The Relativity of Simultaneity

[Motor Daddy]

May I just test my understanding here; you were referring to light emitted from a source and making the point of origination in space an absolute point relative to the expanding light sphere. Am I right so far? This assumes that the light sphere will move away from the center point equally in all directions at the same speed.

Yes, the light sphere will expand equally in all directions from the point in space that the source was when it emitted the light. Of course, if the source moved in space during that time of light travel, the source is no longer at that original point, but that doesn't change the fact that the light is still expanding from the original point it was emitted.

You are imagining that the specific light sphere is then observed as at passes other points in space by observers that are in motion relative to the fixed point of origin of the light sphere. Right?

The sphere doesn't travel in space, it expands in space. The center of the sphere doesn't ever change, but the sphere expands its radius from that point at the rate of c.

And you are using logic to conclude that if that speed of that original light sphere is measured by a moving observer, that measurement will be different than the speed measured from the point of origin. Is that correct?

I am measuring the velocity of the light source that emitted the light. If the source remains at the center of the expanding light sphere than the source has an absolute zero velocity. If the source is not at the center of the expanding light sphere, then it moved, and therefore had an absolute velocity greater than zero relative to the point in space that it was when it emitted light (the center of the light sphere).

 

[quantum_wave]

Yes, the light sphere will expand equally in all directions from the point in space that the source was when it emitted the light. Of course, if the source moved in space during that time of light travel, the source is no longer at that original point, but that doesn't change the fact that the light is still expanding from the original point it was emitted.

The sphere doesn't travel in space, it expands in space. The center of the sphere doesn't ever change, but the sphere expands its radius from that point at the rate of c.

Yes, my wording was poor. The light sphere expands equally in all directions at the speed of light.

I am measuring the velocity of the light source that emitted the light. If the source remains at the center of the expanding light sphere than the source has an absolute zero velocity. If the source is not at the center of the expanding light sphere, then it moved, and therefore had an absolute velocity greater than zero relative to the point in space that it was when it emitted light (the center of the light sphere).

I've got you. I was getting ahead.

I can envision the circumstances and so my understanding is up to speed as far as we have gone with this brief exchange. Thank you.

Now if I may test further, in regard to the carriage and embankment example. I now understand what a reference body is and the carriage or train is a reference body and the embankment is a reference body. Are you applying the reasoning that we just reviewed to the example of the train and the embankment by establishing two absolute points in space from which separate spherical light waves are expanding?

And are you establishing the position of M on the embankment to coincide with the position of M' on the train at the moment that the light is emitted from the two absolute points in space? And if so then you are envisioning the motion of the train relative to the two separate expanding light spheres?

If so you see M' moving toward one of the oncoming light spheres and away from the other oncoming light sphere from the reference body of the train?

Edit: Are you pointing out that the point M' will reach the forward oncoming light sphere before the following oncoming light sphere which is agreed?

You explanation is that the motion of the train relative to the presence of the two expanding light spheres can be measured by reasoning and by doing so you can bring the two reference bodies into the same coordinate system and show that the speed of light [edit] [would be measured to be] different depending on the motion of the observer? Is that right?

 

[Motor Daddy]

Now if I may test further, in regard to the carriage and embankment example. I now understand what a reference body is and the carriage or train is a reference body and the embankment is a reference body. Are you applying the reasoning that we just reviewed to the example of the train and the embankment by establishing two absolute points in space from which separate spherical light waves are expanding?

Yes. What we just established is a baseline for all absolute motion, so it is valid for the train as well as the embankment. Neither the train or the embankment are a preferred frame, it's just that in Einstein's example the embankment happens to be at an absolute zero velocity. We could make another example and the train would have an absolute velocity of 10 m/s and the embankment could have an absolute velocity of 40 m/s in the opposite direction. The relative motion between the train and the embankment would be 50 m/s.

And are you establishing the position of M on the embankment to coincide with the position of M' on the train at the moment that the light is emitted from the two absolute points in space? And if so then you are envisioning the motion of the train relative to the two separate expanding light spheres?

Correct, M and M1 are aligned when the strikes occurred simultaneously at A and B. The train's and embankment's absolute velocities are relative to the points in space that the lights were emitted. If the lights impact either observer simultaneously, that means that observer is at the midpoint of the original points in space that the lights were emitted, hence that observer had an absolute zero velocity. It just so happens that the embankment observer in this example is impacted by the lights simultaneously, so he had an absolute zero velocity.

If so you see M' moving toward one of the oncoming light spheres and away from the other oncoming light sphere from the reference body of the train?

Correct, the train observer is moving closer to the point in space that one light sphere was emitted, and further from the point in space that the other light sphere was emitted.

Edit: Are you pointing out that the point M' will reach the forward oncoming light sphere before the following oncoming light sphere which is agreed?

Yes, the train observer is traveling towards one original point in space and further away from the other original point in space that the lights were emitted. Since light travels at a constant speed, one light will impact him before the other light will impact him. Or, another way to state it is that he will no longer be at the midpoint between the original points in space that the lights were emitted simultaneously, due to his velocity during the time of light travel.

You explanation is that the motion of the train relative to the presence of the two expanding light spheres can be measured by reasoning and by doing so you can bring the two reference bodies into the same coordinate system and show that the speed of light is different depending on the motion of the observer? Is that right?

Correct.

 

[quantum_wave]

Yes. What we just established is a baseline for all absolute motion, so it is valid for the train as well as the embankment. Neither the train or the embankment are a preferred frame, it's just that in Einstein's example the embankment happens to be at an absolute zero velocity. We could make another example and the train would have an absolute velocity of 10 m/s and the embankment could have an absolute velocity of 40 m/s in the opposite direction. The relative motion between the train and the embankment would be 50 m/s.



Correct, M and M1 are aligned when the strikes occurred simultaneously at A and B. The train's and embankment's absolute velocities are relative to the points in space that the lights were emitted. If the lights impact either observer simultaneously, that means that observer is at the midpoint of the original points in space that the lights were emitted, hence that observer had an absolute zero velocity. It just so happens that the embankment observer in this example is impacted by the lights simultaneously, so he had an absolute zero velocity.



Correct, the train observer is moving closer to the point in space that one light sphere was emitted, and further from the point in space that the other light sphere was emitted.



Yes, the train observer is traveling towards one original point in space and further away from the other original point in space that the lights were emitted. Since light travels at a constant speed, one light will impact him before the other light will impact him. Or, another way to state it is that he will no longer be at the midpoint between the original points in space that the lights were emitted simultaneously, due to his velocity during the time of light travel.



Correct.

Then, if I understand the contention between you and Pete it is that he is attempting to convince you that your are wrong, not in the sence of the Special Theory and its axioms, but in the sence of your own axiom which we have just reviewed?

 

[Motor Daddy]

Then, if I understand the contention between you and Pete it is that he is attempting to convince you that your are wrong, not in the sence of the Special Theory and its axioms, but in the sence of your own axiom which we have just reviewed?

Pete is taking Einstein's postulate as true, and also assuming length contraction and time dilation, with no basis for using either, other than Einstein's method uses them.

So he basically starts off with the premise that time dilation and length contraction are postulates, along with the speed of light being measured to be the same in all frames, and also as an additional bonus, that two clocks can never be sync'd, that no experiment could prove an absolute motion, and that simultaneity doesn't exist.

I say, BS!! I say there is no way that the speed of light can be constant in space and at the same time be measured to be the same in all reference frames! That means Einstein's second postulate is wrong, hence his entire theory needs to be discarded.

 

[rpenner]

Mathematically, Einstein's postulate + Widely-held beliefs about symmetry of space-time => Lorentz Transform => Length Contraction + Time Dilation
AND
Length Contraction + Time Dilation => Lorentz Transform => Consistency of the speed of light + various statements of the symmetry of space-time

The claims are logically equivalent, in that if you take one, you get all the others.

 

[quantum_wave]

Pete is taking Einstein's postulate as true, and also assuming length contraction and time dilation, with no basis for using either, other than Einstein's method uses them.

So he basically starts off with the premise that time dilation and length contraction are postulates, along with the speed of light being measured to be the same in all frames, and also as an additional bonus, that two clocks can never be sync'd, that no experiment could prove an absolute motion, and that simultaneity doesn't exist.

I say, BS!! I say there is no way that the speed of light can be constant in space and at the same time be measured to be the same in all reference frames! That means Einstein's second postulate is wrong, hence his entire theory needs to be discarded.

I see .

I haven't followed the debate but I can see that if you and Pete are going in the directions that you describe, the conversation would be quite detailed and understanding each one's points would require having followed along, but ... it is not a discussion of the details of the train and embankment written by Einstein any longer, it is a discussion that has taken on a path of it own, a side track so to speak.

That resolves the question I had about why Pete felt the specific debate between you and him has been fogged up by all the late comers (maybe like me). Your discussion is taking on a new direction.

Do you plan to enter a formal debate, or will you pass on that. If you don't enter the debate are you interested in continuing to follow the path of the side discussion between you and Pete but in the normal thread context instead of a formal debate? And if so do you want to do that here or in a new thread?

 

[Tach]

I say, BS!! I say there is no way that the speed of light can be constant in space and at the same time be measured to be the same in all reference frames! That means Einstein's second postulate is wrong, hence his entire theory needs to be discarded.

You realize that no one gives a rat's a$$ about what you say, no?

 

[Motor Daddy]

I see .

I haven't followed the debate but I can see that if you and Pete are going in the directions that you describe, the conversation would be quite detailed and understanding each one's points would require having followed along, but ... it is not a discussion of the details of the train and embankment written by Einstein any longer, it is a discussion that has taken on a path of it own, a side track so to speak.

That resolves the question I had about why Pete felt the specific debate between you and him has been fogged up by all the late comers (maybe like me). Your discussion is taking on a new direction.

Do you plan to enter a formal debate, or will you pass on that. If you don't enter the debate are you interested in continuing to follow the path of the side discussion between you and Pete but in the normal thread context instead of a formal debate? And if so do you want to do that here or in a new thread?

I'm pretty sure Pete knows where I'm coming from, and so do you and James.

I spell out my method using the very definitions of distance and time, like I've done for you, and you can understand that. Pete and James are not going to admit that my way is correct and Einstein's ways are incorrect. That is simply not going to happen, it goes against everything they believe in. Pete will just ignore questions that he knows will lead to his demise. He will not take the logical road, because he holds Einstein's ways to be the truth, as if it were some absolute truth.

But we know, for a fact, that the constant speed of light and that objects can be in motion during the same duration of time means that the speed of light can not be measured to be the same in all reference frames. That is a contradiction in the most basic concept of distance and time. It simply can't happen.

 

[quantum_wave]

You realize that no one gives a rat's a$$ about what you say, no?

I take it you don't agree with how MD has explained what he means. And you are wrong to speak for everyone. At the very least this thread has entertainment value even if you don't want to put yourself inside MD's thinking.

I can see his thinking and can differentiate it from SR. That makes his view a separate theory with his own particular postulates and Pete apparently can see that too. The discussion of how to falsify MD's theory could be interesting.

 

[origin]

For crying out loud! How can this possible be described as a debate!?!

Motor Daddy says the relative speed of light will change depending on the velocity of the observer. This is wrong, the speed of light is always measured as the same value. Motor Daddy's explanation is that the measurements are wrong. There is nothing to debate.

If you think this is debatable then try this one. Larger objects fall faster than smaller object. Don't try to give me measurements - I will just say the measurements are wrong.

It is feaking ludicrous. It is like trying to having an intellectual discussion with an Ardvark.

 

[Tach]

If you think this is debatable then try this one. Larger objects fall faster than smaller object. Don't try to give me measurements - I will just say the measurements are wrong.

It is feaking ludicrous. It is like trying to having an intellectual discussion with an Ardvark.

You got the idea. I would replace Ardvark with my door jamb.

 

[quantum_wave]

I'm pretty sure Pete knows where I'm coming from, and so do you and James.

I spell out my method using the very definitions of distance and time, like I've done for you, and you can understand that. Pete and James are not going to admit that my way is correct and Einstein's ways are incorrect. That is simply not going to happen, it goes against everything they believe in. Pete will just ignore questions that he knows will lead to his demise. He will not take the logical road, because he holds Einstein's ways to be the truth, as if it were some absolute truth.

But we know, for a fact, that the constant speed of light and that objects can be in motion during the same duration of time means that the speed of light can not be measured to be the same in all reference frames. That is a contradiction in the most basic concept of distance and time. It simply can't happen.

Thank you for that update about how the participants feel or might feel.

I will comment from my view of reality that has very little rigor behind it, lol. The way you view the speed of light is logical but not measurable. And the ability to measure it doesn't center around length contraction and time dilation, IMHO. It centers around the coordinate system of the reference bodies. If I may add what I think you are saying, you are saying that reality can be described in a coordinate system that does not invoke hyperbolic geometry . Or is there more to it?

 

[quantum_wave]

For crying out loud! How can this possible be described as a debate!?!

Motor Daddy says the relative speed of light will change depending on the velocity of the observer. This is wrong, the speed of light is always measured as the same value. Motor Daddy's explanation is that the measurements are wrong. There is nothing to debate.

If you think this is debatable then try this one. Larger objects fall faster than smaller object. Don't try to give me measurements - I will just say the measurements are wrong.

It is feaking ludicrous. It is like trying to having an intellectual discussion with an Ardvark.

Maybe, but if you follow how MD's argument is developed then you know he is saying that a particular light sphere can be viewed from multiple reference frames. You must believe that is not true or you must believe that the speed of that particular expanding light sphere cannot be measured from more than one frame. Do you understand my point?

 

[Emil]

If the next "technology" is possible then I admit I was wrong and I will apologize.

Solar panels that provide electricity converted from the light.
Refractive indices of air 1.000277 speed of light in air c/1.000277
Refractive indices of ethyl alcohol (ethanol) 1.36 speed of light in ethanol c/1.361
http://en.wikipedia.org/wiki/List_of_refractive_indices

Due to length contraction, the light from ethanol "sees" length 28.8 times higher that the light from the air. (0.6783339/0.0235372)
Surface 28.8X28.8=829,4 times higher.
So if we dive in ethanol the panel, we obtain an energy of 829.4 times higher.

 

[rpenner]

Nevertheless, let us not assume that MotorDaddy or Einstein is right and push the agnostic version of Galilean/Special relativity for relative motion of observers in the agreed-upon X direction.

$$\begin{eqnarray} \Delta x' & = & \frac{\Delta x - v \Delta t}{\sqrt{1 - K v^2}} \\ \Delta y' & = & \Delta y \\ \Delta z' & = & \Delta z \\ \Delta t' & = & \frac{\Delta t - K v \Delta x}{\sqrt{1 - K v^2}} \end{eqnarray}$$

If $$\Delta x = u \Delta t$$ then this tells us that
$$u' = \frac{\Delta x'}{\Delta t'} = \frac{\Delta x - v \Delta t}{\Delta t - K v \Delta x} = \frac{u \Delta t - v \Delta t}{\Delta t - K u v \Delta t} = \frac{u - v}{1 - K u v}$$ as the "agnostic" law of velocity transformation.

If $$\Delta x = v \Delta t$$ then this tells us that $$\frac{\Delta t '}{\Delta t} = \frac{\Delta t - K v \Delta x}{\sqrt{1 - K v^2}} \times \frac{1}{\Delta t} = \frac{\Delta t - K v^2 \Delta t}{\sqrt{1 - K v^2} \Delta t} = \sqrt{1 - K v^2}$$.

If two parallel world lines are given by $$x - v t = C_1$$ and $$x - v t = C_2$$ then their transformed versions are given by $$x' = C_0 + C'_1 = C_0 + \frac{1}{\sqrt{1 - K v^2}} C_1$$ and $$x' = C_0 + C'_2 = C_0 + \frac{1}{\sqrt{1 - K v^2}} C_2$$ respectfully and so $$\frac{C'_2 - C'_1}{C_2 - C_1} = \frac{1}{\sqrt{1 - K v^2}} $$

MotorDaddy asserts that there is no length contraction, that there is no time dilation and there is no consistency in the speed of light. All of these are consistent with $$K = 0$$. This gives the MotorDaddy assertions that $$u' = u - v$$, $$\Delta x = v \Delta t \quad \Rightarrow \quad \frac{\Delta t '}{\Delta t}$$, and $$ x - v t = C_1 \quad \wedge \quad x - v t = C_2 \quad \Rightarrow \quad \frac{C'_2 - C'_1}{C_2 - C_1} = 1$$. This was the assumption of physics prior to the twentieth century and the approximate experimental picture based on low precision, low velocity experiments which was the bulk of the experimental record, at least prior to 1859.

FitzGerald asserted length contraction, and Lorentz eventually demonstrated for that to lead to consistent physics, $$K = \frac{1}{c^2}$$ in all the above places.

Einstein asserted $$c' = c$$ thus $$\frac{c - v}{1 - K c v} = c$$ thus $$c -v = c - K c^2 v$$ thus $$K = \frac{1}{c^2}$$.

// Edit -- Fixed K to be an actual expression.

As others divined from my partial post, the question is how can you assert K = 0, when Fizeau (1859), Michelson-Morley (1887) and every other high-precision experiment capable of distinguishing $$K = \frac{1}{c^2}$$ from $$K = 0$$ disfavors K = 0? You are welcome to your own opinions, not your own facts.

 

[AlexG]

I say, BS!! I say there is no way that the speed of light can be constant in space and at the same time be measured to be the same in all reference frames!

It's not so much that MD refuses to accept actual measurement and experiments, it's more that he never acknowledges there are any actual measurements and experiments.

He's more comfortable in his own reality than he is in the one the rest of the universe inhabits.

 

[quantum_wave]

Nevertheless, let us not assume that MotorDaddy or Einstein is right and push the agnostic version of Galilean/Special relativity for relative motion of observers in the agreed-upon X direction.

$$\begin{eqnarray} \Delta x' & = & \frac{\Delta x - v \Delta t}{\sqrt{1 - K v^2}} \\ \Delta y' & = & \Delta y \\ \Delta z' & = & \Delta z \\ \Delta t' & = & \frac{\Delta t - K v \Delta x}{\sqrt{1 - K v^2}} \end{eqnarray}$$

If $$\Delta x = u \Delta t$$ then this tells us that
$$u' = \frac{\Delta x'}{\Delta t'} = \frac{\Delta x - v \Delta t}{\Delta t - K v \Delta x} = \frac{u \Delta t - v \Delta t}{\Delta t - K u v \Delta t} = \frac{u - v}{1 - K u v}$$ as the "agnostic" law of velocity transformation.

If $$\Delta x = v \Delta t$$ then this tells us that $$\frac{\Delta t '}{\Delta t} = \frac{\Delta t - K v \Delta x}{\sqrt{1 - K v^2}} \times \frac{1}{\Delta t} = \frac{\Delta t - K v^2 \Delta t}{\sqrt{1 - K v^2} \Delta t} = \sqrt{1 - K v^2}$$.

If two parallel world lines are given by $$x - v t = C_1$$ and $$x - v t = C_2$$ then their transformed versions are given by $$x' = C_0 + C'_1 = C_0 + \frac{1}{\sqrt{1 - K v^2}} C_1$$ and $$x' = C_0 + C'_2 = C_0 + \frac{1}{\sqrt{1 - K v^2}} C_2$$ respectfully and so $$\frac{C'_2 - C'_1}{C_2 - C_1} = \frac{1}{\sqrt{1 - K v^2}} $$

MotorDaddy asserts that there is no length contraction, that there is no time dilation and there is no consistency in the speed of light. All of these are consistent with $$K = 0$$. This gives the MotorDaddy assertions that $$u' = u - v$$, $$\Delta x = v \Delta t \quad \Rightarrow \quad \frac{\Delta t '}{\Delta t}$$, and $$ x - v t = C_1 \quad \wedge \quad x - v t = C_2 \quad \Rightarrow \quad \frac{C'_2 - C'_1}{C_2 - C_1} = 1$$. This was the assumption of physics prior to the twentieth century and the approximate experimental picture based on low precision, low velocity experiments which was the bulk of the experimental record, at least prior to 1859.

FitzGerald asserted length contraction, and Lorentz eventually demonstrated for that to lead to consistent physics, $$K = {1}{c^2}$$ in all the above places.

Einstein asserted $$c' = c$$ thus $$\frac{c - v}{1 - K c v} = c$$ thus $$c -v = c - K c^2 v$$ thus $$K = {1}{c^2}$$.$$$$

$$$$Yikes Rpenner, you have taken us to the equations. I'll just have to accept that part but I would like to hear MD confirm that that he asserts that there is no length contraction, that there is no time dilation and there is no consistency in the speed of light. I think you have him wrong but maybe not; I haven't followed long enough to know.

What about it MD. Do you confirm that there is no time dialtion for example. There is ample proof that clocks in different relative motion will measure time at different rates. That may not be time dilation but I think it is evidence that is used to support it. What do you say MD?$$$$

 

[Pete]

So you deny a light can be emitted at a point in space?? You're going off the deep end to defend Einstein's postulate, and he is leading you down the wrong road, Pete.

I deny a point in space can be identified without reference to an object.

MD, you can't argue with hard data.
The speed of light is measured to be the same in all reference frames.

That's reality.

You're wasting your own time chasing your tail in circles defending Einstein's second postulate. You don't want to answer my questions because you know you can't defend Einstein's position when you honestly answer my questions, so you avoid them.

Rubbish, MD.
My time is wasted chasing you in circles, because you can't honestly consider the possibility that the world doesn't work the way you want it to.

Get hard data, MD. Either measure it yourself, or read about real experiments. It's out there.

What time did the race start, Pete? Suddenly you have time again to talk about the subject?? Shouldn't you be preparing for the exams?

Yes, I should be preparing for exams. Procrastination is ruining my life.
I gave up on our discussion because following through your sidetracks is a tremendous waste of time.
Take the time the race started, for example.
It's irrelevant. The race was run separately. They didn't necessarily start at the same time. If you think it's important, then you pick a starting time yourself, and follow it through.

Stop wasting my time.

 

[Neddy Bate]

I say there is no way that the speed of light can be constant in space and at the same time be measured to be the same in all reference frames!

Hello MD,

Are you aware of how the Global Positioning System (GPS) works? There are a bunch of satellites in orbit around the earth, and they have very accurate clocks on board. They also have radio transmitters that constantly emit signals with their time and location relative to the earth. These radio signals arrive at the surface of the earth, and GPS devices (such those in your car) are able to triangulate your location on earth by comparing the signals from a number of GPS satellites. The timing of the signals requires nanosecond accuracy in order for the location to be calculated accurately.

But your "theory" predicts that the speed of radio waves (light) in different directions changes throughout the year, due to the earth's absolute velocity. Since no one else in the world of physics is aware of this, the GPS devices do not account for absolute velocity at all.

Now. Can you explain how the GPS system maintains its accuracy without accounting for absolute velocity at all? Thanks.