Bjarne-7

Correct, they can't possibly do that Right, the problems is not limited to Bob and Alice. Bob and Alice cannot agree about any speed or any distance anywhere in the universe or even at planet Earth, - except in their own gravitational environment. You have good reason to be confused. Remember that the "problem" is not limited to the speed of light. No matter how Bob and Alice tries to relate to distances or speeds in other gravitational environments, they encounter the same problem over and over again. They pretty much always disagree about speeds and distances everywhere in the universe. Imagine that Bob and Alice have measured the orbital period of Saturn's orbit. Bob will naturally say that the orbit-time he has measured is a split second shorter than what Alice has measured. Bob must of course then conclude that this means that the orbit must be shorter than what Alice can conclude, - t * v = d Einstein would probably answer that Bob and Alice must both be right, but it seems that Einstein forgot to tell why? No one will properly dispute that the distance being "d" must be firmly anchored. We know that Bob and Alice define "t" differently, and hence also necessarily must define "v" differently. "v" consists of: - meters "m" per second "s". The only remaining parameter left to "manipulate" is therefore "m" - (the ruler). We need to deal with this rationally, logically and mathematically. And must conclude that different perception of "deformable distances" can not only be due to variation of "t", - but also must include "m", (the ruler) which then must be considered as a proportional relativist variant. This is the only mathematical possibility which can allow Bob and Alice to explain that they measure distances differently. It means when time in a gravitational environment stretches, there is a proportional corresponding stretch of the ruler too. In other words, Bob and Alice rulers are absolutely the same length when they come from the factory. But when Bob and Alice bring them to different gravitational environments, the rulers are changing size (stretching) proportionally with the change / stretch of time. Only this solution can justify the claim that both Bob and Alice are right. The alternative is that nobody is right.. maybe only except for Peter who lives infinitely far away in a environment completely without any gravitation, which means far far far far away.

Correct Correct We cannot conclude that Bob is doing something "wrong", but only that Bob does not agree with Alice, because Bob has measured the travel time for the same photon to be shorter than Alice. Both Alice and Bob measure an event taking place in outer space. - Neither of them is part of the event apart from the fact that they both measure the arrival of the same photon to Earth. But Bob and Alice get 2 different results. (Bob measures the photons journey to take 41 seconds less than the time Alice has measured. ) - This must mean that either c must be a variant and/or Bob and Alice ruler must be a variant. Which of these 2 factors is changing in a gravitational field?

A photon sent from the same source, - 14 billion years earlier, - by the same path, can signal Bob and Alice to start timing when this first photon is received. PS. I am not allowed to post more that 5 post today, so I have to take a brake In the meantime, consider that , we can also imagine that the photon is simply trapped in a skyscraper and reflected between Alice and Bob, endlessly up and down for 14 billion years. The problem is the same. Bob and Alice cannot agree on how far the photon has traveled in 14 billion years. It will not make sense to claim that there is a 41 second difference between Alice's and Bob's perception of simultaneity.

We now assume there is only 1 photon, it is less confusing. The photon can only be emitted at the same moment. Alice and Bob can easily agree to start their timing at the same moment.

Alice will reflect photon-2 , - 90 degree to Bob The path that the two photons travel is exactly the same (except the last 1000 meter) . The time measured is different, - this is a fact, - thus either c, - distance, - cannot be t the same for both Alice and Bob. Or the ruler must be a variant. It is assumed that both photons follow the same route all the way to Alice. In principle, we could imagine that there is only 1 photon, and that Alice measures the travel time it took that one photon, - at the exact moment when she reflects this one photon further on to Bob. On the one hand Alice will measure the travel time to be 1/300,000 of a second longer for the Photon to reach Bob. However, on the other hand Bob can confirm that the journey took 41 seconds less than the time Alice has measured. So the consequence must be that Bob and Alice will never be able to agree, unless either: - the travel distance , - or c, - must be perceived differently by Alice and Bob

It's a thought experiment. Photons can theoretically be fired from the same "cannon", in the exact same direction and with an insignificant split-second interval. I assume that the speed of light does not change because the 2 photons travel the same path. I also don't expect the distance to change, again because the 2 photons travel by the same path. The only rational / logical question that remains is therefore, is it possible that rulers may be relativistic variants?

A thought experiment Let's say that the Earth is 14 billion years old today and that 2 photons from a light source 14 billion light years from us sent 2 photons towards the Earth 14 billion years ago. (4.41504e17seconds) Both photons followed exactly the same path. Allice received both of these photons today. – She reflected the one photons to Bob. Alice lives on top of a skyscraper which is 1000 meters high. Bob lives on the first floor. Bob's clock loses 1e-15 seconds every second compared to Alice's clock. Alice agrees with the theory of relativity that the speed of light is 3e8 m/s and she also agrees that the distance that the photon she received has travelled excatly: 14 billion light years. But Bob disagrees with Alice, - well it took the photon 1/300,000 second longer to reach him at 1st floor, because - (after Alice reflected one of the photon to him) - the photon had to travel an extra 1000 meter . The problem is that Bob's watch shows that the photon has travelled 441 seconds less than the time Alice has measured. (4.41504e17seconds x loss of time factor 1e-15) Now who is right Alice, who 100% agrees with the theory of relativity? Or Bob? If Bob is right, then either the distance to the source that emitted the photon must be 132300000 km shorter than the distance that Alice has agree about, - OR - the speed of light must be faster than c, at least for Bob . or what ?