Twin paradox (Pete and MacM)
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James R: No clock ever displays two different times at once!
MacM: I do agree and point out that that is what I have said all along.
MacM (5 minutes later): Show me your clock with multiple displays at the same time, then we can talk.
Your memory is fading, old man.
MacM: I do agree and point out that that is what I have said all along.
MacM (5 minutes later): Show me your clock with multiple displays at the same time, then we can talk.
Your memory is fading, old man.
Pete said:
Now it is you that don't understand. Certainly it doesn't draw your attention to that fact. It tends to confuse you with mathematical loops.
But if you clear away the fog by eliminating the masking of mathematics such as simultaneity, it becomes glaringly appparent.
You will scream you can't do away with simultaneity. Well you not only can, I have but no need to argue that point since I know you and others refuse to acknowledge it.
Try this. Considering a clock must always tick at its local proper time, it can therefore NEVER tick at anyother rate. Therefore any observation of a different rate MUST be perception.
In a case where start/stop times are not at issue and the test is sufficiently long, it is clear that we can discuss tick rates without the issue of simultaneity.
You cannot claim a duality of tick rates as a physical reality - PERIOD.
MacM said:
I'm sorry Mac, but like I've said before, your "understanding" of SR is laughable. I know the maths confuses you. However, it doesn't confuse me.
You still think that SR is simply time dilation and length contraction, with a fudge factor thrown in that introduces some foggy "simultaneity delay", don't you? You haven't looked at the Lorentz transform yet, have you?
It's really very funny, in a sad kind of way.
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My god Mac, get with it. The time it displays WILL NOT CHANGE. Your position in time does change. Relativity states (and experiments show) that processes go through time at different realitve rates depending on velocity.
They are NOT showing to different times at the same instant.
Persol said:
Your ability to glaze over truth is impressive. Certainly I know a clock can't display two times at once. That sort of has been the point do you not think.
HINT: Clock "A" at rest displays it's local time i.e. - 12:00PM. Clock "B" moving relative to "A" "APPEARS" to display 10:30AM. But "B" local time displays 12:00PM and THINKS "A" reads 10:30 AM.
Gee two times that are actually displayed and two other times that are never displayed and cannot be displayed, are therefore perception and not reality.
Thank you for finally understanding.
MacM said:
Sorry, your provided HINT does not include any application of relativity concept or consideration of the fact that you can't possibly see the clock in other reference frame (perhaps separated very far away from you) in real time.
May be you wanted to say that "B" just zooming by at very close distance and therefore "A" could see B's clock right away. If that the case you have just created a demonic clock. You claimed that "B" see his clock displaying 12:00PM and "A" -- at that same instance -- reads 10:30AM? How could that possible????? As spooky as any one could imagine, relativity does not produce such a thing.
Paul T said:
You need to go back to school my friend. That is exactly what Relativity claims. When "A" local proper time actually reads 12:00PM "B" in relative motion will claiom it reads 10:30AM (or some other number other than earlier than 12:00PM).
This has been the point the entire time. !2:00PM is reality, any time claimed by an observer in relative motion is perception.
MacM said:
My dear old friend....please get a book such as "Relativity for Dummy" or the like and read it until you really understand the concept. Your provided hint was incomplete. You did not say where is "A" and "B". Are they separated very far away? If yes, then what's wrong when "A" see B's clock 10:30AM? You know that information doesn't travel immediately, so that A sees B's clock displaying 10:30AM that was sent a few hours ago -- say, depending on their separation. Even without knowing relativity one should arrive to that conclusion.
May be, you will reply: "That's exactly the point...time dilation is nothing but delayed information!"...and I will remind you about that "Relativity for Dummy" book and ask you if you read it and understand its content. Time dilation is not merely delayed information. If you understand relativity, you will know.
MacM:
Wrong.
The question here is this:
When clock A reads 12:00 PM (EVENT 1), what does clock B read, simultaneously?
The answer depends on your frame of reference. Unless a reference frame is specified, the question is meaningless.
The answers, in two particular reference frames, are:
In the frame of A, clock B reads 10:30 AM (EVENT 2).
In the frame of B, clock B reads some time after 12:00 PM (EVENT 3).
Note that these two answers refer to two different events on clock B, not the same event. So, clock B never "displays two times at once".
The issue is simultaneity, not that you'll ever understand.
According to A, events 1 and 2 are simultaneous.
According to B, events 1 and 3 are simultaneous.
Events 2 and 3 are NEVER simultaneous, for ANY observer.
How about addressing this, MacM?
Wrong.
The question here is this:
When clock A reads 12:00 PM (EVENT 1), what does clock B read, simultaneously?
The answer depends on your frame of reference. Unless a reference frame is specified, the question is meaningless.
The answers, in two particular reference frames, are:
In the frame of A, clock B reads 10:30 AM (EVENT 2).
In the frame of B, clock B reads some time after 12:00 PM (EVENT 3).
Note that these two answers refer to two different events on clock B, not the same event. So, clock B never "displays two times at once".
The issue is simultaneity, not that you'll ever understand.
According to A, events 1 and 2 are simultaneous.
According to B, events 1 and 3 are simultaneous.
Events 2 and 3 are NEVER simultaneous, for ANY observer.
How about addressing this, MacM?
Twin paradox again, sigh....
Well, nothing new about this topic. Much have been said about it in those other threads. I noticed however, there was one argument about the so-called "reciprocity" requirement in relativity that creates impossible physical reality (whatever this mean). I failed to see that relativity (SR) contain such impossibility. Here, I present one simple exercise concerning the issue...of course not to prove the correctness of SR; but just showing my failure to find that "imposible physical reality".
Consider three observers:
A - in a spacecraft moving at velocity 0.6c away from earth
B - in another spacecraft identical to that of A but moving at velocity -0.6c away from earth
C - on earth
Experiment starts with event A and B moving away from earth (assume that the time for acceleration is very short and therefore can be ignored). Each observer send a short light pulse every one second (call this time 'local time'). The first pulse was sent while those three observers stay close one to another, near the earth.
Applying SR's time dilation concept gives us one second in A and B as 1.25 second in C (as g = 1.25). Observer C receives second pulse (from A and B) after 1.25 + 1.25*0.6c/c = 2 seconds. Light pulse from A reaches B, 3 seconds after it passes C (time as measured by C). Therefore the total time interval (in C reference frome) for any two consequitive pulses from B to reach A (also from A to reach B) is 5 seconds (4 seconds in A or B reference frames). Ratio between local time interval and received pulse interval for A is 1/4, and so does for B as they are symmetrical. Using relativistic doppler effect equation we get relative velocity of B according to A (and vice versa) is (15/17)c. Of couse this relative velocity can be also obtained using SR's addition of velocities formulae.
Say, after a certain period of time A and B turn back to earth and eventually return to C. We should find that clock in A and B record the same elapse time. However, clock in C will record more elapse time than either A or B as "A and C" or "B and C" are not symmetrical. This later case is the same as the usual "twin paradox" case, in which time dilation effect persist. We can evaluate the situation for A and C similarly as for A and B above. If this is done, we will get that A and C both find interval time ratio of 1/2, which indicates that C detects A relative speed as 0.6c and A detects C relative speed as 0.6c. There is no reciprocity problem here.
Argument that time dilation is merely a "delayed information transfer" effect is completely wrong. In the above exercise, time dilation applies to A and B only, but not to C and therefore after A and B return to C, this effect (which can be also monitored during the process) shows up. Demanding that time dilation must be applied equally for "A and C" or "B and C" (since they are not symmetrical) is just plain silly. The "delayed information transfer" is a separate effect. In relativistic doppler effect, both time dilation and "delayed information transfer" work together, in fact that what relativistic doppler effect really is.
Well, nothing new about this topic. Much have been said about it in those other threads. I noticed however, there was one argument about the so-called "reciprocity" requirement in relativity that creates impossible physical reality (whatever this mean). I failed to see that relativity (SR) contain such impossibility. Here, I present one simple exercise concerning the issue...of course not to prove the correctness of SR; but just showing my failure to find that "imposible physical reality".
Consider three observers:
A - in a spacecraft moving at velocity 0.6c away from earth
B - in another spacecraft identical to that of A but moving at velocity -0.6c away from earth
C - on earth
Experiment starts with event A and B moving away from earth (assume that the time for acceleration is very short and therefore can be ignored). Each observer send a short light pulse every one second (call this time 'local time'). The first pulse was sent while those three observers stay close one to another, near the earth.
Applying SR's time dilation concept gives us one second in A and B as 1.25 second in C (as g = 1.25). Observer C receives second pulse (from A and B) after 1.25 + 1.25*0.6c/c = 2 seconds. Light pulse from A reaches B, 3 seconds after it passes C (time as measured by C). Therefore the total time interval (in C reference frome) for any two consequitive pulses from B to reach A (also from A to reach B) is 5 seconds (4 seconds in A or B reference frames). Ratio between local time interval and received pulse interval for A is 1/4, and so does for B as they are symmetrical. Using relativistic doppler effect equation we get relative velocity of B according to A (and vice versa) is (15/17)c. Of couse this relative velocity can be also obtained using SR's addition of velocities formulae.
Say, after a certain period of time A and B turn back to earth and eventually return to C. We should find that clock in A and B record the same elapse time. However, clock in C will record more elapse time than either A or B as "A and C" or "B and C" are not symmetrical. This later case is the same as the usual "twin paradox" case, in which time dilation effect persist. We can evaluate the situation for A and C similarly as for A and B above. If this is done, we will get that A and C both find interval time ratio of 1/2, which indicates that C detects A relative speed as 0.6c and A detects C relative speed as 0.6c. There is no reciprocity problem here.
Argument that time dilation is merely a "delayed information transfer" effect is completely wrong. In the above exercise, time dilation applies to A and B only, but not to C and therefore after A and B return to C, this effect (which can be also monitored during the process) shows up. Demanding that time dilation must be applied equally for "A and C" or "B and C" (since they are not symmetrical) is just plain silly. The "delayed information transfer" is a separate effect. In relativistic doppler effect, both time dilation and "delayed information transfer" work together, in fact that what relativistic doppler effect really is.
James R said:
Only if you reframe (no pun intended) the question.
Only if you want to ask you own question rather than answer mine.
Only if you choose to weave and dodge and not simply answer the question.
Wrong. In frame "A" clock "B" is perceived as reading 10:30AM it actually is 12:00PM. A's view did not change clock B. Otherwise you create the duality of clock readings which is not physically possible.
Wrong. There is no basis to assume any number other than the one initially assigned 12:00PM.
We at least agree that the clock does not read two different times. The problem is when you accept your view of isolating different clock readings as seperate events you mask the problem. It is when you terminate the test and then bring the clocks back to see what they actually read that your view becomes clearly false.
So says James R.
Sorry. Mickey Mouse gibberish avoiding the truth. Do we need to once again start over with the synchronization of the clocks. Use light beams to keep them in constant communication and show that no such thing occurs???
Do we need to point out for the 14th time that simultaneity BS doesn't cut it.
Two clocks in relative motion. Forget all other specifics. How fast, what direction, how far apart, what time according to who, etc.
Tick rate is tick rate. This is not an Event 1 / Event 2 question.
Rate is rate and no clock can physically run at two different rates. t2 = t1 ( v^2 / c^2 ) ^.5 expresses only an altered, distorted view of the other clock. Its rate is always its local proper time tick rate.
No other observers view changes that tick rate.
HINT: the view of an observer in relative motion is an observation and not the reality of the clock in question. You cannot weave and dodge this issue.
PS: While you can preach your SRT BS and claim to not accept it on faith shows I don't understand, I clearly have a better grasp on reality than yourself. Your repeated assertions about my competence does not change reality so try addressing the question and forget the grand standing.
Ditto.
Paul T said:
No need to read further. You have already assumed to much.
In your scenario.
What are the tick rates of A, B, C when all are together on earth? Doesn't matter just call it 1 tick per second and all clocks are identical and synchronized at 12:00PM, 5 Oct, 2004.
Assume a 1 year trip. During the trip.
What is A's view of its tick rate? 1 tick per second. What does clock "A" read upon return to earth? Well you might try 12:00PM, 5 Oct, 2005.
What is B's view of its tick rate? 1 tick per second. What does clock "B" read upon return to earth? Well you might try 12:00PM, 5 Oct, 2005.
What is C's view of its tick rate? 1 tick per second. What does clock "C" read upon clock A and B's return to earth? Well you might try 12:00PM, 5 Oct, 2005.
There is no basis for your assumption of any time shift and indeed you are merely trying to invoke information delay and relavistic mathematics to prove relativity.
You have proven nothing. If you keep the clocks in constant communication using my side band modulation of information exhange via modulated light beams regarding their actual tick rate you find your assumption in the first instance is false.
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