The source of radiation is the point of space with its respective coordinates, and it has nothing to do with the fact whether the material device is at rest in this point or not.

That abstracts from fundamental physics. Light has a physical source. If you insist on only one emission event, then if the emitter is at rest in O, then O' will detect two different photon energies. If it is at rest in O', then O will measure two different energies. There will four different detection events.

Will we agree upon that?

I absolutely do not agree.

 

[PeterDonis]

@DmitryS you have made the same error multiple times now, and have persisted in it despite repeated corrections. Enough is enough. The correct answer is given multiple times in this thread, and there's no reason to repeat it any more. Thread closed.