jefswat said:
I don't understand why you won't take what I say without putting your own spin on it.
Non-Fundamental disagreement The quote would be a definition of Non-Fundamental disagreement. Clearly they are just disagreeing about something superficial. I say a car has length(the traditional sense) of 6 and you say it has length 2. there is a contradiction here because one says 2 and one says 6. However if I then told you one thought 6 feet, the other thought 2 yards you would agree there is no contradiction because they simply did not agree on something superfical like the scale they were using. In general non-fundamental disagreement is about the details like definitions or how fast you were going. I am going south at 10 m/s on a given cordinate system. a ball is stuck at the origin. You are going 15 m/s north. obviously we both conclude that the ball is moving at a different velocity relative to ourselves. Then the uneducated one assumes that one must be wrong. but when you look at the details you see that both answers are in fact correct because of the word relative.
Fundamental disagreement is far more severe. All parties involved agree on everything except the final outcome. I define red to be 600nm wavelength(I made that up). We measure light of 600 nm. I think its red, you think its blue but we both agree that 600nm wavelength is red light. obviously the person who thinks its blue is just not thinking clearly. This is the kind of disagreement that leads to fatal flaws in theories and contradictions that can't be solved. It is also the type of disagreement that after 100 years, SR still have not been proven to have. Does anyone else have a problem understanding this? Its basic philosophy.(Thats actually where I stole it from)
I agree. I usually put it this way: you cannot mistake Cinderella by the slipper, which is just a crafty way to catch her, a clever invention of the human mind for hunting purposes, but not the target itself.
Everything Althnonhare says makes sense if you substititute “measurement” (the slipper) for “quantitative” and “reality” (Cinderella) for “qualitative”.
What else can be the final outcome, other than what you seek from the beginning = solve practical problems where real things that “exist” are involved and interact with others, producing events that “happen” and causing us practical concerns (did Althon murder Mathe?, was the duel fair?).
I do not see why Althonhare insists on labelling as the outcome or the target of the exercises, on putting at the privileged place of things that are unique and fundamental, a mere concept like simultaneity. Simultaneity, like time, does not exist, it is not real. It is a concept, a mere human invention that, in itself, is neither absolute nor relative: it is, like all other concepts (like the slipper), either functional or non-functional, it serves its purpose or not. If thanks to the trick, you catch and marry the real Cinderella, it was good; if instead, because one of the step sisters has trimmed off her heel and manages to put on the slipper, you marry her, it is clear that the trick didn´t work, probably because you had lost the north of the exercise and had started to reify the slipper and think that the instrument, a certain configuration of the trick, was the game itself.
The concept of relative simultaneity of SR cannot be accused of this mistake, because it has been framed so as to respect reality: all observers who apply it (by combination with other measurement of other relative concepts) agree that the same “events” happen, which leads to a single outcome, a single solution to the issue at stake: the real murderer is sent to jail and the bad referee is sanctioned. Here the simile is legal but you can replace it with any other practical problem you encounter in real life (if this life is real, but apparently it seems so!).
Therefore, the “different judgments of simultaneity” are valid and true, as long as each of them works and enables us to identify the real murderer or the referee who rightly declared the duel fair or unfair. But we must not forget in which sense they are both valid and true: only because they did the trick, they wouldn’t if they didn’t!
Forgetting this may lead us to two kinds of mistakes.
1) Althonhare’s mistake: identifying as preferable in absolute terms just one version of simultaneity, just because it happens in the same frame where the rest of the instruments are placed. Preferring the reading of the clocks of the train, just because the hot chair is on it or the duel takes place on the train. That is conceptually wrong. That equates to saying that what is relative, what has been designed as a relative concept precisely because it thus serves its purpose, is absolute, just because it is absolute. And what does that mean? Nothing? The judgment of the train is only an instrumental concept, and as such it will be valid and useful if it works and invalid if it doesn’t work, just like the judgment on the ground.
But there is a caveat! I can concede that he is somehow (not conceptually but instrumentally) right if we introduce the element of test and trial. In his configuration, he mentions that electrical engineers have tested the device numerous times and checked that it works. Certainly, even in that case, the observer on the ground may obtain the same prediction of the outcome and if this is so, both are right and saying that the electrical bolts (or the instants when the dueller see the signal for shooting) are simultaneous or not is just an accessory matter, where both parties are entitled to be right. (Accessory, Jesse, only in the sense that it is a piece to reconstruct the puzzle of reality, not the puzzle itself, but of course it is an essential part of the puzzle). However, if it is proved that the system works on the train, on the basis of its judgment of simultaneity, and that it wouldn’t work on the basis of the judgment of simultaneity of the ground, then it is clear that there is something wrong…
Where? Well, in that case, I would not still dismiss SR. The idea, the trick, is still valid. We would just have to check how we have adapted the idea to reality. And this has a lot to do with the way we have designed our physical measurement instruments and the way we have drafted our formulas, in order to better account for how things work. Because that, and not other, is the way things are: the universe does not conform to relativity, relativity must conform to the universe if it aspires to catch reality and solve problems successfully! You shape the slipper following the mould of Cinderella’s foot, not the other way round.
2) Thus we introduce the second mistake. You often hear the contention that time and simultaneity are relative because… that is the way the universe is! Other times you hear that SR, as a scientific theory, does not enter into the philosophical discussion of what time is, but it can be affirmed that time is always and will always be measured as relative.
That is also conceptually wrong. Time is neither absolute nor relative, because it does not exist. Time, I agree, is what is measured as such. The rest of the concept that is usually intermixed with measured time in common language is the idea that things happen, “reality”. But I agree that in science reality must be kept as the north (if only we could plug it into the equations!) and then we must work and do mathematics with measured time, that is to say, the periodic motion of “objects” (whether mechanical or electromagnetic) within some portion of space that encapsulates it.
But is there any physical reason why forcefully you always have to hit on a relative measurement, different for each frame with a different state of motion? You can never know. Sometimes there may exist funny compensations of effects that lead to homogenous results, which are identical for different observers. If there is no dogmatic barrier, we cannot discard that this might eventually happen, unless of course there is a sound physical reason forbidding it.
That was the argument of classical relativity. If you take out from it Newton’s never clear assertion that there is an absolute time (did he refer to a real entity, which would be wrong, or to a mere intellectual concept, which would be legitimate, as a tool for discussion?), you find that it is the same model as SR, except for the belief that mechanical clocks give homogeneous measurements, no matter the state of motion of the holders. That is to say, when you say that two events happen simultaneously as measured by synchronized mechanical clocks, you can be certain that it is logically impossible that, right after their conclusion, one is and the other one is not yet real. Thus, no matter if you traveled from one to the other 1,000 times FLT, you could not prevent the second from happening. In other words, the idea is what has been discussed here: reality is one, it is the one fundamental thing, and you predict its behaviour by measurements, it is only that in classical relativity you combine for this purpose a relative space with purportedly homogeneous length and time measurements, while SR points out that your instruments, in practice, will also render relative results in terms of length and time, so you have to follow a more complicated route, a few more turnings, in order to reach the same target.
However, what are the practical reasons? All examples I’ve seen are based on light instruments, light clocks and light rods. I am clearly shown that, if you measure time and length with light and postulate that the speed of light is constant, you get the Lorentz Transformation, with which you catch reality and marry Cinderella. But which Cinderella? For sure, a light Cinderella. But also a mechanical one?
Well, at this stage, I am told that, if it were not so, the principle of relativity would not be respected and the universe would not fully conform to it. But for me the principle of relativity is just an intellectual trick, a slipper. The universe has no obligation to conform to it. It is valid if it is practical, if it catches reality and solves practical problems. And if it didn’t, under certain circumstances, and to the extent it didn’t, what should we do? We should still not dismiss it, but we should adapt either our measurement instruments or our laws of physics so that it works again. Again: if the slipper is not a valid mould any more, you simply have to reshape it.
Maybe that is what has been done and I have not realized it. But if it is so, please, experts on SR, tell me how it has been done: how have you shaped your instruments and formulas so that, even if they are made on light, they catch mechanical Cinderellas?
That is a sort of discussion that would be exciting. Let us forget aprioristic constraints about the principle of relativity and explain how we have shaped it (because we have shaped it, no doubt, that is what SR means versus Galilean relativity) so that it matches both light and mechanical Cinderellas, to the maximum degree of certainty.
Of course I do not expect to prove that anything is wrong with mainstream science. I am neither stupid nor a crankpot. I just think that this conceptual framework is right and hence it is more pedagogical, it serves to better explain the theory, most probably not to change it. The idea is: start talking about the physical configuration of your instruments and how they interact with the environment, note the differences between light and mechanical objects (which do exist, otherwise why SR?) and then explain to me how, in spite of those differences, SR has been carefully shaped in order to catch all aspects of reality.
For this purpose, I thought that both Althonhare’s and the duel example were a good stage. The question is very simple. Take for example the show of the duel. The signals for the duellers to shoot have been given through light, which does not take the motion of the source. If the duellers shoot with laser guns, it is clear that the match is fair. But if they received light signals and shot normal bullets with conventional arms, which do take the state of motion of the source, would it be still fair? It is clear that, if the ground observer uses the relativistic formula for the addition of velocities, he predicts that the duel is fair. But those are calculations. That doesn’t mean that this is what is going to happen on the train. What am I missing here? Can you please be pedagogical and explain this to me? Sincerely I have no hidden intention and just want to learn. If you want to continue your discussion and prefer not to take this question, am I then allowed to start a new thread without being labelled as a crankpot…? Thanks for your comments.
But I don’t want to personalize on anybody and less on Brian Greene, whose writings are delicious.
