On Einstein's explanation of the invariance of c

You were talking about the same one-way times, which is a zero velocity!

 

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So "it" is independent of the velocity of the frame (of the source)?

So you mean the identical paths for light depends on the velocity of the frame, despite the velocity of light being a constant, and the path-lengths also being constant?

Yes, you defined this above and I noticed it corresponds to the frame in which Einstein synchronization can occur. By zero velocity, you mean of the frame of reference?

A stationary frame of reference can have a velocity. The "stationary" part refers to the objects in the frame which remain at constant distance from each other (as determined by standard measuring rods). The stationary frame can have an unknown velocity as long as the objects in the same frame don't move relative to each other.

This has been explained. Quite a few times, in various ways.

 

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Why can't you understand a simple concept?

Two clocks are separated by a distance. If one-way times are the same, the frame has a zero velocity, and the light traveled the same distance in space as the distance between the clocks.

If the frame has a velocity, the distance light travels in space is not equal to the distance between the clocks.

Do you understand that concept?

 

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Do you understand that concept?

 

Hey Motor Daddy, did you ever answer whether you think the speed of light through water depends on the absolute speed of the water? I can't find it in the thread.

Here's another thing to think about. What if there is no absolute motion along the line between the two clocks, but there is absolute motion 90 degrees to that line? In other words, what if the "country" you used in your earlier example were to be moving north instead of west? Wouldn't both "one-way" times be equal in that case?

 

No, it means the two clocks stay the same distance apart. It means the clocks have zero RELATIVE velocity.

No, if the frame has a velocity but the clocks stay the same distance apart, light travels an identical distance each way. In identical intervals of time.

 

No, you are wrong. The clocks can remain the exact same distance apart from one another, and the one-way times could be different, as if the clocks are moving in the same direction at the same velocity, remaining the same distance apart (like they would be if they were bolted to a train that is in motion), light has to travel further in space one-way than it does the other way to travel from clock to clock.

If you can;t grasp that concept you can't understand what I am talking about.

 

Is that because it takes longer to walk towards the front of a moving train than it does to walk towards the rear (of the moving train)?

It doesn't of course, unless you walk slower towards the front than towards the rear, in which case, it won't matter if the train is moving. But light has a constant velocity.

 

OK, let's say there is a train which is moving in absolute motion down an absolutely stationary track. Put one clock on the ceiling of the train, and the other clock directly under it, on the floor.

Surely the one-way light travel times up and down will be equal. Thus, your theory fails to detect the motion of the train. :blbl:

 

It is because light travels independently of frames, so if you send a light from the rear clock towards the front clock, the front of the train is moving forward, making the distance light has to travel farther than the light traveling from front to rear when the rear is traveling towards the light.

 

The train has a zero velocity in the direction from the floor to the ceiling, and vise versa if the times are the same. It does however have a velocity in the direction of travel down the tracks, presumably if the one-way times are different.

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But the light is sent from the rear of the moving train. It doesn't "have to" travel further because it travels independently of the motion of the source. It travels at a constant velocity, period. Why can't you understand this?

 

I understand now. Your test for absolute motion would have to be performed in every possible direction, if you really wanted to know the true absolute velocity. Okay, that is not a contradiction.

But I bet I can find a contradiction if you answer my question about the speed of light through water.

 

Once the source emits light the source has nothing to do with it. Light travels a consatnt speed in space, and since the front clock moves in the same direction of travel as the light from the rear source, the light has to travel a greater distance to reach the front clock. It is no different than timing the amount of time it takes you to rear end the car in front of you. If you are spaced 20 ft away and you are doing 60 MPH and he is doing 40 MPH it takes less time to rear end him than if he was doing 59 MPH. Of course, if he is 20 ft away coming towards you, then that is even less time until you collide!

 

He's not trying to understand relativity. He is proffering his own theory.

 

Motor Daddy,

You still have not answered whether you think the speed of light through water depends on the absolute speed of the water.

While you think about that, here is another question. Do you think that laser beams only propagate straight from the laser when the laser is at absolute rest? Your theory seems to predict that laser beams would be deflected away from the direction of absolute motion of the frame.

For example, imagine a laser pointer on board the train we talked about a few posts ago. When the laser is pointed straight up, the beam should be deflected toward the back of the train, right?

 

No, light travels independently at a constant velocity. It takes the same time to reach the front clock as it takes for light reflected from that clock to reach the rear clock.

This is easily demonstrated: set up a source of light that 'sends' a beam simultaneously towards both clocks, after positioning it midway between the clocks. The light will reach both the clocks simultaneously, regardless of the train's velocity.

Or use a device that sends two balls in opposite directions simultaneously and at the same speed. The balls will also reach the clocks at the same time after traveling the same distance, equal to half the distance between the clocks, regardless of the train's velocity.

 

The speed of light in water is slower. If you use the same method as mine to measure, say, a fish's velocity, and you know the reduced speed of light in water, you can accurately measure the fish's velocity. The speed of light in water should not depend on the water's velocity, as if both light sources are under water, both lights will travel at the same reduced absolute speed. I'm not sure of that answer but i think that is what my theory says.

I think if you check it perpendicular to the velocity you will find that the light will not be deflected. But, we are measuring the distance light travels in space, not the distance between sources. So again, the distance light travels in space will be different than if the train had a zero velocity.

Say the times are .1 and .1 each way along the line from front to rear of the train. That indicates a zero velocity. When checked from ceiling to floor with the sources placed the same distance apart as the sources in the line of front to rear, if the train had a zero velocity in the line of ceiling to floor the one-way times will be the same as each other, and the same .1 times as the front to rear times. If the train has a velocity in the line of front to rear, the times could be more than .1, but equal to each other along the line from ceiling to floor if the ceiling to floor velocity is zero. That is because you are measuring the distance light travels in space, not the distance between the sources. Again, I'm not 100% sure that is what my theory predicts, so I may be wrong.

 

Yes, if the man is sitting on a bus, and the man remains in his seat, he does not move relative to the bus. Simple as that. That says nothing about the bus's velocity which is also the man's velocity.

Again, the bus is moving along the road. You measured the distance the bus moved on the road and the time of travel and calculated the speed of the bus along the road. That says nothing of the road's velocity in space. If you want to measure the length of the road with light you need to know the velocity of the road in space first.

The speedometer is not an absolute speed in space, it is measuring the speed of the bus compared to the road. If the road has a velocity in space, the speedometer will reflect the correct speed of the bus compared to the road, but that will not be an accurate speed using light travel times if the road has a velocity in space. If the road has a velocity and the bus is traveling 60 MPH on the road, and you checked velocity of the bus using light travel times on the bus, you will find the bus is not traveling 60 MPH. 60 MPH is in reference to the road, not space. Light travels in space, independently of the road.

I've repeated over and over, the speed of light is a constant because we define it that way. It is a constant by definition. You can not change the speed of light unless you change the definition of a meter to reflect a different amount of light travel time, or, you change the definition of a second. It is as simple as that, the speed of light is DEFINED, not measured.

I said to tell me the velocity of the train, any velocity. Einstein says the train has a velocity. Surely he must know the train's velocity since he has determined it has a velocity? What is the velocity, any velocity. Do you want to say the train is traveling 60 MPH? How about 100 m/s? Tell me the velocity in the experiment, as Einstein has assumed the train has a velocity based on the tracks, but then goes on to use light to try and prove relativity of simultaneity using light. Again, He is dead wrong and I can prove it. Tell me what the velocity of the train is and I will show you the tracks MUST have an absolute zero velocity, and the train's velocity is just what you say it is, and that means....Ta da, that there is no relativity of simultaneity in the example. The train passenger will have the lights hit him at different times, and the embankment observer will have the lights hit him simultaneously, and when the math is done properly using my method, they will both agree the lights were EMITTED simultaneously, which Einstein says is relative to the observer. NO, it is NOT relative to the observer. Both observers will agree that the lights were emitted simultaneously, as the embankment observer was at a true zero velocity, and the train had a velocity.