- #1
jeffkosmo
- 7
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I’ve been trying to get my brain around Einstein’s theory of special relativity, and I find I'm a bit perplexed about his thought experiment (TE) involving the speeding train and the two simultaneous lightning strikes.
To briefly summarize, observer M is standing on a stationary “embankment” alongside the railroad tracks, midway between two points A and B. The train is about to speed by, with another observer M’ sitting in the exact middle of the train. The length of the train is identical to the distance from A to B. At the exact moment that M’ aligns with M, two simultaneous lightning strikes occur; one at A and one at B. (The complete description can be found in Einstein’s book, “Relativity: The Special and the General Theory, Chapter 9)
Einstein then contends that whereas M will experience both lightning flashes simultaneously, M’ will NOT.
I don’t disagree with Einstein’s contention; but I have two questions regarding his logic.
1) As I read it, he’s trying to set the stage so that he can demonstrate the manifestation of a “peculiar phenomenon”; i.e., that because light has a universally consistent speed for all observers, the passage of “time” may be different for different reference frames.
However, in the TE, he seems to violate, or forget about this fundamental concept. That is, he predicts that the reason M’ will see the light from B, before A, is because M’ is speeding TOWARDS the light coming from B, and AWAY from the light coming from A. In other words, relative to M’, the light from B is traveling faster than the light from A; i.e., at different speeds.
However, if we invoke the theory of the Consistency of C (the speed of light), and define the moving train as a legitimate frame of reference, we would then view the lightning strikes as occurring TO the train, and each beam progressing down the aisle towards M’ at equal speeds, propagating through identical distances, and consequently, arriving at M’ SIMULTANEOUSLY. Ergo, no “peculiar phenomenon”.
(We should also assume that the train has windows at both ends, and M’ either has eyes in the front and back of his head, or has some other clever contrivance by which he could make such an assessment.)
Question 1: Am I missing something, or is there a reason that Einstein did not invoke the theory of Consistency of C?
2) I would argue that the reason M’ (as described in the original TE) experiences the bolt from B before the bolt from A (and not in the same simultaneous manner of M) is NOT because of the train’s velocity V, but simply because M’ happens to be situated closer to B than A at the moment of interest (i.e., when the wave-front from B is passing by).
That is, we could imagine a similar TE, with no train whatsoever. In this TE, M is again at a midpoint between A and B, but M’ is a few feet closer to B - and perfectly stationary. If we again ask the two simultaneous lightning strikes to occur at A and B, M’ will see the flash from B before M does, and experience the flash from A a short time thereafter - while M experiences both flashes simultaneously. The “peculiar phenomenon” occurs exactly the same as the original TE, even though there’s no motion involved whatsoever. And in reality, there’s nothing “peculiar” about it at all. Everything can be explained with simple math. And there’s no need to begin speculating about how we now need to reassess our understanding of time and reality.
In other words, it seems that Einstein is trying to make it appear as if “speed” is the generator of the curious phenomenon, when it really has nothing to do with it.
Question 2) Isn’t Einstein un-necessarily complicating things by including this speeding train into his TE? And thereby creating a “solution” for a problem that doesn’t even exist.
In conclusion, I should say that I actually have no problem with the idea that “time” (i.e., the speed at which “physical information” is propagated between physical “stuff”) may be affected by the speed at which the stuff is plowing through space.
But…
A) I would think some type of “aether-like property of space” would be required to produce this phenomenon, and
B) I’m puzzled why Einstein chose this peculiar, confusing, somewhat irrelevant thought experiment as the springboard to justify his theory.
Any and all insights greatly appreciated.
Thanks in advance…
To briefly summarize, observer M is standing on a stationary “embankment” alongside the railroad tracks, midway between two points A and B. The train is about to speed by, with another observer M’ sitting in the exact middle of the train. The length of the train is identical to the distance from A to B. At the exact moment that M’ aligns with M, two simultaneous lightning strikes occur; one at A and one at B. (The complete description can be found in Einstein’s book, “Relativity: The Special and the General Theory, Chapter 9)
Einstein then contends that whereas M will experience both lightning flashes simultaneously, M’ will NOT.
I don’t disagree with Einstein’s contention; but I have two questions regarding his logic.
1) As I read it, he’s trying to set the stage so that he can demonstrate the manifestation of a “peculiar phenomenon”; i.e., that because light has a universally consistent speed for all observers, the passage of “time” may be different for different reference frames.
However, in the TE, he seems to violate, or forget about this fundamental concept. That is, he predicts that the reason M’ will see the light from B, before A, is because M’ is speeding TOWARDS the light coming from B, and AWAY from the light coming from A. In other words, relative to M’, the light from B is traveling faster than the light from A; i.e., at different speeds.
However, if we invoke the theory of the Consistency of C (the speed of light), and define the moving train as a legitimate frame of reference, we would then view the lightning strikes as occurring TO the train, and each beam progressing down the aisle towards M’ at equal speeds, propagating through identical distances, and consequently, arriving at M’ SIMULTANEOUSLY. Ergo, no “peculiar phenomenon”.
(We should also assume that the train has windows at both ends, and M’ either has eyes in the front and back of his head, or has some other clever contrivance by which he could make such an assessment.)
Question 1: Am I missing something, or is there a reason that Einstein did not invoke the theory of Consistency of C?
2) I would argue that the reason M’ (as described in the original TE) experiences the bolt from B before the bolt from A (and not in the same simultaneous manner of M) is NOT because of the train’s velocity V, but simply because M’ happens to be situated closer to B than A at the moment of interest (i.e., when the wave-front from B is passing by).
That is, we could imagine a similar TE, with no train whatsoever. In this TE, M is again at a midpoint between A and B, but M’ is a few feet closer to B - and perfectly stationary. If we again ask the two simultaneous lightning strikes to occur at A and B, M’ will see the flash from B before M does, and experience the flash from A a short time thereafter - while M experiences both flashes simultaneously. The “peculiar phenomenon” occurs exactly the same as the original TE, even though there’s no motion involved whatsoever. And in reality, there’s nothing “peculiar” about it at all. Everything can be explained with simple math. And there’s no need to begin speculating about how we now need to reassess our understanding of time and reality.
In other words, it seems that Einstein is trying to make it appear as if “speed” is the generator of the curious phenomenon, when it really has nothing to do with it.
Question 2) Isn’t Einstein un-necessarily complicating things by including this speeding train into his TE? And thereby creating a “solution” for a problem that doesn’t even exist.
In conclusion, I should say that I actually have no problem with the idea that “time” (i.e., the speed at which “physical information” is propagated between physical “stuff”) may be affected by the speed at which the stuff is plowing through space.
But…
A) I would think some type of “aether-like property of space” would be required to produce this phenomenon, and
B) I’m puzzled why Einstein chose this peculiar, confusing, somewhat irrelevant thought experiment as the springboard to justify his theory.
Any and all insights greatly appreciated.
Thanks in advance…