SR Simultaneous Lines Drawn in the Sand

ram2048

so they DON'T hit you at the same time if i move left or right.

which is what i thought, so why the arguments if everyone agrees?

geistkiesel

In the first post of this thread the moving observer at M' was at M the midpoint of sources of photons when the photons were emitted simultaneously. These photons were instantaneously detected in the moving frame as the were emitted in the stationary frame. The moving frame detected the simultaeous emission of the photons in the moving frame. .

Using the detected arrival times of the photons in the moving frame, SR theory calculates that the photons were not emitted simultaneouslly in the moving frame. THE PHOTONS WERE DETECTED SIMULTANEOUSLY IN THE MOVING FRAME AT THE INSTANT THE PHOTONS WERE EMITTED IN THE STATIONARY FRAME.

All you theorists can argue all you want about SR theory, speed of light, Einstein, laws of physics, constancy of the speed of light foreever. The fact of the observation the photons were emitted simultaneously in the moving frame remains invariant under any theoretical perturbation.

Your problem is one of embarrassment when you ponder: "How could I ever have accepted special relativity in the first place?" Like I said, it is your problem, you solve it.

geistkiesel

In the first post of this thread the moving observer at M' was at M the midpoint of sources of photons in the stationary frame when the photons were emitted simultaneously. These photons were instantaneously detected in the moving frame as they were emitted in the stationary frame. The moving frame detected the simultaeous emission of the photons in the moving frame.

This is an experimental observation.

And you say no they were not emmitted in the moving frame simultaneously.

geistkiesel

In the first post of this thread the moving observer at M' was at M the midpoint of sources of photons in the stationary frame when the photons were emitted simultaneously. These photons were instantaneously detected in the moving frame as they were emitted in the stationary frame. The moving frame detected the simultaeous emission of the photons in the moving frame.

What are you talking about " ...seeming more intuitve . . ?.Aren't observations intuitive enough for you?

ram2048

why must you use a moving frame and a stationary frame?

i think that's what is throwing me off

do one experiment where he's stationary and THEN do the exact same thing when it's moving

combining the two creates unnecessary confusion :P

1) A -> ________________M________________ <- B
1) A ____ ->____________M____________<- ____ B
1) A __________ ->______M______<- __________ B
1) A _________________ xMx _________________ B

2) A -> ________________M________________ <- B
2) A ____ ->______________M__________<- ____ B
2) A __________ ->__________M__<- __________ B
2) A ________________ ->______Mx ___________ B
2) A ______________________ ->__Mx _________ B
2) A ____________________________xMx _______ B

so i'm still not seeing the contradiction. everyone AGREES that the photons don't hit him at the same time in the moving frame. How hard would it be to do the calculations in reverse for the moving frame setup and acquire that the beams WERE emitted simultaneously BECAUSE of the frame shift, extrapolate it using M's velocity towards B.

geistkiesel

Why do we need two frames?
Because SR theory says that events that are simultaneous in the stationary frame are not simultaneous in the moving frame. We are talking about the same physical event. We must do the experiment with two frames, one stationary and one moving to test the theory. Hence we have the photo-sensitive strips to measuee the emission of the photons.
Here is the contradiciton that everyone is having such a difficult time with.

[b]"Were the photons that were emitted simultaneously in the stationary frame also emitted simultaneously in the moving frame?"[/b ]

There was the record of the phosensitive strips attached to the moving frame that were exposed just when the photons were emitted in the stationary frame. These photo-sensitve strips were within a photon wave length of the emitted photons at A and B in the stationary frame when they wee exposed.

SR theory says, the photons were not emitted simultaneously in the moving frame. SR Theory gets to work backwards in time and redo the physical events that occured there.

Hurkyl

Because we're disagreeing about what SR says when we analyze the exact same events from different frames.

Specifically, Geistkiesel is asserting that both of these diagrams are representing the exact same sequence of events:

We have two relatively stationary light sources (A and B), and an observer who starts in the middle and moves towards A.

The first diagram depicts how things look in the rest frame of the lights, if the lights are activated simultaneously.

The second diagram depicts how things look in the rest frame of the observer, if the lights are activated simultaneously.

However, there is a very important difference between the two diagrams; in the first diagram the photons do not meet M at the same event, however in the second diagram the photons do meet M at the same event.

The conclusion is that these diagrams cannot possibly represent the same events. Among the possible assumptions we can abandon, abanding that of absolute simultaneity is by far the most reasonable; the emission of photons is simply simultaneous in one frame but not the other.

Doc Al

You cannot arbitrarily set all clocks in O' to read t'=0. Doing so requires assuming that simultaneity is independent of the reference frames. Since that's what we're trying to discover, we can't just assume it.
Absolutely not! I don't want anyone making assumptions or stipulations about simultaneity. The entire point of Einstein's simple argument is to deduce the nature of simultaneity, not make assumptions about it.
Once again, the point of Einstein's argument is to deduce the relativity of simultaneity, not assume it. The invariant speed of light is fundamental to any gedanken experiment concerning light. Without that, there is nothing to discuss.
Don't be cute. Re-read my post and tell me exactly where you think Einstein's argument fails. If you can't accept the starting point--the invariant speed of light--then there is no point in continuing.

Doc Al

Please tell me exactly where I am being ambiguous. Refer to my post #2 in this thread. And dishonest? Come now, geistkiesel, have you run out of intellectual ammunition this early in the game?
Anyone curious as to what I actually said, can read my own words in post #2.
We have "discussed" this many times. I am giving geistkiesel a golden opportunity to clearly and unambiguously point out the flaws in Einstein's argument. Is he up to the challenge?

Doc Al

Re-read my response in post #2.
Right!
Now what possibly can you mean by this garbled statement? Are you talking about photons being detected by O'? Or O' deducing that they were emitted simultaneously? Speak clearly and stop wasting people's time.

Doc Al

I defy anyone to understand your point. See my last post. Talk sense, man!

Doc Al

Assuming observers in the moving frame were posted at the right positions, then they WILL detect the photon emissions. But what makes you think that they will detect them SIMULTANEOUSLY? Since that is the point we are arguing, please give us your argument. (Note how Einstein's simple argument does not involve multiple moving observers. Why not deal with that argument directly?)
We all agree that the moving observer detects the photons as arriving at different times. Using that fact, plus simple assumptions of the invariance of light speed, Einstein deduces that the moving observer must conclude that the photons were emitted at different times. Every observation made in the moving frame--including the direct observation of the photon emissions by the moving observers--must agree with this conclusion!
Again, you merely ***ume, where Einstein argues.
I truly believe that you believe this. But you are still wrong. Rather than add questionable assumptions to Einstein's gedanken experiment, please deal directly with Einstein's simple argument.
Geistkeisel, I am making a special effort in this thread to be nice. Why don't you do the same?

geistkiesel

The instant photons were simultaneously emitted from A and B in the stationary frame the photo-sensitve strips in the moving frame were exposed (|||) at both ends of the moving frame, at locations equally spaced from M'. This is the point, the only point. For your convenience we give another picture.

|||----M'----||| -->moving frame-->
-A-----M-----B-| XX stationary frame XX

This is the picture the instant photons were emitted from A and B in the stationary frame.

Said another way, the instant the photo-sensitive strips were exposed in the moving frame by photons emitted in the stationary frame..

Is this enough "sense talk, man"?

I title this: A Simultaneous Line in the Sand for Doc Al.

If you were from Texas, or had spent any time in Texas, maybe, just maybe you would be able to understand. And this even though it is common knowledge that Texans have half their brains tied behind their back, leaving one loose piece of gray matter to rattle around inside their skull cavities.

You defied anyone to understand the point. OK, someone from Texas, splain it to Doc Al.

geistkiesel

You don't know how to be nice. There were no added assumptions that corupted Einstein's gedunken. You just haven't realized that you've lost this game.

As from me to you, this is as nice as it gets.

russ_watters

If the thought process of the theory is wrong, then it can easily be shown to be wrong through experimentation. You you can't prove that a theory is wrong if you don't address what the theory says. You are stating (assuming, as Doc says) the theory is wrong and building a thought experiment around how you think the universe should work, then offering it up as a proof that the theory is wrong. Sorry, science doesn't work that way.

Depending on the theory you apply to the thought experiment, the outcome is different. Which is right and which is wrong? Well, that's a question answered by experimentation.

What's funny about this is you think you're making an argument against Relativity, but what you are actually doing is demonstrating you don't even understand the scientific method, much less Relativity. The other guys here aren't so much defending Relativity as trying to explain to you what it says.

Doc Al

Can observers in the moving frame detect the emission of the photons? Yes.
Are the marks on the photo-sensitive strips (caused by the photon emissions) in the moving frame equally spaced from the point M' (which passed M at the exact moment that the clock at M read t=0): YES!
Do the moving observers detect the photon emissions as happening simultaneously: NO!

By building incorrect assumptions into your "thought" experiment, you have left the realm of real physics. (As we know it today.)

Note that Einstein makes no such assumptions--and is able to simply deduce the relativity of simultaneity. Why not address Einstein's actual argument?

Doc Al

You ***umed that:

(1) The marks on the photo-sensitive strips (caused by the photon emissions) in the moving frame are equally spaced from the point M' (which passed M at the exact moment that the clock at M read t=0): True!
(2) That the moving observers detect the photon emissions as happening simultaneously: Not true!

As long as you insist on adding these assumptions, there is no point in continuing the discussion.

However, if you would like to discuss Einstein's actual argument--which you refer to constantly but obviously fail to grasp--have at it. If you truly understand Einstein's point, this should be no problem--since he makes fewer assumptions than you do.