Is Faster-Than-Light Travel Possible Relative to Other Celestial Bodies?

[GoodPR]

If two planets were traveling at .99c away from a planet in the center. What would be the speed difference between them?

If you were on one of those traveling planets and launched a rocket in the direction you were already travelling, you could get it to go .99c away from you. If you related that rocket to the planet in the middle it's now traveling at 1.98c correct?

You may say that's not possible, but If you didnt compare yourself to the planet in the middle, you wouldn't even know how fast your travelling. Similarly how do we know which direction and how fast Earth is actually moving? We could send a rocket .99c relative to us in any direction we want, that could be traveling faster than light relative to another celestial body.

Its true that you cannot travel past the speed of light, because light always travels light speed away from you, but it seems can you travel faster than light, relative to another stationary body.

 

[stovepipe]

If two planets were traveling at .99c away from a planet in the center. What would be the speed difference between them?

If you were on the planet in the middle, the distance between them would appear to grow faster than c. If you were on either of the other planets the distance would appear to grow at less than c.

 

[stovepipe]

If you were on one of those traveling planets and launched a rocket in the direction you were already travelling, you could get it to go .99c away from you. If you related that rocket to the planet in the middle it's now traveling at 1.98c correct?

No, it's still traveling at less than c. To the observer on the planet that launched the rocket, the distance between the rocket and the middle planet would appear to be growing faster than c.

You have to use the velocity addition formula to calculate the speed of the rocket with respect to the middle planet. It will always come up less than c.

Distances are allowed to grow faster than c because they do not have mass. Rockets and planets have mass, so they cannot travel faster than c.

 

[stovepipe]

If you want more information, read this http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html

 

[GoodPR]

This is because of the difference in the passage of time when stationary vs. traveling at near light speed correct?
Distance itself is also either compressed or expanded as well as time, when looking at the planet from either in front or behind it?
Because mass increases with speed, if something with mass x traveled at me at .99c its mass would increase, and the distance it occupies is smaller.
Could it travel with high enough velocity that to me it appears to be a black hole because of its incredible mass and shrunk distance?

 

[Phrak]

If two planets were traveling at .99c away from a planet in the center. What would be the speed difference between them?

The difference (actually the addition) of velocites as measured by the planet in the middle is what addition has always been.

If you were on one of those traveling planets and launched a rocket in the direction you were already travelling, you could get it to go .99c away from you. If you related that rocket to the planet in the middle it's now traveling at 1.98c correct?

This is where addition of velocites will fail you. Velocities do not combine in special relativity by the addition of vector components in this scenario. Maybe someone can supply an equation for the combination of velocities.

 

[GoodPR]

Yes phrac stovepipe explained that to me, thank you. Got an idea for my question in my last post?

 

[GoodPR]

I wanted to say two things I picked up on in that link you sent me stove pipe.
That one, relativity and Einstein did not directly say that FTL is not possible only that it would require infinite energy to do so.
Also, that velocity can only be measured in reference to something else.
So let's say I'm the only thing in the universe, I could accelerate at 1g constantly, why would my mass increase as I approached light if for all I know I could be standing still?

So, then if I were in a black hole, with nothing to compare my speed to, I could accelerate indefinitely without adding mass. Which is why I asked the question, if something were traveling at you nearly light speed, is it possible that it could appear as a black hole.

 

[russ_watters]

That one, relativity and Einstein did not directly say that FTL is not possible only that it would require infinite energy to do so.

Which means the same thing...

Also, that velocity can only be measured in reference to something else. So let's say I'm the only thing in the universe, I could accelerate at 1g constantly, why would my mass increase as I approached light if for all I know I could be standing still?

According to you, your mass never increases. Relativity effects are something that exists between two reference frames - like velocity.

So, then if I were in a black hole, with nothing to compare my speed to, I could accelerate indefinitely without adding mass. Which is why I asked the question, if something were traveling at you nearly light speed, is it possible that it could appear as a black hole.

I still don't know what a black hole has to do with anything, but yes, you can accelerate forever at 1g if you could find a a power source to do it. But that doesn't mean you'll ever get to C.

[edited to fix quotes]

 

[GoodPR]

Sorry, that didn't entirely answer my question, could I accelerate so that I had so much mass I would be perceived as a black hole from whatever I'm traveling towards.

 

[Nabeshin]

Maybe someone can supply an equation for the combination of velocities.

In one dimension,
Frame S' moving with velocity v with respect to frame S,
Object moving with velocity u' with respect to frame S', u with respect to S:
<br /> u=\frac{u&#039;+v}{1+\frac{v u&#039;}{c^2}}<br />

<br /> u&#039;=\frac{u-v}{1-\frac{v u}{c^2}}<br />

 

[eekf]

Light speed is the speed of light in a vacuum. The way theat Einstein originally (1905) came to the conclusion that light speed can not be exceeded basically boils down to providing energy using light to an object and then trying to accelerate it to faster than light. This can not be done. If the object is going faster than light, the light you use to supply the energy with can not catch the object.

You have to understand that once emitted, the light is not connected to the emitter or the receiver. It travels at its own speed, independent of any observer, only link to the medium it is in. You can compare this with sound traveling through water. Once you emit the sound, it travels at a fixed speed independent of the boat you are on.

Therefore, even if you are traveling at -0.99c (with regards to Earth) and sending a radio message to your friend traveling at 0.99c in the other direction, your message will be traveling at c in the medium (vacuum) and will eventually reach your friend.

For a comparison, if you were traveling at 300 m/s through the atmosphere and your friend passes you at -300 m/s, if you shout a message, it will still be heard by your friend, as the sound travels at 330 m/s irrespective of your velocity.

If you and your friend were blind (and could not detect any electromagnetic waves), you would have to measure time somehow. You can decide to measure time through a "click" every second. If you are brilliant, you can derive a set of equations where the speed of sound is constant irrespective of the observer (which it is). However, you need a way to synchronise your clocks. A clever way to do this would be to transmit a click to an object which is stationary with respect to you, get the reflection of the click and divide the time by 2 to get the distance to the reflecting object. Now that you know the distance, you can synchronise your clocks. You would not be able to synchronise your clocks if you were moving faster than sound though, as your reflected click would not be able to get back to you or reach the object, depending on whether or not the reflecting object is in front or behind you.

This will lead you to a Lorentz transformation with s (the speed of sound) as your maximum speed. This is not a physical limitation though. All it would mean is that if somebody was to shoot you, you would probably feel the shot before you hear it. In your reference frame, the bullet would hit you before the shot went off.

Whether these ramblings point you to if it is possible to move faster than light, only you can tell. I do know that if there was something moving faster than light, we can not detect it (our eyes being sensitive to light). We would also have trouble with causality. We would therefore struggle to find cause and effect.

 

[A.T.]

You have to understand that once emitted, the light is not connected to the emitter or the receiver. It travels at its own speed, independent of any observer, only link to the medium it is in.

Light doesn't need a medium.

You can compare this with sound traveling through water. Once you emit the sound, it travels at a fixed speed independent of the boat you are on.

No, the speed you measure for the sound in your frame depends on how fast you move relative to the water (the medium). This is very different from light, where every inertial observer measures the same speed of any light ray in vacuum.

 

[eekf]

Quite the contrary.

If I have two boats moving in the same direction at a fixed distance from each other and define c as the speed of sound in the water, I can use the Lorentz transform exactly, provided I define my clocks and synchronisation according to c. Just remember you have to also measure distance using the sound (actually you set your clocks according to sound and then measure distance according to your clocks on the two boats).

Einstein used this method in 1905 (only using light instead of sound). The consequence of the transform is that you do not need to have a velocity relative to an absolute medium. You just need relative velocities between two boats.

 

[eekf]

Light doesn't need a medium.

No, the speed you measure for the sound in your frame depends on how fast you move relative to the water (the medium). This is very different from light, where every inertial observer measures the same speed of any light ray in vacuum.

If the vacuum is not a medium, you are right.

Actually I meant the speed is not linked to the speed of the boat when you emitted the sound or the speed at which you are receiving it.

In order to measure the one-way speed of sound/light, you need to have synchronised clocks. Einstein's method for sychronising the clocks was to have light travel in both directions (reflected) to measure distance between two "stationary" objects and divide it by. You then use the "constancy" of the speed of light to determine the distance. This you can then use to synchronise the clocks, allowing you to measure lengths.

If I follow exactly the same procedure with sound, I can use exactly the same transformations.

 

[vin300]

You used a complete analogy of light as sound and that is a disaster.The speed of sound is constant,true.
But you cannot use the lorentz trnsform with the speed of sound instead of c because that simply gives a completely different interpretation of theLT so all the concepts in relativity change altogether.
You can definitely travel faster than sound but not if used this way, so it is plainly false
To measure velocities with sound you can only use the doppler effect but the frequency becomes ultrasonic at comparatively very less velocities.
Sound does not bend as light to make up transformations.It follows the same path in every frame

 

[eekf]

You used a complete analogy of light as sound and that is a disaster.The speed of sound is constant,true.
But you cannot use the lorentz trnsform with the speed of sound instead of c because that simply gives a completely different interpretation of theLT so all the concepts in relativity change altogether.
You can definitely travel faster than sound but not if used this way, so it is plainly false
To measure velocities with sound you can only use the doppler effect but the frequency becomes ultrasonic at comparatively very less velocities.
Sound does not bend as light to make up transformations

Please do not blame me for interpretations people make.

I am only making observations with respect to the LT and the way Einstein set up the original derivations in his paper. I also show you new ways (actually not that new) to use the same mathematics.

I believe that is actually progress. May I just note that there was a time when people believed it impossible to move faster than sound (and for that matter that the Earth was flat).

Many people believe you can not move faster than light (most of them because of the Lorentz transformation and Einstein's derivation. I personally have no opinion on this matter. I believe it is impossible to tell. I am merely suggesting that you do not have to limit yourself because of the Lorentz transformation. Maybe somebody finds a way...

If a scientist tells you something is possible, he is probably right. If he tells you something is impossible, he is probably wrong...

 

[vengy]

Can light speed be exceeded? Tug-Of-War

I've often wondered that too. The speed of light in a vacuum is 299 792 458 m/s.

Recently I was thinking of this example:

In a game of tug-of-war, suppose the rope is 299 792 458 m in length and
the players pulled on it. Would both teams have to wait at least 1 second
before the affect of a tug reached the opposite end? Or would the tug effect
be propagated instantaneously thereby violating the speed of light? ;)

Just curious!

Thanks.

 

[Dmitry67]

Yes, of course they will have to wait.
And the pull or push impulses propagate with the speed of sound (usually few km/s), so in your example the game would be quite boring.

 

[vin300]

And the pull or push impulses propagate with the speed of sound (usually few km/s), so in your example the game would be quite boring.

First, he was talking of the speed of light and second, the speed of the impulse has nothing to do with either light or sound speed, this was discussed in an earlier thread
The tug affect woud be propogated instantaneously if none of the masses on the tug reaches close to light speeds(the masses on the tug increase with speed and such speeds also require more force than the trditional calculations) but this does not violate nothing because no mass trvels faster than c

 

[Dmitry67]

no impulse can travel faster then c because it carries INFORMATION (even if parts of the rope move slower then c). So if you were right ('woud be propogated instantaneously ') then you would be able to use a rope to send info using Morse code instantaneouly :)

 

[DrGreg]

Dmitry67 is right. "Causal effects" can never travel faster than light. Event A cannot influence event B if you would have to travel faster than light to travel from A to B. If it were possible to do that, the maths proves that it would also be possible to send influence backwards in time.

And, yes, the speed at which pressure or tension travels through a solid, liquid or gas is the speed of sound. Sound is a pressure wave.

 

[vengy]

I'm assuming the rope is "ideal" and not subject to tension/pressure/friction, and the game is being played in a vacuum. ;)

 

[Dmitry67]

In special relativity (contrary to the classical mechanics) no ideal, absolutely rigid objects (including ropes) exist.
So SR does not allow your 'ideal' rope to exist.

 

[A.T.]

Many people believe you can not move faster than light (most of them because of the Lorentz transformation and Einstein's derivation. I personally have no opinion on this matter. I believe it is impossible to tell.

Yeah: Some people say Elvis is dead, some say he's still alive. But I'm a skeptic and don't believe neither the first not the later.

- A sound-signal propagates at different speeds in different directions if the medium is moving in the reference frame.

- A light-signal propagates at the same speed in all directions in every inertial reference frame.

Sound are light are not the same.

 

[Phrak]

Light doesn't need a medium.

No, the speed you measure for the sound in your frame depends on how fast you move relative to the water (the medium). This is very different from light, where every inertial observer measures the same speed of any light ray in vacuum.

It's certainly not a classical medium that can have two natural velocities: a zero velocity in which the medium is at rest, and the velocity at which waves propagate. Spacetime seems to have only one natural velocity.

 

[stovepipe]

Spacetime seems to have only one natural velocity.

Would it be wrong to assert, that the speed of light is the rate at which change in space-time occurs?

 

[Phrak]

I'm already pushing the boundries of this folder toward the philosophical. Afterall, what in the world does 'natural' velocity mean, anyway?

But what would you mean by change--that is, change with respect to what?

 

[Wangf]

Space itself can expand faster than light speed. This is exactly what is happening to those galaxies running away from us faster than light.
it does not violate anything in relativity.

 

[Phrak]

Space itself can expand faster than light speed. This is exactly what is happening to those galaxies running away from us faster than light.
it does not violate anything in relativity.

Could you supply a list of effects that are faster than c?

 

[GoodPR]

As for you guys arguing about sound, I don't know about in a mathmatical way, but in a thought experiment way sound is identical to light.
As someone moving very quickly towards you emits a sound, the sound waves compress giving a higher pitched sound with more energy, and opposite when they move away from you.
Light does the same, the wavelength compresses and it gives you more energy,
And in both cases sound or light shone at you from perpendicular to the object is unchanged.


my question remains however,
Can you travel with enough velocity towards Earth, that from Earths perspective, you would appear as a black hole, (because of your incredible mass).

 

[GoodPR]

Also, in closer relation to the title of the thread,
If I am accelerating at a rate that feels like 1 g constantly it would provide me with a constant acceleration regardless of how fast I am going,

It is known that the faster you travel the more mass you accumulate, however we know that the rocket itself will never feel itself to have more mass, because it is always in a rest frame.
Therefor, traveling closer and closer to the speed of light, will not require more rocketfuel to maintain the 1g acceleration, from the perspective of the rocket itself. It is only the time that rocketfuel burns for, that changes relative to the rocket and Earth. From the rockets perspective it burns 1 kg of fuel persecond.
From Earth perspective it burns 1kg of fuel per .1 second, or whatever.

Therefor, if accelerating at 1g took 2 years to reach light speed relativity excluded, if we gave the rocket 3 years of fuel, the rocket would feel as though it is traveling faster than light compared to Earth, even though from the rockets perspective light is still traveling light speed away from the rocket, and from the Earths perspective we have not attained light speed.

And the method which allows all of this to be true at the same time without violating relativity, is that the relative mass would play an increasing role in balancing the passage of time, so that all parties can experience the same things, without any laws being violated.

In the case where the rocket thinks its going faster than light based on its acceleration over time, from Earths prospective the rocket would appear to be a black hole moving towards earth, at less than light speed. From the rockets perspective, Earth would appear to be a black hole moving towards him at less than light speed.
Due to the warping of space time of the black holes nothing is violated.

 

[russ_watters]

If a rocket had an inertial navigation system that was programmed to calculate velocity via v=a*t, then yes, it could calculate a velocity faster than C. But so what? That just means it was programmed wrong.

 

[GoodPR]

Not entirely true.
Rest mass does not change in any frame regardless of your velocity, and time always ticks by at 1 second per second.
So for the sake of the rocket, that would be an accurate measurement of its true velocity.

It is only when you want to compare your velocity with something else that you need to account for relativity.(which obviously for the case of a rocket is always true)
Since we know that the rocket's rest mass never changed, it is time that is different between the rocket and the observer. The rocket perceives itself buring 1 kg of fuel per second. However on Earth it seems to burn 1kg per 0.1 seconds, or whatever.

Since Light speed is a constant regardless of your velocity or gravity, I believe you could relate your speed directly to that, when you reach the speed of light based on your simple formula, I believe any photon you are emitting directly in front of you would either double in Energy or become two photons as observed by the stationary object your traveling towards.
Keep in mind that despite the simple calculation showing your going faster than light, I'm not claiming light doesn't move light speed away from you in all directions.

 

[russ_watters]

Not entirely true.
Rest mass does not change in any frame regardless of your velocity, and time always ticks by at 1 second per second.
So for the sake of the rocket, that would be an accurate measurement of its true velocity.

No, it wouldn't - otherwise, you could plug that number into appropriate equations and get nonsensical responses. Velocity is something you measure between two objects.

What you would be measuring is rapidity: http://en.wikipedia.org/wiki/Rapidity

 

[GoodPR]

Did you read what you quoted and stop? Because I immediately said the same thing as you did after the quote.

 

[eekf]

I am going to comment on quite a few submissions made before.

1. There will be no Doppler shift between two objects moving at the same velocity whether you are using sound in a medium propagating sound or a medium (or non-medium) propagating light. There will be a Doppler shift on the transmit side, and the inverse at the receive side.

2. You would be able to set up an experiment such as the Michelson-Morley experiment for both environments. When you do this (remembering that we actually know that the speed of sound can be exceeded) you can now check to see if you can measure a speed relative to an "absolute rest" environment, which in the case of sound would be the medium.

However, what becomes suddenly clear if you use the sound environment, is that the sound going 90 degrees to your velocity, will not reach you when reflected. In order for the sound you send sideways to reach you, you have to send it slightly ahead of you, depending on your speed. If you travel close to the speed of sound in the medium, it will only reach you if you send it out close to straight ahead.

Apart from the distance increase of the path in the moving frame, you will therefore also have a Doppler shift in the 90 degree arm which will increase in relation to your velocity (wrt the medium), corresponding (either totally or to a large degree) with the shift in phase you are expecting because of the longer path length the light has to travel in an "absolute frame" when your velocity relative to this frame increases.

Interference will be in the "absolute rest" frame, before you measure your intervals. You may also have to consider the phase shifts and possibly Doppler effects at the "mirrors".

I have not checked these calculations, but have been lead to believe that you get a Null result for all velocities. Please do not quote me on this. I have the document where this is described by an 80 year old scientist, but have not worked through it. Do the calculations.

3. Assuming the constancy of the speed of light through the vacuum (or sound in a sound medium) is a fact (and we have very little if anything to doubt this), the question becomes if the speed of light in each reference frame is aconstant in both directions. The Lorentz transformation assumes this to be true and then just works with the speed of light c.

Now it is important to consider this: I can either assume the speed of light in both directions is c constant in any moving frame, and use the average of the time to an object and back to determine the distance, or I can assume that they are different, but that by assuming it constant I can have a model which describes mathematics for any frame without knowledge of my velocity relative to my "absolute rest" frame, bearing in mind that I might get some discrepancies.

The part I struggle with most when assuming that the actual relative speed of light is the same in both directions, is the Sagnac effect. The Sagnac effect is used in (amongst others) laser Gyro's and is also needed in keeping the GPS system up to date. In gyro's it is used to send light in two directions to come back to the starting point, where the difference in travel time between the two pulses are measured, when the gyro is rotating.

I have read that SRT explains this effect just as well as other models because the "extra" length causes the time difference. If I evaluate a small straight section of the gyro, I can however not find how to explain this if the assumption is that the constant c is the same in both directions. The velocity of the environment is constant. There should therefore not be any path length difference between the directions the light is traveling in according to SRT.

4. I want you to understand that I am not claiming that it is possible to move faster than light. If atoms are actually held together through EM fields (as we believe currently), and there is a "preferred absolute reference frame" (which most mainstream modern scientists do not believe), the atoms may actually fly apart when approaching or exceeding light speed.

I am saying that the Lorentz transformation prevents traveling faster than the speed of light, but that the mathematical models we use to represent the world has restrictions and assumptions (believes) built into them. We have to try and understand those restrictions.

We humans have a tendency to restrict ourselves with our own knowledge or beliefs. When we "know" it is impossible to go faster than light or for an object to be heated by a colder object or for energy to be created, we tend to overlook opportunities.

The more knowledge we accumulate, the more we tend to restrict ourselves by what we know. Most of the times we do not even realize that we have made a subtle change to what we assume (believe), and that that change is restricting us.

5. I am not trying to start a new belief or theory.

 

[jreelawg]

My take is that relativity only makes sense mathematically not intuitively.

 

[Razzor7]

My take is that relativity only makes sense mathematically not intuitively.

It makes as much intuitive sense as any theory. It's just wha' happens.

 

[GoodPR]

EEkf
I don't even see what your trying to say, everything you said appeared to be in agreeance with all modern theories, the only thing you seemed to make a statement on was that the more knowledge we seem to gain, the more we close our minds to other knowledge. On that I'd have to agree, I think any GUT out there is going to be a simple equation, at face value.

 

[eekf]

My take is that relativity only makes sense mathematically not intuitively.

The only way I could understand it was to plot a spacecraft traveling at 0.8c and emmitting a "spherical" light pulse every second. After 4 seconds (as seen from a stationary frame), I drew the position of the light pulses with compasses. I ended up with a drawing looking exactly like the drawings in high school physics books representing the sound waves of an aircraft approaching the speed of sound.

The problem comes in if you consider the positions of the light pulses from the spacecraft 's point of view. If you use the same clock synchronisation (not rate) in the spacecraft 's reference frame, you end up with the first light pulse being much further behind the spacecraft than in front of it. In addition, the light pulse behind would seem to have traveled much faster than the speed of light (actually 1.8c).

If you use this mathematical model, you end up with calculations which have the speed of light dependent on the direction you are traveling in and not isotropic. By adjusting your clocks, you can however rescale to have the light in both directions move at c. You end up that you have to change the scaling of your x-axis as well as your clocks if you want the transformation to be consistent through all reference frames.

If you consider the same setup for sound in air, you realize that the ony reason you can (or have to) do this is because the speed of sound in the medium is a constant, independent of your relative movement. If the air was traveling with you (i.e. in a closed van), you can use the same transformations, but the speed of sound (as viewed from outside the van) would not be isotropic.

 

[eekf]

EEkf
I don't even see what your trying to say, everything you said appeared to be in agreeance with all modern theories, the only thing you seemed to make a statement on was that the more knowledge we seem to gain, the more we close our minds to other knowledge. On that I'd have to agree, I think any GUT out there is going to be a simple equation, at face value.

Actually what I am saying is not in complete agreeance with modern theories, or should I say better: the interpretations given to modern theories.

Consider a spacecraft 1 lightsecond long with two independent atomic clocks (one in the front and one in the back) which is synchronised when it is in "a stationary Earth" reference frame. It then accelerates to a speed of 0.9c. Once stabilised at this speed, a light pulse is sent from the front to the rear at t=0 and reflected back to the front from the rear.

I am saying that the time difference measured between transmitting from the front till reflection at the rear will be much lower than the time difference measured from the reflection to the reception at the front.

As such I am saying that clocks have to be re-synchronised after reaching 0.9c for c to be measured constant in both directions.

I believe most modern interpretations are that the clocks will stay synchronised because they are in the same reference frame.

 

[matheinste]

eekf,

But your interpretation would allow you to detect absolute motion.

Matheinste

 

[eekf]

eekf,

But your interpretation would allow you to detect absolute motion.

Matheinste

Possibly. I believe experiments like this have been done. See http://xxx.lanl.gov/abs/astro-ph/0608223.

 

[eekf]

eekf,

But your interpretation would allow you to detect absolute motion.

Matheinste

Another recent paper: http://blog.hasslberger.com/docs/Cahill_Experiment.pdf.

The conclusions of this paper (amongst others):
1. Speed of light is anisotropic (eight different experiments).
2. Fitzgerald-Lorentz contraction is real effect in interferometers.

It might be that if the Doppler shift because of the fact that the 90 degree light in the arm in interferometer equipment can not come back to interfere (interference can only be with light that is not at 90 degrees and angle is dependent on v) might even indicate no contraction needed.

 

[Ich]

I believe most modern interpretations are that the clocks will stay synchronised because they are in the same reference frame.

I believe that
1. Interpretations must not disagree on facts, therefore, if your "interpretation" does not agree with mainstream results, it is a disguised ATM theory.
2. If ATM proponents would spend only a tenth of their effort disproving the mainstream on actually learning what it says, there'd be no more ATM proponents.

Please calculate your example in SR, and present the result here. If you can't, you're surely not in a position to challenge anything. If you can, your "belief" is moot.

 

[vin300]

Here's the values:If 0.9c is its velocity, the timr taken from front to back in the frame of reference of the ship is 1/1.9s which is 0.52s and the time taken for the reverse is
1/0.1s,i.e. 10s

 

[eekf]

I believe that
1. Interpretations must not disagree on facts, therefore, if your "interpretation" does not agree with mainstream results, it is a disguised ATM theory.
2. If ATM proponents would spend only a tenth of their effort disproving the mainstream on actually learning what it says, there'd be no more ATM proponents.

Please calculate your example in SR, and present the result here. If you can't, you're surely not in a position to challenge anything. If you can, your "belief" is moot.

I agree with vin300's calculation.

I would like to know what you believe the whole purpose of clock (re-)synchronisation in each reference frame is, if it is not to get c isotropic?

Please tell me what ATM theory is about. I do not know it. I am not trying to disguise any theory. I am trying to make sense of what I see - especially in the mathematics.

 

[matheinste]

I agree with vin300's calculation.

I would like to know what you believe the whole purpose of clock (re-)synchronisation in each reference frame is, if it is not to get c isotropic?

Isn't this reasonong back to front. Clocks in a common inertial reference frame are synchronized to make them show the same time,not to make light speed isotropic. The standard synchronization process depends on the average of the two way directional speed of light being constant which it assumed to be. If clocks are not first synchronized how can you measure speed.

vin300's calculation assumes that the light inside the spaceship travels different distances. It does not. Light emitted from the centre of the ship travels the same distance from emitter to front and back to emitter as it does from emitter to rear and back to emitter.

Matheinste

 

[vin300]

vin300's calculation assumes that the light inside the spaceship travels different distances. It does not. Light emitted from the centre of the ship travels the same distance from emitter to front and back to emitter as it does from emitter to rear and back to emitter.

Matheinste

Er a little misconception Light inside the spaceship does go different distances in the f of stationary observer because the spaceship itself is in motion.If you'd like to know how derive it's simple t(back to front) is [L/c-v ]t(f to b) is [L/c+v]