The Relativity of Simultaneity

[quantum_wave]

MD's rules are much simpler than yours. You say MD's theory only applies to cubes in rectilinear motion, in outer space. But MD has been very clear that his claims apply everywhere. Here he is saying that his theory applies to a train on earth:

http://sciforums.com/showpost.php?p=2763688&postcount=1262



I don't know how you missed that he claims the only way the speed of light can be measured to be c is if the observer is at absolute rest. This claim is proven wrong by every measurement of light speed on earth which finds the speed to be c. Unless of course you want to argue that the earth is always at absolute rest?

Thank you for reporting that inconsistency. From the SR perspective and in that post discussing the motion of the light sphere from a point of emission fixed in space, the answer is confusing. If you read it from the perspective of the fixed position in space of the emission and then discuss the prime issure that under the rules of the moving box the observer would have to either assume a different fixed location or a different speed of light, MD may not fully appreciate that he has to be careful with his language.

He may have started the thread with the seed of an idea and from the teaching and help he seems to have evolved the idea. It isn't fully mature and can't yet convince anyone to consider Lorentz invariance to be tentative. When I asked for the graphic I did so because there was some merit in his position and I was surprised that the community was so convinced that SR was so close to reality that any possible falsification was almost out of the question. I don't think that and so I took up the cause to try to solidify some rules that seemed to put the issue into a context that I could not answer, that being the experimental evidence of Lorentz invariance.

I took the opportunity while MD was gone to try to shape the issue more to how I see it. I would like to hear your position on the importance of the inconsistency between QM and GR and if you think there is no chance that GR will ever be falsified as we learn to test it at relativistice speeds and as the incompatibility is resolved.

I'll concede to MD's wishes and drop my rules if he wants me to.

 

[Motor Daddy]

quantum_wave, Thanks for holding down the fort while I was away. I'll try to respond to some of the posts. Let me know if there is anything in particular you wound like clarified.

 

[quantum_wave]

Welcome back, MD. I'm glad my self-appointed role as stand in can come to an end without me coming to verbal blows with all of the responders, lol. I do think you should read my posts and let me know if you see any merit in pushing to well recognized inconsistency between QM and GR. And explore the contention of mine that Lorentz invariance is a relativistic cosmological consensus and not a part of the particle model.

Light is clearly radiated from atomic and molecular dipoles. We just don't understand particles enough yet to reconcile QM and GR and yet all of the members who attack you seem to feel that there results as somehow already in. There are volumes of science about optical mechanics and wave mechanics that I would also think come into play. How does light act when traveling in and from deep space, etc.

Interesting thread if you ask me. Thanks.

 

[Motor Daddy]

Alright, so let's get back to my question. Let's say the speed of the cube is 0.80c along the x-axis, and there is no y or z component to the velocity. The distance relative to the cube is 0.5 lightseconds in both directions, AS MEASURED WITH MEASURING BARS, so I think you would predict the one-way times to be like this:

t_forward = 0.50 / (1.0c - 0.8c)
t_forward = 2.50 seconds

t_backward = 0.50 / (1.0c + 0.8c)
t_backward = 0.28 seconds

t_total = 2.50 + 0.28 = 2.78 seconds

Thus, using the "round-trip" times, the speed of light inside the cube would be measured to be:

c_measured = 1.00/2.78 = 0.36c

Now could you please explain why we always measure the speed of light to be 1.00c on earth (which is not at absolute rest), and not a variety of different numbers, such as 0.36c?

Sure, because you measure the round trip time of light, divide by two to get the length, and it always comes out to be c due to the length being wrong.

Show me were you've measured the speed of light using one-way light travel times. Round trip times don't cut it!

Also, you use a different clock sync method.


If you think you always measure the speed of light to be c, how is the speed of light measured the same in the cube in the x direction and the y direction, when all the clocks in the cube are time dilated, and in the x direction there is length contraction but no length contraction in the y direction? So the length is shorter in the x direction, and yet you claim it always takes the same amount of time for light to travel as in the y direction? Your numbers don't add up! It takes .65 seconds in the y direction, with a zero component velocity. How do you reconcile that fact in the cube?

 

[Motor Daddy]

I've drawn a diagram that shows the speed of light towards a mirror is nearly infinite, and the speed of the reflected light is nearly zero.

This diagam, and two numbers, supports the theory that you never see a reflection in a mirror unless you are traveling at infinite velocity towards it.
So since you do see a reflection in a mirror, you must have infinite velocity.

Now, who wants to prove my theory is wrong? Remember, I have a diagram.

Don't make me use it. It will rock your socks.

WOW, that's great arfa brane!! I look forward to critiquing your diagram. Please start a new thread attaching the diagram for all to see. I'm so looking forward to the thread, it sounds like a well thought out idea and I'm sure it is coming from you.

 

[Motor Daddy]

I was done with you before we were even started.

I agree!

 

[Neddy Bate]

Alright, so let's get back to my question. Let's say the speed of the cube is 0.80c along the x-axis, and there is no y or z component to the velocity. The distance relative to the cube is 0.5 lightseconds in both directions, AS MEASURED WITH MEASURING BARS, so I think you would predict the one-way times to be like this:

t_forward = 0.50 / (1.0c - 0.8c)
t_forward = 2.50 seconds

t_backward = 0.50 / (1.0c + 0.8c)
t_backward = 0.28 seconds

t_total = 2.50 + 0.28 = 2.78 seconds

Thus, using the "round-trip" times, the speed of light inside the cube would be measured to be:

c_measured = 1.00/2.78 = 0.36c

Now could you please explain why we always measure the speed of light to be 1.00c on earth (which is not at absolute rest), and not a variety of different numbers, such as 0.36c?

Sure, because you measure the round trip time of light, divide by two to get the length, and it always comes out to be c due to the length being wrong.

One one-way time is 2.50 seconds. The other one-way time is 0.28 seconds. Thus, the "round-trip" time is 2.78 seconds. The round-trip distance is 1.00 lightseconds. So the speed of light inside the cube would be measured to be:

c_measured = 1.00/2.78 = 0.36c

So, it does not come out to be 1.00c. Sorry, please check your math.

Show me were you've measured the speed of light using one-way light travel times. Round trip times don't cut it!

Perhaps your reading comprehension has gone down during your vacation from sciforums?

This is a one-way travel time:
t_forward = 0.50 / (1.0c - 0.8c)
t_forward = 2.50 seconds

This is a one-way travel time:
t_backward = 0.50 / (1.0c + 0.8c)
t_backward = 0.28 seconds

Also, you use a different clock sync method.

Nope, I'm using all your rules for the cube. The synch method is your plastic card method, with the strings attached. You have told everyone that pulling strings is a good synch method!

If you think you always measure the speed of light to be c, how is the speed of light measured the same in the cube in the x direction and the y direction, when all the clocks in the cube are time dilated, and in the x direction there is length contraction but no length contraction in the y direction? So the length is shorter in the x direction, and yet you claim it always takes the same amount of time for light to travel as in the y direction? Your numbers don't add up! It takes .65 seconds in the y direction, with a zero component velocity. How do you reconcile that fact in the cube?

I could show you how that works, if you were interested.

 

[Motor Daddy]

Motor Daddy:

Light cannot take 0.65 seconds to reach a detector that is 0.5 light seconds away from the point of emission of the light. And that's the distance as measured in the train frame. In the train frame, the light must take 0.5 seconds, as measured by clocks that move with the train.

It is impossible for light to get to the y receiver in .5 seconds in your diagram. The x direction is length contracted and the y direction isn't. ALL the clocks on the train are time dilated, so how do you explain how you measure light to always be measured to be c on the train, with different length contractions in all different directions?

How much time does it take for light to travel from the y receiver to the x receiver, which is .7071 light seconds in length on the train?



a^2+b^2=c^2
.5^2+.5^2=c^2
.25+.25=c^2
.5=c^2
sqrt(.5)=c
c=.7071 light seconds

 

[Motor Daddy]

One one-way time is 2.50 seconds. The other one-way time is 0.28 seconds. Thus, the "round-trip" time is 2.78 seconds. The round-trip distance is 1.00 lightseconds. So the speed of light inside the cube would be measured to be:

c_measured = 1.00/2.78 = 0.36c

So, it does not come out to be 1.00c. Sorry, please check your math.



Perhaps your reading comprehension has gone down during your vacation from sciforums?

This is a one-way travel time:
t_forward = 0.50 / (1.0c - 0.8c)
t_forward = 2.50 seconds

This is a one-way travel time:
t_backward = 0.50 / (1.0c + 0.8c)
t_backward = 0.28 seconds




Nope, I'm using all your rules for the cube. The synch method is your plastic card method, with the strings attached. You have told everyone that pulling strings is a good synch method!




I could show you how that works, if you were interested.

Are you trying to compare what I predict using my method, compared to what SR predicts using SR method? SR uses round trip time and uses a different clock sync, along with length contraction and time dilation.

 

[James R]

It is impossible for light to get to the y receiver in .5 seconds in your diagram.

In the embankment frame, yes, you're right. And it doesn't take 0.5 seconds in that frame.

In the train frame, you're wrong, as my diagram for that frame clearly shows.

Why are you ignoring my train-frame diagrams?

In fact, why are you in general ignoring the detailed responses I have given you, only to make incorrect statements that ignore half of what I wrote?

The x direction is length contracted and the y direction isn't. ALL the clocks on the train are time dilated, so how do you explain how you measure light to always be measured to be c on the train, with different length contractions in all different directions?

Because if you measure the distance light travels from point to point and divide by the time taken, you always get c!

How much time does it take for light to travel from the y receiver to the x receiver, which is .7071 light seconds in length on the train?

a^2+b^2=c^2
.5^2+.5^2=c^2
.25+.25=c^2
.5=c^2
sqrt(.5)=c
c=.7071 light seconds

What are a, b and c?

Do you mean a is the distance the light needs to travel in the x direction, and b is the distance in the y direction?

What happened to your 0.65 seconds number for the light travel time? Where did 0.7071 light seconds come from?

Are you changing the train's speed now?

Also, you haven't specified which frame you're working in for whatever the calculation above is supposed to refer to.

 

[AlexG]

I’m just a pea brained layman

Well QW, at least you've got something right.

You ask for experimental evidence and then when you're presented with it, you simply ignore it.

You're every bit as looney as MD.

 

[quantum_wave]

Well QW, at least you've got something right.

You ask for experimental evidence and then when you're presented with it, you simply ignore it.

You're every bit as looney as MD.

False words like that come easily of the lips of people like you, Lol. I answered here:
http://www.sciforums.com/showpost.php?p=2764294&postcount=1312

http://www.sciforums.com/showpost.php?p=2764370&postcount=1314

I feel your pain for being a lowly troll. FYI pea brains are above trolls on the "man up" scale. Man up young man or you will always go through life afraid to do anything for fear trolls like yourself will come along and follow you. Man up or you'll go nowhere and be miserable just like you appear now.

I haven't ignored your points, but here are the points you have ignored:
What physically causes time dilation and length contraction or aren't they physical effects?

Does a light sphere that is expanding in space have a fixed point of emission?

Why be so confident that Lorentz invariance is realty when the incompatibility between QM and GR exists?

And stop following me to other threads and trolling there too; it is not only bad form but proves you have nothing to offer.

 

[Motor Daddy]

In the embankment frame, yes, you're right. And it doesn't take 0.5 seconds in that frame.

In the train frame, you're wrong, as my diagram for that frame clearly shows.

Why are you ignoring my train-frame diagrams?

In fact, why are you in general ignoring the detailed responses I have given you, only to make incorrect statements that ignore half of what I wrote?

I'm not ignoring your train frame diagrams, you haven't answered the question, how do you explain that the light has not yet reached the y receiver in your Einstein embankment diagram? I know you would like to move past that point because you have no answer and it is an inconsistency in SR. Tell me what time the light reached the y receiver? How do you explain that the length between the x receiver and the source is contracted, but not contracted between the y receiver and the source, and all the clocks are dilated? That causes an inconsistency in the measured speed of light.

I'm not avoiding your responses, you're avoiding mine. You haven't answered my questions yet.

Because if you measure the distance light travels from point to point and divide by the time taken, you always get c!

Again you fail to grasp the concept of a ruler in motion and the amount of time it takes for light to traverse the ruler.

Take a meter stick. Measure the time it takes light to traverse the stick one-way on a train when the train is going 60 MPH. Now increase the speed of the train to 200 MPH and measure the time again. Does it take light the same amount of time to traverse the stick at the two different speeds? NO, James, it does not!!! If you think it does, then you are saying it always takes light the same amount of time to reach you if you run away from a lamp post when the light is emitted, when running at two different speeds, 60 MPH and 200 MPH. It simply is not possible for light to reach you in the same amount of time, because light has to travel a greater distance to catch you when you are running away at 200 MPH.

Better yet, measure the time it takes light to travel the length of the stick one-way when the stick is pointing rear to front of the train. Now rotate the stick 90 degrees and measure the one-way time again. You say all the clocks are dilated on the train, and the length is contracted in the x direction, but not the y direction. Are you saying it takes the same amount of time for light to traverse the stick, from rear to front and side to side? How is that possible, James? The stick is shorter in the rear to front direction than it is side to side, and the clocks are dilated the same each way??????

What are a, b and c?

Do you mean a is the distance the light needs to travel in the x direction, and b is the distance in the y direction?

What happened to your 0.65 seconds number for the light travel time? Where did 0.7071 light seconds come from?

Are you changing the train's speed now?

Also, you haven't specified which frame you're working in for whatever the calculation above is supposed to refer to.

The distance from the y receiver to the x receiver is the hypotenuse. To find the length of the hypotenuse you use the Pythagorean Theorem, which is a^2+b^2=c^2. The distance between the y receiver and the x receiver is .7071 light seconds.

 

[arfa brane]

Does a light sphere that is expanding in space have a fixed point of emission?

No. There is no such thing as a fixed point.
There are freely-chosen coordinates instead.

Note that MD is now making up imaginary "problems" with SR.

MD thinks there's an inconsistency in measurement. There is no inconsistency, he just wants one to exist. Real bad.

Let's get real for just a moment: you can't draw light on a piece of paper. You can't make light behave like a drawing, no matter how much you want to.

This stunning fact makes the whole exercise look pretty dumbass wouldn't you say?

 

[quantum_wave]

No. There is no such thing as a fixed point.
There are freely-chosen coordinates instead.

Note that MD is now making up imaginary "problems" with SR.

MD thinks there's an inconsistency in measurement. There is no inconsistency, he just wants one to exist. Real bad.

Let's get real for just a moment: you can't draw light on a piece of paper. You can't make light behave like a drawing, no matter how much you want to.

This stunning fact makes the whole exercise look pretty dumbass wouldn't you say?

Dumbass, no, I wouldn't say that but I would agree with you if you allow some rephrasing about the difference between a fixed point in space and freely chosen coordinates. If a light flash is emitted at a freely chosen coordinate, does it expand from that freely chosen coordinate at c or does the coordinate change depending on the frame of the observer?

 

[arfa brane]

If a light flash is emitted at a freely chosen coordinate, does it expand from that freely chosen coordinate at c or does the coordinate change depending on the frame of the observer?

It depends where the observers are.

Think about it. If you want to know about where and when the light was emitted, you need observers who are somewhere in the vicinity to intercept some of the emitted light. If you have two observers in relative motion they will measure different times and distances. Does that make sense? They can measure the distance between them, and their relative velocity to each other, and the time the light is emitted by the source, so, a kind of dynamic triangulation from each observer to the "point" of emission.

They will find a drawing is no help at all. They will have to use detectors of some kind, and have a way to measure time intervals (i.e. have clocks). They won't agree on the time of arrival of light from the source if they have relative motion; they will agree on the speed of transmission from the source.

 

[quantum_wave]

It depends where the observers are.

Think about it. If you want to know about where and when the light was emitted, you need observers who are somewhere in the vicinity to intercept some of the emitted light. If you have two observers in relative motion they will measure different times and distances. Does that make sense? They can measure the distance between them, and their relative velocity to each other, and the time the light is emitted by the source, so, a kind of dynamic triangulation from each observer to the "point" of emission.

They will find a drawing is no help at all. They will have to use detectors of some kind, and have a way to measure time intervals (i.e. have clocks). They won't agree on the time of arrival of light from the source if they have relative motion; they will agree on the speed of transmission from the source.

Of course, but why set up a new scenario? I have a concept of coincident frames that two observers in different frames can occupy the same patch of space like an observer on a train and on the embankment. They can both witness the flash. That is the same flash that is expanding from the point of emission in both frames. Is that too weird?

I'm wondering if you think that flash can expand at c from the point of emission from the perspective of both frames? I already know your answer is yes, and you explain the effect of their relative motion by claiming that they each will see the same light wave to have different characteristics due to time dilation and length contraction. Is that right?

But there is just one flash expanding from the point of emission in both coincident frames. The light was emitted from an oscillating dipole that had a physical loction in the shared space. The frames move away from each other but the light is independent of the relative motion. It is how the light is perceived in each frame that you are saying is different, right, not how the light acts from its point of emission?

 

[arfa brane]

Of course, but why set up a new scenario? I have a concept of coincident frames that two observers in different frames can occupy the same patch of space like an observer on a train and on the embankment. They can both witness the flash. That is the same flash that is expanding from the point of emission in both frames. Is that too weird?

It isn't a new scenario, it's the train scenario over again. And again "the point of emission" is relative to observers in motion.

they each will see the same light wave to have different characteristics due to time dilation and length contraction. Is that right?

Yes. Because they can only transform distances and times via the Lorentz frame of reference.

It is how the light is perceived in each frame that you are saying is different, right, not how the light acts from its point of emission?

Right. There is no "the light acts from its point of emission", there is only time and distance, measured by observers. Who have (possibly identical) measuring rods and (possibly synchronised) clocks.

 

[Motor Daddy]

No. There is no such thing as a fixed point.
There are freely-chosen coordinates instead.

Wrong! A light sphere has a center point, and that point is not an object, nor is it capable of motion. The center point is a point in space from which the light expands. The light sphere doesn't travel as an object does in space, it expands in space away from the center point in all directions. Until you understand that concept you will never understand how distance and time are measured using light.

Note that MD is now making up imaginary "problems" with SR.
MD thinks there's an inconsistency in measurement. There is no inconsistency, he just wants one to exist. Real bad.

I don't need to make up imaginary problems in SR, all I need to do is point out the real problems, as I've done. Are you trying to say the Pythagorean Theorem is wrong? Are you trying to say I've somehow calculated the acceleration wrong in my "MD's accelerated cube" diagram? If you claim those numbers are wrong, give me the correct numbers. You know why SR can't do acceleration? Because the numbers don't add up, because SR is BS!! My method works flawlessly with acceleration, the numbers add up perfect! Not one little hiccup.

Let's get real for just a moment: you can't draw light on a piece of paper. You can't make light behave like a drawing, no matter how much you want to.

This stunning fact makes the whole exercise look pretty dumbass wouldn't you say?

There is math behind distance and time, and you can in fact draw math on a paper. What SR draws on a piece of paper is a bunch of objects all claiming to be at rest. Yes, that's right, SR says that every object in the universe is at rest, just ask them, they'll tell you. Ask any observer in the SR universe and they will say they are at rest. That means all observers are at rest in SR, so can you explain the observed motion in the universe while at the same time saying all observers are at rest?

Here's an SR diagram:

My cube is motionless.
So is mine.
So is mine.
So is mine.

 

[Tach]

Why be so confident that Lorentz invariance is realty when the incompatibility between QM and GR exists?

Why do you keep spamming the threads with non-sequiturs?