On Einstein's explanation of the invariance of c

But imbecile, the scenario explained by MD is viewed from the frame of the embankment. Even MD understands that, you are even stupider than he is. When I tried explaining it to him, you had to jump in and demonstrate that you are an even bigger idiot than he is. If you kept your mouth shut, you would have appeared a lot smarter. As it is, you are a bigger idiot than him.

But it affects the travel time making it direction dependent, stubborn imbecile.

I am not but you demonstrate such stupidity in grasping much simpler concepts that it isnn't possible to explain it to you,

Tell your parents that they are wasting their money paying for your college, you went an idiot, you are returning an even bigger idiot.

 

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Wrong, I was in the country frame and measured the light travel times. Light travel time is distance, do you understand that? What external frame did I supposedly use to do the calculations of the absolute velocity of the country??

There is no time dilation in my example. Using Einstein's sync method results in those problems.

 

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The catch-cry of the internet crank!

So, you don't have a clue, you don't know why the GPS system has to compensate (or not) for the Sagnac effect. Your inept response gives away your idiocy.

That you even asked the question is plenty of evidence you don't have a clue; all you have is carping and denial to fall back on. Get a life, idiot.

 

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There is no such thing as "opposite directions" for a "round-trip" signal.

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When you calculated the continent's absolute velocity of 100 mph, you were using two different one-way signals. One was 5.00 hours, and the other was 0.26 hours. Then I postulated that the clocks might have gone out of synch, such that they measure the one-way signals to be 2.63 hours in each direction. The speed of the continent has not changed. Can you still calculate its absolute velocity to be 100 MPH?

 

I don't understand why you persist in your denial. Especially since your crackpot position is so easy to refute. Read paragraph 2.

 

Do you know, and can you explain, why that article you linked to says:

"The Sagnac effect can be regarded as arising from the relativity of simultaneity in a Lorentz transformation to a sequence of local inertial frames co-moving with points on the rotating earth. It can also be regarded as the difference between proper times of a slowly moving portable clock and a Master reference clock fixed on earth’s surface. "

Whereas the 'real' effect is interference between counter-rotating beams of light, which are synchronous? That article talks about synchronization, not how to determine if a coordinate system is accelerating.

Wait, in a coiled fiber the beams are synchronous unless the frame rotates. In the GPS system the frame is rotating but synchronous only if each satellite can determine its coordinate time relative to a set of 'master' coordinates. The satellites nearest the equator are analogous to a rotating waveguide.

None of this supports the claim that light will take longer to travel towards the front of a moving train than towards the rear. In the train scenario, the train is straight and so are the paths light travels.
So by the laws of physics, light (or anything that travels with a constant velocity relative to the train) will take the same amount of time either way if the length of the train stays constant.

 

I don't know why you have so much difficulty with elementary physics. Actually, light does take a different amount of time in crossing the same width of the Earth in opposite directions as judged from the ECI frame (see the Ashby paper I linked for you). You can find the explanation in many introductory books on SR:

c*t1=L+R*omega*t1 in the W->E direction

i.e. t1=L/(c-R*omega)

c*t2+R*omega*t2=L in the E->W direction

t2=L/(c+R*omega)

So, t1>t2 , while light speed is isotropic.

You need to start learning about frames of reference.

 

True, but the GPS still needs to account for the Sagnac effect, no matter how many crackpot arguments you bring up.

Yet, the Sagnac effect, contrary to your crank ideas, occurs when light travels in a straight line in free space between the satellites. Does not need any "coiled fiber-optics" in order to occur. You can't learn physics by googling, you need to go to school and you need to study.

You need to understand how they communicate. You still don't, based on the stuff you keep posting.

I don't know why you maintain this so easy to refute crackpottery.

 

What's an ECI frame? How do you tell that it takes different amounts of time, and according to which frame of reference?

P.S. your pathetic opinion of your intelligence is only making you look ridiculous. Wait, you ARE ridiculous. Totally ridiculous.

 

I notice how Tach has obstinately avoided my question about the "Ashby paper", concerning this extract:
"The Sagnac effect can be regarded as arising from the relativity of simultaneity in a Lorentz transformation to a sequence of local inertial frames co-moving with points on the rotating earth. It can also be regarded as the difference between proper times of a slowly moving portable clock and a Master reference clock fixed on earth’s surface. "

I bet he doesn't have a clue about the difference between coordinate time and proper time.

My understanding of the Sagnac effect is that it isn't seen in null geodesics that light follows in flat spacetime. The authors of the paper are really referring to a generalisation of the effect, which is due to the rotating satellites' 'inertial' frame and the comoving terrestrial frame. In that case the light isn't itself rotating, the coordinates are. Hence "the relativity of simultaneity in a Lorentz transformation to a sequence of local inertial frames co-moving with points on the rotating earth."

Simultaneity corresponds to rotating beams of light which don't interfere in the case of light traveling both ways around a loop. In the GPS system it corresponds to rotating systems of satellites which 'interfere' by communicating--so they can cancel any phase difference in the signal. In the first case the signal is the frequency of the light, in the second case it's the frequency of a standard clock.

 

Yes there is, I mean from A to B to A, and then from B to A to B.

 

You mean the clocks went out of sync. I told you that in order to go out of sync, one must have changed its rotational velocity. If it changed its rotational velocity, it will either read more than 5.26 hours round trip, or it will read less than 5.26 hours round trip.

Here's another way to sync watches. You'll need two battery operated watches that have exactly the same rate of tick. Put a piece of plastic in between the batteries and the contacts, so the watches stop running. Set the watches to exactly 12:00:00. Now you have two inoperable watches that read 12:00:00.

Cut a piece of wire exactly 100 miles long. Position the wire in such a fashion that it is attached at the midpoint to the midpoint of the country on a vertical pole (you can use the equal length stick method I previously described to find the midpoint of the country so that you can attach the midpoint of the wire to a pole at the midpoint of the country).

Devise a mechanical pulley system so that you crank one handle, and it transports each watch to each coast at the exact same rate (easily done, let me know if you need ideas). Now attach each watch to the system so that each will go separate directions from the midpoint. Attach each end of the wire attached to the pole, to each plastic on each watch.

What happens is, the watches travel simultaneously towards each coast, all the while reading 12:00:00. When they get to the end of the wire, the plastic is removed simultaneously from each watch at each coast. The watches start ticking simultaneously. You can now be confident that the watches are sync'd, and ticking as one. Let the one-way light travel time measuring begin!!

Questions??

 

In order for you to learn physics, you need to first learn how to read. The notion of ECI frame is explained in the text that refutes your crackpot denial of the Sagnac effect in the GPS.

Ad - hominems will not help you in learning physics.

 

I have one. Do you think a radio transmission frequency changes depending on which side of the radio tower you stand?

 

Awe, you're no fun. I thought you could pick apart my sync method, or maybe tell me how my absolute velocity and width calculations using my sync method are somehow wrong? I thought you might tell me how there is no absolute simultaneity? I thought you were going to tell me that you can't measure one-way light travel, or that it is impossible to tell if an inertial frame has a velocity using no external frame as a reference.

 

How did you measure the 1-way transit times?

You can only calculate the transit times if you know the absolute speed of the frame you use. How do you determine that

The clocks are moving relative to the frame, thus experience different rate of time dilation than the frame.
Each clock is moving relative to the other, thus have different rates of time dilation.

 

I've already told you that your math is right in a world with a preferred frame for c and no length contraction. Then I said that world does not jibe with our observations. What else would you like me to do? You are PRESUMING that rigidity is absolute, that a 1 meter = 1 meter from any perspective, then demanding that others show you why this isn't true. Well, I just did.

More proof...absolute movement against a preferred frame would produce redshifting. Do lights appear different colors depending on your viewing angle?

 

Here's another way to sync watches. You'll need two battery operated watches that have exactly the same rate of tick. Put a piece of plastic in between the batteries and the contacts, so the watches stop running. Set the watches to exactly 12:00:00. Now you have two inoperable watches that read 12:00:00.

Cut a piece of wire the exact length of the country to be measured. Position the wire in such a fashion that it is attached at the midpoint to the midpoint of the country on a vertical pole (you can use the equal length stick method I previously described to find the midpoint of the country so that you can attach the midpoint of the wire to a pole at the midpoint of the country).

Devise a mechanical pulley system so that you crank one handle, and it transports each watch to each coast at the exact same rate (easily done, let me know if you need ideas). Now attach each watch to the system so that each will go separate directions from the midpoint. Attach each end of the wire attached to the pole, to each plastic on each watch.

What happens is, the watches travel simultaneously towards each coast, all the while reading 12:00:00. When they get to the end of the wire, the plastic is removed simultaneously from each watch at each coast. The watches start ticking simultaneously. You can now be confident that the watches are sync'd, and ticking as one. Let the one-way light travel time measuring begin!!

It takes 5 hours for light to travel from one coast to the other, and 15.789473684210526315789473684211 minutes for light to travel back to the starting coast.

Immediately that sends up a red flag, as I now know the country must have an absolute velocity, as the times would be exactly the same from coast to coast and back if the country didn't have a velocity (zero velocity).

Since I know the speed of light is 200 MPH (for the purpose of this exercise), that means light traveled 1,000 miles in one direction, and 52.631578947368421052631578947367 miles in the opposite direction.

Soooo, from those light travel times, I can calculate the absolute velocity of the country:

Light traveled 1,000 miles in one direction, and 52.631578947368421052631578947367 miles in the opposite direction. That means the light is 947.36842105263157894736842105263 miles from its starting point 5.2631578947368421052631578947368 hours later, which also means the country traveled 947.36842105263157894736842105263 miles from its starting point in 5.2631578947368421052631578947368 hours. 5.2631578947368421052631578947368 hours is 315.78947368421052631578947368416 minutes, so the country traveled 3.0 miles per minute. 3 miles per minute is 180 miles per hour.

Since the country traveled 180 miles per hour for 5 hours, the country traveled 900 miles, and the light traveled 1,000 miles. That means the country is 1,000-900=100 miles wide!