Trying to Understand Light in Motion: A Frustrating Puzzle

[ghwellsjr]

if the strikes at exactly the same time happen in the trains reference frame at t=0 and the observer is 1 light second away from the centre of train then at t=1 he will see the flashes hit.

do you agree with that?

If you mean that the light from the two strikes arrive simultaneously at the center of the train at t=0 when the passenger sees them simultaneously (this is after the two strikes occurred) and the platform observer is 1 light second away, then, yes, at t=1 he will see the reflected light from those two events also at the same time. But this has nothing to do with all the prior discussion in this thread.

If this isn't what you mean, then you're going to have to spell out in detail what you mean in each post because otherwise everyone will interpret what you are saying differently.

Actually, I'm sure this isn't what you mean but I can't tell so I'm just taking a shot in the dark.

 

[solarflare]

Example: You and I are exactly 1 mile from the same point and we travel exactly at the same speed. Do we necessarily arrive at that point at the same time? Of course not: I started off at 1pm and you started off at 1:15pm. We only arrive at the same time if we left at the same time.

if we set off at the same time and was moving at the same speed -would we both be 1 mile away from that same point at the same time?

 

[Doc Al]

if we set off at the same time and was moving at the same speed -would we both be 1 mile away from that same point at the same time?

If we started from the same point, sure. (Assuming we went straight, of course.)

 

[solarflare]

when you watch the video at 28 seconds the train is paused to show the motion of the light from the two strikes. clearly the light is coming from the two ends of the train to his eyes. the video is agreeing with what I am saying. by saying that the light that hit the train at the same time gets to the platform observer at different times means that you will disagreeing with the video.

 

[Dale]

the point is that by saying the observer on the platform is equidistant from the flashes implies that the strikes must happen at the same time in both frames.

The strikes cannot happen at the same time in both frames. See:
http://en.wikipedia.org/wiki/Relativity_of_simultaneity
\Delta t'=\gamma (\Delta t - v \Delta x / c^2)
Since both v and Δx are nonzero then it is impossible for Δt and Δt' to both be zero.

 

[Doc Al]

when you watch the video at 28 seconds the train is paused to show the motion of the light from the two strikes. clearly the light is coming from the two ends of the train to his eyes. the video is agreeing with what I am saying. by saying that the light that hit the train at the same time gets to the platform observer at different times means that you will disagreeing with the video.

Uh, no. The video has the light hit the train at the same time according to the platform frame and thus the flashes reach the platform observer at the same time. (The flashes reach the passenger at different times.)

 

[solarflare]

yes and because he is equidistand from each end then the flashes must have come from the train at the same time

 

[solarflare]

you are saying that if he sees the flashes at the same time then the flashes occur at different times - but if he is equidistant from the falshes then that would mean light traveled at different speeds to reach his eyes at the same time

 

[Doc Al]

yes and because he is equidistand from each end then the flashes must have come from the train at the same time

If the lightning strikes occur at the same time according to platform clocks (as in the video), and at the moment of the strikes the platform observer is equidistant from the ends of the train, then the flashes will reach him at the same time.

The flashes will reach the middle of the (moving) train at different times.

you are saying that if he sees the flashes at the same time then the flashes occur at different times - but if he is equidistant from the falshes then that would mean light traveled at different speeds to reach his eyes at the same time

No, the flashes will reach the woman (train passenger) at different times, who therefore concludes that according to her train clocks the lightning strikes were not simultaneous. It is a basic principle of relativity that the light travels at the same speed with respect to all observers.

 

[Chestermiller]

If the two lightning strikes hit the ends of the train at the same time, as reckoned from the platform observer's frame of reference, then the two flashes will not arrive at the same time in the train rider's frame of reference, even though the distances between the rider and each of the two flashes as measured on the train were the same. If there were a train rider positioned at the front of the train and another train rider positioned at the rear of the train, then according to their synchronized clocks, the train rider at the front of the train would measure the flash at his location to occur at an earlier time than the train rider at the rear of the train. So the rider at the center of the train would have to reckon that the flash from the front of the train occurred first, followed by the flash from the rear of the train (if the speed of light is the same in all directions in his frame of reference).

Now, let's consider the opposite situation.

If the two lightning strikes hit the ends of the train at the same time, as reckoned from the train rider's frame of reference, then the two flashes will not arrive at the same time in the platform guy's frame of reference, even though the distances between the platform guy and each of the two flashes as measured on the ground were the same. If there were a platform guy positioned exactly at the location of the front lightning strike and another platform guy positioned at exactly the location of the rear lightning strike, then according to their synchronized clocks, the platform guy at the location of the front lightning strike would measure the flash to occur at a later time than the platform guy at the location of the rear lightning strike. So the guy at the center of the platform would have to reckon that the flash at the rear of the train occurred first, followed by the flash at the front of the train (if the speed of light is the same in all directions in his frame of reference).

Chet

 

[solarflare]

Why in the world do you think that? According to the platform frame, the passenger is moving to the right (say) at speed v and the light is moving to the left at speed c (of course). So it's just simple arithmetic to realize that they approach each other at a rate of 'c + v'. All measurements were made in the frame of the platform.


Well, no. Just the opposite. (Just repeating the same thing louder will not make it true. Why not read an introductory treatment of relativity where this is all layed out in explicit detail?)


That part is true. "If" is the key word here.

so what your saying is that they do strike at the same time but because she has forward momentum she sees the front stike first and the back strike second?

 

[solarflare]

Whenever you make a statement about the lightning strikes, get in the habit of say which frame sees the lightning strikes as simultaneous. Otherwise we'll just keep going in circles.

If the lightning strikes simultaneously in the platform frame, then the flashes will hit the platform observer at the same time. But if the lightning strikes simultaneously in the train frame, then the flashes will hit the platform observer at the different times. (Remember that they are moving with respect to each other. And that each sees the light traveling at the same speed.)

here you say that if they strike in the trains frame the flashes will reach him at different times

 

[Doc Al]

so what your saying is that they do strike at the same time but because she has forward momentum she sees the front stike first and the back strike second?

No, they strike at the same time in the platform frame. You've got to remember that saying 'at the same time' is meaningless unless you specify according to what frame.

here you say that if they strike in the trains frame the flashes will reach him at different times

Right! If the strikes occur simultaneously in the train frame, they occur at different times in the platform frame.

 

[solarflare]

but how can light from the trains frame that travels the same distance from each end not reach the platform frame at the same time.

you have to apply the same maths to the platform frame as you do to the passengers frame.

 

[solarflare]

here is what i think happens - the two observers see the same thing - they both see the two bolts hit simultaneously - but they will disagree on the time that the two bolts hit. the passenger might say they hit at 3:00 and the platform observer might say they hit at 3:01

they agree on what happened but they disagree on when it happened

 

[Chestermiller]

here is what i think happens - the two observers see the same thing - they both see the two bolts hit simultaneously - but they will disagree on the time that the two bolts hit. the passenger might say they hit at 3:00 and the platform observer might say they hit at 3:01

they agree on what happened but they disagree on when it happened

No. If the two strikes occur at the same time according to the set of synchronized clocks in the platform frame of reference, then they will be observed to occur at different times according to the set of synchronized clocks in the train frame of reference. If there are actually observers from each of the two frames of reference present at the locations of the lightning strikes when they hit, and if the 4 observers at these locations (2 on the platform and 2 on the train) write down on pieces of paper the times on their clocks that the two strikes hit, the times written down on the platform observers' pieces of paper will be identical to one another; the times written down on the train observers' pieces of paper will not be identical to one another. According to the team of observers on the train, the clocks on the platform are out of synchronization, and according to the team of observers on the platform, the clocks on the train are out of synchronization.

 

[Doc Al]

but how can light from the trains frame that travels the same distance from each end not reach the platform frame at the same time.

For the same reason that light from each end of the train (simultaneously emitted in the platform frame) can arrive at the middle of the train at different times.

you have to apply the same maths to the platform frame as you do to the passengers frame.

Exactly! You must apply the same math and the same rules for all frames. But what you cannot do is just ASSUME that the lightning strikes are simultaneous in both frames. (If you do, you'll contradict the basic assumption that the speed of light is the same for everyone.)

So don't keep flipping back and forth between two physically different scenarios. Pick one scenario, such as the lightning strikes being simultaneous in the platform frame (as in the video) and analyze it properly.

 

[Doc Al]

here is what i think happens - the two observers see the same thing - they both see the two bolts hit simultaneously - but they will disagree on the time that the two bolts hit. the passenger might say they hit at 3:00 and the platform observer might say they hit at 3:01

they agree on what happened but they disagree on when it happened

They do agree on what happened, but not in the way that you think.

Since the lightning bolts hit simultaneously in the platform frame, we can mathematically deduce that the flashes must arrive at the middle of the train at different times.

The train observers agree of course. But the train observers also say that the lightning strikes were not simultaneous according to their clocks. Furthermore, they claim that the clocks on the platform are not synchronized.

Simultaneity is frame dependent, just like length and clock rates.

 

[Dale]

Let's try it this way. Given that there are two lightning flashes and an inertially moving observer which sees both flashes at the same time, and given that the light from the flashes travels at c, under what conditions did the flashes occur simultaneously? The condition is that the observer must be equidistant from the flash points at the time he receives the light.

This can be true in at most one frame. In other frames the observer will have moved off center.

 

[solarflare]

According to the special theory of relativity, it is impossible to say in an absolute sense whether two distinct events occur at the same time if those events are separated in space, such as a car crash in London and another in New York. The question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in other frames (in a different state of motion relative to the events) the crash in London may occur first, and in still other frames the New York crash may occur first. If the two events are causally connected ("event A causes event B"), then the relativity of simultaneity preserves the causal order (i.e. "event A causes event B" in all frames of reference).

http://en.wikipedia.org/wiki/Relativity_of_simultaneity

this states that in some reference frames the two accidents may happen at the same time. yet you claim that it is not possible for two frames to agree

 

[Dale]

this states that in some reference frames the two accidents may happen at the same time. yet you claim that it is not possible for two frames to agree

It is not possible for these two frames to agree in this scenario because the relative motion is in the x direction and the lightning strikes are separated in the x direction. See the formula I posted earlier which clearly shows the impossibility of agreement here.

The wiki article appears to refer to the possibility of two frames moving in the x direction to agree on events separated only in y or z. That does not apply here.

 

[Doc Al]

this states that in some reference frames the two accidents may happen at the same time. yet you claim that it is not possible for two frames to agree

In one frame the two (non causally connected) accidents may happen at the same time; but in a frame moving with respect to that one, they will not happen at the same time. You won't find them happening at the same time in two frames moving with respect to each other (along the line between the two accidents).

 

[Muphrid]

I think the problem is that you're trying to assume certain things are the same in both frames that aren't. Let's turn the problem around a little bit.

Let's say two lightning strikes hit opposite ends of a stationary platform again. Person P, stands in the middle of the platform; person T is riding a train. The strikes both hit at the same time according to person P, and at that moment, person T is in the middle of the platform (or as close as he can be while riding a train passing it by) as well.

Now, let's equip both person P and person T with two simple light sensors that tell when they have seen the light from each lightning strikes.

Person P sees both light flashes at the same time, and both his sensors light up at the same time. Now, according to person P, person T can't possibly see both flashes at the same time because T is moving forward and will catch up to the forward light pulse while running away from the backward light pulse. T will see the forward strike first, and then the backward strike.

Now, T doesn't agree on why he sees the two strikes at different times. He thinks the strikes must've happened at different times, with the forward strike first and hte backward strike second. But, he thinks person P is moving backward and that the time delay between the strikes is enough so P will still see both strikes at the same time.

In other words, P and T both believe P will see the strikes at the same time and that T will see them at different times. That is the physically meaningful statement they can make. That is what both frames agree on. Everything else, well, is relative.

 

[ghwellsjr]

Solarflare, it doesn't appear that we are making any headway with you on this issue. Perhaps it would help if we changed the scenario so that it basically happens in the reverse order.

Let's consider a totally different scenario:

We have a very long train, much longer than the length of the platform and so long we don't care where the front and rear are. But instead of just one observer, we have an observer at every window, all along the train.

Then on the ground, we have a platform of some arbitrary length. At the center of the platform, we have a flash bulb that will produce a bright flash of light sometime while the train is passing but we don't care when. Then at each end of the platform, we have a mirror placed at a 45 degree angle so that when the flash of light reaches it, it will reflect the light towards the train.

What we want to do is have whatever train observer is adjacent to the flash bulb when it flashes make note of the event. We'll call him Observer A. In a similar way, we want whichever two train observers see the light reflected off the two mirrors make note of those two events. We'll call the one toward the front of the train Observer F and the one toward the rear of the train Observer R.

Now isn't it obvious that by the time the light reaches the mirrors, the train has moved forward along with Observer A and so he will be closer to Observer F and farther from Observer R?

So now let's say that we take a video of this scenario and we play it backwards. We also pretend that Observer F and Observer R represent the ends of the train (except that now F and R are interchanged because the train will appear to be going backwards). Won't this be exactly the same scenario that we have been discussing in this thread, except that Observer A is not in the center of our now truncated train? And if Observer A sees the light from the two mirrors (which are analogous to the two lightning strikes) impenging on the flash bulb (analogous to the man in the original video) then Observer A cannot be the same as the woman on the train in the original video. In other words, if Observer A, who is not midway between Observer F and Observer R, sees the two flashes arriving simultaneously, then another observer who is midway between Observer F and Observer R cannot also see the two flashes arriving simultaneously.

Please note that this analysis does not require defining any frames of reference or synchronizing any clocks.

Does this make sense to you?

 

[solarflare]

I think the problem is that you're trying to assume certain things are the same in both frames that aren't. Let's turn the problem around a little bit.

Let's say two lightning strikes hit opposite ends of a stationary platform again. Person P, stands in the middle of the platform; person T is riding a train. The strikes both hit at the same time according to person P, and at that moment, person T is in the middle of the platform (or as close as he can be while riding a train passing it by) as well.

Now, let's equip both person P and person T with two simple light sensors that tell when they have seen the light from each lightning strikes.

Person P sees both light flashes at the same time, and both his sensors light up at the same time. Now, according to person P, person T can't possibly see both flashes at the same time because T is moving forward and will catch up to the forward light pulse while running away from the backward light pulse. T will see the forward strike first, and then the backward strike.

Now, T doesn't agree on why he sees the two strikes at different times. He thinks the strikes must've happened at different times, with the forward strike first and hte backward strike second. But, he thinks person P is moving backward and that the time delay between the strikes is enough so P will still see both strikes at the same time.

In other words, P and T both believe P will see the strikes at the same time and that T will see them at different times. That is the physically meaningful statement they can make. That is what both frames agree on. Everything else, well, is relative.

the problem is that your using the results from the platform frame to explain what the person in the train sees - they are different frames and so what the person on the platform believes the person on the train will see is not actually what they will see - for all the person on the platform knows the person on the train might be blind and won't see anything.

 

[cepheid]

I made this spacetime diagram a while ago, and I *think* it corresponds to the original scenario that is being discussed here. Maybe it will help. The "worldline" of the train (which is its path through spacetime) is clearly indicated, and it of course coincides with the t' axis:

The worldline of the photon that is coming in from the front (i.e. from the positive side) clearly intercepts the worldline of the train before (i.e. at a smaller value of t') the worldline of photon that is coming in from the rear (negative side) does.

The coordinate grid I've drawn is for the train observer, in the primed (t',x') coordinate system.

 

[Muphrid]

the problem is that your using the results from the platform frame to explain what the person in the train sees - they are different frames and so what the person on the platform believes the person on the train will see is not actually what they will see - for all the person on the platform knows the person on the train might be blind and won't see anything.

If that's what you think, you're sorely mistaken. Both observers agree on spacetime intervals. This is fundamental to the theory. Cepheid has pretty clearly shown how the points of reception are not the same. Both observers must agree on the proper time between the two reception events for the train observer--or that they're different at all.

 

[solarflare]

I made this spacetime diagram a while ago, and I *think* it corresponds to the original scenario that is being discussed here. Maybe it will help. The "worldline" of the train (which is its path through spacetime) is clearly indicated, and it of course coincides with the t' axis:

The worldline of the photon that is coming in from the front (i.e. from the positive side) clearly intercepts the worldline of the train before (i.e. at a smaller value of t') the worldline of photon that is coming in from the rear (negative side) does.

The coordinate grid I've drawn is for the train observer, in the primed (t',x') coordinate system.

this diagram says that if the stikes happen simultaneously - on the tracks - the the observer will see them simultaneously also. just at a different time.

 

[solarflare]

now look at post 49 and post 50.

 

[solarflare]

Sure. The lightning struck the ends at the same time in her frame and since they traveled the same distance they reach her at the same time. No mystery there.

the diagram shows that the lightning struck in the trains frame of reference simultaneously and also in the platform observers frame.

so according to Doc Al's statement above the train observer will see the bolts a the same time also.

 

[Doc Al]

this diagram says that if the stikes happen simultaneously - on the tracks - the the observer will see them simultaneously also. just at a different time.

The observer on the tracks will see them simultaneously, not the observer on the train.

the diagram shows that the lightning struck in the trains frame of reference simultaneously and also in the platform observers frame.

No it doesn't. The diagram shows that the flashes are not simultaneous in the train frame.

so according to Doc Al's statement above the train observer will see the bolts a the same time also.

And no again.

 

[MikeLizzi]

If anyone is interested, here is an analysis of a train/lightening problem using straightforward math, no diagrams. It's not the same as the OP original but I believe it addresses the same issues.

http://www.relativitysimulation.com/Documents/Train and Lightning.htm

 

[solarflare]

two simultaneous strikes on the train - cause - the observer on the platform to see the two strikes simultaneously because he is the same distance from each strike.

you seem to be ignoring the cause of the strikes which occur simultaneously - if they did not the man on the platform could not see them simultaneously

 

[Doc Al]

two simultaneous strikes on the train - cause - the observer on the platform to see the two strikes simultaneously because he is the same distance from each strike.

Not true. (Unless those strikes are simultaneous in the platform frame.)

you seem to be ignoring the cause of the strikes which occur simultaneously - if they did not the man on the platform could not see them simultaneously

The strikes occur simultaneously in the platform frame.

Don't keep flipping back and forth between the two physically different scenarios:
(1) The lightning strikes are simultaneous in the platform frame.
(2) The lightning strikes are simultaneous in the train frame.

They cannot both be true. Stick to scenario 1 (as in the video) until you understand it.

 

[solarflare]

the lines being drawn from the x-axis are at -4 and +4 but both are at t=0

 

[Doc Al]

the lines being drawn from the x-axis are at -4 and +4 but both are at t=0

Yes. The lightning strikes are simultaneous in the platform frame.

 

[solarflare]

there are tree different events

the first is lightning hitting the train
the second is the light getting to the observer on the platform
the third is the the light getting to the passenger

the third has nothng to do with the second just the first

 

[solarflare]

Yes. The lightning strikes are simultaneous in the platform frame.

the x-axis is the train frame because that is where the light originated from - there are two train frames - one when the lightning strikes the train and one when the light reaches the passenger

 

[Muphrid]

the x-axis is the train frame because that is where the light originated from - there are two train frames - one when the lightning strikes the train and one when the light reaches the passenger

The x-axis measures distance according to someone on a stationary platform (that is, someone standing talong the track).

The diagram is very clear. The two photons' worldlines cross the platform/track observer's worldline at the same time (as expected) but do not cross the train observer's worldline at the same time. Hence, they do not reach the train observer at the same time. They cannot be perceived simultaneously in this situation.

 

[Doc Al]

the x-axis is the train frame because that is where the light originated from - there are two train frames - one when the lightning strikes the train and one when the light reaches the passenger

No, the x-axis is the platform frame. The lightning strikes do not originate in a frame, they happen in all frames. The x' frame is the train frame.

Don't confuse events (such as: lightning striking the front of the train, lightning striking the rear of the train, light from the front of the train reaching the passenger) with frames. In this analysis there are two frames of interest: the platform frame and the train frame.

 

[Doc Al]

there are tree different events

the first is lightning hitting the train
the second is the light getting to the observer on the platform
the third is the the light getting to the passenger

the third has nothng to do with the second just the first

And because the lightning strikes hit the train ends at different times according to train frame clocks, the light from each gets to the passenger at different times.

 

[ghwellsjr]

there are tree different events

the first is lightning hitting the train
the second is the light getting to the observer on the platform
the third is the the light getting to the passenger

the third has nothng to do with the second just the first

the x-axis is the train frame because that is where the light originated from - there are two train frames - one when the lightning strikes the train and one when the light reaches the passenger

Solarflare, it is clear that you don't know what an event is nor what a frame is. All you are doing is taking one "sound bite" that you have heard from Special Relativity, "Light travels at the same speed for all observers" and misapplying to this scenario. Everyone is trying to use advanced concepts from SR to help you understand but they are all going over your head. I tried in post #74 to help you in a way that did not require any understanding of SR but you ignored it. Please read, try to understand and respond to my post which I repeat here:

Solarflare, it doesn't appear that we are making any headway with you on this issue. Perhaps it would help if we changed the scenario so that it basically happens in the reverse order.

Let's consider a totally different scenario:

We have a very long train, much longer than the length of the platform and so long we don't care where the front and rear are. But instead of just one observer, we have an observer at every window, all along the train.

Then on the ground, we have a platform of some arbitrary length. At the center of the platform, we have a flash bulb that will produce a bright flash of light sometime while the train is passing but we don't care when. Then at each end of the platform, we have a mirror placed at a 45 degree angle so that when the flash of light reaches it, it will reflect the light towards the train.

What we want to do is have whatever train observer is adjacent to the flash bulb when it flashes make note of the event. We'll call him Observer A. In a similar way, we want whichever two train observers see the light reflected off the two mirrors make note of those two events. We'll call the one toward the front of the train Observer F and the one toward the rear of the train Observer R.

Now isn't it obvious that by the time the light reaches the mirrors, the train has moved forward along with Observer A and so he will be closer to Observer F and farther from Observer R?

So now let's say that we take a video of this scenario and we play it backwards. We also pretend that Observer F and Observer R represent the ends of the train (except that now F and R are interchanged because the train will appear to be going backwards). Won't this be exactly the same scenario that we have been discussing in this thread, except that Observer A is not in the center of our now truncated train? And if Observer A sees the light from the two mirrors (which are analogous to the two lightning strikes) impenging on the flash bulb (analogous to the man in the original video) then Observer A cannot be the same as the woman on the train in the original video. In other words, if Observer A, who is not midway between Observer F and Observer R, sees the two flashes arriving simultaneously, then another observer who is midway between Observer F and Observer R cannot also see the two flashes arriving simultaneously.

Please note that this analysis does not require defining any frames of reference or synchronizing any clocks.

Does this make sense to you?

 

[solarflare]

im saying that the lightning strikes on the train - that happen before the platform observer sees them - must happen simultaneously in order for him to see them simultaneously in his frame of reference. how can he be equal distance from them but but they do not happen at the same time. forget the passenger on the train and go step by step

first the cause then the effect

the cause is lightning strikes
the effect is the observer on the platform seeing the strikes when the light reaches him

he cannot see them if they did not happen - if he was not equal distance he could see two strikes that occurred at different times but because he is equal distance they must happen at

the strikes happen simultaneously in the trains frame (at the time of the strikes)

the strikes happen simultaneously in the platform observers frame ( after the light from the strikes move to meet his eyes)

 

[cepheid]

Horizontal lines (parallel to the x-axis) are lines of constant t, with t being time
according to the observer in the track/platform frame. Since both strikes occur along the x-axis, which is the line corresponding to t = 0, both strikes are simultaneous *in the platform frame.*

Now, the important thing to realize is that what the train observer experiences as time (t') runs in a *different direction* through spacetime than what the track observer experiences as time. In particular, for the train observer, the lines of constant t' are the *slanted* lines that are parallel to the x'-axis. So, in order for two events to be simultaneous in the train frame, they both have to have the same t' coordinate, which means they both must lie along the same one of these *slanted* lines. You can see that the right and left flashes don't satisfy this condition. Taking the right flash, and running from it to the t'-axis along a slanted line parallel to the x'-axis, you see that this line intercepts the t'-axis at a point four tick marks *below* the x'-axis, which is the line of t' = 0. So the first flash occurs at t' = -4 (in whatever units correspond to the arbitrary grid spacing I drew). In contrast, if you project the left flash event onto the t'-axis in a similar manner, you find that the line of constant t' that it lies on is 4 grid spacings *above* the t' = 0 line (which is the x'-axis). Therefore the left flash occurs at t' = +4 in my arbitrary units. So the diagram clearly shows that the two flash events do not occur simultaneously in the train observer's frame. It also shows that, as a result, they don't *arrive* simultaneously at the train either. They arrive at the two different points on the t'-axis that I've labelled 'not simultaneous' with two arrows.

It is the Lorentz transformation that has the effect of rotating and skewing the coordinate axes of the train observer in the manner depicted, so that he experiences space and time differently from the platform observer.

We're a page on from my diagram and still going on, which I didn't expect. I'm sorry if it caused any additional confusion. My intention was the opposite: to provide clarity.

 

[solarflare]

you keep talking about the train observer seeing the light

im talking about when the train get hits by the lightening. the observers cannot see light that has not yet been emitted

 

[solarflare]

your saying that the lightning in reality does not strike the train simultaneously

yet the fact that he is equal distance means that they must have

 

[Muphrid]

the strikes happen simultaneously in the trains frame (at the time of the strikes)

the strikes happen simultaneously in the platform observers frame ( after the light from the strikes move to meet his eyes)

No, as has been repeatedly shown, these statements are contradictory. They cannot both be true. Look at the diagram. The strikes are at the same time according to the platform observer. The train observer is moving toward the forward strike, so that strike's light reaches him sooner.

That the train observer believes instead that that that forward strike is sooner (and he's not moving relative to the light). Relativitiy of simultaneity is exactly what resolves the issue, so that the train observer still perceives the foward strike sooner and still measures the speed of light to be the same relative to him.

you keep talking about the train observer seeing the light

im talking about when the train get hits by the lightening. the observers cannot see light that has not yet been emitted

We can still talk about the location and time that these events happened according to one observer or the other's coordinate system.

your saying that the lightning in reality does not strike the train simultaneously

yet the fact that he is equal distance means that they must have

To one observer, yes. You keep missing the point that just because one observer believes two events to be simultaneous means any other observer might not.

 

[solarflare]

No, as has been repeatedly shown, these statements are contradictory. They cannot both be true. Look at the diagram. The strikes are at the same time according to the platform observer. The train observer is moving toward the forward strike, so that strike's light reaches him sooner.

That the train observer believes instead that that that forward strike is sooner (and he's not moving relative to the light). Relativitiy of simultaneity is exactly what resolves the issue, so that the train observer still perceives the foward strike sooner and still measures the speed of light to be the same relative to him.



We can still talk about the location and time that these events happened according to one observer or the other's coordinate system.



To one observer, yes. You keep missing the point that just because one observer believes two events to be simultaneous means any other observer might not.

you keep talking about the passenger on the train so it is you that is missing the point.

the strike on the train must occur before any observer can see them - in order for the platform guy to see the light at the same time the strikes must have happened at the same time. forget about the passenger on the train she does not matter

 

[solarflare]

if the platform observer was anywhere but in the centre what you are saying would be correct but if he is central then it cannot be

 

[solarflare]

if he was in line with the rear of the train and saw them strike simultaneously he would conclude that because he saw the strikes happen at the same time and he is not equal distance from each strike that the person on the train would not see them at the same time because she is in the centre of the train.