Let me join MacM in welcoming you. Although I am firmly in disagreement with him on the existence of any "absolute velocity" etc. I can (and do) also concur that it is best to ignore posts that rely more on innuendo, name calling, etc. - Generally that only indicates they have little rational to state in support of their position. I also want to thank MacM for clearly exponding what he means by Reciprocity (and almost clearly by "accumulation" - see below). Although we disagree strongly, I respect MacM and think he respects me. I will briefly, state where, IMHO, MacM is not clear and in fact is in error: MacM thinks that "reciprocity" would imply that clocks A & B can not both accumulate the same times, if seen from C, they show the same accumultion, and yet each also thinks (sees - what ever verb you like) the other's clock as slow. According to MacM, that is just silly (if I understand him correctly - this is sometimes a problem as we have such different starting points and unstated presumptions). I won't say any more about what MacM thinks - He is quite capable of stating that for himself and if I have misrepresented him, I appoligize. I only said the above to outline and set, approximately, the correct context for my remarks that now follow. MacM is obviously self contradictor here. He states that "can't sense it" {it = absolute velocity} and also "it affects clocks." Either it is unsensible because it has no affect upon anything or if it has some affect on anything, then it is sensible by observing the thing it affects. It is a philosophical position, which I subscribe to, but others may not, that If something has, in principle, no possible affect upon anything, then that "something" does not exist. Because of MacM's "yet," I think one can safely infer that MacM really does not mean that, in principle, "The only motion we can sense is relative velocity." I.e. I infer that it is only some "technological limitations," not any limitation in principle, that prevents MacM from telling me the "absolute velocity" of the top of the Washington moment in DC. Thus I will allow MacM (or his co belivers in the existence of "absolute velocity") to assume any values or reference frames, etc. they need for the calculation of the "absolute velocity." I am not really interested in knowing the number correctly. What interests me is know how (the procedure by which) the absolute velocity would be determined. One "co-belierver" in "absolute velocity" (Geistkiesel, who often draws very attractive color illustrations, even though they may be internally inconsistent and usually are nonsense, MHO) has spelled out exactly what would be required for the procedure of determining the "absolute velocity." All Geist needed was one other frame with specif relative speed. - I of course made up one for him to use in illustration of the method of calculating the "absolute velocity." The "required frame" I suggested was a boat going SE down the Patomac River at 10mph. Unfortunately I am still waiting for the illustration of how this information is used to compute the "absolute velocity." Superficially, what MacM is saying sure seems to imply SRT is false as it is "obvious" that both clock A & B can not "accumulte" half the time of the other. But lets examine what we mean by "accumulte" a little more closely and not just rely on some vague notion of it. - A clocks "ticks" at some fixed rate (if it is a good clock, not broken, etc.) To "accumulte" time in an interval, there mus be both a well defined "start" and "stop" accumulating events or times. For clock A, I will call them A1 & A2, respectively. Likewise for clock B, we have B1 & B2. I am not sure, because MacM does not state it, but think MacM is asserting that (A2 - A1) = (B2 - B1), BUT HOW DOES HE KNOW THIS IS TRUE? Lets try to be coperative and help MacM out a little: We can assume that there is no problem in making sure that A1 = B1. For example, lets imagine that the two travels both start from Earth side by side with identical lift off times (earth clocks) for their identical rockets. Both have identical chronometers (MacM always speaks of "clocks" but I prefer "chronometers" as only they "accumulte" time in an interval.) The latches holding the rockets down are released "simultaneously" (no problem as they are at launch i n the same reference frame) and the breaking of an electrical circuit with the latch releases, starts each chronometer acumulting simultanously. Thus we can be sure that A1 = B1. Now the problem of knowing if or if not (A2 - A1) = (B2 - B1) reduces to the problem of knowing if (or if not) A2 = B2. But by assumption the two travelers accelerated differently and soon are in reference frames with realitive velocity of 0.866c. I like to make every thing well define, not vague, so I postulate that they had identical "flight plans" except at every instant (seen from Earth, by Doppler radar or round trip communication delays etc.) their velocities were equal in magnitude but exactly oppositely directed. That is Earth, if it did not move in orbit, would always on the mid point of the line joining the two rockets. (We could imagine that "missin control", the Doppler radars, etc. were all in a spacecraft that "hovered" at the launch point in space, except for brief periods every 365 days, when it had to get out of the way for Earth to pass by again.) MacM never gives any operational details of how he Assures that A2 = B2. But again in the spirit of cooperation, I suggest that aafter a year (earth time) Earth sends out (simultaneously, of course) a powerful laser pulse to each rocket, which immediately stops the equally distant (from Earth) chronometers. If this is done, then A2 does equal B2 and despite the fact that both A&B have seen the other's clocks tick at half their own clocks rate, the accumulated times now fixed in the chronometers are the same. Lets say both show "Y" years have passed. (I am not giving a number because if I did it would be less than the time that has passed on Earth clocks and this would needlessly provoke agruements with MacM about the "validity" of the "twin paradox.") You might ask: How can it be that A, who knows that B's clocks are running slow, records the same accumulation of time when the chronometers were stopped "simultaneously"? Ah - that is the core of the problem! A does not see B as stoping his clock as "simultaneously." A sees B as stopping his chromometer when A's "backup chronometer," (the one that was not stopped when the laser pulse was received because the primary chronometer was working fine) shows 2.3 years. That is, both A & B think the other must have been in "hibernation state" when they them selves locally received the laser pulse. Each believes the other stopped his chronometer, 1.15 years too late. Clearly 2.3 years times (tick rate/2) = 1.15 years times tick rate. Thus, it is not surprizing that the time recorded on the chronometers is the same, despite the "reciprocity" that has each seeing the others tick rate as their own tick rate / 2. As I stated earlier, MacM is only taking a "superficial" or "intuitive view" that no doubt is based on his belief that absolute velocities and absolute universal time exists. I don't want to put words in MacM's mouth, so this is only my way to try to understand what is underlying MacM's views. He may very well disagree, but about a year ago he, in another thread, spent several months and many posts showing how (with digital encoding etc.) universal time could be distributed to different frames. (Again I may both have mis understood him at the time and am relying on my memory of the main point of that thread) I don't deal in innundios, or name calling, as you can see. I don't need to. I have quite detailed arguments to present. MacM is a very worthy opponent. I am sure he will have some counter arguments. You must decide which of us has the better case. Mine is the generally accepted position, I.e. Einstein was corrrect, SRT is valid and MacM's is his own, but has a lot of co-believers in the general conclusion that SRT is in error, althought they don't agree on just why. For example, MacM and Geist are often not singing from the same page, but both are sure SRT is wrong.
I think What You think is irrelevant is actually irrelevant. This is not Your Crackpot Forum and nither U a Mod, Please Do Not make this Crakpotess an moderator in this forum
Assuming that the typer and sipper both wore watches, that according to them read the same time, then yes, the plane observer would determine that those two watches would not read the same time.
That's what James R says, but i asked 2 wrist watches worn by the same guy - the typer/typist, would not show the same time for the plane observer?
As long as the two watches are not separated by any distance as measured along a line parallel to the direction of relative motion, then, yes, they will show the same time for the plane observer. If however, they are separated by any distance as measured along that line, they will not and the difference will depend on that distance and the relative velocity of the plane.
Billy, you have not quite got it. I have not objected to the "Perception" of moving observers "Seeing" different times. I have and do object to those such as James R that have claimed that the perception is physical reality for the clock being observed, since that would necessarily require a physical clock to actually accumulate time at multiple rates and clocks only accumulate time as a function of conditions in their local proper frame. MacM is obviously self contradictor here. He states that "can't sense it" {it = absolute velocity} and also "it affects clocks." Either it is unsensible because it has no affect upon anything or if it has some affect on anything, then it is sensible by observing the thing it affects.[/quote] Not true again. "Sense" is being used in the meaning of our capacity to sense. There are many things that we cannot sense which affect physics around us. I could accept this statement. However, it does not describe my view of absolute motion. My position is that we are unable to sense it but that it does exist and does affect clocks, etc. So in reality we can sense it if we poperly analyze clock dilations. This jwould appear to be a valid statement. I do believe if we could instantaneously record the vector and magnitude of every particle and object in the universe it would allows the identification of a common rest point. However, as I have pointed out in another thread it is further recognized that acceleration of any object would shift this point and in view of the magnitude of moving objects in the universe and the number of accelerting objects this instantaneous point of common rest would in fact be very dynamic and in constant motion itself. In the vane I have debated this issue "Physical Reality of the Clock" that is true. It is true if the parameters cited are true. 1 - Simultaneous launching. 2 - Opposite Vectors. 3 - Equal Acceleration. 4 - Equal Duration. Under these conditions there can be no correct answer but that both are the same distance and have suffered the same relavistic consequence of their trip. You have missed the point. I gave a symmetrical case to make the jpoint easy to see but I also stated that non-symmetrical trips with collective motion results in time dilation between these clocks. It just isn't based on the gamma of total relative velocity as advocated by SRT. Gamma Effective is instead a collective computation of respective component velocity gammas of the two clocks relative to "C" that compute the correct time dialtion between these clcoks and not the collective gamma of the total relative velocity. This is precisely correct. Even though there might be a relative veloicty of 0.866c between these two clocks the gamma between them can be anything from 1.000 to 2.000 depending on the component velocities which comprise the total relative velocity. That is if A and C are at relative rest then the relative velocity of 0.866c is indeed all in B and the gamma calculation between A and B is valid. However, using the C as a physical referance the reciprocity advocated by SRT of claiming B at rest and reversing the dilation is prohibited. This view matches physical reality SRT does not. This becomes clear if you then specify that A also has some velocity component which comprises the total relative velocity. The easiest case to see this is the symmetrical one where both A and B have equal velocities but opposite vectors. In the symmetrical case while there still exists the same 0.866c relative velocity there is NO dilation between these clocks. Here is where you screw up. You have introduced the term "See" or "Perceive". We don't care what each observer "Sees". We only care about them being started and stopped simultaneously from "C", which they are. No quite the opposite. I am advocating the physical reality view, you advocate the intuitive view where perception, not physical accumulated time becomes asserted. And that is why I hold respect for you even though I have not yet been able to get you on the right track. Maybe this ost, just maybe you can see the rightful claims I am making. Please Register or Log in to view the hidden image!
Janus58, 1. If there are 3 clocks at some distances among them along the line parallel to the direction of relative motion, which clock the observer on the plane prefer to determine the time at typer's frame at any given moment in the observer's frame ? Please remember, for the observer these 3 clocks don't show the same time for any of the observer's moment in his own time. 2. In James example, if James and the guy sipping drink, say MacM, indulge in short dialogue (lets assume a sensible dialogue that involves mutual questions and mutual answering) while James typing 'computer' and MacM sipping drink, whether the observer in the plane should "listen" James's nonsense first and MacM's nonsense next? It involves not only break down of simultaneity but breakdown of casuality too. Have we observed any thing like this really?
Nobody has ever argued otherwise. The issue, which you are now attempting to ignore, is whether or not, given that they are started and stopped simultaneously from "C", they are ALSO started and stopped simultaneously from "A" or "B". I don't think you have the mental power to even begin to contemplate the question.
No, that's wrong. Simultaneity is lost immediately one clock moves relative to the other. The only thing which determines how much the concept of simultaneity changes is the relative speed. It doesn't matter how long the clocks have been travelling, or how they have varied their speeds during the trip. At one particular time, one particular observer has one particular notion of simultaneity, which varies from that of another observer only on the basis of relative speed.
OOooouu , YAaaa. Two frames , Different times, What decides which races faster and which races slower. Naa, Dont answer that, I forgive U and let U save your face.
His own. No break down of casuality is involved. Remember, for James and MacM to have that conversation, sound must travel between them over the distance separating them. You have to apply the Addition of velocities theorum to the sound in both directions. If you do so, you will find that neither will reply to a question that hasn't reached them yet. The same is true if they were to signal each other with light.
The rule is simple: the other guy's time always runs slower due to relative velocity. Your own time runs at the same rate as always.
Unfortunately what "A" or "B" thinks based on a moving observation is irrelevant. The discussion is time dilation of physical clocks when compared in a common frame. That is the only ture time dilation. Everything else is perception only. And I don't have to think you lack the mental power to understand, I know you lack such mental power. You have demonstrated that numerous times.
How do you know that A or B is moving? You can't point to any absolute frame. Maybe A is stationary. ... Or maybe B is stationary. You can't say which. Can you?
No, that's wrong. I realize you are reciting from Special Theory, but that is not the way it works in the real world. Simple synchronize the clocks of one frame with the clocks in the other frame, there is no loss of simultaneity. You are stating clock synchronization has nothing to do with it. In that case, simultaneity is not lost even when there is relative velocity and NO clock synchronization. I thought you had been studing GPS, James R. GPS proves simultaneity is not lost between moving frames millions of times per day. That is empirical evidence. I will be glad to discuss this with you. State how you think relativity of simultaneity is preserved in GPS. I am pretty sure what you are going to say and I have a counter arguement. Show me an empirical experiment where relativity of simultaneity is demonstrated, not some childish gedanken or simple two dimensional animations.
When compared in a common frame, there is no ambiguity. The clocks will be in sync or dilated wrt each other based on who did the frame matching maneuver. Everything else is just perception. But, who's perception? I see my clock running normally while you see it running slow, and vice-versa. Who's right? Neither. Both. At the same time. Within my frame my judgments about my local environment are completely valid as are yours for your local environment. This is not a simple "optical illusion". Spacetime for moving observers really changes. Only when you match-up frames can you make a comparison that makes any sense to your primitive primate earth-evolved brain.
Nor can you but unlike you I have enough brains to understand that if I declare one at rest it is physical nonsense to then turn around and declare the other at rest as part of the same relative velocity consideration. That MUST constitute a physically seperate situation and only one (if either) will be verified physically by the accumulated time on the clocks. At no time will you ever produce a case where both will be dilated relative to the other as a consequnce of reciprocity advocated by SRT.
