2clockdude said:
The argument was given. It is the fact that events occur independently of frames and their clocks combined with the fact that relative simultaneity exists only when these clocks are used. The opposite of relative time is absolute time, so that exists when the other does not. But there is more to the simultaneity story; see below.
You are wrong, and it's because you failed to read the whole train example story. I am not here to educate, but I will take the time to ask you what this phrase from that story means: "able meteorologist."
There is no evidence that light's one-way speed per two same-frame clocks is c in all frames. But there is evidence from Einstein himself that is not c in all frames when truly or absolutely synchronous clocks are used. Again, I am not here to educate, but look at Einstein's equation w = c - v at
http://www.bartleby.com/173/7.html where he said that "The velocity of propagation of a ray of light relative to the carriage thus comes out smaller than c."
How ironic that you accuse someone above of not having read the whole example, when you yourself obviously didn't read the whole section that you are quoting above. The quote comes from a part where he is discussing the state of physics before Relativity and is pointing out what,
at the time, seemed a incompatibility between the propagation of light and the principle of Relativity. He then goes on later on the same page to state
"in reality there is not the least incompatibility between the principle of relativity and the law of propagation of light, " Put another way, he is giving a little background before going on to present his theory. He is
not arguing for the statement you quoted. He hasn't even gotten to presenting his argument yet.
As promised above, here is the rest of the simultaneity story:
The only "proof" or "evidence" of the relativity of simultaneity is the train example.
However, it is easy to show that this example has nothing to do with the relative simultaneity of events.
Einstein believed that observers' different views of light rays from events say something about the events' occurrence times. It is easy to agree with Einstein when two events are involved because this makes it difficult to see what is really happening. However, if we look at only one event, e.g., the right-hand lightning strike, then we can clearly see Einstein's mistake.
Let's label the right-hand lightning strike event E. Let the rail observer be R, train observer be Tf, and an added rearward-moving train observer Tr.
-------------Tr--------R---------Tf-----------E
---------light<--------------------------------
The forward-moving train observer (Tf) sees the light ray before R, and Tr sees the ray after R. (These are absolute before-and-after's because these are three light-like events.) For example, Tf sees the ray at 11am, R sees it at noon, and Tr sees it at 1pm. (There are no clocks in the train example, but we can use these times to help us visualize the example. They merely echo the fact that the events have absolute before-and-after's.)
However, the observers now know that Einstein's view is false because a single event cannot occur at different times; that is, the observers must reject Einstein's belief that different views of a light ray from an event say something about the time of the event itself.
Why do the observers see the light ray arrive differently? The cause is simply the observers' physical separations. If the observers separate during the experiment, then the light ray must reach them differently, and this clearly has nothing to do with the time of the lightning event or simultaneity.
Here is Einstein's conclusion regarding his train example:
"Events which are simultaneous with reference to the embankment are not simultaneous with respect to the train, and vice versa (relativity of simultaneity). Every reference-body (co-ordinate system) has its own particular time; unless we are told the reference-body to which the statement of time refers, there is no meaning in a statement of the time of an event."
http://www.bartleby.com/173/9.html
But we have found that seeing light rays from events differently says nothing about events' occurrence times or the RoS, but merely says that the observers were in different locations. The observers do disagree, but not about time or simultaneity, only about the light ray arrivals.
You are missing the whole point of the exercise. The railway observer sees the from both flashes simultaneously. and because he is halfway between the strike points, he can conclude that the strikes took place simultaneously.
He will also note that the train observer sees one flash before the other. (The train observer will be next to different points of the tracks when each flash reaches him).
Now, as you noted a single event can only occur once, so the train observer must also agree that he was next to two different points of the track upon seeing each flash and thus agrees that he sees the flashes at different times.
However, the train observer sits at the midpoint of the train,
and the lightning strikes hit the end of the train. Due to the invariance of the speed of the light, the flashes approaching from each end of the train have to travel at the same speed
relative to him as determined from his frame. If the light from the rear of the train approaches at 300,000 km/sec, and the light from the front of the the train approaches at 300,000 km/sec and the distances from from the observer to the two ends are equal, and he sees the flashes at different times, then he
must conclude that the strikes occurred at different times.
The fact that the train observer see the flashes at the "same time" as the embankment observer is a red herring.
In fact, we can rearrange the experiment so that both observers do see the flashes at the same time. by changing the scenario so that the flashes
arrive at the embankment observer at the same time as he is next to the train observer, like this:
[URL]http://home.earthlink.net/~jparvey/sitebuildercontent/sitebuilderpictures/train1.gif[/URL]
The expanding circles represent the flashes.
Again, according to the embankment observer, the flashes both occur simultaneously and he sees them simultaneously.
The train observer also sees them simultaneously. However, he is moving with respect the embankment. Thus he will be closer to one lightning strike than the other when the strikes occur.
Again, since the speed of light must be constant for him, the light from the strikes expand out as even circles from points that maintain a constant distance from himself. (while the points on the embankment where the strikes occurred move away from these centers. )
Thus this is what happens according to the train observer:
[URL]http://home.earthlink.net/~jparvey/sitebuildercontent/sitebuilderpictures/train2.gif[/URL]
In order for him to see both flashes at the same time and at the same time as the embankment observer, the strikes that caused them have to occur at different times.
Thus even though both observers see the flashes simultaneously, One concludes that they originated at the same time and the other that they originated at different times
