Timeline for Traveling between two planets at rest to one another [duplicate]
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22 events
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| Jul 6, 2014 at 23:29 | history | closed |
Brandon Enright Colin McFaul Qmechanic♦ |
Duplicate of How is the classical twin paradox resolved?, How can time dilation be symmetrical? [duplicate] | |
| Jul 6, 2014 at 23:08 | comment | added | user12262 | @dmckee: "Pros solve relativity problems in terms of invariants." -- Pros solve relativity problems in terms of proper quantities. The whole talk of "varying perspectives (frames)" (not to mention coordinates) in order to recognize some quantities as "invariant" is a severe (un-)pedagogical failure. "Lorentz scalars (like the proper time)" -- Saying "time" (which according to Einstein is "what a clock indicates") when instead meaning "duration" (as a measure of an entire set of successive times of a given clock, or participant) is a failure, too. | |
| Jul 6, 2014 at 22:11 | answer | added | user12262 | timeline score: 0 | |
| Jul 6, 2014 at 21:39 | comment | added | bright magus | @ACuriousMind: But I absolutely accept the concept of invariance of proper time. (So why are you bringing this up?) | |
| Jul 6, 2014 at 21:27 | comment | added | ACuriousMind♦ | @bright magus: SR speaks clearly about Lorentz invariance. The whole talk of frames and who sees what is an unfortunate pedagogical failure, just as dmckee says. Proper time is Lorentz invariant no matter whether anything is accelerating or not. If you do not understand the power of Lorentz invariant quantities, you have not understood SR. dmckee is absolutely right. | |
| Jul 6, 2014 at 21:04 | comment | added | bright magus | SR speaks clearly about inertial frames. That's what the basic equation showing time dilatation is about (and what OP is asking about) - there are no accelerations there and the amount of dilatation is the function of difference in uniform velocity, and nothing else. | |
| Jul 6, 2014 at 20:53 | comment | added | C. Towne Springer | How are you accounting for acceleration in SR? Don't all these "paradoxes" boil down to - he who experiences acceleration has the slower clock? | |
| Jul 6, 2014 at 20:35 | comment | added | bright magus | @Krel: There is no answer to your question. Cause you are absolutely right: as long as the situation is pure SR, i.e. if both compared frames of reference are inertial, there must by full symmetry - according to the theory, you can rightfully claim that my clock is the slower one, and I can claim that your clock is the slower one. All mathematical plays here (with accelerations or sophisticated concepts) are mere detours that cannot change this fact. Because if the situation is not symmetrical, then it is not an SR case, by definition. You just trust your own reason and don't let be confused. | |
| Jul 6, 2014 at 20:26 | answer | added | Moonraker | timeline score: 0 | |
| Jul 6, 2014 at 20:25 | answer | added | Alfred Centauri | timeline score: 4 | |
| Jul 6, 2014 at 20:21 | comment | added | dmckee --- ex-moderator kitten | The things that lets the symmetry of time dilation be real and not cause problems is that you can't assign a unique meaning to comparison of clocks at spatially separated locations, so passing spaceships can sync their clocks as they pass but can not thereafter compare their clocks directly unless one or both maneuvers so that they come together again. Once they do that it is some version of the twin paradox. | |
| Jul 6, 2014 at 19:48 | comment | added | dmckee --- ex-moderator kitten | The secret that pros in relativity know is that Lorentz scalars (like the proper time) are invariant. It is a shame that this fact is rarely mentioned and never emphasized in popular treatments, but it is the case (and it is related to the speed of light being invariant). Pros solve relativity problems in terms of invariants. If you are not going to take our word for these things that you will have to go back to the basics and figure them out for yourself. | |
| Jul 6, 2014 at 19:13 | history | edited | Qmechanic♦ |
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| Jul 6, 2014 at 19:12 | answer | added | ACuriousMind♦ | timeline score: 0 | |
| Jul 6, 2014 at 19:04 | history | edited | Krel | CC BY-SA 3.0 |
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| Jul 6, 2014 at 18:55 | comment | added | Krel | Not to mention every answer I have received regarding proper time seems to fly in the face of SR in that they eliminate the relative part of relativity. Something moving experiences less time, I understand this, but "movement" is relative. In all my other questions, as in this one, I have yet to receive an intuitive explanation as to why one frame that is moving absolutely experiences less time than the other, since you can easily switch which is moving and which is stationary and thus which experiences less time. So is the idea that the effects are symmetrical so "weird?" | |
| Jul 6, 2014 at 18:54 | review | Close votes | |||
| Jul 6, 2014 at 23:29 | |||||
| Jul 6, 2014 at 18:43 | comment | added | Krel | Because it has been taught that if you are flying in a ship at relativistic speeds and pass another ship you will see time running slower for them while they will see time running slower for you. Thus it seems symmetrical. | |
| Jul 6, 2014 at 18:40 | comment | added | ACuriousMind♦ | And, as to all your other questions, the answer is: Proper time is a Lorentz invariant. I really don't know where you get the weird idea from that it should be "symmetrical". | |
| Jul 6, 2014 at 18:40 | comment | added | Krel | I asked that question, the reason I'm asking this one is that I did not find the answer on the last one satisfactory so figured I'd ask a better version of the question. Linking it as a duplicate does not help me much. | |
| Jul 6, 2014 at 18:38 | comment | added | ACuriousMind♦ | possible duplicate of How can time dilation be symmetrical? | |
| Jul 6, 2014 at 18:35 | history | asked | Krel | CC BY-SA 3.0 |