On light clocks and reference frames

[Raymond Potvin]

Yes, it is (https://en.wikipedia.org/wiki/Proof_by_contradiction) , but that is not what is happening here.

If a laser beam that would not spread is an impossibility, then it seems to me that we cannot use it to show how light would travel. To test my questioning with maths, I think that we would have to let the beam spread at a known rate and calculate if it spreads enough with distance to travel the way I suggest it could between the mirrors. If the calculations show that it could, then we could ask ourselves by what means that clock would slow down for real when it moves wr to the observer at rest. On the other hand, it seems to me that if a light clock would really slow down, while at the same time, light would not really travel this way between the mirrors, is also an impossibility. I can understand that the original direction of light might not be observable, because I think that it could be a real possibility, but I have a problem to accept that, for the same clock, an imaginary direction considered locally as a physical impossibility, can be transformed mathematically into a real possibility, again locally, but when observed at a distance. Why is it that a reasoning about an impossibility gives the same numbers as the data? Are we missing something? Do we really have to accept that as a given?

First, aberration is well understood by the scientific community. This analysis is not presented because it is not informative, not because it is mysterious.

To me, the information gets not informative only if the light path is not considered real, but as my fig. 3 shows, if light would really travel diagonally, it would still appear to travel directly, and there would be no doppler effect either, which is exactly what is expected to happen when observer and source are considered to be in the same reference frame.

With a little dust in the atmosphere, we can easily see the path of the lasers.

We see what we think is the original light path, but again, if light would really travel diagonally between the dust and us, it would be impossible to see its diagonal direction, because it would suffer aberration and it would always appear to travel directly from the source or directly to us.

Other's ideas are as difficult to follow as light paths, so maybe it would be wiser to end our discussion here. If I continue, I know I will only repeat the same questioning, and I think that I would always get the same answering, so I'm afraid it would get boring. If I had a proposition that doesn't seem to contradict the data, we could discuss its details, but I have none. Even if I am still not convinced that SR is already answering my questions, the discussion helps me to add precision to my ideas a bit, and everybody does it with kindness, which is all I need to be happy. You are very nice guys, nicer that on many forums I know, and you do a very good job too, but I know that you cannot suddenly accept the possibility that SR is not what it appears to be, and its what my OP is about. I hope that our discussion at least helps other readers to better understand SR!

 

[PeterDonis]

If a laser beam that would not spread is an impossibility, then it seems to me that we cannot use it to show how light would travel. To test my questioning with maths, I think that we would have to let the beam spread at a known rate and calculate if it spreads enough with distance to travel the way I suggest it could between the mirrors. I

Do you understand what an idealized model is? A laser beam that does not spread is an idealized model. Mathematically, it is perfectly consistent and allows us to "test with maths" claims like yours (and see that they are false).

 

[PeterDonis]

Thread closed for moderation.

Edit: the thread will remain closed, we are just going in circles now. Also, whenever you think something like "SR is not what it appears to be" then either you have misunderstood SR or you have been contradicted by experiment.