The Underlying Problem With Some Science Is Interpretation.

[xyz]

Crap!!! I made another mistake, this one's not as important. B needs to move at three quarters the speed of light, not half. B is moving away from A at half the speed of light. The whole thing should look like this.

 

 

Step 1:

A is moving at 25mph relative to the road. B is in front of A and is moving at 75mph relative to the road. C moves past A at 75mph. What speed does B observe C overtaking them?

 

Answer: 25mph.

 

 

Light moves past every non accelerating (inertial observer at the same relative velocity. Let's slow down light (C) to 100mph but keep its speed constant, so...

 

Step 2:

A is moving at 25mph (.25c / quarter the speed of light) relative to the road. B is in front of A and is moving at 75mph (.25c / three quarters the speed of light) relative to the road. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

 

Step 3:

The only way to get C to move past A and B at the same velocity is through length contraction and time dilation.

 

 

Solution 1:

If B is time dilated from A's perspective so that B is moving through time at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B.

 

This works because now B would observe C moving past them (moving past themselves) at the same speed that A observed C moving past them (moving past themselves).

 

 

Solution 2:

If B is length contracted from A's perspective so that B is moving through space at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B.

 

Again, this works because now B would observe C moving past them (moving past themselves) at the same speed that A observed C moving past them (moving past themselves).

 

 

Real Solution:

Time dilation and length contraction are always equal so you just have to get the square root of what the TD or LC would need to be on their own because velocity is distance over time so the effect of TD and LC are multiplied together.

 

 

 

Yes! You're using the word 'subjective' in the wrong context yet again, you say that light moves a c relative to all inertial objects but not if you're moving towards the sun (wtf!), you seem unable to understand simple scenarios and you're assuming your own inability to comprehend this is because everyone else is wrong (hilarious and infuriating at the same time).

 

:fool: Start again.

 

 

Step 1:

A is moving at 25mph relative to the road. B is in front of A and is moving at 75mph relative to the road. C moves past A at 75mph. C moves past B at 25mph.

 

 

From A's perspective C moves past themselves at 75mph and still from A's perspective, C moves past B at 25mph.

 

From B's perspective C moves past A at 75mph and moves past themselves at 25mph. Both perspectives are the same so no time dilation and length contraction.

 

 

 

Step 2:

Light moves past every non accelerating (inertial observer at the same relative velocity. Let's slow down light (C) but keep its speed constant, so...

 

A is moving at 25mph (0.25c / quarter the speed of light) relative to the road. B is in front of A and is moving at 75mph (0.75c / three quarters the speed of light) relative to the road. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

 

Unlike the first example, C passes A at the same speed that C passes B. From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

 

 

Do you understand that?

You are talking about relative speed of course I understand what you are saying/getting at.  However the objective , actual speeds relative tot he road, you already state so I know the speeds of the vehicles.  So the vehicles speeds are as you stated, there is no change in the speeds of either vehicle. Perspective does not mean actual . 

The stars in the night sky look quite close, but if I further investigate it would take me light years to get there. 

What you are explaining is trivial and pretty meaningless to reality.  

And light passes at c  regardless of relative speed , the light is c constant, it travels at c past the vehicles, but relative to the vehicles there is an illusion of different speeds.  The trained eye knows the light is travelling at c, but also knows the distance between point sources , i.e the vehicle and light source is relatively contracting because that is the direction of travel.

[A-wal]

And light passes at c  regardless of relative speed , the light is c constant, it travels at c past the vehicles, but relative to the vehicles there is an illusion of different speeds.  The trained eye knows the light is travelling at c, but also knows the distance between point sources , i.e the vehicle and light source is relatively contracting because that is the direction of travel.

Okay you're getting there, slowly. There's one BIG hurdle you now need to jump. If you do I'll be so proud and you'll never look at time and space in the same way again. Ready?

 

You are talking about relative speed of course I understand what you are saying/getting at.  However the objective , actual speeds relative tot he road, you already state so I know the speeds of the vehicles.  So the vehicles speeds are as you stated, there is no change in the speeds of either vehicle. Perspective does not mean actual .

There's no need to use the road. :) Think about that for a moment. It's a completely arbitrary coordinate system to give you a familiar frame of reference that I snuck out of the final step. This is what matters:

 

Unlike the first example, C passes A at the same speed that C passes B. From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

 

No mention of velocity relative to the road, it can be whatever you want it to be, it makes sod all difference. ;) Here it is without it:

 

Step 2:

Light moves past every non accelerating (inertial observer at the same relative velocity. Let's slow down light (C) but keep its speed constant, so...

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 50mph (0.5c / half the speed of light) relative to A. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

Unlike the first example, C passes A at the same speed that C passes B. From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

[xyz]

Okay you're getting there, slowly. There's one BIG hurdle you now need to jump. If you do I'll be so proud and you'll never look at time and space in the same way again. Ready?

 

There's no need to use the road. :) Think about that for a moment. It's a completely arbitrary coordinate system to give you a familiar frame of reference that I snuck out of the final step. This is what matters:

 

Unlike the first example, C passes A at the same speed that C passes B. From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

 

No mention of velocity relative to the road, it can be whatever you want it to be, it makes sod all difference. ;) Here it is without it:

 

Step 2:

Light moves past every non accelerating (inertial observer at the same relative velocity. Let's slow down light (C) but keep its speed constant, so...

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 50mph (0.5c / half the speed of light) relative to A. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

Unlike the first example, C passes A at the same speed that C passes B. From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

I don't know why you didn't just use the two spaceship and laser example in space. However you are missing the picture that the road is still there but in the form of space, light and the vehicles pass through space, space being the virtual road. 

 

The same as the Caesium frequency passes through space. 

[A-wal]

Yes you're right that space is 'the road', that's where I was going but you need to think of space as the road instead of thinking of the road as space. What I mean by that is that it makes absolutely no difference what speed A and B are moving at relative to the road, it's simply not part of the equation. Look again:

 

Unlike the first example, C passes A at the same speed that C passes B.

 

From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

 

An object's 'speed through space' is a totally meaningless concept. It can't be defined because it makes no difference. Velocity (distance in space over distance in time) can only exist relative to other objects because space and time can only exist using objects as reference points. You just need to let go of your imaginary master reference frame and you'll be there.

 

The road is just another object...

 

Step 2:

A is moving at 0.25c / quarter the speed of light relative to the road. B is in front of A and is moving at 0.75c / three quarters the speed of light relative to the road. C moves past A at c / the speed of light. C moves past B at c / the speed of light. None of them accelerated.

 

Unlike the first example, C passes A at the same speed that C passes B.

 

From A's perspective C moves at 1.25c relative to the road and from the road's perspective C moves at 0.75c relative to A.

 

From B's perspective C moves at 0.75c relative to the road and from the road's perspective C moves at 1.25 relative to B.

 

Can you see how the choice of reference frame is an arbitrary one and the combined velocity of light from the perspective of any two objects is always 2c?

 

The amount of time dilation and length contraction (really just the difference in speeds that light passes an object from different frames of reference) varies according to an object's velocity relative to that frame of reference to always keep the speed of light at c relative to themselves from every observer's own frame of reference.

Edited December 4, 2016 by A-wal

[xyz]

Yes you're right that space is 'the road', that's where I was going but you need to think of space as the road instead of thinking of the road as space. What I mean by that is that it makes absolutely no difference what speed A and B are moving at relative to the road, it's simply not part of the equation. Look again:

 

Unlike the first example, C passes A at the same speed that C passes B.

 

From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

 

An object's 'speed through space' is a totally meaningless concept. It can't be defined because it makes no difference. Velocity (distance in space over distance in time) can only exist relative to other objects because space and time can only exist using objects as reference points. You just need to let go of your imaginary master reference frame and you'll be there.

 

The road is just another object...

 

Step 2:

A is moving at 0.25c / quarter the speed of light relative to the road. B is in front of A and is moving at 0.75c / three quarters the speed of light relative to the road. C moves past A at c / the speed of light. C moves past B at c / the speed of light. None of them accelerated.

 

Unlike the first example, C passes A at the same speed that C passes B.

 

From A's perspective C moves at 1.25c relative to the road and from the road's perspective C moves at 0.75c relative to A.

 

From B's perspective C moves at 0.75c relative to the road and from the road's perspective C moves at 1.25 relative to B.

 

Can you see how the choice of reference frame is an arbitrary one and the combined velocity of light from the perspective of any two objects is always 2c?

 

The amount of time dilation and length contraction (really just the difference in speeds that light passes an object from different frames of reference) varies according to an object's velocity relative to that frame of reference to always keep the speed of light at c relative to themselves from every observer's own frame of reference.

If I travelled towards the Sun through space at c, the light coming towards me from the Sun from my perspective would be travelling at 2c, is that what you are trying to say?

[OceanBreeze]

Nonsense! The only maths you need to understand is this: (snipped Galilean relativity calculations)

 

 

 I don't see why the SR equations are so complex. Surely that's a really cack handed way of doing it?

 

That depends on the level of understanding you aspire to.

The calculations you have posted are trivial relative velocities that were well known to Galileo and Newton, among many others, and not the ground-breaking theory that was formulated by Einstein.

You will never derive e = mc^2 out of that!

 

But, if you are able to work with the Lorentz transform as a four-vector, in Minkowski spacetime, you might, and Einstein did just that.

Edited December 4, 2016 by OceanBreeze

[A-wal]

If I travelled towards the Sun through space at c, the light coming towards me from the Sun from my perspective would be travelling at 2c, is that what you are trying to say?

No! Light always moves at the speed of light relative to any inertial observer, always start with that. It doesn't matter if you're moving towards or away from the sun, light moves past you at c.

 

What I mean is that light has to move past an object that's in motion relative to you at a speed other than the speed of light. In this example...

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 50mph (0.5c / half the speed of light) relative to A. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

...light moves past B at 0.5c from A's perspective but moves past B at c from B's own perspective. The difference is time dilation and length contraction. From A's perspective B is time dilated and length contracted so that light moves past B at 0.5c from A's perspective.

 

From B's perspective A is moving towards the light so from B's perspective light moves past A at 1.5c but moves past A at c from A's own perspective. Again, the difference is time dilation and length contraction. From B's perspective A is time dilated and length contracted so that light moves past A at 1.5c from A's perspective.

 

Notice that from A's perspective time dilation and length contraction slow down the light's velocity relative to B (0.5c from A's perspective) but from B's perspective time dilation and length contraction speed up the light's velocity relative to A (1.5c from B's perspective. That's simply because B is moving in the same direction as the light from A's perspective but A is moving in the opposite direction to the light from from B's perspective.

 

 

That depends on the level of understanding you aspire to.

The calculations you have posted are trivial relative velocities that were well known to Galileo and Newton, among many others, and not the ground-breaking theory that was formulated by Einstein.

You will never derive e = mc^2 out of that!

 

But, if you are able to work with the Lorentz transform as a four-vector, in Minkowski spacetime, you might, and Einstein did just that.

Huh? This is Galilean...

 

A is moving at 10 mph relative to the road. B is in front of A and is moving at 20 mph relative to the road. C moves past A at 20 mph. What speed does B observe C overtaking them?

 

Answer: 10 mph.

 

 

This is with a constant speed of light which is all you need to derive everything...

 

A is moving at a quarter of the speed of light relative to the road. B is in front of A and is moving at three quarters the speed of light relative to the road. C moves past A at c (the speed of light). What speed does B observe C overtaking them?

 

Answer: c, the speed of light. In the first example the only way to get C to move past A and B at the same velocity is through length contraction and time dilation. If B is time dilated from A's perspective so that B is moving through time at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B but B would observe C moving past them at the same speed that A observed C moving past them.

 

Similarly, If B is length contracted from A's perspective so that B is moving through space at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B but B would observe C moving past them at the same speed that A observed C moving past them.

 

Then you just have to get the square root of what the TD or LC would need to be on their own because velocity is distance over time so the effect of TD and LC are multiplied together. Because they're equal it should just be a case of what the square root of one of them on its own would need to be. I don't see why the SR equations are so complex. Surely that's a really cack handed way of doing it?

[OceanBreeze]

 

 

 

Huh? This is Galilean...

 

A is moving at 10 mph relative to the road. B is in front of A and is moving at 20 mph relative to the road. C moves past A at 20 mph. What speed does B observe C overtaking them?

 

Answer: 10 mph.

 

 

This is with a constant speed of light which is all you need to derive everything...

 

A is moving at a quarter of the speed of light relative to the road. B is in front of A and is moving at three quarters the speed of light relative to the road. C moves past A at c (the speed of light). What speed does B observe C overtaking them?

 

Answer: c, the speed of light. In the first example the only way to get C to move past A and B at the same velocity is through length contraction and time dilation. If B is time dilated from A's perspective so that B is moving through time at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B but B would observe C moving past them at the same speed that A observed C moving past them.

 

Similarly, If B is length contracted from A's perspective so that B is moving through space at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B but B would observe C moving past them at the same speed that A observed C moving past them.

 

Then you just have to get the square root of what the TD or LC would need to be on their own because velocity is distance over time so the effect of TD and LC are multiplied together. Because they're equal it should just be a case of what the square root of one of them on its own would need to be. I don't see why the SR equations are so complex. Surely that's a really cack handed way of doing it?

 

And just how do you know the speed of light is constant? Because Einstein tells you so?

 

My point is, you haven't derived anything and all you are doing is comparing relative velocities with the speed of light being constant.

 

That's fine, as far as it goes, but there is no indication that you have anything more than a very superficial understanding of what special relativity is all about. To have a deeper understanding of how Einstein arrived at a constant speed of light, and especially E=mc^2, you would need to delve into vector and tensor calculus, as I said earlier.

 

The "cack handed way of doing it', (your words) with the complex math, is how Einstein arrived at his theory, and that is the only way to truly understand his theory.

 

By the way, this is not meant as a criticism of you. I am just stating my opinion of what is required for anyone to say they truly understand SR and especially GR.

Edited December 4, 2016 by OceanBreeze

[A-wal]

And just how do you know the speed of light is constant? Because Einstein tells you so?

No because experiments show it to be constant. That knowledge is what lead to SR, not the other way round.

 

My point is, you haven't derived anything and all you are doing is comparing relative velocities with the speed of light being constant.

You can derive time dilation and length contraction purely from comparing the velocity of light relative objects that are in inertial motion relative to each other. Look...

 

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 50mph (0.5c / half the speed of light) relative to A. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

C passes A at the same speed that C passes B. From A's perspective C moves past themselves at 100mph (c / the speed of light) and still from A's perspective, C moves past B at (0.5c / half the speed of light).

 

From B's perspective C moves past A at 150mph (1.5c / one and a half times the speed of light) and moves past themselves at 100mph (c / the speed of light).

 

 

Solution 1:

If B is time dilated from A's perspective so that B is moving through time at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B.

 

This works because now B would observe C moving past them (moving past themselves) at the same speed that A observed C moving past them (moving past themselves).

 

 

Solution 2:

If B is length contracted from A's perspective so that B is moving through space at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B.

 

Again, this works because now B would observe C moving past them (moving past themselves) at the same speed that A observed C moving past them (moving past themselves).

 

 

Real Solution:

Time dilation and length contraction are always equal so you just have to get the square root of what the TD or LC would need to be on their own because velocity is distance over time so the effect of TD and LC are multiplied together.

 

 

So time dilation and length contraction = the square root of (the relative velocity of the object - c).

 

 

That's fine, as far as it goes, but there is no indication that you have anything more than a very superficial understanding of what special relativity is all about. To have a deeper understanding of how Einstein arrived at a constant speed of light, and especially E=mc^2, you would need to delve into vector and tensor calculus, as I said earlier.

 

The "cack handed way of doing it', (your words) with the complex math, is how Einstein arrived at his theory, and that is the only way to truly understand his theory.

Still utter nonsense. You don't need anything other than simple algebra and basic common sense.

 

What you're talking about is just for people who who can't understand it and so have to memorise formulas instead of actually working it out because they've got no other choice. You don't need any level of understanding to work through memorised equations!

[OceanBreeze]

No because experiments show it to be constant. That knowledge is what lead to SR, not the other way round.

 

 

 

 You don't need any level of understanding to work through memorised equations!

 

You are too funny!

 

Do you think the measurement of a finite speed of light would have led to the equivalence of energy and mass?

 

Who said anything about "memorizing" equations?

 

But, I can see any further discussion with you is pointless.

 

Carry on!  

[billvon]

I am glad you  mentioned blue shift. 

 

What ''colour'' is light passing through free space?

First off, there is no observable "colour" to a photon until it hits something (like a detector, or your eye.)  Once it does, its "colour" is determined by its wavelength.  It might be a visible color (about 400 to 800nm) or it might be invisible, and have a wavelength anywhere from nanometers to kilometers.

[A-wal]

You are too funny!

I'm not the one who thinks that consistency of the speed of light was derived from SR or that using a more complex formulation somehow gives a deeper understanding than a simplified version that gives the same results.

 

Do you think the measurement of a finite speed of light would have led to the equivalence of energy and mass?

Yes! Looky here.

 

B accelerates to a quarter of the speed of light from A's frame of reference. Work out the time dilation and length contraction from B's frame. Apply that to get the difference.

 

B then accelerates to half the speed of light from A's frame of reference. From A's perspective B accelerated by the same amount the second time but B's own perspective they accelerated by a greater amount the second time from and therefore more energy was used the second time.

 

From A's frame a greater amount of energy was used the second time to produce the same amount of acceleration therefore the mass of B was greater the second time B accelerated than it was the first time.

 

The greater the relative velocity of an object, the greater the object's mass because of time dilation and length contraction. Work out the difference in the amount of energy required to accelerate an object by the same amount at different relative velocities and you should be able to get E=mc^2.

 

Who said anything about "memorizing" equations?

You expect me to believe that you derived the tensors you referred to? If not then you merely memorised them.

 

But, I can see any further discussion with you is pointless.

I agree.

[xyz]

First off, there is no observable "colour" to a photon until it hits something (like a detector, or your eye.)  Once it does, its "colour" is determined by its wavelength.  It might be a visible color (about 400 to 800nm) or it might be invisible, and have a wavelength anywhere from nanometers to kilometers.

ok good, you recognise that light passing through space is colourless,

 

 

Do you accept that 400nm blue is a shorter wavelength than the colourless gin_clear light permeating through space?

[xyz]

No! Light always moves at the speed of light relative to any inertial observer, always start with that. It doesn't matter if you're moving towards or away from the sun, light moves past you at c.

 

What I mean is that light has to move past an object that's in motion relative to you at a speed other than the speed of light. In this example...

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 50mph (0.5c / half the speed of light) relative to A. C moves past A at 100mph (c / the speed of light). C moves past B at 100mph (c / the speed of light). None of them accelerated.

 

...light moves past B at 0.5c from A's perspective but moves past B at c from B's own perspective. The difference is time dilation and length contraction. From A's perspective B is time dilated and length contracted so that light moves past B at 0.5c from A's perspective.

 

From B's perspective A is moving towards the light so from B's perspective light moves past A at 1.5c but moves past A at c from A's own perspective. Again, the difference is time dilation and length contraction. From B's perspective A is time dilated and length contracted so that light moves past A at 1.5c from A's perspective.

 

Notice that from A's perspective time dilation and length contraction slow down the light's velocity relative to B (0.5c from A's perspective) but from B's perspective time dilation and length contraction speed up the light's velocity relative to A (1.5c from B's perspective. That's simply because B is moving in the same direction as the light from A's perspective but A is moving in the opposite direction to the light from from B's perspective.

 

 

 

Huh? This is Galilean...

 

A is moving at 10 mph relative to the road. B is in front of A and is moving at 20 mph relative to the road. C moves past A at 20 mph. What speed does B observe C overtaking them?

 

Answer: 10 mph.

 

 

This is with a constant speed of light which is all you need to derive everything...

 

A is moving at a quarter of the speed of light relative to the road. B is in front of A and is moving at three quarters the speed of light relative to the road. C moves past A at c (the speed of light). What speed does B observe C overtaking them?

 

Answer: c, the speed of light. In the first example the only way to get C to move past A and B at the same velocity is through length contraction and time dilation. If B is time dilated from A's perspective so that B is moving through time at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B but B would observe C moving past them at the same speed that A observed C moving past them.

 

Similarly, If B is length contracted from A's perspective so that B is moving through space at half their own rate then B would observe C moving past them twice as fast as A observes C moving past B but B would observe C moving past them at the same speed that A observed C moving past them.

 

Then you just have to get the square root of what the TD or LC would need to be on their own because velocity is distance over time so the effect of TD and LC are multiplied together. Because they're equal it should just be a case of what the square root of one of them on its own would need to be. I don't see why the SR equations are so complex. Surely that's a really cack handed way of doing it?

awal do you drive?

 

You clearly do not understand collision relative speeds .

[A-wal]

awal do you drive?

 

You clearly do not understand collision relative speeds .

There you go again. The fault isn't with the model! The model is NOT wrong, YOU ARE!!!

 

Start again.

 

 

Step 1:

A is moving at 25mph relative to the road. B is in front of A and is moving at 75mph relative to the road. C moves past A at 75mph. What speed does B observe C overtaking them?

 

Answer: 25mph.

 

I assume you agree with this. You did before so...

 

 

Step 2:

Light moves past every inertial (non accelerating) observer at the same relative velocity, so...

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 0.5c relative to A.

 

C moves past A at c and C moves past B also at c. None of them accelerated.

 

 

This is what's important to understand...

Unlike the first example, C passes A at the same speed that C passes B.

 

From A's perspective C moves past themselves at c and still from A's perspective, C moves past B at 0.5c.

 

From B's perspective C moves past A at 1.5c and moves past themselves at c.

 

Do you understand that?

[xyz]

There you go again. The fault isn't with the model! The model is NOT wrong, YOU ARE!!!

 

Start again.

 

 

Step 1:

A is moving at 25mph relative to the road. B is in front of A and is moving at 75mph relative to the road. C moves past A at 75mph. What speed does B observe C overtaking them?

 

Answer: 25mph.

 

I assume you agree with this. You did before so...

 

 

Step 2:

Light moves past every inertial (non accelerating) observer at the same relative velocity, so...

 

A is moving away from a light source and B is moving in the same direction away from the light source and moving at 0.5c relative to A.

 

C moves past A at c and C moves past B also at c. None of them accelerated.

 

 

This is what's important to understand...

Unlike the first example, C passes A at the same speed that C passes B.

 

From A's perspective C moves past themselves at c and still from A's perspective, C moves past B at 0.5c.

 

From B's perspective C moves past A at 1.5c and moves past themselves at c.

 

Do you understand that?

Yes of course I understand unless I can't read correctly.  

 

You are failing to understand and avoiding the counter argument. 

 

Let's start with some simplicity. 

 

There is two cars a distance apart. (A) and ( :cool:

 

(A) travels towards ( :cool: head on at 30 mph

 

( :cool: travels towards (A) head on at 30 mph

 

 

How fast does the distance between the two cars decrease?

 

 

(A)>>>>30mph>>>>>>[]<<<<<30mph<<<<<( :cool:

 

Do you understand ?

 

added- notice no use of a road, relative to either observer it is them that is stationary and it is the other that is moving. 

Edited December 5, 2016 by xyz

[billvon]

ok good, you recognise that light passing through space is colourless,

 

 

Do you accept that 400nm blue is a shorter wavelength than the colourless gin_clear light permeating through space?

There is no such thing as "gin clear light."  Light has a wavelength.  White light is a mix of wavelengths, easily decomposed back into its component wavelengths.  None of those wavelengths are "clear."