Relativity of Simultaneity (Not Quite)

Joined: March 30th, 2013, 7:19 am

January 13th, 2015, 3:18 am #21

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
<font>Jose : Ufonaut99, we have had this discussion a year or two ago. You didn't retain much from then.
First of all, let's just use unit dimensions. ... Secondly, The pulse must have a duration....
</font>
Ohhh, I've retained. I just don't agree with all that any more now than I did then

Unit dimensions – OK. Personally, I don’t see how you find nano-seconds easier to deal with than actual seconds (I think it’s easier to see that there’s a difference between 2:59:50 and 2:59:55 than between 2:59:59.99999999 and 2:59:59.999999999, for example). Still, if you want to use lengths and times scaled on nano-seconds, that’s what we’ll run with. You'll have noticed that I gave a "realistic" length platform rather than Light-seconds long one, for example.

Duration, and things like “<font>the actual distance between the Earth and the Sun is continually changing</font>” I still find needlessly pedantic and pointless. Mathematics, by its very nature, is an idealisation of points and lines. Pointing out (repeatedly) the obvious fact that nature does not match this idealisation, not only adds nothing to the discussion - in fact, it detracts from it. Since mathematics is an idealisation, it succinctly captures and exposes the behaviour being studied. Bringing in all the real-life messiness around it does nothing but obscure and distract from that behaviour with irrelevant detail - not to mention increasing the workload of equations, etc.

I’m curious, though – would you make these same complaints about all physics equations (eg, Newton’s), or reserve them only for Relativity?

Ok, onto the main topic. Firstly, to clarify :
<font>Jose : If the bolt strikes a single spot on each end of the platform, these spots will become scorched lines on the side of the train. .... </font>
Great ! If you hadn't mentioned scorch-marks, I would have - you beat me to it .
<font>Jose : if you meant that I was directly across from you when you saw the flashes simultaneously, I would have been 75 feet to the rear of the midpoint between scorch marks on the train. (In which case I would see the pulses more or less simultaneously just as you
</font>
Yes, that is exactly what I meant, and I tried to phrase it to make that as clear and unambiguous as possible when I said “just at that moment, the wavefronts from lightening strikes at the front and rear of the platform reach our eyes” (so no, I have not made any fallacy about you being in two places at once).

I'm also glad that you've correctly identified your position (the bit I've underlined); I'll mention that bit again in a moment.
<font>Jose : Likewise the duration of time I would be aligned* with you would be in the femtosecond range. Not much time to be setting clocks.. </font>
Again, it's not relevant how long we were aligned; any information transfer can happen while we are.

One small, but IMHO important, point though. I said "yes, we both happened to notice that our watches both happened to read exactly the same time as we were passing". Notice that - I never said "I set my watch" - I said it was already reading that, just as yours was already that as well.

Why is that important? Because I'm implying/asserting that every watch on the train was ALREADY synchronised before the experiment started - in other words, that the time IN THE TRAIN FRAME was 3pm. Ditto, of course, for every clock on the platform - just as you implicitly and correctly picked-up on / implied / asserted when you said "100 nanoseconds before 3 o'clock,".

Of course, I could have said "set my watch to 3pm and every clock on the train automatically synchronised as well" (which gets the same end result), but that's an unnecessary extra layer of detail/confusion - not to mention that it also means that none of the clocks would have been synchronised at the time the lightening struck. It's much simpler and more consistent to simply make it part of the given initial conditions
<font>Jose : If you had synchronized clocks located at the points of the strikes, they would show the strikes started 100 nanoseconds before 3 o'clock,(When at 3 o'clock you saw the pulses arrive at your midway station,)</font>
Now, I have 8 questions for you. Since we're still in SR mode, remember that I measure light travelling at one foot per nanosecond relative to me, and you sitting on the train also measure light travelling at one foot per nanosecond relative to you.

Ok, but as we're about to compare clock readings, let's adopt the standard, clear, unambiguous and specific way of showing clock readings in hours:minutes:seconds format (eg "2:59:59.98765")

Q1) What time do I reckon that the lightening strike at the front of the platform started.
Q2) What time do I reckon that the lightening strike at the front of the platform ended.
Q3) What time do I reckon that the lightening strike at the rear of the platform started.
Q4) What time do I reckon that the lightening strike at the rear of the platform ended.

Q5) What time do you reckon that the lightening strike at the front of the train started.
Q6) What time do you reckon that the lightening strike at the front of the train ended.
Q7) What time do you reckon that the lightening strike at the rear of the train started.
Q8) What time do you reckon that the lightening strike at the rear of the train ended.

To clarify, the phrase "what time do you / I reckon" could equally well have been re-phrased as "If your / my clock at the site of each strike, stops at the first (or last) instant the lightening strike touches it, then what time would it be left showing?"

Now of course, the lightening strikes on the platform WERE the strikes on the train, but your measurements would always relate to your reference frame (which is also something to think about if your initial reaction is that the answers to 5-8 would be the same as 1-4 - remember that bit of your response that I underlined above ).

Finally, for myself, I reckon just the 4 odd-numbered questions (or just the even numbered ) would be sufficient for the point - but of course, I know durations are important to you, so you'll want to complete all 8 of them, eh ?
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Joined: March 30th, 2013, 7:19 am

January 13th, 2015, 3:19 am #22

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
<font>Nakayama: From just above, plane waves of light are coming horizontally. At the front edge and rear edge each on the roof of a moving passenger car, a sensor and a light source is set. In response to a special change of plane waves, the two flash. Two flashes will be simultaneous also to an observer stands on the ground. “relativity of simultaneity” seems not to stand up. </font>
Hi Nakayama,

Sorry, haven't forgotten you

I hope you can see the similarity between your scenario above, and the train scenario I'm discussing with Jose. Suppose that when the plane wave arrives, the flashing of the light sources is so hot that it causes scorch marks on both the passenger car (ie train) and the ground (ie. Platform). Replace "light source" with "lightening strikes that are simultaneous in the ground's frame", and it's the same scenario.

Given that, have a shot at answering the questions I've just asked Jose (maybe just the odd-numbered ones!). After all, it's not enough to just pluck scenarios out of thin air and just declare SR is wrong without even working out what SR says in the first place ! Since we're interested in what SR says here, answer the questions on the (temporary) assumption that both postulates are true.

... And yes, I know I could just go ahead and give my answers, but it's by working through scenarios and discussing disagreements as they arise that everybody benefits
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Jose Rodriguez
Jose Rodriguez

January 13th, 2015, 7:16 am #23

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
UFO: "Ohhh, I've retained. I just don't agree with all that any more now than I did then happy.

"Unit dimensions – OK. Personally, I don’t see how you find nano-seconds easier to deal with than actual seconds (I think it’s easier to see that there’s a difference between 2:59:50 and 2:59:55 than between 2:59:59.99999999 and 2:59:59.999999999, for example). Still, if you want to use lengths and times scaled on nano-seconds, that’s what we’ll run with. You'll have noticed that I gave a "realistic" length platform rather than Light-seconds long one, for example."
I chose what I did because light nanoseconds automatically gives the distance or duration directly when the opposite type of measure is known.
UFO: "Duration, and things like “the actual distance between the Earth and the Sun is continually changing” I still find needlessly pedantic and pointless. Mathematics, by its very nature, is an idealization of points and lines. Pointing out (repeatedly) the obvious fact that nature does not match this idealization, not only adds nothing to the discussion - in fact, it detracts from it. Since mathematics is an idealization, it succinctly captures and exposes the behavior being studied. Bringing in all the real-life messiness around it does nothing but obscure and distract from that behavior with irrelevant detail - not to mention increasing the workload of equations, etc.
And leaves you with some imaginative, void of logic fantasy.
UFO: "I’m curious, though – would you make these same complaints about all physics equations (eg, Newton’s), or reserve them only for Relativity?
I look at everything as best I can what happens in real life. The Devil is in the details.
<blockquote>Jose: "If the bolt strikes a single spot on each end of the platform, these spots will become scorched lines on the side of the train."
</blockquote>
UFO: "Great ! If you hadn't mentioned scorch-marks, I would have - you beat me to it happy."
I didn't say "scorch marks" except in the first paragraph. I missed changing it to "scorch lines." The lightning strikes are in the platform frame.
<blockquote>Jose: "if you meant that I was directly across from you when you saw the flashes simultaneously, I would have been 75 feet to the rear of the midpoint between scorch marks on the train. (In which case I would see the pulses more or less simultaneously just as you"
</blockquote>
UFO: "Yes, that is exactly what I meant, and I tried to phrase it to make that as clear and unambiguous as possible when I said “just at that moment, the wavefronts from lightening strikes at the front and rear of the platform reach our eyes” (so no, I have not made any fallacy about you being in two places at once).
"I'm also glad that you've correctly identified your position (the bit I've underlined); I'll mention that bit again in a moment."
I meant to edit that out after rereading your post. But stay on your toes.
<blockquote>Jose: "Likewise the duration of time I would be aligned* with you would be in the femtosecond range. Not much time to be setting clocks"
</blockquote>
UFO: "Again, it's not relevant how long we were aligned; any information transfer can happen while we are."
I forgot. we are in fantasy land. Anything goes.
UFO: "One small, but IMHO important, point though. I said "yes, we both happened to notice that our watches both happened to read exactly the same time as we were passing". Notice that - I never said "I set my watch" - I said it was already reading that, just as yours was already that as well.

"Why is that important? Because I'm implying/asserting that every watch on the train was ALREADY synchronized before the experiment started - in other words, that the time IN THE TRAIN FRAME was 3pm. Ditto, of course, for every clock on the platform - just as you implicitly and correctly picked-up on / implied / asserted when you said "100 nanoseconds before 3 o'clock,".
Of course, I could have said "set my watch to 3pm and every clock on the train automatically synchronized as well" (which gets the same end result), but that's an unnecessary extra layer of detail/confusion - not to mention that it also means that none of the clocks would have been synchronized at the time the lightening struck. It's much simpler and more consistent to simply make it part of the given initial conditions happy."
You claim you are in SR mode. In that fantasy land, clocks in one frame run at a different rate than in the other. So what kind of coincidence caused all the clocks in both frames to read "3PM"? In fact SR predicts that clocks run both faster and slower simultaneously.
<blockquote>Jose: "If you had synchronized clocks located at the points of the strikes, they would show the strikes started 100 nanoseconds before 3 o'clock,(When at 3 o'clock you saw the pulses arrive at your midway station,"
</blockquote>
UFO: "Now, I have 8 questions for you. Since we're still in SR mode, remember that I measure light traveling at one foot per nanosecond relative to me, and you sitting on the train also measure light traveling at one foot per nanosecond relative to you.

"Ok, but as we're about to compare clock readings, let's adopt the standard, clear, unambiguous and specific way of showing clock readings in hours:minutes:seconds format (eg "2:59:59.98765")"
Let's not.
UFO: "Q1) What time do I reckon that the lightening strike at the front of the platform started.
Q2) What time do I reckon that the lightening strike at the front of the platform ended.
Q3) What time do I reckon that the lightening strike at the rear of the platform started.
Q4) What time do I reckon that the lightening strike at the rear of the platform ended.

"Q5) What time do you reckon that the lightening strike at the front of the train started.
Q6) What time do you reckon that the lightening strike at the front of the train ended.
Q7) What time do you reckon that the lightening strike at the rear of the train started.
Q8) What time do you reckon that the lightening strike at the rear of the train ended.

"To clarify, the phrase "what time do you / I reckon" could equally well have been re-phrased as "If your / my clock at the site of each strike, stops at the first (or last) instant the lightening strike touches it, then what time would it be left showing?"
If you notice I gave parameters for the leading edge, each instance.
UFO: "Now of course, the lightening strikes on the platform WERE the strikes on the train, but your measurements would always relate to your reference frame (which is also something to think about if your initial reaction is that the answers to 5-8 would be the same as 1-4 - remember that bit of your response that I underlined above )."
I said that there is a place on the train where the strikes are seen simultaneously. It is not midway between the scorch lines on the train. The train moves away from the strikes, even as they happen. The light pulses travels at a foot /nanosecond from the platform points regardless of the speed of any train. Regardless of it's speed or direction. In SR, the several trains find the platform shrunk, but to various lengths depending on the speed of the receding platform.
UFO: "Finally, for myself, I reckon just the 4 odd-numbered questions (or just the even numbered ) would be sufficient for the point - but of course, I know durations are important to you, so you'll want to complete all 8 of them, eh ?"
I spoze not. Let's stipulate burn marks on both the platform and the train, exactly where both of us see the lightening bolts strike simultaneously. Or do you claim that there is no spot on the train that one can see both you and the lightning strikes simultaneously?

There is only one light sphere at each lightning strike. They are continuously expanding in the platform frame. They cannot detach themselves from there and also expand in any other reference frame. The scorch marks on the platform make a scorched line on the train. The point that you love at the platform strikes are not points in the train frame.

According to SR, the platform sees the train clocks running slow and the train sees the platform clocks run slow, yet all you want to fret about is what time it is.



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Jose Rodriguez
Jose Rodriguez

January 13th, 2015, 2:17 pm #24

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
UFO, Einstein uses the "measure the train length from the platform" gedankin to show how the moving train ends up measuring shorter from the platform reference frame. It goes something like this: The train's length is marked at rest with the platform. "When the front of the train reaches the far end of the platform,(at the platform "at rest mark" for the train length) the engineer there on the platform signals the rear of the platform engineer to mark the rear of the train. (The signal is traveling against the motion of the train.) Since the signal has to travel at c to the back of the train, and the back of the train is still moving forward, the moving train measures shorter than it did when at rest with the platform. (His gedankin uses the wave front travel. Anything else is circular reasoning.)

Now, If the opposite engineer (the one that just received the signal from the front of the train) sends the "mark" signal to the front of the train, from the original platform mark, now the signal is traveling with the motion of the train, and since the train is still moving, the train measures longer than it was when it was at rest. Starting the measurement from the rear of the passing train is just as legitimate as the original way Einstein did the gedankin, therefor the train is both shorter and longer than when it is at rest He uses wave fronts to do the gedankin. So your remark about "this has nothing to do with the arrival of wave fronts" is a bluff. Having the lightning bolts mark both ends of the platform and the train simultaneously, gets around the signals having to travel down the train to measure it, so what makes the train shorter then when at rest with the platform? Just the imagination of Einstein and his followers.


In your scenario, all the clocks are regulated to the same rate and time of day when they are at rest with the platform. The train is then backed up a great distance and then passes the platform at 3/4 c. Somehow, magically, I, in the train, end up right across from you right when you see the initiation of both lightning strikes, and right when your clock and mine both read 3 O'clock. At that point all the clocks on the platform read 3 O'clock. Now, according to you, the train clocks are running slow because the train is in motion. However, since all the train clocks are regulated and set to the same time of day, all those clocks register 3 O'clock too, at this moment.

So, if we go back in time to when the lightning strikes actually hit the platform, (100 nanoseconds before 3 O'clock on the platform clocks), what time do you say the train's clocks indicate at the actual lightning strikes? What ever time you say it is, all the clocks on the train will report the identical time.(but not because they all see the simultaneous strikes.) That means that both the rear train's clock and the front train's clock will show identical times for their respective strikes, but not for the opposite ended strikes.

One thing for sure is that from the train reference frame, I cannot be half way between the two strikes to see them simultaneously.






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nakayama
nakayama

January 14th, 2015, 2:30 am #25

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
I am sorry for an irrelevant posting to the flow of discussion.

“Relativity of simultaneity”, “ Constancy of light speed (to observers)” both seem not to stand up (a picture below is done in vacuum).

From windows of a moving passenger car, flashes are sent to the right and the left at 90 degrees. Regard two flashes as two photons. Ahead of each photon, a wall stands on the ground and on the wall, a vertical line is drawn. This line is 90 degrees to the emitted point of the photon. The photon will hit on the point out of the line a little (to the moving direction of the passenger car ; there is no rest frame).

But, what does it mean ? Imagine light sphere that is formed in the passenger car and photons in this sphere. From viewpoint of an observer on the ground, every photon will have the same motion component v (to the moving direction of the passenger car).
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Jose Rodriguez
Jose Rodriguez

January 14th, 2015, 3:50 am #26

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
Nakayama: "I am sorry for an irrelevant posting to the flow of discussion."
Don't be sorry about your posts. I just haven't responded because they are a bit obtuse. In what follows, I will suggest some pointers which you may want to incorporate in your questions and examples. Or not.
Nakayama: "Relativity of simultaneity”, “ Constancy of light speed (to observers)” both seem not to stand up (a picture below is done in vacuum)."
I agree.
Nakayama: "From windows of a moving passenger car, flashes are sent to the right and the left at 90 degrees. Regard two flashes as two photons. Ahead of each photon, a wall stands on the ground and on the wall, a vertical line is drawn. This line is 90 degrees to the emitted point of the photon. The photon will hit on the point out of the line a little (to the moving direction of the passenger car; there is no rest frame)."
A restatement of what I think you mean to communicate:

A pair of lasers are oriented perpendicular (transverse or normal) to their straight line motion, (with respect to the ground) whose pulses are emitted directly opposite (diametrically to) each other . Walls, a good distance from the line of motion, on either side , and parallel to the direction of their motion, have a line normal (perpendicular) to the ground engraved upon each of them.

Your conjecture is that if a switch, firing the lasers, is placed in the line of motion such that the placement removes the latency of the switch; This placement will fire the lasers exactly when they are aimed directly at the distant lines on the walls. Your prediction is that they will miss the lines in the direction of their motion.

I agree.

My humble opinion is that it is less confusing (in naming reference frames) ifn one refers to the source frame and the receiving frame. The source frame is the lasers, the receiving frame is the ground and the walls.
Nakayama: "But, what does it mean ? Imagine light sphere that is formed in the passenger car and photons in this sphere. From viewpoint of an observer on the ground, every photon will have the same motion component v (to the moving direction of the passenger car)."
Restatement:

You think that laser pulses will have the transverse component of the velocity of the lasers themselves, all with respect to the ground. (The ground is moving in the opposite direction from the laser point of view.) I agree with this idea, unless there is an aether with motion not common to either reference frame.

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nakayama
nakayama

January 16th, 2015, 1:48 am #27

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
Thank you Jose so much for your reply ! Yes, two photons cannot recognize the ground at all. So, photons will miss the lines.

About aether, I wrote my view in my web-site. I guess, within moon – earth scale, aether will have no effect.
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nakayama
nakayama

January 16th, 2015, 1:55 am #28

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
About optional two points in the space, if some condition (of a light wave) guarantees the simultaneity, Newton’s absolute time will revive.
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nakayama
nakayama

January 17th, 2015, 4:29 am #29

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
Allow mw to rewrite yesterday’s comment on aether.
“In everywhere of universe, emitted light will follow the emission theory for a few seconds. And then, light will follow aethe frame, I guess”.
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nakayama
nakayama

January 18th, 2015, 12:46 am #30

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

Relativity of simultaneity

From Wikipedia, the free encyclopedia


Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

The author here is writing as if the events actually occur in different order just because some observer or other is moving in relation to the events. The truth is that observers stationary to the events will observe events in different order. The order of events does not depend on motion, at all. It depends on the position of the observer in relation to the two or more events. In fact the observer at A will observe the event at A before the event at B, and the observer at B will observe the event at B before the event at A. So0 much BS here!

See link for the next picture.

Events A, B, and C occur in different order depending on the motion of the observer.

The author is misinforming again: The order of events does not depend on motion, it only depends upon the position of the observer with respect to the events, when the wave fronts from the events simultaneously meet the observer's eyes.


The white line represents a plane of simultaneity being moved from the past to the future.

In real life there is no plane of simultaneity. Each of us live in the present. Events close to us happen in the present. Events which we see being further away happened further into the past. Events happening now on the sun are 8 minutes into our future as far as light is concerned, further into the future as far as the effects of a CME. The 8 minute delay is not caused by motion, it is caused by distance from the Sun

In physics, the relativity of simultaneity is the concept that simultaneitywhether two events occur at the same timeis not absolute, but depends on the observer's reference frame.

Wrong-O; If a moving observer and a stationary observer are at the event at the same time, they will both see the event happen at the same time!


According to the special theory of relativity, it is impossible to say in an absolute sense whether two events occur at the same time if those events are separated in space.

Not true! If one is known to be located half way between two locations and sees that both events happen at the same time, they did absolutely happen at the same time!

Where an event occurs in a single placefor example, a car crashall observers will agree that both cars arrived at the point of impact at the same time. But where the events are separated in space, such as one car crash in London and another in New Delhi, the question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in others (in a different state of motion relative to the events) the crash in London may occur first, and in still others the New Delhi crash may occur first.

Not true either, see above comment.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage.

In reality, the shrunken ladder/ garage is fiction. Einstein arrived at the idea of matter shrinking wrt observers in relative motion to objects by means of a Train Gedanken: For instants: the "measure the moving train gedanken:" As the front of the train passes the signalman at the far end of the platform, he simultaneously marks the platform and signals the rear signalman to mark the platform at the rear of the train. Einstein claims that due to the finite speed of light, the train will be measured shorter than it is, since the train moved while the signal traveled back to the rear signalman.

Now, stop and think: If the rear signalman sends the signal to the front of the train, while the train is moving, the same train will measure longer! Duh!


A mathematical form of the relativity of simultaneity ("local time") was introduced by Hendrik Lorentz in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by Henri Poincaré in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:

1. The principle of relativitythe equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;

2. The constancy of the speed of light detected in empty space, [is](sic) independent of the relative motion of its source.

This second postulate is bogus! Most people acknowledge that light propagates away from a source in an expanding sphere, centered upon where the source was when the wavefront was emitted. All other observers in relative motion to the source, when the wave front was emitted, will see either aberration or Doppler shift. Do you need to consult Sherlock to see the fantasy?
About Newton’s absolute time

Imagine optional two points (but the two are not in a relative motion, also are not in an orbital motion) in space. It’s possible to settle a light source at the position in the same distance from the two points. By the above, simultaneity of two points will be guaranteed. Newton’s absolute time will be flowing in this space.
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