The Relativity of Simultaneity

[Motor Daddy]

According to the train observer, the distance from source to y receiver is 0.5 light seconds. It takes light 0.5 seconds to travel that distance, as measured by the train clocks.

So the length from the source to the y receiver isn't contracted, but the clocks are all dilated equally in all directions in the train?

 

[Motor Daddy]

Einstein's 2nd postulate specifies that the speed of light is measured to be the same in all directions in the box. That's the starting point.

It's you who says that the speed of light will be measured to be different in different directions in the train frame.

Correct, I do say that if the train has a .5c velocity in the x direction, and the distance between the source at the center of the train and the x receiver in the train frame is .5 light seconds, that the light will take 1 second to reach the receiver. That is because light traveled at c for 1 second (299,792,458 meters), and the train traveled 149,896,229 meters in the same 1 second. So the x receiver started .5 light seconds away from the source at t=0, and was 1 light second away from the point in space the source emitted light a second later. In the train frame, the observer measures the light to travel .5 light seconds in 1 second, or, he measures the speed of light to be .5c, which is due to the .5c absolute velocity of the train that the measurements don't include.

 

[Motor Daddy]

Special relativity doesn't deal with acceleration, so don't go introducing that now. We're dealing with a situation where the box moves at constant velocity with respect to the embankment.

Do you dispute my "MD's Accelerated Cube" diagram's numbers? I can play with acceleration and absolute velocities, and they play very nicely together. You can't do that with SR because the numbers don't add up!

In Einstein's universe that is true in the train frame but not in the embankment frame.

Are you telling me the embankment observer can't determine that it's .5 light seconds from the source to the receiver on the train?

You're not keeping your frames straight. You're mixing them up.

In the embankment frame, your above statement is true. In the train frame it is not.

The times are measured on the train. Where do you think the times come from? The times are measured on the train!

You have shown no inconsistency of SR, here or anywhere. Often you refuse to work with Einstein's postulates when you attempt to discuss SR, and that refusal leads you to make errors. The problem is not that SR is inconsistent; it's that you never apply it properly. In fact, you refuse to learn how to apply it. And that's why you really don't understand it at all. You're not imaginative enough to explore an alternate kind of mathematical or conceptual universe. You are stuck in the "common-sense" one that you have devised, to the point where you deny reality.

Not only do I refuse to work with Einstein's postulates, I say they are BS! I've shown plenty of inconsistency in his 2nd postulate. His numbers don't add up! I'm gonna make an example with an embankment that has an absolute velocity greater than zero, and a train that has an absolute velocity greater than zero, and you will not tell me the relative velocity between the two, because you have to ASSUME one frame is at rest using SR.

Not absolute velocity. Velocity in whatever frame you're measuring the time.

Yes it is the absolute velocity that causes the times to the y receiver to be greater than .5 seconds. The times on the clocks are not affected by what the embankment does. The times on the clocks on the train are affected by the train's absolute velocity. The clocks on the train are either in motion or not. The embankment's motion has no affect how much time it takes for light to reach the y receiver on the train.

This is true in the embankment frame, which sees the source moving.

Correct!

This is wrong, because you're mixing the frame in which the source moves with the frame in which the source doesn't move.

Correct!

Both the distance and time increase. The ratio of the two remains the same: the constant speed of light.

Correct!

Only in a frame where the source is stationary (such as the train frame).

The source is stationary to what, the train? Of course the source is stationary to the train, it is bolted to the center of the train and remains in that position relative to the train. But the source travels away from the point it emits light in space if the train is in motion. You don't seem to understand that the train can travel in space, with the source remaining at the center of the train, traveling with the train.

In which frame are the times being measured? Are we using embankment clocks or train clocks? You haven't specified.

The times are measured on the train. Do you think the embankment observer measures the time to the y receiver? The y receiver records the time. The time stays on the clock. If the train stops and the embankment observer jumps aboard, he can clearly see what the recorded time was. Once the time is recorded it is written in stone! There is no changing that time, regardless of what the train does after the clock stopped.

Galileo, back in the 1600s, had a theory essentially the same as yours, with no time dilation, no length contraction, and a speed of light that varied in different frames in a "common sense" way. The only claim he didn't make is that there is an absolute reference frame.

Well I make a claim there is an absolute reference frame, so our theories are not the same, not even close if he didn't know what an absolute frame was, or how to go about taking measurements in that frame!

Using your theory, light travels different distances in the train frame in the same amount of time, depending on the train's "absolute" speed. So, what you say is wrong by your own theory.

Light always travels 299,792,458 m/s in space. Trains can also travel in space. When will you learn that?

Anybody can use your method on the embankment to determine the speed of the train relative to the embankment. They use embankment rulers and clocks, and they're done.

If they know the absolute velocity of the embankment, and they know the relative velocity between the embankment and the train, then they know the absolute velocity of the train, and vise versa.

Don't imagine for a moment that this method gives you any kind of absolute speed though.

Don't imagine for a moment that I can't calculate the absolute velocity of an object in space, with no other object to relate to, because I can, and have done so, and have shown you many times.

 

[Motor Daddy]

On the indirect tests, of course!

Relativity makes many many predictions about all sorts of experimental situations. Each one that is confirmed with real-world evidence supports the entire, self-consistent theory.

Thousands of real-world experiments that confirm Einstein's relativity are done every day.

So relativity predicts length contraction by using length contraction in the calculations?

 

[przyk]

Are you saying the mistake James shows in his diagram is not interesting?

I haven't even read his posts. I have no particular reason to either. They're intended for you.

Because it's an inconstancy in SR which you can't explain, which is precisely the reason you aren't interested in it.

There are no inconsistencies in relativity. It is pretty trivial to prove that (it amounts to a few exercises in group theory).

Have you ever in your life actually used the Lorentz transformation to work out what relativity predicts or drawn a Minkowski diagram? In my experience that's the problem with practically everyone who thinks they've found an inconsistency in SR.

You mentioned it earlier, and made reference to my beliefs dating back to ancient times. You've still not backed up your claim that my method was used in the 1900's and has long since proven wrong. Show me!

I said your belief that space and time were absolute was universally believed until relativity came along. Nothing else. Don't put words in my mouth.

Do you have anything productive to add to the conversation, or are you just here to heckle?

Right back at you: you've filled your post with accusations I'm scared and demands I should explain James R's posts. Substantial replies to the points I raised? None! So instead of throwing accusations and inventing conspiracy theories, try explaining why everyone should just take your word for it that distance and time intervals are absolute. Why can't you answer that simple question?

 

[Motor Daddy]

I haven't even read his posts. I have no particular reason to either. They're intended for you.

You haven't read his posts, so you probably haven't read my previous posts either, correct? Or maybe you just skipped over his and read mine?

There are no inconsistencies in relativity. It is pretty trivial to prove that (it amounts to a few exercises in group theory).

Well then, you have your mind made up, so no use in talking to you, because you are closed minded to the idea that there could be an inconsistency in SR. You've already ruled out the possibility in your mind, and the case is closed as far as you are concerned. What's the point?

Have you ever in your life actually used the Lorentz transformation to work out what relativity predicts or drawn a Minkowski diagram? In my experience that's the problem with practically everyone who thinks they've found an inconsistency in SR.

Have you ever considered that a train can travel in space in the same duration of time as light travels? Have you ever asked yourself what "at rest" is relative to?

I said your belief that space and time were absolute was universally believed until relativity came along. Nothing else. Don't put words in my mouth.

So nobody ever really believed what I believe, that there is an absolute frame and objects travel in that absolute frame relative to the point of emission of light? So you are just trying to tie me to old outdated, previously disproved theories to throw me into that category? If you want to claim my theory has been thought of before and found to be disproved, show me! Don't pretend that my theory has long been dis-proven back in the 1900's, because it isn't true. Stop pretending! I've noticed the average relativist likes to pretend, it's a common theme in relativity.

Right back at you: you've filled your post with accusations I'm scared and demands I should explain James R's posts. Substantial replies to the points I raised? None! So instead of throwing accusations and inventing conspiracy theories, try explaining why everyone should just take your word for it that distance and time intervals are absolute. Why can't you answer that simple question?

I have been explaining my position, maybe you should actually read the previous posts and respond to them instead of just jumping in with wild accusations and insults, without having read the previous posts or understand where I'm coming from. You are just on the band wagon, assuming (like the relativist does quite frequently) that I'm wrong, with your closed mind.

 

[funkstar]

I really, really don't see why this thread is still here.

 

[przyk]

You haven't read his posts, so you probably haven't read my previous posts either, correct? Or maybe you just skipped over his and read mine?

No, I haven't read the past 1200 post in this thread. I said as much in an earlier post. And my initial post in this thread wasn't even directed at you. The only reason I'm talking to you now is because you started the dialogue between us.

Well then, you have your mind made up, so no use in talking to you, because you are closed minded to the idea that there could be an inconsistency in SR. You've already ruled out the possibility in your mind, and the case is closed as far as you are concerned. What's the point?

No, I know how to prove that SR is internally consistent. Not quite the same thing.

You see, SR at its heart is just a theory that asserts that all the laws of physics are symmetric under Lorentz transformations. Whenever someone says relativity must be wrong they're effectively saying that the laws of nature aren't allowed to possess a particular symmetry, which is just narrow minded. Either that or they're effectively claiming they've found and inconsistency in the Lorentz group itself. Yet mostly they turn out never to have actually learned what a Lorentz transformation is or how to apply it.

Have you ever considered that a train can travel in space in the same duration of time as light travels?

Have you considered your questions might be over-simplistic?

Have you ever asked yourself what "at rest" is relative to?

That's meaningless in any absolute sense in relativity.

So nobody ever really believed what I believe, that there is an absolute frame and objects travel in that absolute frame relative to the point of emission of light?

You tell me. How is this any different to the aether theories that were being considered in the late nineteenth century?

I have been explaining my position, maybe you should actually read the previous posts and respond to them instead of just jumping in with wild accusations and insults

I didn't jump in with the intent of attacking your position. I answered a post by quantum wave. Then you started asking me questions and I answered them.

You're not the center of the universe, you know. I never ever said I was interested in debating your "scenario" or backing up James R. It's only when I pointed out exactly what you were (let's cut the pretense, deliberately) misunderstanding about SR, and asked you why everyone should believe you when you say distance and time must be absolute, that you suddenly wanted to change the subject.

You are just on the band wagon, assuming (like the relativist does quite frequently) that I'm wrong

I don't need to assume anything. It is obvious you have made no effort to learn the theory to which you are objecting. In SR distance and time are not absolute. You know this because it's been explained countless times to you. Yet instead of acknowledging this you demand simple answers to loaded questions where you presuppose distance and time are absolute.

There are two possible explanations for this: either you're intellectually dishonest and being deliberately disingenuous, or you're plain thick. Either possibility makes any further discussion pointless. As long as you won't even pretend you're open minded about the possibility of distance and time intervals being frame-dependent, I've got no reason to pretend to be interested in any specific scenarios you want to look at. Show me you can get the basics right before asking me to worry about details.

with your closed mind

You blindly assume distance and time are absolute and obviously won't consider any other possibility. So kindly take your pathetic ad hominem and apply it to yourself.

By the way:

try explaining why everyone should just take your word for it that distance and time intervals are absolute.

I take it you don't have an answer to this?

 

[arfa brane]

It's a study of the persistence of vision. MD has a dream, he's been to the mountain top.

It's where he gets his numbers from.

 

[Motor Daddy]

No, I haven't read the past 1200 post in this thread.

So because you're too lazy to read the past 1200 posts, or you don't have time, or whatever your excuse is, you expect me to waste my time explaining every question you have, effectively possibly doubling the 1200 posts to 2400 posts covering the same ground over again because you haven't read the thread? Not likely. If you ask a question that's already been addressed, I'll refer you to the previous 1200 posts, fair enough?

No, I know how to prove that SR is internally consistent. Not quite the same thing.

You see, SR at its heart is just a theory that asserts that all the laws of physics are symmetric under Lorentz transformations. Whenever someone says relativity must be wrong they're effectively saying that the laws of nature aren't allowed to possess a particular symmetry, which is just narrow minded. Either that or they're effectively claiming they've found and inconsistency in the Lorentz group itself. Yet mostly they turn out never to have actually learned what a Lorentz transformation is or how to apply it.

Big deal, James R. has already admitted that my theory is internally consistent and mathematically sound. What's your point?

Have you considered your questions might be over-simplistic?

No, I've never considered that. What method should I use in the future to determine how simplistic my questions should be, in order to effectively get my point across to someone that disagrees with me? Are you one of those people that pat yourself on the back for being complicated? Would you rather have it as simple as possible, or as complicated as possible, in order to make yourself appear smarter??

That's meaningless in any absolute sense in relativity.

There is no absolute sense in relativity. Relativity doesn't acknowledge there exists a word as absolute. Relativity pretends objects are at rest. If you asked every observer in the SR universe what their motion is, they would tell you they are at rest. So they all claim to be at rest, so according to SR observers, there is no motion in the universe, just ask them, they'll tell you!

You tell me. How is this any different to the aether theories that were being considered in the late nineteenth century?

Refer to the last 1200 posts.

I don't need to assume anything. It is obvious you have made no effort to learn the theory to which you are objecting. In SR distance and time are not absolute. You know this because it's been explained countless times to you. Yet instead of acknowledging this you demand simple answers to loaded questions where you presuppose distance and time are absolute.

There are two possible explanations for this: either you're intellectually dishonest and being deliberately disingenuous, or you're plain thick. Either possibility makes any further discussion pointless. As long as you won't even pretend you're open minded about the possibility of distance and time intervals being frame-dependent, I've got no reason to pretend to be interested in any specific scenarios you want to look at. Show me you can get the basics right before asking me to worry about details.

Refer to the last 1200 posts. Nice insults. You must be really smart, eh?

You blindly assume distance and time are absolute and obviously won't consider any other possibility. So kindly take your pathetic ad hominem and apply it to yourself.

By the way:

I take it you don't have an answer to this?

Refer to the last 1200 posts.

 

[quantum_wave]

No, I haven't read the past 1200 post in this thread. I said as much in an earlier post. And my initial post in this thread wasn't even directed at you. The only reason I'm talking to you now is because you started the dialogue between us.


No, I know how to prove that SR is internally consistent. Not quite the same thing.

You see, SR at its heart is just a theory that asserts that all the laws of physics are symmetric under Lorentz transformations. Whenever someone says relativity must be wrong they're effectively saying that the laws of nature aren't allowed to possess a particular symmetry, which is just narrow minded. Either that or they're effectively claiming they've found and inconsistency in the Lorentz group itself. Yet mostly they turn out never to have actually learned what a Lorentz transformation is or how to apply it.


Have you considered your questions might be over-simplistic?


That's meaningless in any absolute sense in relativity.


You tell me. How is this any different to the aether theories that were being considered in the late nineteenth century?


I didn't jump in with the intent of attacking your position. I answered a post by quantum wave. Then you started asking me questions and I answered them.

You're not the center of the universe, you know. I never ever said I was interested in debating your "scenario" or backing up James R. It's only when I pointed out exactly what you were (let's cut the pretense, deliberately) misunderstanding about SR, and asked you why everyone should believe you when you say distance and time must be absolute, that you suddenly wanted to change the subject.


I don't need to assume anything. It is obvious you have made no effort to learn the theory to which you are objecting. In SR distance and time are not absolute. You know this because it's been explained countless times to you. Yet instead of acknowledging this you demand simple answers to loaded questions where you presuppose distance and time are absolute.

There are two possible explanations for this: either you're intellectually dishonest and being deliberately disingenuous, or you're plain thick. Either possibility makes any further discussion pointless. As long as you won't even pretend you're open minded about the possibility of distance and time intervals being frame-dependent, I've got no reason to pretend to be interested in any specific scenarios you want to look at. Show me you can get the basics right before asking me to worry about details.


You blindly assume distance and time are absolute and obviously won't consider any other possibility. So kindly take your pathetic ad hominem and apply it to yourself.

By the way:

I take it you don't have an answer to this?

This post really is a summary of the situation. Your first post was directed to me and I think you could see that in my own efforts to get to the bottom of SR from a reality stand point I was trying to equate an expanding light sphere, EM, to the rest frame and to the moving frame since in SR they are both inertial frames. When I concluded that EM in the rest frame expanded at c, and if it was actually a physical energy wave traversing space, then in any frame moving relative to the rest frame that spherical EM wave would have different characteristics, i.e. it didn't act like EM acts when viewed from the rest frame.

You correctly pointed out that the different shape of the EM wave in the moving frame is attributed to the relativistic Doppler effect. I verified that and posted the Google link.

In this last post of yours you clearly state the facts. SR is the best theory we have to explain observations and it does not claim to be reality, which I think we agree is a philosophical concept.

So, to MD:

Please acknowledge that the math of SR works perfectly and the postulates are completely consistent with the math. You may have acknowledged that in the past year but for the record and to help me (and Pete) do some facilitating, would you acknowledge that? It is not a capitulation from your clear position, and it does not refute that your math is perfectly correct and
supports your postulate. It does acknowledge that the guys who are trying to advocate for SR in every conceivable way do have a sound theory, even though that theory requires that the expanding EM wave will look substantially different from a frame of reverence moving at relativistic speeds relative to the EM wave as observed from the rest frame. Can you acknowledge that????????????

 

[Motor Daddy]

So, to MD:

Please acknowledge that the math of SR works perfectly and the postulates are completely consistent with the math. You may have acknowledged that in the past year but for the record and to help me (and Pete) do some facilitating, would you acknowledge that? It is not a capitulation from your clear position, and it does not refute that your math is perfectly correct and
supports your postulate. It does acknowledge that the guys who are trying to advocate for SR in every conceivable way do have a sound theory, even though that theory requires that the expanding EM wave will look substantially different from a frame of reverence moving at relativistic speeds relative to the EM wave as observed from the rest frame. Can you acknowledge that????????????

No, I don't acknowledge that. If in SR a train observer can consider the train to be at rest, and measures the times to be .5 second for light to travel .5 light seconds in the train, then the train is at rest, and there is no motion, and the story is over, period. The train is not in motion, and has no reference to the outside world, and the case is closed.

SR relies on known other times, and then changes those times and distances and says, see what I can do, I can determine relative velocity, and it's always the other guy that's in motion, not silly old me.

 

[quantum_wave]

No, I don't acknowledge that. If in SR a train observer can consider the train to be at rest, and measures the times to be .5 second for light to travel .5 light seconds in the train, then the train is at rest, and there is no motion, and the story is over, period. The train is not in motion, and has no reference to the outside world, and the case is closed.

SR relies on known other times, and then changes those times and distances and says, see what I can do, I can determine relative velocity, and it's always the other guy that's in motion, not silly old me.

No one is disputing that specifically. They are saying that if you are allowed to make postulates, Einstein and you included, you are allow to derive theory related truths from those postulate that are correct if the postulates are the basis of what is correct. Will you agree to that? Because that is what you are doing with your postulate. It is self-evident to you, and you derive the theory related math and statements from the postulate. They are correct if your postulate is correct, and if you cannot go that far toward acknowledging how the scientific method works and applies to everyone, then you don't want to convince anyone you are right, you want the discord which is perpetuated by not acknowledging how science works. Would you rather agree to that instead?

 

[wellwisher]

SR has three equations, one for mass, one for distance and one for time. I like to focus on the mass equation, since it forces you to do an energy balance, providing a check for possible illusionary relative references, while allowing one to define hierarcal reference. Even if see such and such, if it violates energy conservation, it is an illusion like a mirage.

For example, if I was moving close to C (1 mph slower), it will take infinite energy to get to go a little bit faster all the way to C, since relativistic mass is increasing toward infinity. Say I was looking at this moving reference, while moving at very slow speed, and assume the two references are relative.

If that was true, if I fired my rockets, I should not move any faster than a tiny increment of speed, since my relative reference is already close to C. If I was near C, it would seem like I have the brakes on, no matter how fats I burn the engines; will need an infintie burn. But if I notice I start to pick up speed and accelerate with less than infinite energy, I know I can't be at C. Whatever visual illusion I see in my reference will not change these energy burn requirements.

There may be a way to determine absolute reference. Measure how much energy is needed to move between two velocities for a given reference; V1 to V2. In terms of absolute reference, the closer to C we are in absolute terms (when we start the engine burn ) the more energy that will needed to go V1 to V2 in our reference. If we are already near C it may take infinite energy. If start close to absolute zero, it will take minimium energy. The proportions are in the mass equation.

 

[Motor Daddy]

No one is disputing that specifically. They are saying that if you are allowed to make postulates, Einstein and you included, you are allow to derive theory related truths from those postulate that are correct if the postulates are the basis of what is correct. Will you agree to that? Because that is what you are doing with your postulate. It is self-evident to you, and you derive the theory related math and statements from the postulate. They are correct if your postulate is correct, and if you cannot go that far toward acknowledging how the scientific method works and applies to everyone, then you don't want to convince anyone you are right, you want the discord which is perpetuated by not acknowledging how science works. Would you rather agree to that instead?

You make it sound like it's ok to create a postulate, change everything according to that postulate to make it work, and then create a mathematical world, and if everything is internally consistent it's ok.

NO! It's not ok.

The difference being, one can create an illusion of correctness, but in the end, it's still an illusion. The illusion being, that you can always be considered to be at rest and the other guy is actually doing all the moving. While it is possible that could be true, the odds of that in reality are slim to none.

Again I direct your attention to two cars traveling down the road, one in front of the other. The distance between them at t=0 is 20 feet. One car is traveling at a constant 60 MPH. What is the distance between the cars at t=1? You can't answer that anymore than a train observer can say he was at rest while the tracks were doing all the moving. That is absurd! EACH object has it's own velocity, and yes, there can be a relative motion between two objects, but that doesn't mean one is at rest and the other is doing all the moving!!!

 

[quantum_wave]

SR has three equations, one for mass, one for distance and one for time. I like to focus on the mass equation, since it forces you to do an energy balance, providing a check for possible illusionary relative references, while allowing one to define hierarcal reference. Even if see such and such, if it violates energy conservation, it is an illusion like a mirage.

For example, if I was moving close to C (1 mph slower), it will take infinite energy to get to go a little bit faster all the way to C, since relativistic mass is increasing toward infinity. Say I was looking at this moving reference, while moving at very slow speed, and assume the two references are relative.

If that was true, if I fired my rockets, I should not move any faster than a tiny increment of speed, since my relative reference is already close to C. If I was near C, it would seem like I have the brakes on, no matter how fats I burn the engines; will need an infintie burn. But if I notice I start to pick up speed and accelerate with less than infinite energy, I know I can't be at C. Whatever visual illusion I see in my reference will not change these energy burn requirements.

There may be a way to determine absolute reference. Measure how much energy is needed to move between two velocities for a given reference; V1 to V2. In terms of absolute reference, the closer to C we are in absolute terms (when we start the engine burn ) the more energy that will needed to go V1 to V2 in our reference. If we are already near C it may take infinite energy. If start close to absolute zero, it will take minimium energy. The proportions are in the mass equation.

No reason to disagree with that but it is beyond where we are right now from what I can tell.

 

[przyk]

So because you're too lazy to read the past 1200 posts, or you don't have time, or whatever your excuse is, you expect me to waste my time explaining every question you have, effectively possibly doubling the 1200 posts to 2400 posts covering the same ground over again because you haven't read the thread? Not likely.

Not laziness. Disinterest. I never expressed any interest in the thread. As I said my first post here wasn't even addressed to you. You started discussing something with me, not the other way around. You have no right to suddenly demand I read 1200 posts when things suddenly start getting difficult for you. If you wanted I read the whole thread as a precondition for discussing with you, you should have invited me to do it up front.

If you ask a question that's already been addressed, I'll refer you to the previous 1200 posts, fair enough?

No. See above. If I ask a question that's already been addressed and you don't want to duplicate the effort of addressing it again, you provide a link to the post where you already addressed it.

Big deal, James R. has already admitted that my theory is internally consistent and mathematically sound. What's your point?

What does this have to do with the internal consistency of SR?

No, I've never considered that.

Yes you have. You've had it explained to you countless times.

There is no absolute sense in relativity. Relativity doesn't acknowledge there exists a word as absolute.

It also doesn't acknowledge that there is such a word as "cinema". What's your point?

Relativity pretends objects are at rest.

No it doesn't.

If you asked every observer in the SR universe what their motion is, they would tell you they are at rest.

No they wouldn't.

So they all claim to be at rest, so according to SR observers, there is no motion in the universe, just ask them, they'll tell you!

Straw man.

Refer to the last 1200 posts.

Refer to the last 1200 posts. Nice insults. You must be really smart, eh?

Refer to the last 1200 posts.

I'll pass, thanks. It's so much easier for me just to assume you've run out of answers.

 

[Motor Daddy]

Not laziness. Disinterest. I never expressed any interest in the thread.

If you never expressed any interest, why did you click on it?

You have no right to suddenly demand I read 1200 posts when things suddenly start getting difficult for you. If you wanted I read the whole thread as a precondition for discussing with you, you should have invited me to do it up front.

It's pretty darn rude of you to enter a thread you haven't read, and then start asking questions, and expect me to waste my time answering questions that were already answered. It's wasting my time to have to find the question, find the answer, and provide a link. Why should I have to pay for your laziness? Do you do that in school? Does the professor give information to you, or give a reading assignment, you blow it off, and then later ask him the very questions the reading already answered? Your laziness is your problem, not mine!

No. See above. If I ask a question that's already been addressed and you don't want to duplicate the effort of addressing it again, you provide a link to the post where you already addressed it.

Again, that's wasting my time. Refer to the previous 1200 posts.

 

[quantum_wave]

You make it sound like it's OK to create a postulate, change everything according to that postulate to make it work, and then create a mathematical world, and if everything is internally consistent it's OK.

NO! It's not OK.

Have it your way. I have no problem with you insisting that everything make sense, and being internally consistent is not the measure of making sense.

The difference being, one can create an illusion of correctness, but in the end, it's still an illusion. The illusion being, that you can always be considered to be at rest and the other guy is actually doing all the moving. While it is possible that could be true, the odds of that in reality are slim to none.

True, but science does not claim to BE REALITY. Theory that is internally consistent is a step toward a better understanding of reality. From there it is tested to the limits of our ability and if it is not in accord with nature we will falsify it. Some things are hard to falsify and until we can make measurement from frames that are in motion at relativistic speeds relative to a control rest frame, all we can do is explain the test results and go on testing.

When you say,"While it is possible that could be true, the odds of that in reality are slim to none", I point out that we are talking about the other guy moving at speeds where the effects of the postulates can be in play. We can't test that yet. You may be vindicated if we could, right?

Again I direct your attention to two cars traveling down the road, one in front of the other. The distance between them at t=0 is 20 feet. One car is traveling at a constant 60 MPH. What is the distance between the cars at t=1? You can't answer that anymore than a train observer can say he was at rest while the tracks were doing all the moving. That is absurd! EACH object has it's own velocity, and yes, there can be a relative motion between two objects, but that doesn't mean one is at rest and the other is doing all the moving!!!

OK, let me see, one car moving at 60 and ... oh, I see what you mean, we don't know how fast the other guy is moving so we can't answer the question. And you are relating that scenario to the train observer. Is your point the obvious one, i.e. the train observer can be certain that he is moving and the tracks are, well train track which are not normally considered to be moving? But you can see that from the perspective, right or wrong, of SR that it is completely within the rules to consider the train at rest and the embankment moving; tell me you understand that it is allowed within the rules of SR, even though it is stupid as far as you are concerned.

I'm going to make another espresso Americano, work in the yard, and come back and see if you want to talk with me or not, lol.

 

[Motor Daddy]

Is your point the obvious one, i.e. the train observer can be certain that he is moving and the tracks are, well train track which are not normally considered to be moving? But you can see that from the perspective, right or wrong, of SR that it is completely within the rules to consider the train at rest and the embankment moving; tell me you understand that it is allowed within the rules of SR, even though it is stupid as far as you are concerned.

SR determines the relative motion, which says NOTHING as to the motion of each object.

Two vehicles approaching each other on a road. The distance is closing at the rate of 100 m/s. The cars will collide in 1 second if the motions are inertial. What is the velocity of each car?

ah, is it 50m/s each in opposite directions? Is it 60 m/s and 40 m/s? How about 10/90, or 5.5/94.5?

The only thing that SR can say is that the closing speed is 100 m/s, because it always assumes that one car is at rest and the other car is the one in motion, or vise versa. It never considers, nor is it capable of measuring that both cars are in motion with their own velocities.