# Basic Special Relativity Question

Discussion in 'Physics & Math' started by Fednis48, Apr 22, 2013.

1. ### OnlyMeValued Senior Member

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I too am interested, but I agree that getting into that side discussion now would be distracting. I do hope you have something new in mind, like something in the last couple of years that I have not heard about.., but let it wait a bit.

3. ### TachBannedBanned

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I fully understand that you don't have a clue how to run this experiment. Your first answer, where you acknowledged that you don't know how to run the experiment was the only honest one, all the subsequent ones where your attempts at covering up that you do not have a clue. You do not know how to do this measurement.
Let's try to help you out a little: you have a very long set of cameras strung along the $x"$ axis in $S"$ . The cameras are snapping pictures of the passing train , with the rod inside, at a very fast shutter setting. The cameras time stamp each snapshot and the snapshot snapping is synchronized in $S"$. Each camera is a one pixel motion detector, each camera can only capture only one pixel at a time: on if the rod is lined up with the camera objective and off if it isn't. What data do you collect from these cameras and what does the data tell you?

So, they are wrong. So are you. Do you still want the references that show that length contraction is physical or are you going to dig your heels in your new-found lie?

Old enough to prove that you don't know what you are talking about.

Last edited: May 7, 2013

5. ### Beer w/StrawTranscendental Ignorance!Valued Senior Member

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Sure.

Otherwise this thread (90% of which I haven't read) may be too much semantics. Since relativity is counter intuitive, experiments are worth a thousand words.

7. ### TachBannedBanned

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deleted

Last edited: May 7, 2013
8. ### TachBannedBanned

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One proof that the Lorentz contraction is physical: here and here. It explains the physics of heavy ion collisions I was talking about. I will give one proof at a time since Pete is intent on dragging this charade indefinitely, so I am certain that he'll argue about the validity of each proof. This will make it painful but any interaction with Pete is painful, especially when science disagrees with his prejudices.

9. ### OnlyMeValued Senior Member

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While both of these experiments can be classified as "physical", neither one represents direct evidence. The measurements in experiments like these are interpreted from the data. They support the theoretical basis, but they do not represent direct measurement of length contraction... So in a strict sense continuing to refer to this kind of evidence, as "physical" evidense, while technically accurate, is misleading, as it implies that length contract has been "proven".

I did not retain a copy but I remember reading an analysis of the heavy ion collision reference that did raise alternate explanations for the bunching. There is a lot going on in the process of accelerating the ions that has to be accounted for and ruled out, which may contribute to the bunching.

We now have a great deal of evidence, physical observations.., that supports the existence of dark matter, still dark matter remains theoretical.., waiting for some "direct" observation/evidense.

BTW Tach neither of the links mentions length contraction, though it has been discussed elsewhere.., in the at least heavy ion case.

10. ### TachBannedBanned

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All measurements in experiments are interpreted from the (collected) data. Did you ever run an experiment?

You are wrong on both accounts, both articles specifically mention length contraction, you need to read carefully.

11. ### OnlyMeValued Senior Member

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Yes, Lorentz Contraction is mentioned, but there is nothing that explains how that conclusion is reached... In these references.

Where the ion pancaking is concerned, it is not a measured phenomena, it is suggested by a theoretical interpretaion of how the data from the impact, works out. That is actually the best supporting "evidence", as far as I am concerned, but it only supports rather than proves the contraction, because it is the theoretical interpretation that leads to that conclusion. What they are actually saying (not in these references) is that the way the scattering "looks" after impact, is what would be expected if the ions were length contracted. The actual data does not say that length contraction is the only possibility. It says the Lorentz-contraction is an explanation...

I don't mean to suggest there is nothing that supports the theory, just that we as yet have no direct measurements that proves it.

12. ### TachBannedBanned

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Good, you changed your tune. It means that found the relevant sections but you still do not understand the explanation, which is not unexpected knowing you.

You are the same crackpot you've always been, when presented with scientific evidence, you come up with some cockamammie "explanation" of your own.

13. ### OnlyMeValued Senior Member

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Reference an autaul research paper on the "pancaking" of heavy ions, and my "incoherent babbling" will be supported by the research, in intent, if not in the wording. I believe I have even seen some reference to similar conclusions involving individual high energy proton/neutron collisions. No where I have ever, in either lay publication or research paper, seen anyone doing the research suggest that they were measuring the shape of the heavy ions or protons/neutrons directly.

Indirect measurement "supports" the theory. Direct measurement would prove the theory. We are unable to carry out experiments that would prove Lorentz contract direct at classical scales of length and velocity.., and we have no rods and clocks useful in carrying out direct measurement at the scales of subatomic particles or heavy ions... That leaves the evidence referenced as "supporting" Lorentz contraction, not as "proving" Lorentz contraction.

To the extent that your posts degrade to the point of name calling, your credibility is also degraded... Since that is where we seem to be now, it would be best to leave this discussion until the discussion of the OP has been resolved.

P.S. here are the two mentions of Lorentz contractions in the articles you referenced,

The ions appear as flat disks because of the relativistic effect called "Lorentz contraction".

and
One can see an example of a Au+Au collisionat a centre-of-mass energy of 200 GeV per nucleon pair and at an impact parameter of 5 fm as calculated in RQMD in the animation on the right. You can see the Au nucleus as a Lorentz-contracted pancake-shaped object moving in one direction (at about 99.995% of the speed of light, spheres look like pancakes, they are contracted 100 times in their direction of motion).

In the first note, "The ions appear...", not a proof of measurement...

In the second, the reference is to an animation, but the lead in describing the experimental context, references the impact not a measurement of the ions, and also includes, "You can see the Au nucleus as a Lorentz-contracted pancake-shaped object.., spheres look like pancakes...".

In one the ions "appear" to be pancakes and the other they "look" like pancakes.., in an animation of the impact.

Last edited: May 7, 2013
14. ### TachBannedBanned

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Knowing you , it doesn't really matter what you have "seen" and what you "haven't seen". BTW: what is an "autaul"?

1. You cannot "prove a theory". Ever.
2. For 100 points: what can you actually do?
3. For additional 20 points, what is "indirect measurement"? How do you perform it?

15. ### OnlyMeValued Senior Member

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Since all you have left is spelling and semantic errors, in statements which are not proof read... There really is no discussion here.

16. ### TachBannedBanned

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No, items 1 and 3 point at your crackpot statements, as does this one:

17. ### PeteIt's not rocket surgeryRegistered Senior Member

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I'm glad we agree that it can be done. I knew you'd figure it out.
But as I said, we actually have detectors not just on the x''-axis, but covering the x''-y'' plane in the area of interest.
As I said before, the data collected is the $(t'',x'',y'')$ coordinates on the rod worldline, and possibily the rod element's k-values as well.
It tells us this:

Are say saying length contraction is not frame dependent?
Or are you disagreeing with the semantics of "physical effect"?

18. ### TachBannedBanned

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Well, since you were clearly unable to figure it out by yourself, somebody needed to help you. So I helped you. <shrug>

OK, go ahead, let's see if you can finish the setup, now that you have received appropriate tutoring.

So, how would you do that?

What gives you this bright idea?

I have provided you with the proof that, contrary to your fringe misconceptions, length contraction is a physical effect. have you read the references? I gave you two.

19. ### UndefinedBannedBanned

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You have the nerve to call other people "cranks" while you come up with rubbish "proofs" of "length contraction" like this reference?

How many times have you told a "crank" that animations and simulations only show the assumptions and interpretations that went into them, and that they are not proof of anything except your theory interpretations of the inputs and not the actual physical phenomena itself? No one "sees" anything. No one "proofs" anything by such simulation and animation computer code "illustrations" of their theoretical interpretations rather than actual known facts of what is happening physically.

You are a sham "expert" who depends on others to do the work while you pretend to "know" and "correct" using others work references which you yourself do not even understand in any way that is relevant to the issue. You are the worst sort of "crank", one that pretends to "authority" he doesn't have by any measure of competency in physics understandings. You are a troll and a crank that science doesn't need in any way shape or form. Game playing nincompoop and stupid troll to boot. Where are the moderators? Don't they care that you lie and muddy the threads like this, pretending to knowledge and authority you don't have? The site is getting a bad reputation I think from your silly games. Moderators should do something about it by telling you to put up "proof" of your "correct solution" or shut up and get lost.

20. ### PeteIt's not rocket surgeryRegistered Senior Member

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Previously, you said it can't be done.

How would we collect the k-values of the rod elements? Write them on the rod so the cameras can see them. Embed RFID chips. Paint the rod as a rainbow along its length. Like I said before, the details aren't important, unless you're actually planning to set up a relativistic train.

Semantics. 'Physical effect' is an ambiguous term. You mean something different to what Gron and Johanessen mean.
All I'm saying is that length contraction is frame dependent, the bending of the rod is frame dependent, and that they are exactly as physical as each other.

They mentioned length contraction of individual ions, but didn't mention the density of the ion beam, and didn't describe how the effect was measured.
I'm interested in this:

21. ### TachBannedBanned

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I dared you to come up with the setup, I still say that and I still dare you. You aren't able to complete the setup, even after I gave you a running start.

The cameras capture only one pixel in the setup I helped you with, so they cannot capture any numbers. If you have a different setup in mind, please post it, my challenge to you is on.

Quite the opposite, the details are important, I challenge you to come up with a complete setup.

You are being evasive: length contraction is measurable, the rod "bending" is not. You haven't managed to come up with any experimental setup that can do it.

I'll show you, it is a different setup, first do the honest thing and admit that length contraction is "physical".

22. ### PeteIt's not rocket surgeryRegistered Senior Member

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I'm not interested in your dares, Tach. I'm satisfied that the data can be collected in theory. The Lorentz transformation from $S'$ tells us what events would be measured in $S''$. The practical details aren't going to change that.
If you want to talk about how to set up a practical experiment, open another thread.

Yes, it is. Recording rod events in $S''$ reveals this:

Why are you playing games?
Look, this is as clear as I can be, because I don't know precisely what you mean by 'physical':

Length contraction is physical, in the sense that it is measurable with clocks and rulers moving relative to an object.
Length contraction is not physical, in the sense that it doesn't affect the physical structure of the object.

The rod bending is physical, in the sense that it is measurable with $S''$clocks and rulers.
The rod bending is not physical, in the sense that it doesn't affect the physical structure of the rod.

23. ### TachBannedBanned

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So, you are unable to construct a valid setup.

You keep repeating the same mistake, Lorentz transforms aren't measuring devices.

I challenged you to produce a setup in this thread, you made a laughable attempt and you failed. The fact is, you are unable to show a valid way as to how the "rod bending" effect would be measured experimentally. Digging your heels or trying to evade doesn't work, you already know that the effect is not measurable because it isn't physical.

Posting animations doesn't prove your case.

True.

False, the links I provided show exactly the opposite, ions are length contracted. I can provide even more proof that you are wrong. You managed to score higher on the crackpot scale than even Undefined and OnlyMe have done in this thread.