How to explain Einstein's Special theory of Relativity.

[Doc Al]

Thanks for your correction. Now, I will rewrite my sentence.

How do observers everywhere in the stationary system S measure the "time period" Δt of ONE SPECIFIC SECTION of continuous events from event 1 at point A to event 2 at point B? They use the synchronized stationary clocks in S. For the observers everywhere in the moving system S', they will use the synchronized moving clocks to measure the "time period" Δt' from event 1 to event 2. Now, we have a better defined case.

OK, that's better. But so far you've not placed any restrictions on those events.

There are two ways to do the measure jobs.

The easy way is to measure event time t1 and t1' for event 1 at point A and measure event time t2 and t2' for event 2 at point B. We will have Δt' = t2'-t1' and Δt = t2-t1.

OK. I assume by 'easy way' you mean for there to be observers in both frames at the location of the events so that they do not have to account for light travel time. Good.

The difficult way is to measure event time by assigned observers, one in S and one in S'. The simplest assginment is let them stay at origin points O and O'.

OK, these single observers must take light travel time into account when interpreting their direct observations. So what? The two methods of measuring the time intervals between those events will give the same answer. (What is your point in mentioning these "two ways"?)

Let us look at this simplest situation. Since the distances of each pair of four points A, B, O and O' could be different, we must adjust the influence of the distance. When A=B=O', it will be the situation arranged by Einstein. We will have Δt' = t2'-t1' and Δt = t2-t1.

OK, now you have restricted the pair of events to be events that take place at the same location in S'. (At least that's what I think you mean.)

For this SPECIFIC SET of t1,t2, t1' and t2', SR states based on the relative speed "v", the relation of the speed of time in S' and S should be Δt' = Δt/γ, but regarding the "time period", we should go by Δt' = γ(Δt-(vΔx/c^2)). Am I correct?

No. You are incorrect in thinking that those methods (using the time dilation formula or using the LT) yield different results.

In this particular case, you can relate the time intervals using the time dilation formula since the events take place at a single location in S'. So Δt' = Δt/γ is perfectly correct.

Or you can use the LT: Δt = γ(Δt' + (vΔx'/c^2)). Since Δx' = 0, we are back to the same result, Δt' = Δt/γ.

Yes, "In words, the time dilation formula says that 'moving clocks run slow'." and for relative speed v, the time dilation formula Δt' = Δt/γ stands.

Sure, for the simple case in question, the time dilation formula applies just fine. Of course, you get the same result by applying the full Lorentz transformation.

In Δt' = Δt/γ, Δt' is for the time period in the moving system S' of a given SECTION OF EVENTS and Δt is for the stationary system S of the same SECTION OF EVENTS.

Δt' and Δt represent the time interval between those two events as seen in different frames.

I'm still not getting what your point is. And you still seem to speak as though you think "SR" just means time dilation. There is more going on than that. What about length contraction? What about the relativity of simultaneity? Sure, in certain special cases (like the one discussed here) you can directly apply the time dilation formula. But in general you must include all three relativistic effects. And the LT does that for you automatically.

 

[John Huang]

If that is not clear to you, please ask.

Thanks. Your point is clear.

 

[harrylin]

Thanks. Your point is clear.

Sorry I did not mean if my point is not clear (although that is also useful to get feedback on), but if it is clear to you how to calculate it.

 

[John Huang]

I'm still not getting what your point is. And you still seem to speak as though you think "SR" just means time dilation. There is more going on than that. What about length contraction? What about the relativity of simultaneity? Sure, in certain special cases (like the one discussed here) you can directly apply the time dilation formula. But in general you must include all three relativistic effects. And the LT does that for you automatically.

Thanks. I will explain my point in a more spesific way. But before that, let me report what I understand about the history of SR:

1. Most physicists BELIEVED that MMX is not compatible with the Newtonian Space & Time and the Galilean Transformation (GT).

2. Mr. Lorentz SUGGESTED that we might let the moving rulers shrink 1/L(v) along the moving direction so that the distance measured in S' will expand L(v) times and the x'=x-vt ---(1) in GT will change to x'=L(v)(x-xt) ---(2). He then applied the principle of relativity to get the x=L(v)(x'+vt') ---(3) and combined (2) and (3) to derive t' = L(v)(t-(vx/c^2)) ---(4) then estabished the LT. Physicists use γ for L(v) but I like to use L(v) for γ.

3. Mr. Einstein CLAIMED that he proved LT. Then he extended the idea of ruler construction to time. He liked to let a moving clock speed up or slow down. If he let a moving clock speed up then combined with the shrinking rule the speed of an object would be measured the same in S and S', then it would be no fun at all so that he selected to let a moving clock slow down at the same rate 1/L(v), Δt' = Δt/L(v) ---(5). To make the situation even more interest, he did not use the symbol Δ to show the purpose of (5) is for the relation of speed only. Any way, he created SR in year 1905.

4. Mr. Einstein went further, ASSUMED that a clock will also slow down in a stronger gravitational field that dt=1-G(r) ---(6), G is the gravitational potential. Then he created General Relativity (GR) based on SR and (6).

5. Most physicists EXPALINED some observations and experiments to support GR and GR support SR so that SR is established in the 20th century.

I think it is the time to dig into all of the fun and interesting part of SR and eventually remove them. I think we can have fun to apply our knowledge or to make the learning of knowledge easier, but, in knowledge itself, we don't need fun and interest. All we need is to match fact with logic and math.

 

[John Huang]

Sorry I did not mean if my point is not clear (although that is also useful to get feedback on), but if it is clear to you how to calculate it.

I will explain my understanding regarding the math of SR later.

 

[ghwellsjr]

3. Mr. Einstein CLAIMED that he proved LT. Then he extended the idea of ruler construction to time. He liked to let a moving clock speed up or slow down. If he let a moving clock speed up then combined with the shrinking rule the speed of an object would be measured the same in S and S', then it would be no fun at all so that he selected to let a moving clock slow down at the same rate 1/L(v), Δt' = Δt/L(v) ---(5). To make the situation even more interest, he did not use the symbol Δ to show the purpose of (5) is for the relation of speed only. Any way, he created SR in year 1905.

Einstein merely pointed out that if you consider the propagation of light to be c in any inertial state you choose and not just in one illusive inertial state referred to as the ether, then the same LT that was previously discovered to describe how clocks moving with respect to that illusive ether run slower and rulers contract along the direction of motion through that illusive ether, would also work the other way around. In other words, you can assume that any Inertial Reference Frame is just like the illusive inertial ether state and so you don't have to bother looking for that illusive inertial ether state anymore because you will never find it.

I think it is the time to dig into all of the fun and interesting part of SR and eventually remove them. I think we can have fun to apply our knowledge or to make the learning of knowledge easier, but, in knowledge itself, we don't need fun and interest. All we need is to match fact with logic and math.

I think you're asking to get banned. This forum is dedicated to learning relativity, not fixing it because it's not broken. If you think it is, then it's your own misunderstanding that's broken and needs to be fixed.

 

[Dale]

All we need is to match fact with logic and math.

Agreed. Please see:
http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

 

[John Huang]

Agreed. Please see:
http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

You may name the best experiment you like and I will study it in more detail.

Here is my first logical issue: Two stories of Mr. Time.

Let Mr. Time in the stationary system S of LT. Mr. Time moves from a point A at time t1 to a point B at time t2. I name the case when A=B=O' as story1 and when A=B=O as story2, O and O' are origin points respectively. After observers in S' records the event time t1' and t2' we will have two results.

In the story1, LT supports SR and in the story2 LT supports anti-SR.

We are ready for my first logical issue. If LT can support SR and anti-SR in separate situations then, lopgically speaking, should we say that anti-SR and SR are equally possible solutions for the actual time formula of the nature?

 

[Dale]

You may name the best experiment you like and I will study it in more detail.

Any alternative theory must explain ALL of those experiments (as SR does), not just one.

Here is my first logical issue: Two stories of Mr. Time.

Let Mr. Time in the stationary system S of LT. Mr. Time moves from a point A at time t1 to a point B at time t2. I name the case when A=B=O' as story1 and when A=B=O as story2, O and O' are origin points respectively. After observers in S' records the event time t1' and t2' we will have two results.

In the story1, LT supports SR and in the story2 LT supports anti-SR.

Nonsense. SR uses the LT to determine the answer in both cases. Any contradiction is entirely a figment of your imagination.

We are ready for my first logical issue. If LT can support SR and anti-SR in separate situations then, lopgically speaking, should we say that anti-SR and SR are equally possible solutions for the actual time formula of the nature?

No, you are simply confused, despite having been corrected on this point numerous times. Your logical arguments are not arguments against SR, they are arguments against some strawman distorted theory of your own imagining.

In honor of its inventor I name this theory you are discussing "John Huang Theory" (JHT). JHT obviously has problems, as acknowledged by its inventor.

 

[John Huang]

This forum is dedicated to learning relativity, not fixing it because it's not broken. If you think it is, then it's your own misunderstanding that's broken and needs to be fixed.

That is my purpose here to fix my misunderstanding.

 

[John Huang]

Any alternative theory must explain ALL of those experiments (as SR does), not just one.

Please just show me one experiment and explain it briefly why it is a good one. I will spend time on it. Thanks.

Nonsense. SR uses the LT to determine the answer in both cases. Any contradiction is entirely a figment of your imagination.

Sorry, I should make the event1 and event 2 easy to recognize, I will let Mr. Time do something at event 1 and event 2 as following:

Here is my first logical issue: Two stories of Mr. Time.

Let Mr. Time in the stationary system S of LT. Mr. Time points his forefinger upward and moves from a point A at time t1 to a point B at time t2 and curls his forefinger. I name the case when A=B=O' as story1 and when A=B=O as story2, O and O' are origin points respectively. After observers in S' records the event time t1' and t2' we will have two results.

In the story1, LT supports SR and in the story2 LT supports anti-SR.

 

[Dale]

Please just show me one experiment and explain it briefly why it is a good one. I will spend time on it. Thanks.

They are all good, you should spend time on each. At a minimum you need to understand Michelson-Morely, Ives-Stillwell, and Kennedy-Thorndike.

In the story1, LT supports SR and in the story2 LT supports anti-SR.

LT always supports SR.

In the story1, LT supports JHT and in the story2 LT supports anti-JHT. JHT has some serious problems.

 

[ghwellsjr]

Sorry, I should make the event1 and event 2 easy to recognize, I will let Mr. Time do something at event 1 and event 2 as following:

Here is my first logical issue: Two stories of Mr. Time.

Let Mr. Time in the stationary system S of LT. Mr. Time points his forefinger upward and moves from a point A at time t1 to a point B at time t2 and curls his forefinger. I name the case when A=B=O' as story1 and when A=B=O as story2, O and O' are origin points respectively. After observers in S' records the event time t1' and t2' we will have two results.

In the story1, LT supports SR and in the story2 LT supports anti-SR.

As far as I can tell, the example and explanation that I gave you in post #81 at the top of the previous page would fit in nicely with your two stories, the first diagram applying to story2 and the second diagram applying to story1. In the frame in which Mr. Time is stationary, the first diagram, event 1 is at the coordinate time of 1 second which is also the Proper Time on Mr. Time's clock. Event 2 is at the coordinate time of 2 seconds, the same as the time on Mr. Time's clock. Here is the first graph of story2 with annotations:

Now we use the Lorentz Transformation process on both of the events to determine their coordinates in a new frame moving at 0.866c with respect to the first frame. This gives us story1:

You will note that in this frame the coordinate times for Mr. Time's clock are double what they were for story2. I don't see any problem with SR or LT.

When you read my previous post and I asked you if you got it, you said Thanks, implying that you understood it. But now you're asking the same question all over again, implying that you didn't get it.

Rather than continue on like this, please tell me what you are having problems with in my explanation on post #81. I tried to address all of your concerns.

 

[John Huang]

When you read my previous post and I asked you if you got it, you said Thanks, implying that you understood it. But now you're asking the same question all over again, implying that you didn't get it.

Rather than continue on like this, please tell me what you are having problems with in my explanation on post #81. I tried to address all of your concerns.

I knew that you tried to help. That is why I thanked you.

I also know your solution to the SR and anti-SR issue. You let the clock stay at event point. I think it is just a tool you used to work around the issue. As a matter of fact, clocks are with observers in S and S', not with the event. I think your answer to my first logic question is not good but I appreciate your help. Thanks again.

 

[ghwellsjr]

I knew that you tried to help. That is why I thanked you.

I also know your solution to the SR and anti-SR issue. You let the clock stay at event point. I think it is just a tool you used to work around the issue. As a matter of fact, clocks are with observers in S and S', not with the event. I think your answer to my first logic question is not good but I appreciate your help. Thanks again.

Mr. Time is present at both events along with his clock in both IRF's. What other observers are you considering and where are they?

 

[John Huang]

Mr. Time is present at both events along with his clock in both IRF's. What other observers are you considering and where are they?

Mr. Time is the object creating events, he does not have to have a clock at all. Observers are in S and S' who record the location and event time in their respective frams.

 

[John Huang]

They are all good, you should spend time on each. At a minimum you need to understand Michelson-Morely, Ives-Stillwell, and Kennedy-Thorndike.

Very good. Let try one by one, please try to answer my question in the link:
https://www.physicsforums.com/showthread.php?p=4197629#post4197629
Thanks.

 

[ghwellsjr]

Mr. Time is the object creating events, he does not have to have a clock at all. Observers are in S and S' who record the location and event time in their respective frams.

Oh, Mr. Time doesn't have a clock. Any particular reason why you called him Mr. Time if he has no concept of time? Can we assume that he has a heart that beats once per second or that he can count out approximate seconds of time interval? Or is it important to you that he just raises his finger at any arbitrary and random time and then curls his finger at any arbitrary and random time later?

Now about these other observers in S and S'--can we assume that at each light-second of spacing from the origin there is another observer who has a clock that has been synchronized to the observer's clock at the origin according to Einstein's convention? Do you want to assume that both sets of observers are present in both IRF's?

 

[Dale]

Very good. Let try one by one, please try to answer my question in the link:
https://www.physicsforums.com/showthread.php?p=4197629#post4197629
Thanks.

You didn't have a question there. But the point remains that SR explains ALL of the experiments listed, not just one or two. If the MM experiment confuses you, then select one of the many others on that page. They are organized topically, so there should be an equivalent one that makes sense to you.

 

[John Huang]

You didn't have a question there. But the point remains that SR explains ALL of the experiments listed, not just one or two. If the MM experiment confuses you, then select one of the many others on that page. They are organized topically, so there should be an equivalent one that makes sense to you.

Sorry, it is not clear in that link. Here is the question. What is the definition of the speed of a beam or a ray of light in the beam?

 

[John Huang]

Oh, Mr. Time doesn't have a clock. Any particular reason why you called him Mr. Time if he has no concept of time? Can we assume that he has a heart that beats once per second or that he can count out approximate seconds of time interval? Or is it important to you that he just raises his finger at any arbitrary and random time and then curls his finger at any arbitrary and random time later?

Mr. Time has concept of time but he does not need to kinow when he raises or curls his finger. That is why there are a lot of possible event points times as of where is A then where is B and the related event time as of when is t1 that Mr. Time is at A and raising his finger then when is t2 that Mr. Time is at B and curling his finger.

I just let A to represnt the location of event 1 (the raising event) and B to represent the location of event 2 (the curling event). I also use t1 and t2 to represent the respective event time measured by observers in S.

The easiest way to measure event times is to ask observer at A to measure t1 for event 1 and the observer at B to measure t2 for event 2.

If we select one obsever at point D in S to measure events then we must adjust the measured event time T1 and T2 to actual time t1=T1-(AD/c) and t2=T2-(BO/c), c is the speed of light.

Now about these other observers in S and S'--can we assume that at each light-second of spacing from the origin there is another observer who has a clock that has been synchronized to the observer's clock at the origin according to Einstein's convention? Do you want to assume that both sets of observers are present in both IRF's?

In the real world we are unable to test Galilean Transformation (GT), because the arranged systems are unable to coexist due to one space allows only one observer, when O' meet O, two observers at origin points will collide. Both of GT and LT are mathematical settings.

Since it is a mathematical setting, we assume that there are stationary observers everywhere in S with synchronized clocks and there are also moving observers (but they are stationary in S') everywhere in the S' with another batch of synchronized clocks.

 

[ghwellsjr]

I'll take that answer to be yes to my last two questions.

Now I want to make sure I got the scenario correct. Mr. Time is stationary at the origin of the S' frame and maps out story 2 as depicted in the first graph in post #103, correct?

And Mr. Time is traveling at some high speed in frame S, starting at the origin of both frames when they coincide and maps out story 1 as depicted in the second graph in post #103, correct?

Now I hope you realize that I used the LT to create the second graph from the first graph, so I presume that you have no problem with either graph, correct?

And we are going to consider that the observers who are stationary in the respective frames are the ones that establish the coordinates of the two events for Mr. Time, correct?

And what's the problem?

 

[Dale]

Sorry, it is not clear in that link. Here is the question. What is the definition of the speed of a beam or a ray of light in the beam?

There are two basic velocities useful for defining the speed of a wave: phase velocity and group velocity. Here is a good page on their definitions and their relation to the propagation of information:
http://www.mathpages.com/home/kmath210/kmath210.htm

 

[Dale]

In the real world we are unable to test Galilean Transformation (GT), because the arranged systems are unable to coexist due to one space allows only one observer, when O' meet O, two observers at origin points will collide.

This is not true. If the Galilean transformation were correct then there would be no time dilation and Doppler shifts would take their pre-relativistic form. So any experiment testing time dilation or Doppler is an experimental test of the Galilean transformation. See the page I posted earlier for many such experiments, all confirming the LT and experimentally falsifying the Galilean transformation.

 

[John Huang]

There are two basic velocities useful for defining the speed of a wave: phase velocity and group velocity. Here is a good page on their definitions and their relation to the propagation of information:
http://www.mathpages.com/home/kmath210/kmath210.htm

That is for a group of photons or a pulse of light. What we need in MMX is for continuous wave, a ray or a group of ray, a beam.

 

[John Huang]

This is not true. If the Galilean transformation were correct then there would be no time dilation and Doppler shifts would take their pre-relativistic form. So any experiment testing time dilation or Doppler is an experimental test of the Galilean transformation. See the page I posted earlier for many such experiments, all confirming the LT and experimentally falsifying the Galilean transformation.

I will talk about Ives-Stilwell Experiment after we finish the MMX issue. One by one.

 

[Vorde]

That is for a group of photons or a pulse of light. What we need in MMX is for continuous wave, a ray or a group of ray, a beam.

What is the difference to you? How do you think you would go about defining the speed of 'a ray of photons' without talking about the speed of the photons themselves?

 

[John Huang]

I'll take that answer to be yes to my last two questions.

Now I want to make sure I got the scenario correct. Mr. Time is stationary at the origin of the S' frame and maps out story 2 as depicted in the first graph in post #103, correct?

And Mr. Time is traveling at some high speed in frame S, starting at the origin of both frames when they coincide and maps out story 1 as depicted in the second graph in post #103, correct?

Now I hope you realize that I used the LT to create the second graph from the first graph, so I presume that you have no problem with either graph, correct?

And we are going to consider that the observers who are stationary in the respective frames are the ones that establish the coordinates of the two events for Mr. Time, correct?

And what's the problem?

The story 2 is maped out by two figures in your #81, the first one is for S and the second one is for S'.

To put the story 1 on figure, the first figure for S will be event 1 (0.866, 1) and event 2 (1.732, 2); the second figure for S' will be event 1 (0, 0.5) and event 2 (0, 1).

The problem is LT supports SR in the story 1 but LT supports anti-SR in the story2 so that logically speaking, if LT is correct then anti-SR and SR should have equal chance to be selected by the nature.

 

[John Huang]

What is the difference to you? How do you think you would go about defining the speed of 'a ray of photons' without talking about the speed of the photons themselves?

You talked about two issues.

My opinion for the first one is, the speed of a ray is different from the speed of a pulse of light. My comment for the second one is, I did not say so and in my definition of the speed of a ray of light do relate to the speed of a photon.

What is your definition for "the speed of a ray of light"?

 

[Vorde]

You talked about two issues.

My opinion for the first one is, the speed of a ray is different from the speed of a pulse of light. My comment for the second one is, I did not say so and in my definition of the speed of a ray of light do relate to the speed of a photon.

What is your definition for "the speed of a ray of light"?

What is a ray of light? A group of photons.

What is the speed of a ray of light? The speed of the constitute photons. (Here is where one might differentiate between phase and group velocity).

What is the speed of the constitute photons? C.