Thanks for some issues to ponder. I have not been happy with the paradox at any time but others who are more into relativity say that one does not really exist. Perhaps they are correct, but so far I have not been able to come to that conclusion.
Like I said, I can not defend any good solution to that problem. My thoughts about the trains equally accelerating around the earth is that both should calculate the same time changes due to symmetry. When they meet, a stationary observer would determine that they are both moving at the same velocity but in opposite directions. I would think that he finds their clocks reading the same slow rate. It seems also that each train rider would measure a different time dilation for passengers on the other which is the original paradox modified. Each passenger would come to the conclusion that everything is normal regarding his measure of time. Other observers may not agree. One day I hope that all of us will understand how this works. Dave -----Original Message----- From: John Berry <[email protected]> To: vortex-l <[email protected]> Sent: Wed, Feb 19, 2014 9:32 pm Subject: Re: [Vo]:Time Dilation impossibility On Thu, Feb 20, 2014 at 2:49 PM, David Roberson <[email protected]> wrote: Harry, I have battled with that issue many times attempting to make sense of it. The best that I can come up with is that it actually is the acceleration which leads to the difference in clocks. Since velocity is the integral of acceleration, you can always determine it by having access to the acceleration that the object is subjected to. I admit that I have not pursued this far enough for a proof, but at least it has some traction. If my suspicion is correct, once the acceleration has had an opportunity to operate upon the object then the instantaneous velocity can be used as a short way to figure the total time differences. I can only speculate that this holds true at this point. I will only defend the concept weakly. Here are some thoughts that may weaken that further. Acceleration can be extremely rapid, indeed arbitrarily so, there are many accelerations that happen very suddenly. Next, it is possible to have both observers accelerate equally, consider 2 trains that go around the earth on parallel tracks, but in opposite directions, before they start moving the clocks in all carriages can be synchronized from a pulse from the center of the earth. The clocks could be made for easy observation even at high speed. And with a stroboscopic light, it would even be possible to see the person in one of the carriages, write notes on paper to each other, make faces. And the same for an observer on the earth frame. John Dave -----Original Message----- From: H Veeder <[email protected]> To: vortex-l <[email protected]> Sent: Wed, Feb 19, 2014 6:25 pm Subject: Re: [Vo]:Time Dilation impossibility John, Eric is right about the constancy of c being a *postulate* from which time-dilation and length contraction are derived. However, that doesn't discount your thought experiments as a way of probing the coherence of SR. Imagine two friends with synchronized watches. One friend boards a train and zips away for a time at near c and then gets off and walks back to his friend so that they can compare the time on their watches. Which watch is ahead? Using the principles of SR I can come up with contradictory answers. harry Harry On Wed, Feb 19, 2014 at 3:45 PM, John Berry <[email protected]> wrote: On Thu, Feb 20, 2014 at 4:54 AM, Eric Walker <[email protected]> wrote: On Wed, Feb 19, 2014 at 2:38 AM, John Berry <[email protected]> wrote: Are you arguing that this is impossible? This is a thought experiment so it only has to be theoretically possible to make such a measuring instrument. I would consider it obvious that such an instrument is possible. I have no need to argue that it's impossible. Clarity of thought suggests that we start from something we already know about, rather than a hypothetical measurement I've never seen before. If it is reasonably and obviously possible, then it is valid. If you wanted to do this experiment, there would be no great difficulty in doing so. The separation and velocity of the of the moving platform may or may not be beyond practical implementation. About the possibility of the instrument -- I would assume any photon would be likely to be scattered during the first reading, and then, even if it was not, the act of being retransmitted to en route to the second detector would add in an unacceptable time delay that would invalidate our measurement. I have read that photon detectors can be put in double slit experiments and while the wave function will be collapsed by knowing which slit the photon went through, the photon wasn't absorbed. Of course this is another ridiculous objection that makes it seem like you would rather have a tooth pulled than accept an obvious truth. There could be many photons released in a single pulse, each detector only absorbs a small number of photons. According to SR, no we wouldn't. But if what was moving was anything else including a particle moving at almost the speed of light. If it was anything that can possibly be understood we would. Right now you are using circular reasoning that seems very much like arguments for belief in God. I think you misunderstand. You're claiming that SR is logically inconsistent. I'm hoping you can help me to understand this and come to the same conclusion. In order to do so, I have to be convinced that you're not setting up a straw man. Right now I'm persuaded of exactly the opposite. SR claims, as an assumption, that light in a vacuum, measured in an inertial frame, will be detected to be moving at c, no matter the reference frame. This is an axiomatic assumption based on empirical evidence. Einstein saw evidence that the speed of light would always be measured at the same velocity in an inertial frame, and then he asked the question of what would happen if this observation was turned into a fixed point, i.e., made into an axiom. He then derived a bunch of weird stuff about length contraction, time dilation, Lorentz invariance, etc. These were conclusions that were based on the earlier assumption (and other assumptions). Do you see the problem in your own statement? The speed of something being the same no matter how your position and velocity may differ from other observers is by default an utter impossibility. The 'bunch of weird stuff' is the only thing that could possibly help it make sense, only there is no way it can as I have shown. SR only works if that weird stuff can make the speed of light look the same to all observers, well it can't as I have shown. The fact that you have taken on faith that this 'weird stuff' can make it all make sense is the problem. Science isn't a religion, you aren't meant to take things that are illogical on faith, not examine them and get dogmatic in your defence of that thing. You are acting like we shouldn't bother our pretty little heads with how this impossibility can occur. If you think that I am misrepresenting how SR argues the speed of light may be measured to be the same, then please read how it makes these arguments. I have read such books long ago and recall the arguments. I'm not arguing that he was correct. I'm arguing that if we're to show that he was incorrect, we should stick to SR and not something that is different from SR. What? You are saying that if Einstein was incorrect we should still keep his incorrect theory Special Relativity? Keeping a theory known to be incorrect makes no sense at all. Keeping it when it is incorrect and impossible when better theories fit all the evidence, honestly I can't believe what I am reading. It's a question of logical reasoning, not faith. If we start talking about how time dilation and length contraction show how the speed of light will not be measured to be c in a vacuum traveling in an inertial frame, we've either come across a trivial logical inconsistency You consider it being illogical 'trivial'? It means that it is not possible for it to be true. That is not trivial. (unlikely, but possible I suppose), or we've misunderstood one or two applications of the basic assumptions in SR. You cannot say that R is illogical, describe R,' pick apart R' (or attempt to pick it apart), and then transfer any conclusions back to R. I'm trying to help you to help me to better understand why SR is incorrect by helping you to avoid setting up a straw man argument. I'm pessimistic that this is going to go anywhere. Me too! If you refuse to have any understanding of how SR works, then anything I argue will look very much like a straw man to you. It is protection by ignorance. I do not understand much about quarks, if you were arguing a flaw in the concept of colour or flavour, or that the top quark must be on the bottom... I would have no idea if your argument was right or wrong since my understanding of quarks and their whimsical qualities is insufficient. But that would not mean that you were wrong, just that I would be wrong in trying to argue it with you since I don't know enough about the subject. You need to read straight forward arguments made by SR on how these things are possible (not abstract Math, Einstein said he didn't understand his own theories once the mathematicians did their work up on it). But if you think that we should keep a theory shown to be incorrect, in favour of theories that fit the evidence and are logical, then i am afraid your thinking is too twisted and far from truth for there to be any meaningful exchange. Hopefully on that point I am mistaken and have just constructed a straw man. John Eric
