[Halc]

So your point is that if you were in a frame, say a very long rocket powered boxcar with no windows, on a track, with a 300 km rod with clocks attached to each end, and the boxcar was moving at 150,000 km/s relative to the track

The box car has need of neither wheels nor rocket since it is (I presume) inertial and there is no force being applied to it. If it had windows, physics would not change, so no need to preclude them. Einstein certainly had everybody looking at each other in the part you quoted.

that you could use beams of light between those two clocks to determine that you were in uniform motion rather than being stationary?

No. There is no test for being stationary at all under SR. There isn't even meaning to the phrase 'being stationary' without a frame reference. This was not anybody's point at all.

You do realize that violates the postulate of reciprocity between inertial frames, right?

Under special relativity, it would violate the Principle of Relativity (PoR) postulate if such a test existed, and assuming that's what you mean by 'postulate of reciprocity'.

Wouldn't that be what Einstein seemed to be naively pushing?

But it isn't naive. Both postulates were empirically verified: Physics isn't frame dependent (there's no known local test for absolute velocity), and speed of light is always measured to be the same value regardless of the frame in which the test was performed. The rest was derived (not postulated) from these principles with rigorous mathematics, not gut feels, wishful thinking, and hand-waving.

I didn't write that the beams would take two different times and therefore give the observers moving with the clocks reason to conclude they were not synchronous, Einstein did.

No he didn't. The observer moving with the rod concluded the clocks were not in sync in his frame because the clocks failed the sync convention. No actual measurement of the time to go from A to B was performed. You're not reading the paper it seems.

Observers moving with the moving rod would thus find that the two clocks were not synchronous, while observers in the stationary system would declare the clocks to be synchronous

Yes, exactly. No mention of times taken to go from here to there. If the clocks are sufficiently out of sync, one might measure a week for light to go from Paris to London, and around negative-1-week for a signal to go the opposite way. It doesn't mean light actually took that long or that it traveled to the past, it just means the clocks are obviously not in sync.

Okay so why did this happen?

Observers moving with the moving rod would thus find that the two clocks were not synchronous, while observers in the stationary system would declare the clocks to be synchronous

It happened because under the postulates of SR, simultaneity is shown to be frame dependent, one of the simplest conclusions that follow directly from the postulates.

Did the light take the same amount of time both ways or not?

Meaningless query in absence of a frame reference. The time taken to go between two light-like separated events is frame dependent, as is the spatial separation between those events.

What it looks like is that the moving observers saw them take different times and the stationary observers saw them take the same time.

No. Nobody saw any times in that description. Times can only be measured by one clock, not two in different locations. All one can do is subtract the reading of one clock from the reading of the other, and from that obtain a difference, the meaning of which is dependent on the convention by which it can be demonstrated that the clocks are or are not in sync relative to a given frame.

[Centra (OP)]

No. Nobody saw any times in that description. Times can only be measured by one clock, not two in different locations. All one can do is subtract the reading of one clock from the reading of the other, and from that obtain a difference, the meaning of which is dependent on the convention by which it can be demonstrated that the clocks are or are not in sync relative to a given frame.

Well what they did was record the time showing on clock A when the beam was fired to clock B, recorded the time showing on clock B when it arrived/reflected back to clock A and they recorded that time of arrival at clock A. They had recorded three times, two for clock A and one for clock B.

For them to conclude that the clocks were not synchronous, the time shown on clock B when the beam arrived/reflected minus the time shown on clock A when the beam was fired would have to be different from the time shown on clock A when the beam returned to it minus that same time that had been recorded at the arrival/reflection time on clock B. There is no way that can be considered a logical thing to have happened, because supposedly you can't tell if you're in uniform motion or stationary by any test. We know the clocks had been synchronized before they started moving so how could they have produced different elapsed times for the two directions of the light beam?

Now if you say "Nobody saw any times in that description", which you did, then how did they have tA and tB for the equations "tB − tA = rAB/c − v and t′A − tB = rAB/c + v"? What did you think t stood for, tribbles?

[Origin]

Hi,

The illusion is caused by the velocity of the particle. In other words, the displacement of the particle through the velocity intrinsically generates space and time in its frame reference.

We could refer to an oscillator to be able to interpret this. Indeed and in second quantification the contraction of the particle in its point of origin corresponds to the annihilation, until the expansion of the particle in space as a creation operator.

Reported for hijacking the thread.  Please only one preposterous, outlandish claim per thread.

[Kartazion]

Reported for hijacking the thread.  Please only one preposterous, outlandish claim per thread.

New thread related to it: https://www.thenakedscientists.com/forum/index.php?topic=83945.0

[Centra (OP)]

I'd like to address something which is related to this discussion, it's the Michelson conjecture about velocity addition/subtraction which was the basis of his experiment with the light beams being reflected off mirrors in E/W and N/S directions. The reason for the null result is that he was simply wrong about things going back and forth in a direction of motion and against it being different from the same thing without the motion. Here's what Michelson thought.

Swimmer speed: 5 ft/s, river speed: 3 ft/s, swim course length:100 ft each way. Going downstream the swimmer’s speed is the sum of his speed plus the river’s flow 5 + 3= 8, and going upstream his speed is his rate minus the river’s flow 5 – 3= 2.The time downstream is 100/8 = 12.5 seconds and the time upstream is 100/2 = 50 seconds. The total time is therefore 62.5 seconds.

In reality, it's simply the average of 8 plus 2. There's no difference in the round trip time compared to the water being completely still, the two directions just average out to 5 ft/s. It might not seem like it from the equations in that quote but if you think about it, it makes sense. Do you seriously think it's going to change from 40 to 62.5 seconds just from it being 8 and 2 instead of 5 and 5? The Michelson-Morley experiment proved it conclusively too. That's the only reasonable explanation for the null result because we now know from actual tests that earth's rotation does affect the time light takes to travel a certain distance East or West. It has been proven with radio transmissions, which are the same speed as light, between NY and San Francisco, 14 nanoseconds are gained going West and lost going East.

[Origin]

I'd like to address something which is related to this discussion, it's the Michelson conjecture about velocity addition/subtraction which was the basis of his experiment with the light beams being reflected off mirrors in E/W and N/S directions. The reason for the null result is that he was simply wrong about things going back and forth in a direction of motion and against it being different from the same thing without the motion.

You are misinterpreting the experiment.  Look at this link http://galileo.phys.virginia.edu/classes/252/michelson.html, I think it will help you understand the experiment.

[Bored chemist]

In reality, it's simply the average of 8 plus 2.

You calculated the "wrong" average.

[Halc]

Well what they did was record the time showing on clock A when the beam was fired to clock B, recorded the time showing on clock B when it arrived/reflected back to clock A and they recorded that time of arrival at clock A. They had recorded three times, two for clock A and one for clock B.

OK. So now we have 3 different measurements. I agree with this, except I'd reword the last (bold) bit as the "time showing on clock A at the arrival event there". Your wording presumes that the clock there actually shows 'the time' which is meaningless in this context.

For them to conclude that the clocks were not synchronous, the time shown on clock B when the beam arrived/reflected minus the time shown on clock A when the beam was fired would have to be different from the time shown on clock A when the beam returned to it minus that same time that had been recorded at the arrival/reflection time on clock B.

Close. From this, everybody concludes that the clocks are not synchronous relative to the frame in which they are stationary. Without the frame reference, the part I bolded above is meaningless.

There is no way that can be considered a logical thing to have happened

Under relativity theory, I agree, which is why I had to fix your comment to make it meaningful. With the frame reference, it becomes a logical thing which can be considered to have happened.

because supposedly you can't tell if you're in uniform motion or stationary by any test.

Nobody concluded that.

We know the clocks had been synchronized before they started moving

Meaningless statement actually. Needs a frame reference, and then it would still be wrong.
If you read the paper, the clocks were not synchronized until after the rod was moving, and then they were synchronized to local clocks stationary in the first frame. In other words, they looked 'out the window' and set each clock to the value they saw going by just then. This sort of syncs them to the first frame, not to the frame of the rod. I say 'sort of' because while both clocks A and B will always read the same value relative to the original frame, they will not continue to read the same value as the clocks they pass by. They will fall behind them.

so how could they have produced different elapsed times for the two directions of the light beam?

No elapsed times were measured (well, except between the first and third measurement, and then only relative to the frame in which clock A was stationary). All we had is 3 specific clock readings, which is different than having 3 times or two elapsed times.

Now if you say "Nobody saw any times in that description", which you did, then how did they have tA and tB for the equations "tB − tA = rAB/c − v and t′A − tB = rAB/c + v"? What did you think t stood for, tribbles?

As you said in the first sentence, they're readings on a device. They're objective. Nobody in any frame disagrees what those clocks displayed at each of the respective events.

I'd like to address something which is related to this discussion, it's the Michelson conjecture about velocity addition/subtraction which was the basis of his experiment with the light beams being reflected off mirrors in E/W and N/S directions. The reason for the null result is that he was simply wrong about things going back and forth in a direction of motion and against it being different from the same thing without the motion.

Wow. You think you're smarter than a lot of people famous for being smarter than all of us. Mind you, I've pointed out errors in every paper you've linked, but those guys are known cranks. Michelson was not a crank.

Here's what Michelson thought.

Swimmer speed: 5 ft/s, river speed: 3 ft/s, swim course length:100 ft each way. Going downstream the swimmer’s speed is the sum of his speed plus the river’s flow 5 + 3= 8, and going upstream his speed is his rate minus the river’s flow 5 – 3= 2.The time downstream is 100/8 = 12.5 seconds and the time upstream is 100/2 = 50 seconds. The total time is therefore 62.5 seconds.

Exactly correct. Round trip time is 62.5 seconds, but if the river is stationary, the speed would be just 5 each way, or 20 + 20 = 40 seconds round trip.

In reality, it's simply the average of 8 plus 2.

His swimming speed relative to the water is, yes. His average speed relative to the 100 foot course is 200 feet/62.5 seconds = 3.2 feet/sec, not 5. If you assert otherwise, you must have failed an awful lot of algebra exams because they always put one like that in them.

There's no difference in the round trip time compared to the water being completely still

Now you're just making a total fool of yourself. Which figure is wrong? The 50 seconds to go upstream or the 12.5 to come back, or both? How do you justify a different number for the ones you feel a need to change? Maybe you're asserting that 50+12.5 = 40.
How can you presume to be even remotely competent at physics if you've not even a grasp on middle school mathematics?

[Centra (OP)]

Before I reply to other things I want to clear up the Michelson thing. Apparently he was right about the different times swimming upstream and downstream, I found a calculator that works out things like that for plane headwinds or water currents with boats and it was exactly like he said, BUT it's not analogous to speed on the rotating earth. When you drive West traveling at 100 mph you're not traveling at 1100 mph due to the earth rotating eastward at approximately 1000 mph, and going East you're not traveling at 900 mph.

It does not take you 6.66 minutes to drive 100 miles East and 5.45 minutes to drive 100 miles West, I think you'll agree. Well that's what you would get if you divided 1100 mph  and 900 mph by 100 miles and multiplied the results by 60 (minutes in an hour). That shows how Michelson made his error and it cost him the whole experiment. We know that light takes 14 nanoseconds less to go from NY to San Francisco than the reverse direction, so the different times of the East and West paths of the reflected beam in the experiment would exactly cancel out. THAT is why the results were null.

[Centra (OP)]

If you read the paper, the clocks were not synchronized until after the rod was moving, and then they were synchronized to local clocks stationary in the first frame. In other words, they looked 'out the window' and set each clock to the value they saw going by just then. This sort of syncs them to the first frame, not to the frame of the rod. I say 'sort of' because while both clocks A and B will always read the same value relative to the original frame, they will not continue to read the same value as the clocks they pass by. They will fall behind them.

I see what you mean in the first part of that quote, Einstein didn't actually say they were synchronized with the stationary clocks before starting to move. Einstein was not very clear in his description so it was easy to misinterpret. However I don't get the rest of the quote. Whenever they were synchronized to the stationary clocks, the hands still moved at the same rate on clocks A and B, so they still should have shown the same interval for the beams in each direction.

Einstein was saying, I presume, that the moving observers would see two different times showing on both moving clocks while the stationary observers would see the same times on both. That would be the reverse of what I saw in a video about a rocket with beams going to each end from the middle. It said the stationary observer would see different times on both clocks at each end while the moving observers would see the same times. So in the article it was simply changed around from that, the moving observers saw them with different times and the stationary observers saw them with the same times. I'll have to think this over some more before I comment further on it.

[Bored chemist]

BUT it's not analogous to speed on the rotating earth.

Nobody said it was.
The MM experiment is designed to look at whether the Earth is moving through the ether.
And the analogy between swimmers on a moving river and light in a moving ether is quite good.
 The problem is that you were looking at the average speed measured WRT the water, when you should have been looking  at the average speed measured WRT the ground.

[Centra (OP)]

BUT it's not analogous to speed on the rotating earth.

Nobody said it was.
The MM experiment is designed to look at whether the Earth is moving through the ether.
And the analogy between swimmers on a moving river and light in a moving ether is quite good.
 The problem is that you were looking at the average speed measured WRT the water, when you should have been looking  at the average speed measured WRT the ground.

I see, well,  I guess they proved there's no aether then huh? But their experiment did not prove that light speed is not affected by earth's rotation.

[Centra (OP)]

I think Einstein wrote the moving rod thing wrong by mistake, because this quote from a page about SR says the exact opposite of what he wrote.

If, for example, a light signal bounces between ends A and B of a rod, an observer at rest on the rod judges the traversal times to be equal. But that is not so for an observer who judges the rod to move in the direction of A to B. For that observer, the light signal traversing from A to B needs more time to catch the fleeing end B; and the light signal traversing from B to A requires less time to meet the approaching end A. This disagreement immediately leads to the two observer's differing judgments concerning the simultaneity of the events at A and B; that is, to the relativity of simultaneity.

https://sites.pitt.edu/~jdnorton/Goodies/magnet_and_conductor/index.html

Einstein said observers WITH the rod, ie; "at rest" in regard to it, would NOT judge the traversal times to be equal.

[Centra (OP)]

I agree with none of the above. It all lacks frame references, and thus is no more than word salad.
Despite my continued pointing out of this error, you continue to make it and post meaningless stuff such as this:

So it's your contention that this is not true? You think you really would be traveling 100 miles in less that 7 minutes?

When you drive West traveling at 100 mph you're not traveling at 1100 mph due to the earth rotating eastward at approximately 1000 mph, and going East you're not traveling at 900 mph. It does not take you 6.66 minutes to drive 100 miles East and 5.45 minutes to drive 100 miles West.

 

[Halc]

So you really are traveling 100 miles in less that 7 seconds?

I am travelling at less than a meter per second relative to the rotating frame of my laptop. Relative to the inertial frame of Earth, I travel 100 km in about 5 minutes. Relative to the sun, it takes about 3 seconds to go that far. Relative to the galaxy, it takes under half a second. But your statement above lacks a frame reference, hence is still meaningless, and something with which I can neither agree nor disagree. It is, as they say, not even wrong.

[Centra (OP)]

I am travelling at less than a meter per second relative to the rotating frame of my laptop. Relative to the inertial frame of Earth, I travel 100 km in about 5 minutes. Relative to the sun, it takes about 3 seconds to go that far. Relative to the galaxy, it takes under half a second. But your statement above lacks a frame reference, hence is still meaningless, and not something with which I can agree.

The frame of reference would be the earth's surface. I know it's surprising that a person would be driving on the earth's surface but so it is, forgive me for not specifying that it wasn't driving on a cloud.

[Bored chemist]

But their experiment did not prove that light speed is not affected by earth's rotation.

What effect did the rotation of the Earth have on their experiment?

[Centra (OP)]

But their experiment did not prove that light speed is not affected by earth's rotation.

What effect did the rotation of the Earth have on their experiment?

None, because why would it? The beam gained maybe 0.00001 nanosecond going one way and then lost the same amount when it bounced back the other way.

[Halc]

The frame of reference would be the earth's surface.

Excellent! You're talking about the rotating frame. Yes, in that frame, it takes an hour to go 100 km in your car. In that frame, Neptune moves faster than c, and light takes longer to go from SF to NY than the other way around (assuming a reasonably straight path and not one that goes the long way around). Such is a known property of rotating frames. Einstein wasn't considering a rotating frame in the sections at which we've been looking. So for instance, relative to the inertial frame of Earth, your eastbound (near the equator) car really does go east at 1100 mph (sorry, I was using metric before), and the westbound car goes -900 mph westward, and thus isn't really westbound, is it?

With relativity discussions, confusion results from omitting frame references. You may think they're implied, but mistakes are made by assuming distances, durations, times, and locations are the same from one frame to the next. The references are absolutely necessary to make unambiguous statements.
So if you're discussing some value (say distance between events), it matters whether you're using the S coordinate system or the R coordinate system to express that distance. Without the reference, all you'll get is annoying replies saying that your statements lack meaning.

[Centra (OP)]

The frame of reference would be the earth's surface.

Excellent! You're talking about the rotating frame. Yes, in that frame, it takes an hour to go 100 km in your car. In that frame, Neptune moves faster than c, and light takes longer to go from SF to NY than the other way around (assuming a reasonably straight path and not one that goes the long way around). Such is a known property of rotating frames. Einstein wasn't considering a rotating frame in the sections at which we've been looking. So for instance, relative to the inertial frame of Earth, your eastbound (near the equator) car really does go east at 1100 mph (sorry, I was using metric before), and the westbound car goes -900 mph westward, and thus isn't really westbound, is it?

With relativity discussions, confusion results from omitting frame references. You may think they're implied, but mistakes are made by assuming distances, durations, times, and locations are the same from one frame to the next. The references are absolutely necessary to make unambiguous statements.
So if you're discussing some value (say distance between events), it matters whether you're using the S coordinate system or the R coordinate system to express that distance. Without the reference, all you'll get is annoying replies saying that your statements lack meaning.

I see, I didn't realize I was writing an article in Scientic American. Just kidding, I'll try to be more specific. Anyway, point being, on the earth's surface you don't get the swimming up and down a river effect, so Michelson's experiment would not show earth rotation effects on light, but would it show effects from earth's orbit around the sun? If there was aether, yes, because it would be the equivalent of the river bank. So Michelson did prove a lack of aether but not a lack of Sagnac effect from earth's rotation.

Apparently you agree that said Sagnac effect exists, but you explain it as a relativity consistent effect because it involves a rotating frame. It doesn't actually confirm relativity, it just doesn't necessarily disprove it either, Einstein just gave himself an out by saying that rotating frames are not inertial. I can agree with that, because an observer on a rotating disk could tell if it was rotating or not, by centrifugal force.

Now there's the conundrum of why a rotating frame can be confirmed to be in rotation like that, what is it in rotation relative to? The same would apply to binary stars in orbit with each other, what are they rotating in relation to? Presumably an imaginary point between them called the barycenter, but how is the barycenter a stationary reference? It seems counter to relativity theory. If there are two equal disks with the same axis, with a space between the two, what is the difference between one being stationary and the other rotating and the other way around, or both rotating in opposite directions at equal angular velocity?

The only difference between the two disk frames is that an observer on one would perceive centrifugal force and one on the other would not. What made them different in that way? The use of energy to create force to produce rotational motion in one. Kinetic energy had been stored in the disk as inertial motion. The disk would continue to rotate, assuming no external friction or resistance, until that kinetic energy was transferred to another mass by exerting a force moving it outward from a position close to the axis to one farther away from it.