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Here is the link to the topic I opened on the french forum:forums.futura-sciences.com/physique/794268-outil-comprendre-relativite.html
L'aberration n'a pas besoin de la contraction des longueurs.
To me, taking the ship as a reference frame would mean that it is the planet that would make the whole roundtrip: it would thus first accelerate away from the ship, then it would decelerate, accelerate back to the ship, and decelerate to land it. It is easier to figure it out with two ships though, and this way, I don't see how we could get out of it without knowing which one has accelerated, and my diagram about the distance between two atoms being contracted during acceleration shows how it would work. Of course, it doesn't fit with relativity, so I'm probably going to be moderated on the forum if I use that kind of argument, but I think it fits with LET. If it doesn't then we may need a new theory.
En d'autres termes, même si on ne peut pas savoir lequel des deux jumeaux se déplace une fois que l'un d'eux a accéléré, on sait lequel des deux a accéléré, et c'est suffisant pour savoir que son horloge s'est contractée, donc que la lumière a pris plus de temps entre les miroirs pour lui que pour celui resté à terre.
Ne mélangeons pas tout. Il y a simulation et représentation, ce n'est pas la meme chose. Une simulation (dans le "vrai" sens du terme), consiste à résoudre des équations, représentatives de modèles. Si vous ne comprennez pas les modèles à l'origine des simulations, vous ne comprendrez pas plus les simulations elles-memes.
A se demander si ce n'est pas de l'auto-promotion...
Although it's possible, it is best to avoid using frames of reference that require you to change frame along the way, so I would never tie a frame (used for analyzing events) to any item that accelerates in any way that involves accelerating the frame with it. In your description, you have the planet "accelerating" away from the ship, but everyone involved knows that the ship is the one accelerating rather than the planet, so it's just adding a host of unnecessary complexities into the analysis. In LET it also serves no purpose to explore accelerating frames as they cannot be the preferred frame, so it's really a game best left to SR fans.
Remember that the one that's felt an acceleration may actually have decelerated, so his/her clock might speed up as a result rather than running slower. All we can know is that on average for the two legs of the rocket's trip, its clocks will run slow.
The interactive diagrams on my page are simulations directly driven by the maths (using JavaScript to move objects about by calculating their now positions on each move). You can see that clearly in the interactive diagram showing the two planets and two rockets because only a simulation can provide that degree of control as you change frame.
By the way, I noticed in your thread at anti-rel that someone showed you a diagram many months ago which showed something just like my moving laser with the light pulse moving down through it vertically while actually tracing out a line down the screen at an angle. It shows how easy it is to see things and not take them in.
There is many english ones, and some of them let us expose our divergences, but I'm not so at ease with english.
I'm new to relativity thinking, a few days ago I was totally anti, so I may be wrong, but I still see no way to tell which twin is getting younger than to know which one has accelerated.
That's what I was saying about the contraction between my two atoms a few posts away: if we decelerate the right atom, the contraction will reverse, so the dilation too.
It's Cryptic, he is really good at it, but he did not use a laser as a source, so I couldn't see how the photon had to travel inside it, and I did not have you to insist on that point either, so I missed it.
I'm having a hard time to convince the guys at the french forum to use that kind of tool to teach relativity
No luck, it's the only scientific french forum I know, and it is exclusively mainstream.
To me, contraction appears at the beginning of acceleration, and it is due to acceleration, not speed.
With that principle in hand, no need to ask which twin is getting younger, it is always the one that has accelerated.
Je peux lui demander de nous montrer son logiciel si tu veux l'analyser!
l'interprétation de Lorentz de la relativité restreinte empêche de poursuivre vers la relativité générale. Elle n'est pas focalisée sur les "bons" concepts.
Mais vous pouvez ne pas y croire, c'est votre problème. Par contre si vous essayez de vendre aux lecteurs que la LET est une bonne voie vers l'abord de la RG, nous manifesterons notre désaccord et demanderons des justifications solides.
Et demande à Cooper (à moins qu'il veuille venir ici l'expliquer) comment il fait pour définir que "le (un) temps s'écoule plus lentement" ( donc qu'une horloge ralentit)?
When B departs, them returns to A, a closed course, the descriptions are NOT symmetrical, but still reciprocal, thus the two ratios, 2:1 and 1:2.
In the 'twin' case, there can be an age difference, just as there is in this example. A can assume a pseudo rest frame with B changing course, or, B can assume a pseudo rest frame with A changing course due to a temporary g-field
With the twins case, it is indeed the one that's accelerated that measures less time passing for him/her, but during one leg of the trip it may be the one that's experienced the accelerations which has the fastest running clock (in which case his/her clock will be the slowest running clock during the other leg of the trip).
What bothers me about what you're doing with the atoms is that you may just be producing a temporary contraction caused by the way you're accelerating it and that the contraction will not have anything to do with the length-contraction of relativity. I asked what would happen if you accelerated the leading atom instead of the trailing one and that appeared to reveal that you haven't bound the atoms together in any way. You should be able to accelerate either atom and have it move the other one with it, and the same length-contraction should then be seen on the molecule afterwards regardless of which one you put the energy into.
Having just looked at it again, I was wrong about that animation - he (JammyTown) does use a laser, but he doesn't show the light pulse moving down through it because the animation starts with the light already on the point of leaving it.
QuoteWith that principle in hand, no need to ask which twin is getting younger, it is always the one that has accelerated.That only holds for the average of the whole time between them separating and reuniting. If you take a pair of twins, send one away from the other and never reunite them, you can't know which one's clock is running slower because you don't know if the acceleration really accelerated a twin or decelerated him/her.
With acceleration causing motion, it is impossible that the twin who is accelerating away from the other is not the one that is moving faster in that direction. So even if I'm wrong about acceleration causing contraction, we could still consider acceleration as a way to know which one is moving away, but you are right, if both twins were already moving in a certain direction with regard to aether before the acceleration, the one that accelerates in the other direction may well be getting older for a while, but as you describe, he would still have to run faster getting back, so he would still be getting younger overall. It works very well, but we absolutely have to know which twin has accelerated, and the relativists cannot take acceleration into account since it would contradict the relativity principle.
For B to measure more time passing than A does, you'd need to apply a temporary g-field to B as well so that when it does it's acceleration to "stop and move back the other way" it is actually maintaining its speed in the same direction throughout (merely firing its engines to cancel out the force from the temporary g-field). That would enable one twin to feel no acceleration at all while the other twin feels a lot of acceleration and yet ends up looking much older than the twin who felt no acceleration.
With acceleration causing motion, it is impossible that the twin who is accelerating away from the other is not the one that is moving faster in that direction.
So even if I'm wrong about acceleration causing contraction, we could still consider acceleration as a way to know which one is moving away, but you are right, if both twins were already moving in a certain direction with regard to aether before the acceleration, the one that accelerates in the other direction may well be getting older for a while, but as you describe, he would still have to run faster getting back, so he would still be getting younger overall.
It works very well, but we absolutely have to know which twin has accelerated, and the relativists cannot take acceleration into account since it would contradict the relativity principle.
I was talking about Kryptic's simulation here (anti-relativity.com/forum/viewtopic.php?p=61995#p61995). Do you have a link for Jammy Town's one?
So, where do we start the sit-in? Time Square, La bastille, Tian'anmen? :0)
Bonjour,bon, on va faire simple : la théorie de l'ether a été réfutée il y a plusieurs décennies déjà .
Et conformément à la charte du forum :6. Ayez une démarche scientifique. Ce forum n'est pas un lieu de discussion sur de soi-disant phénomènes paranormaux ou "sciences" parallèles. Toutes idées ou raisonnements (aussi géniaux soient ils) doivent reposer sur des faits scientifiquement établis et non sur de vagues suppositions personnelles, basées sur d'intimes convictions. [...] D'autre part la seule vocation de Futura-Sciences étant la vulgarisation scientifique de bon niveau ce n'est pas le lieu pour des questionnements ou remises en cause de théories admises dont seuls des spécialistes ont les compétences pour débattre, ni pour l'exposé de théories strictement personnelles. Une telle démarche aurait sa place uniquement dans un séminaire ou un congrès scientifique.Par conséquent, ether = pas ici.
Quote from: David Cooper on 01/07/2017 23:52:48For B to measure more time passing than A does, you'd need to apply a temporary g-field to B as well so that when it does it's acceleration to "stop and move back the other way" it is actually maintaining its speed in the same direction throughout (merely firing its engines to cancel out the force from the temporary g-field). That would enable one twin to feel no acceleration at all while the other twin feels a lot of acceleration and yet ends up looking much older than the twin who felt no acceleration.I'm only showing the B perception of the 4 yr/2 yr scenario. B changes speed which he interprets as a g-field, which explains A's curving course, his perception.
Quote from: Le Repteux on 03/07/2017 15:57:50With acceleration causing motion, it is impossible that the twin who is accelerating away from the other is not the one that is moving faster in that direction.Do you really mean "impossible" there or did you intend to say "possible"?
QuoteSo even if I'm wrong about acceleration causing contraction, we could still consider acceleration as a way to know which one is moving away, but you are right, if both twins were already moving in a certain direction with regard to aether before the acceleration, the one that accelerates in the other direction may well be getting older for a while, but as you describe, he would still have to run faster getting back, so he would still be getting younger overall.Assuming that the accelerations haven't been hidden in some way by temporarily tampering with g-fields, the twin who feels a series of accelerations will measure less time passing by the end of the round trip than the twin whose speed through space never changed. There is no disagreement between LET and SR on this point.
QuoteIt works very well, but we absolutely have to know which twin has accelerated, and the relativists cannot take acceleration into account since it would contradict the relativity principle.No - the accelerations aren't a problem for SR. The only conflict is in the interpretation of events, because SR considers all accounts of events (based on different frames of analysis) to be equally valid whereas LET says that most of the accounts must be wrong because they contradict each other (by such means as having the same acceleration make a clock run both slower and faster than it was ticking before). This dogma in SR about there being no preferred frame flies in the face of logic, but we have generations of physicists who simply reject reason on this point while claiming that they are not rejecting it (in the same way religious people do while breaking the rules of reason), and there appears to be no way to get them to see sense, no matter how clearly you spell things out for them.
Passing the buck - "it is for experts only to discuss such matters, so we are entitled to go on making false claims here and to ban anyone from challenging our false claims".It really isn't worth wasting any more time on them. It's just the world in microcosm - you set a proof before people's eyes and they reject it because they are incapable of reasoning correctly and they don't respect correct reasoning if it generates conclusions that go against the beliefs of the clergy. They are followers who only ever follow authority - they simply do not trust their own minds, and that's really sad.
Do you mean that relativists have the right logical answer about the Twins' paradox and that I simply didn't get it?
On the wiki page about that paradox, many interpretations effectively talk about acceleration, but it is always to determine if acceleration itself affects the clocks. The interpretation that resembles the most the idea that acceleration tells us which twin is traveling is the one that says one of the twins changes reference frames, so if I understand well, for those relativists, that twin is getting younger at the same rate both ways, whereas for LET, the twin might be getting older one way, and a lot younger the other way. To me, that SR interpretation is simply illogical.
They present the muon experiment as a proof that SR works, while with LET, some of those muons could very well be traveling slower than the earth with regard to ether, thus they could be having a shorter life than the laboratory ones.
At one place, they say: «Car objectivement, seul le jumeau voyageur peut mesurer les effets de l'inertie et nous savons donc que le chemin constitué de deux segments est forcément celui du jumeau voyageur.» So they admit that we can use acceleration to determine which twin is traveling, but in the same breath, they don't admit that it breaks the relativity principle.
What is important is that the data can be explained by the theory, and it seems that the muon can really live longer whatever the direction it takes with regard to ether, what contradicts LET.
P.s. After having closed the thread, Obi erased my last message where I cited the wiki page on ether to show that Einstein himself, in a conference at Leyde in 1920, admitted that, without it, light couldn't propagate
I can't see how they're breaking the relativity principle - it puts no ban on accelerating anything, and the same things are accelerating no matter which frame of reference you are using as the base for your observations.
The relativity principle says that any reference frame is good, so if we consider the twin that has accelerated as the reference, we are forced to consider that it is the other twin that changes directions, and we can apply the relativistic calculations to him. I know it's illogical, but it is nevertheless what SR is all about.
Quote from: obi76Bonjour,bon, on va faire simple : la théorie de l'ether a été réfutée il y a plusieurs décennies déjà .That is a common belief, but it is not correct. A number of experiments have supposedly disproved the existence of the aether (fabric of space) by showing that the one-way speed of light is always c relative to the apparatus used to measure it, but in every case they have failed to take some fundamental factor into account, such as Doppler shift (in the case of the experiment with a turntable which has an emitter in the middle and detector at the edge - correct calculations show that the frequency of the radiation at the detector should never change regardless of how fast the apparatus is moving through space) and the twist of rotating cylinders (when light is only able to pass through the slits in both ends if it moves through the cylinder at a very specific speed - the movement of the rotating cylinder through space warps it and thereby tunes it to the actual speed the light is moving at relative to the apparatus). In each case, these experiments and the claims associated with them have remained in the literature long after their claims were shown not to be valid. I even have a university textbook which asserts that the Michelson-Morley experiment proved that there is no aether, so there is an ongoing failure of education which continues to encourage such misinformation to be propagated. The reality is that LET is still a fully viable theory (which has also been extended to cover the full ground of General Relativity in addition to SR, generating the same numbers from the same maths and differing only in interpretation).
Le point déjà soulevé est que vouloir comprendre la Relativité en partant de la LET est une trèèèès mauvaise chose...(pour le moins qu'on puisse dire).
I see what you're saying now - clearly the relativity principle shouldn't apply to "accelerated frames" because that actually involves changing through a wide range of frames of reference. If some people are claiming that it does apply to such "accelerated frames", then clearly they're wrong, but do any of the people making such a claim have any actual authority to make such a claim or are they just SR fans who are overstating the case because they don't really understand SR?
The relativity principle says that any reference frame is good, so if we consider the twin that has accelerated as the reference, we are forced to consider that it is the other twin that changes directions, and we can apply the relativistic calculations to him. I know it's illogical, but it is nevertheless what SR is all about That's what considering the speed of light as invariant leads to. It is invariant with regard to ether, but not with regard to bodies.
SR accounts for it in much the same way as LET, but not everyone in the SR camp understands it correctly and they frequently explain it badly. LET approaches it by saying, "IF the stay-at-home twin is stationary throughout and the other twin moves away and comes back, the moving twin's clock (and functionality) slows down and makes him age less". LET can also produce an infinite range of other conditional accounts of the same kind which all start with "IF" and apply different speeds of movement to the stay-at-home twin. SR does things a little differently by getting rid of the "IF" and replacing it with, "Because the stay-at-home twin is both stationary and moving (depending on which frame you want to use, all of which are equally valid), we can simply assert that he's stationary and that the moving twin will travel through less time on both legs of the trip than the stay-at-home twin, and this is as correct as any other interpretation. It is also correct in SR to claim, "Because the stay-at-home twin is both moving and stationary, we can simply assert that he is moving throughout at a speed which leads to the moving twin being stationary during one leg of his trip and moving very fast on the second leg, so he moves through less time in total than the stay-at-home twin and we don't care about the details as to when he might have been moving through more time than the stay-at-home twin during the first leg because we have banned all discussion of simultaneity at a distance and therefore don't accept any ideas about how much time the stay-at-home twin had travelled through by the time the moving twin had turned around.That is what they always do, and they have to do this in order to hide the point at which they are playing fast and loose with the laws of reason. The only way to push them to the point where their abuse of logic shows up is to get them to program a simulation of what happens and to do it with two sets of twins with the stay-at-home twins moving relative to each other, because at that point they have to commit the system to behaving in a rational manner which forces them to decide which clocks are going to have to run slow (or which legs of which trip travel through less time), and it's then that they suddenly realise that they cannot fudge it if the simulation is to function correctly - they can no longer just assert that the whole round trip for a travelling twin takes him through less time without coming up with proper numbers for each of the two legs of his trip. Very few of them have ever written such a simulation and most refuse to discuss how they would do so when they realise that they're being pushed into a corner. The few who actually have written such simulations must know damn well that they have imposed a preferred frame of reference on the events and that they have no alternative other than to do so. They will also realise that the universe itself cannot work by magic either and that it must likewise control the unfolding of events by using the Newtonian time of a preferred frame to control the unfolding of events.