A Train, Three Clocks, and an Observer

Motor Daddy: Synchronizing clocks complicates your experiment. Just stand in the middle of a square box. Mount mirrors on the four walls. Flash a strobe pulse toward each mirror & measure how long it takes each reflections to get back to you. If relativity is invalid & the box is moving, some reflections get back sooner than others.

Read about Michaelson-Morley experiments. The Earth took the place of the moving box.

The original goal of the experiments was to determine the absolute motion of the Earth. The results could be interpreted as proving that the Earth was stationary. Nobody was willing to accept that interpretation.

If the experiments were performed in Galileo's time, the church (and probably Galileo) would have accepted that interpretation.

Those experiments led to Special Relativity, which you are now trying to disprove.

 

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1. The midpoint clock is a distance away from each end clock.
2. Light takes time to travel a distance.
3. If light leaves an end clock at one time, it will arrive at the midpoint clock at a different time.
4. The two end clocks could appear to the midpoint observer as reading the same, just different than his own clock.
5. The two end clocks could appear to the midpoint observer to read different than each other, and also different than his own.

Can anyone refute any of these claims?

 

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This can be compensated for by knowing the distance to the endpoints.

They could, if we were living in another universe with different laws of nature. In this universe, thousands of experiments starting more than a 100 years ago shows this not to be the case. Every day, billions of micro-experiments corroborate the isotropy of light propagation by our use of devices on which such effects are significant, and which simply would not work if relativity theory did not describe our universe well. (Some of these experiments are also known as the "Global Positioning System", or "GPS". You may have heard of it.)

What claims? There's nothing precise in there to refute.

It's classic crank behaviour: "I dare you to refute my vague claims!" No, do your own damn work!

 

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But distance is defined by light travel time. Are you saying light travel time does not define distance?

Those are very precise statements. Refute each one to the best of your ability, and stop making general statements that don't refute each statement in a very precise manner.

 

GPS. Refutation done.

Move along now, nothing to see here.

 

Again, you can't refute any of those claims. But I knew that.

Are you saying you disagree with all of those statements?

 

You're missing the point. The issue you have is about whether or not special relativity has a viable description of motion and light etc. As such you've come up with a convoluted physical set up to try and justify your views. Experiments of that nature have been done, they have been used to test special relativity, as funkstar commented, and the theory has passed. The issue of whether or not someone here can hold your hand and walk you through the algebra is irrelevant, professional relativity researchers have computed the predictions of special relativity in a variety of systems (Pound-Rebka, atomic clocks on planes, quantum field theory, muon decay times etc) and its passed them all. If SR weren't at least extremely close to reality then it would show up in some or all of those phenomena, the effects/results of which you speak would be observed. Sure they might not have done exactly the set up you talk about but ones which have qualitative behaviour very similar. At the very least such mistakes in SR would bleed through into other predictions. But they don't so the observed experimental accuracy of SR goes against your claims. We don't need to sit around taking you through fiddly and tedious coordinate transformations for your particular set up and so you falling back on the "If you can't do the workings for this specific set up then I am going to ignore you" behaviour is little more than attempt to ignore clear and relevant retorts to your claims.

Jack tried the same arguments, demanding people provide algebra to counter his claims, he'd accept nothing else, and when people did provide the algebra he didn't understand it. You and he attempt to argue that SR is wrong because you find (or you think you find) a particular inconsistency, you're working on the premise that you need to only provide one contradiction or refutation and you knock over the model. This is true but then its also true for people providing a contradiction or refutation of your claims. Funkstar (or anyone else) doesn't have to pander to your wish only to be provided with algebra, he (or anyone else) can provide any kind of refutation they want, all that's relevant is the validity of the argument, not the form is comes in.

When Jack started his whining and demands for maths I commented I wasn't interested in doing tedious algebra for some convoluted set up (though I ended up providing it as Jack didn't understand what I'm about to link to), as considering specific cases is inelegant and often simply confuses more people than it helps (the crank is usually the most confused). Instead there's a much more elegant way to argue against the SR nay-sayers who claim SR is inconsistent and that's to strip away the specific case and consider the underlying mathematical structure of special relativity. More than once I explained it to Jack (though he obviously failed to understand) and given you're making similar mistakes I suggest you read the first large quote in this post of mine. SR is basically the physical implications of saying "Space-time has a metric such that \(ds^{2} = -c^{2}dt^{2} + d\mathbf{x} \cdot d\mathbf{x} = \eta_{ab}dx^{a}dx^{b}\)", which is a straight forward implication of the two SR postulates (I can outline this further if needed).

If SR is inconsistent then Minkowski space-time is but then so is its symmetry group but then (via the Weyl trick) so is the Euclidean rotational symmetry group and then so is Euclidean geometry! SR is simply saying space-time has a particular geometry, which makes an examination of it much simpler. Your convoluted physical set up only confuses you, as you obviously lack experience with SR on a working level.

 

Do you think this is debate class? There's no particular point to me agreeing or disagreeing: In science, nature is the ultimate arbiter. And nature says that there's no such thing as absolute motion. The isotropy of light propagation has been tested so many times over the last 150 years that arguing against it is at best ignorant, and at worst delusional.

You're wrong. End of.

 

Which of the 1-5 statements am I wrong about, and why?

 

Okay, but it should be noted that not everyone will agree as to how much that distance is.

Okay, with the stipulation that not everyone agrees to what the distance traveled is.

Yes, but again, not everyone will agree as to what time the light left the end clock, and what time it arrived at the midpoint clock. They will agree as to what time the end clock read when the light left it and what time the midpoint clock reads when the light reaches it.

As long as the clocks are synchronized in that frame.

No, not as long as the clocks remain synchronized to each other. Now, there are situations, such as if you were to accelerate the whole system, where, even if the clocks keep perfect local time, the observer in the middle will see them drift out of sync. But this would be because they will actually drift out of sync.

Claim 5 is refuted by nature. The other claims are too rife with hidden assumptions to be of much value.

I would say Yes to number 2, but I would be agreeing with something completely different to what you would agree to by saying yes. This is why I qualified my answers. The reason I say this is that you still seem to be laboring under the false assumption that time and space are absolutes, While the rest of modern science realizes that they are not.

 

You say not everyone will agree? There is one observer at the midpoint of the train. That's it. I am talking about the midpoint observer's observations, from that one point, the midpoint. That midpoint observer is trying to determine if the train is in motion or not, and he can do that from just his own midpoint, with nothing to relate to except the light from each endpoint clock.

Sure, since the other endpoint clocks are in sync with the midpoint clock, if there were observers at each of the end points, they would see the other two clocks as reading behind theirs, as the other two clocks would be a distance away from that clock. But, that is not the task at hand. The task at hand is for one observer, at a midpoint position, to determine if the train has an absolute motion, and I just described to you why and how he does that.

Stick with my ORIGINAL scenario, and think about what I am saying, and how it's done. There is no other observer in the train except the one at the midpoint, until we can agree on that scenario, then, we will add more discussion with other observers, which will have no problem fitting in.

 

Wrong. If the train has a velocity the two end clocks will not appear to the midpoint observer as reading the same as each other at any time.

Basically, the two end clocks are light sources. Since light always travels at c, the only way the light from each end clock can reach the midpoint observer simultaneously is if the train has an absolute zero velocity, as if the train has a velocity, the midpoint observer will not be at the light meeting place. That means, if the train has a velocity, the light from each end clock will hit the midpoint observer at different times, making him view each end clock as reading different than each other at all times. If the train has a zero velocity, the midpoint observer will remain at the end clock light meeting place, so he will view each end clock as reading the same, but behind his own clock, even though all the while the clocks remain in sync, which can be verified.

 

Motor Daddy: The Michaelson-Morley experiment showed that the fifth situation will not occur.

The fifth situation will not occur for the train moving at constant velocity.

The results of the Michaelson-Morley experiments are counter intuitive, but they provide experimental evidence that your notions are invalid.

 

There is no valid experiment that could invalidate that concept. If you are centered between the two clocks, and the light from each clock leaves the clocks simultaneously, the light leaves each clock with the same "time stamp" of what time it left the clock. Both lights from the end clocks leave with the same "time stamp" traveling towards each other at the same speed. They each travel the same distance until they crash into each other, regardless of what the train did during that light travel time. If the train remained motionless, ie, absolute zero velocity, each "time stamp" will hit the midpoint observer simultaneously. Since the midpoint observer's clock continued to tick until the endpoint clocks time stamped light impacted him, the midpoint observer's clock will read ahead of the timestamps from the end clocks.

If the train moved during the light travel time, ie, had an absolute velocity greater than zero, the mid point observer will travel a distance towards one time stamp and away from the other. That means the two time stamps will impact him at different times, ie, the end clocks light appear to him as out of sync with each other.

That is not even debatable, it is a rock solid fact.

 

Nature says the contrary.

Your statement that no valid experiment can dispute your claim reminds me of those who, even after looking at the mountains on the Moon with Galileo's telescope, still claimed that they couldn't be there, because it was a "rock solid fact" that the Moon was a smooth sphere.

I've come to the conclusion that you are either:

A. Unteachable. One of those people whose brain is so inflexible, that they can never except that something they "know" could ever be wrong. Once you accept something as "true", it is true forever and ever and ever, despite any and all evidence to the contrary.

Or

B. A troll. One of those people with so little of real interest to offer that the only way they can call attention to themselves is to be a deliberate nuisance.

In either case, I pity you

 

I'm neither, so you've come to another false conclusion. Maybe you can show me why my facts are incorrect, rather than name calling?

 

Motor Daddy, the Michelson Morley experiment is equivalent to this.
The end clocks always appear in sync. That's what actually happens. This is not a thought experiment - it's reality.

You claim a particular result for an experiment.
Conducting the experiment produces a different result.

 

It is impossible for the clocks to appear in sync from a midpoint observer with a velocity. That is like saying the mid point isn't the mid point. Simply impossible.

 

And with that I think we've established your understanding of the scientific process perfectly.

A "fact" contradicted by experiment.

And yet, it is what actually happens when you try to conduct this experiment. You know, when you do science rather than assertion.

You are free to keep on believing that it's impossible, but that makes you either delusional or a troll. Either way, good luck in Pseudoscience: I predict you'll be going there very soon.

 

Light travel time defines the 1983 SI metre, which is an arbitrary unit of distance measurement, chosen for its ability to be reliably and precisely duplicated anywhere. If the distance between the lines etched on the 1799 platinum prototype could be duplicated as precisely, reliably, and conveniently, then that would still be the standard.

Perhaps most people would consider the concept of distance to be better defined by the size of physical objects (eg the length of a rod), and there's no problem with that.


Fundamentally, I think you could define distance as the magnitude of the spacetime interval between simultaneous events.