Einstein did not invent many of the initial concepts of Special Relativity fundamentally, but he found a way for them all to be tweaked and orchestrated in unison. He took 5 conflicting theories and wove them successfully together with the “Two Postulates” already mentioned by others on the post. In the anscence of the atequating “Ether Theories”, people were more willing to buy his explanations.
Work of Others bound together by SR and GR:
(1) Maxwell Equations
(2) Lorentz Dilations, Contractions and Limitations
(3) Poincare’s idea of Relativity
(4) Minkowski 4-space
(5) Fizeau “Light dragging”
(6) Michelson & Morley - Null Observations
(7) … Many, Many more …
Right or wrong, It is truly amazing how he was able to get these theories to all work at the same time.
Actually there’s a lot more to it than that. Your derivation and the one on that page both seem to assume a specific kind of setup to the experiment. It’s really a statement about the behavior of the second moments of a function and its Fourier transform and can be proven without any reference whatsoever to what sort of measurement is being done.
This isn’t to denigrate your derivation, btw. I’d show it to a lay audience, but the math proof makes people react like someone opened the lost ark.
Completely Agreed. I did actually have an ulterior motive for presenting the ball-park figure this way (which is, yes, not the usual explanation) .
I am in the minority in contenting that the math of quantum Mechanics is completely correct (statistically), while the philosophy/interpretation is, to an extent, bogus. This is almost worth another thread, so I won’t go into detail here.
If one were to discover a field that has a lower Energy per Frequency relationship (AKA Gravity, unknown fields, ect.), then the Uncertainty principle will appear differently numerically, yielding a completely different result. h_gravity might be smaller than h_light – just keeping the possibilities open.
Heisenberg’s principle is, no doubt, correct for setting up an experiement. But when one is not using an active scan (or actively looking at all) the rules change a little bit.
I’ve always been curious about this concept. Suppose you found yourself in an room and you felt 1G of force, and you wanted to try to determine which scenario you were in. Now dangle four weights near the corners. If you were in space and were being accelerated by a rocket, wouldn’t the strings holding the weights all be parallel? And if the room were sitting on the earth, wouldn’t the weights be pulled towards the center of the earth, and thus the strings wouldn’t be parallel, but would slightly converge towards the center of the room?
Why wouldn’t this experiment work to tell the difference between gravity and acceleration? What am I missing here?
Actually, it does tell the difference between the gravitational field around a planet and the acceleration from a rocket. The equivalence principle holds locally – in a small enough area around a given point. What you’re measuring is the “tidal forces” of the gravitational field, which are global effects rather than a local description of the observations. General Relativity is what happens when you take the equivalence principle at each point and try to sew together its implications at “nearby” points.
For all I know, your explanation may be accurate and helpful, but I’m struggling with it.
Is he watching the clock or the beam of light? You seem to consider the two activities as being the same. But you’ve already said the beam of light isn’t the clock, it’s the thing which the clock is based on.
How can he watch the beam of light if it’s behind him as he runs away?
No, he doesn’t see it travel along a diagonal. From his point of view, it’s just a vertical line between the floor and the ceiling. He had no perspective from which to gauge a diagonal line.
No, we don’t. The terms ‘straight up and down’ and ‘diagonal’ don’t make sense in this gedanken experiment as described Who is the ‘we’ in the phrase ‘we know it covers a greater distance’, and what’s our frame of reference?
Wait a minute. On what basis would he form this expectation?
Faster? How would he measure this quality of being ‘faster’? What sort of measuring device or clock would he use to achieve this measurement? Where would it be positioned?
By the way, I looked at the .pdf file and couldn’t see the light for the fog. My failing, I’m sure. Or maybe the guy who wrote it doesn’t know much about conveying ideas clearly in prose.
This is the part that gets me. Why doesn’t the runner simply perceive light as traveling faster in his frame than the other observer? Afterall, if at any given point in time the light is in the same position for both observers, but for the runner the light is covering a greater distance… ahhh… ok, lightbulbs are going on as I type this. It’s just difficult to wrap my brain around still.
So if we say, for simplicity’s sake, that one clock cycle = one sec. and at T=0 the light is at the top mirror. At T=.5 the light is at the bottom mirror for both observers yes? And at T=1 it’s at the top again.
But no. Though we can take a snapshot in time when it is at the bottom, it won’t be at T=.5 for both. It can only be that for one of the observers.
But how are we measuring this time? I know the answer to this, and I guess this is where it freaks me out the most. If both are wearing wristwatches that begin synched up, they will actually progress at different rates while the runner is in motion. I know this has been confirmed in actual experiments. So it’s not simply a matter of subjective perceptions of time. In fact, it won’t even register into one’s own perception.
My god, my head hurts.
BTW, ianzin I think you’re taking the thought experiment a little too literally. No need to be concerned with how a runner can see this while running. Just pretend he can, like he’s some eyeball floating through space watching it while still circling it.
Now take every other point of reference out of the image so it’s all just black empty space with this light clock and the eyeball the only things in the image. Be the eyeball. You can’t tell if you (the eyeball) are moving around the clock, or if you’re standing still and it’s the only thing moving.
Wait, (sorry for rambling), I just thought of something. Wouldn’t your pathway have to be elliptical for this to work? If you go around the clock in a perfect circle and are thus equidistant from the clock at any given point on that circle, wouldn’t it still appear to simply go up and down, and not diagnol at all?
Oops, I’m not sure why I assumed the runner’s path would be a circle. I see on re-reading that you mentioned no such thing.
So, would there be any effect if the runner’s path remained equidistant from the clock at all points?
BTW, the movie Young Einstein with Yahoo Serious presented an incredibly simple way to “get” all this. In the movie he looked at a clock and instantly realized that if he were suddenly moving backwards (i.e. in the direction opposite the clock) at the speed of light, that the light from the clock would never reach him. The clock would appear to stand still, thus time would stand still.
Because that’s exactly what the second postulate of relativity forbids. Light always travels at the same speed; this is a fact we observe about the Universe. But if you’re not willing or able to yield on that point, then something else has to give. That something else is the notion that space and time are not, by themselves, absolute.
Completely Agreed. I did actually have an ulterior motive for presenting the ball-park figure this way (which is, yes, not the usual explanation) .
