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Author Topic: Evidence for large scale length contraction?  (Read 56889 times)

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #250 on: 29/10/2012 20:58:28 »
So I ask the forum (whomever might be still be reading this thread), do you agree with the following, a recent summary statement I made here:

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The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.
... as length contraction theory does.

Length contraction theory does not require that. There are two main theories which include length contraction and neither of them requires reality to change in the way you describe. LET (Lorentzian universe) provides for fixed absolute truths in terms of the shapes of things, but provides no means to calculate what those absolute truths are because the preferred frame cannot be identified. SR is a very different approach, but it too can accommodate people who want absolute truths about the shapes of things, so you can easily regard the frame in which an object as stationary as being the one which shows its true shape. Many of the adherents to SR appear to believe that veiwing things from different frames of reference does change their shape though, and however surprising that may be to us, it isn't a requirement of SR that you believe what they do.

I'd be interested to know where you are with this now and whether you feel you've gained anything from it. Have you accommodated length-contraction into your own theory of how things really are, and if so, have you managed to find a way to do so other than LET and SR? So far, you've shown us a model of reality in which you can send light faster than the speed of light simply by switching frames, and that's a broken model. There's no point in going on pushing it unless you can find a way to fix that flaw.
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #251 on: 30/10/2012 19:54:46 »
David Cooper:
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SR is a very different approach, but it too can accommodate people who want absolute truths about the shapes of things, so you can easily regard the frame in which an object as stationary as being the one which shows its true shape. Many of the adherents to SR appear to believe that veiwing things from different frames of reference does change their shape though, and however surprising that may be to us, it isn't a requirement of SR that you believe what they do.

I do not not use the phrase or subscribe to the concept of "absolute truths about the shapes of things." I am a realist, and as such reality does not shift with how things are observed/measured. Physical objects have intrinsic properties (like Earth's well known and precisely measured diameter) and the distance between objects, like between Earth and Sun does not contract, as it might be observed to do from the extreme frames discussed. These bodies were formed by gravity, a natural law of physics, and distributed in space by the same natural law. Nothing about that has anything to do with your quoted phrase above.
"Many of the adherents to SR appear to believe that veiwing things from different frames of reference does change their shape though..."
It is to them (and they are many... and they run the show here) that I address my argument.
Regarding your assertions:
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So far, you've shown us a model of reality in which you can send light faster than the speed of light simply by switching frames, and that's a broken model. There's no point in going on pushing it unless you can find a way to fix that flaw.
I have answered this false assertion many times. Realism is not concerned with switching frames of reference, as is the main criterion for "reality" or "the shape of things" or "the distance between things" in SR. See above, yet again, on the natural, intrinsic shape of things and their natual distribution in space, i.e., the naturally occuring distances between them... which does not change with how they are observed, as length contraction insists based on relativity's version of idealism.

The speed of light is constant. Light carries the images of things observed. These images vary as seen from different frames of reference. This does not mean that the physical objects themselves vary. That is where length contraction theory is confused. My intent for this thread has always been and continues to be to correct this confusion of images observed with those objects emitting or reflecting those observed images.

The MM experiment you have been discussing in another thread for instance has two arms of equal length, as the apparatus was built. An observer at rest with the apparatus sees them as they are, equal in length. Another observer, not at rest with it, sees one arm contracted in the direction of relative motion. No argument... He would see one arm as shorter. But that is just the image distorted by his velocity relative to the object. A rigid object would require a force to squeeze or compact it into a shorter length than it was built. Lenght contraction theorists totlally ignore this fact, as they do not claim that any force is involved. But they also deny that physical objects have the intrinsic property of length, as manufactured or naturally formed, as above.

Here it is again in a nutshell... anyone...:
Quote
The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.
« Last Edit: 30/10/2012 20:03:46 by old guy »
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #252 on: 31/10/2012 21:16:23 »
"Many of the adherents to SR appear to believe that veiwing things from different frames of reference does change their shape though..."
It is to them (and they are many... and they run the show here) that I address my argument.

That difference in opinion has been well established now and it doesn't look as if it will change - there's little to be gained by continuing to try to push them to change their mind. It also has no impact on what they use SR for.

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Regarding your assertions:
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So far, you've shown us a model of reality in which you can send light faster than the speed of light simply by switching frames, and that's a broken model. There's no point in going on pushing it unless you can find a way to fix that flaw.
I have answered this false assertion many times.

It isn't false, unless you've incorporated length-contraction into your model, in which case I'd like to know how you've done that without it turning into either SR or LET. If you have turned it into SR and your only point of difference is with those people who think that observing things from different frames physically changes their shape, then I can't see why the discussion didn't end long ago.

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Realism is not concerned with switching frames of reference, as is the main criterion for "reality" or "the shape of things" or "the distance between things" in SR. See above, yet again, on the natural, intrinsic shape of things and their natual distribution in space, i.e., the naturally occuring distances between them... which does not change with how they are observed, as length contraction insists based on relativity's version of idealism.

The trouble with that is that we have two big theories which both conflict with that. One theory (SR) has as part of its dogma the idea that all frames are equal, and that means that whatever distances are measured in any frame are as true as the distances measured in any other. If that dogma was removed (which could be done without destroying the important core of SR), then the solution becomes the same as the one in LET where there is a correct, hidden truth about any distance, but you can't tell what it is. Your intrinsic distances don't take into account the contractions that may actually be applied to them, unless you take the trouble to declare clearly that they are subject to contractions which can't be determined.

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The speed of light is constant. Light carries the images of things observed. These images vary as seen from different frames of reference. This does not mean that the physical objects themselves vary. That is where length contraction theory is confused. My intent for this thread has always been and continues to be to correct this confusion of images observed with those objects emitting or reflecting those observed images.

With SR, the unnecessary dogma that Einstein tied up in it requires multiple conflicting ideas to be true at the same time. A version of SR with that dogma removed can eliminate the problem. LET likewise contains no confusion. If you don't fit into any of those camps, I'd be interested to know where it is that your position diverges from the one you're closest to. I get the impression that you actually fit into a mainstream camp and don't realise it yet - all you need to do is recognise the vital role of length contraction.

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The MM experiment you have been discussing in another thread for instance has two arms of equal length, as the apparatus was built. An observer at rest with the apparatus sees them as they are, equal in length. Another observer, not at rest with it, sees one arm contracted in the direction of relative motion. No argument... He would see one arm as shorter. But that is just the image distorted by his velocity relative to the object.

That is not the case, as demonstrated by the thought experiment involving a train and a platform where a beam of light is split and sent both along the platform and through the train. Either the train or the platform must be length-contracted for you to get correct results out of the experiment.

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A rigid object would require a force to squeeze or compact it into a shorter length than it was built. Lenght contraction theorists totlally ignore this fact, as they do not claim that any force is involved. But they also deny that physical objects have the intrinsic property of length, as manufactured or naturally formed, as above.

In LET, no force is required beyond the ones which are already acting to generate and maintain separations between particles. In SR, no force is required either, so you're really just attacking some people in the SR camp again over their belief that observing things from different angles physically changes those things.

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Here it is again in a nutshell... anyone...:
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The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.

And here is the same attack on those people again in another guise. I agree with you that things aren't physically changed in shape by looking at them from different angles, and everyone's noted your objection to the belief that they do. I can't see any reason to keep repeating this objection as the point's been made dozens of times now and they simply aren't going to budge. What is much more important now is for you to find a position for yourself where the model you're pushing holds together properly, but that's either going to need length-contraction incorporated into it or some fiendishly clever alternative which no one's thought of yet.
« Last Edit: 31/10/2012 21:20:02 by David Cooper »
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #253 on: 01/11/2012 20:16:44 »
David Cooper:
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The trouble with that is that we have two big theories which both conflict with that. One theory (SR) has as part of its dogma the idea that all frames are equal, and that means that whatever distances are measured in any frame are as true as the distances measured in any other.

"The trouble with that is"... That we have a "scientific theory", length contraction, claiming that, either science doesn't know (for instance) the true diameter of Earth, or that it varies from about 1000 miles, as measured from the old near 'c' fly-by, to nearly 8000 miles, as measured at rest with Earth.
Earth does not change diameters. Therefore the theory that its diameter contracts is false.
Any rigid physical object requires a force to compact it into a shorter length (or diameter.) No force is applied in any case of length contraction. Therefore any observed contraction is due to the image being distorted by observation from extreme velocities. Different observations do not make physical objects change shapes or lengths. Claiming that that do is false.

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If that dogma was removed (which could be done without destroying the important core of SR), then the solution becomes the same as the one in LET where there is a correct, hidden truth about any distance, but you can't tell what it is. Your intrinsic distances don't take into account the contractions that may actually be applied to them, unless you take the trouble to declare clearly that they are subject to contractions which can't be determined.

The truth about Earth's diameter (and the distance between Earth and Sun) is not "hidden." They are well and precisely known by legitimate Earth science and astronomy, yet denied by length contraction theory. The theory that  objects and distances have no intrinsic properties but instead depend on the frame of reference from which they are observed and measured is false.

Realism says that the world exists and has intrinsic properties independent of how it is observed. (Best observed from at rest with the object.) Idealism says that there is no reality independent of observation, so that as observations vary, the objects/distances observed vary. Length contraction is based on idealism. It is wrong.

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What is much more important now is for you to find a position for yourself where the model you're pushing holds together properly, but that's either going to need length-contraction incorporated into it or some fiendishly clever alternative which no one's thought of yet.

My above replies state yet again "my position." So does the summary statement I've repeated several time now... which you still don't seem to understand:
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The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.


... as length contraction theory does.


You still don't get it, and I am again done with this "conversation" with you.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #254 on: 01/11/2012 21:51:39 »
David Cooper:
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The trouble with that is that we have two big theories which both conflict with that. One theory (SR) has as part of its dogma the idea that all frames are equal, and that means that whatever distances are measured in any frame are as true as the distances measured in any other.

"The trouble with that is"... That we have a "scientific theory", length contraction, claiming that, either science doesn't know (for instance) the true diameter of Earth, or that it varies from about 1000 miles, as measured from the old near 'c' fly-by, to nearly 8000 miles, as measured at rest with Earth.
Earth does not change diameters. Therefore the theory that its diameter contracts is false.

There is not a scientific theory of length contraction: there are different theories which involve length contraction as a component of how they work. In LET the diameter of the Earth in its direction of travel cannot be known unless you can tell which direction it's going in and how fast (which can't be known by any method currently available). In SR, you can argue that the diameter is always the one you measure it as being when measuring from the same frame as the Earth, and then you can see any other measurements made from other frames which conflict with your measurement as being less true, merely being related to how you can interact with the Earth from those other frames. That looks like a mainstream position which is may be compatible with your position. The fact that most of the people in the SR camp here don't share that position within the SR camp is no reason for you to exclude yourself from the SR camp when it appears to be able to accommodate you without difficulty.

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Any rigid physical object requires a force to compact it into a shorter length (or diameter.) No force is applied in any case of length contraction. Therefore any observed contraction is due to the image being distorted by observation from extreme velocities. Different observations do not make physical objects change shapes or lengths. Claiming that that do is false.

I agree with you on that in relation to SR (though it doesn't entirely fit with LET where forces are applied, but they are the forces that are already being applied anyway, simply adjusting the distances between atoms as the body changes its speed through the aether/fabric-of-space/vacuum).

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If that dogma was removed (which could be done without destroying the important core of SR), then the solution becomes the same as the one in LET where there is a correct, hidden truth about any distance, but you can't tell what it is. Your intrinsic distances don't take into account the contractions that may actually be applied to them, unless you take the trouble to declare clearly that they are subject to contractions which can't be determined.

The truth about Earth's diameter (and the distance between Earth and Sun) is not "hidden." They are well and precisely known by legitimate Earth science and astronomy, yet denied by length contraction theory. The theory that  objects and distances have no intrinsic properties but instead depend on the frame of reference from which they are observed and measured is false.

In LET, the truth about these dimensions and distances is hidden - it can't be known without knowing how fast things are moving through space, and movement through space affects those dimensions and distances. In a modified SR (with the dogma about all frames being equal removed), the situation is similar, but more complicated due to the complex role of the time dimension, but I think it's still possible to decide that the measured distances as measured within the frame in which the things you're measuring aren't moving are the truest measurements.

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Realism says that the world exists and has intrinsic properties independent of how it is observed. (Best observed from at rest with the object.) Idealism says that there is no reality independent of observation, so that as observations vary, the objects/distances observed vary. Length contraction is based on idealism. It is wrong.

In LET, length contraction is very much part of realism. In SR it can be too, but clearly there are many people about who think that observation is reality and who aren't alarmed by contradicting accounts of their "reality".

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What is much more important now is for you to find a position for yourself where the model you're pushing holds together properly, but that's either going to need length-contraction incorporated into it or some fiendishly clever alternative which no one's thought of yet.

My above replies state yet again "my position." So does the summary statement I've repeated several time now... which you still don't seem to understand:
Quote
The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.

... as length contraction theory does.

Your position on length contraction is the key part that needs resolution. If you are actually in the SR camp but in a place within that camp where you do actually recognise the need for length contraction but regard its effects as being illusions, then there's little left to resolve. I'm just not sure that you've worked out how to handle the train experiment properly, because the train needs to be length contracted relative to the platform for light to travel all the way along through it and still be able to get out at the right point sent out sideways to the platform.

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You still don't get it, and I am again done with this "conversation" with you.

I get all of it, but I'm not convinced that you do. Have you found anyone else who has the patience to continue discussing this with you? Have you met anyone else who has tried so hard to help get to the points of misunderstanding with this? I can see exactly where you're making mistakes, but you still can't. You aren't going to find those points so long as you keep refusing to look at them. You say you're done with this "conversation" with me, but that really means you're not interested in testing your own understanding of this to see if it stands up to scrutiny. It doesn't yet. You've got a lot of it right, and there's a lot that we agree on, but your apparent rejection of length contraction suggests that you've still got some work to do. Length contraction cannot be written off as an illusion or something that can be accounted for by the mysterious behaviour of light.

Think about the train experiment. Better still, describe it here to prove that you've understood it properly. I'll remind you of the essentials: a light beam is sent along the platform, but another beam is sent into the back of a passing train which is passing at 0,866c, then reflected right up the middle of the train to the front where it's reflected out onto the platform where it hits a detector on the platform. The light which travels along over the platform must reach the detector first, and the light coming back out of the train must hit the detector which is located at a very specific point such that the light will miss it if it doesn't leave the train at the right location.

If you can do that without the train (or the platform) being length contracted, then you have good cause to go on attacking the idea of "length contraction theory". If you can't, then you'll have shown that you aren't willing to back up your assertions.
« Last Edit: 01/11/2012 21:57:31 by David Cooper »
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #255 on: 02/11/2012 20:17:31 »
Mods,
I need help (again) to shake this guy and his personal agenda "off my case."

I am a realist. That means that I know (real-ize) that "the physical world" (broadly speaking) does not "contract" as it may appear to contract from various extreme frames. My favorite examples are Earth's diameter and the distance to the sun. Earth's diameter does not in fact vary from 1000 to nearly 8000 miles. If length contraction ("theory", in the broadest sense) claims that it does, it is wrong. Earth and Sun do not move closer together (ignoring trivial variation in its position in elliptical orbit.) Aside from the absence force required to bring them closer together (or to "flatten" Earth), Earth would be incinerated in much closer proximity, and it would be destroyed by any crushing force posited to actually, physically "contract" its diameter.

These are sincere objections which deserve more than pat answers from the math of "time dilation" and its reciprocal, "length contraction"... *assuming* "spacetime" as a malleable entity with no ontological discussion of *what* either component *is*, let alone their *assumed* coalescense into unity.
I do not debate the empirical obervation that clocks slow down as their velocity is increased. This is a far cry away from the *assumptions* which reify time, making it an entity which "dilates." The same can be said for space. It has not been empirically observed to *be* a malleable medium. There is no evidence that space is anything but 3-D volume.
So, when SR theory insists that the distance between stars would contract "for" a high speed craft with a slowed down clock, realism is a reminder that these are real massive bodies distributed "as is" in space, and that moving massive bodies closer together would require "massive" forces... a fact ignored by length contraction "theory."

Please stop ignoring these facts and provide an explanation besides, "It's all in the math" or "The constant speed of light requires physical bodies to change shapes/ lengths, because they look different from different frames." (paraphrazed.)
It doesn't require a professional philosopher to see the fallacy in the above claims. (Realism trumps idealism every time.)
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #256 on: 02/11/2012 21:22:46 »
So I ask the forum (whomever might be still be reading this thread), do you agree with the following, a recent summary statement I made here:

Quote
The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.
... as length contraction theory does.

Here it is again in a nutshell... anyone...:
Quote
The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference.

If you don't mean anyone, don't make it such an open invitation. You're acting as if no one's answered your questions, but they've all been answered repeatedly. Time and time again you simply write off all their replies as if they were worthless and return to where you started, implying that no one has even addressed the issue. This is deeply insulting to everyone here who has tried their best to engage with you.

As expected, you've ignored my invitation for you to show off your understanding of the whole business of length contraction by discussing the train thought experiment, choosing instead to repeat a whole bunch of assertions which are just the same old attack on "length contraction theory" and the beliefs of many people within the SR camp who are comfortable with contradictions. Everyone has got that last point: some people are happy with contradictions in theories while others aren't: we established that this is the case long ago.

And no: you are not a realist. Realism requires you to take length contraction on board in order to account for the results of actual experiments which show your "realism" to be wrong, but you refuse to do that. This is the key point where your position is wrong, so why don't you give it a shot and try to demonstrate that you are actually qualified to push your assertions by picking apart the train experiment to show that it doesn't need to be contracted to half its normal length when moving at 0.866c. If you can't rattle off a sufficiently detailed analysis of that in twenty minutes or so, you shouldn't be firing off all your guns here.

Do you need more help with it? Shall I do 90% of the work for you to make it easier? Let's make it a toy train so that it's only a metre long. We've got a mirror sitting on the top of the train at the back and another at the front, one metre apart if the train's at rest. "Now, hold on a minute!" I hear you say: "There's going to be an alignment problem with the mirrors when they're moving, so they won't reflect the light in the right directions." That's a really good point you make (which only an expert like yourself would spot), so let's instead try to keep the beam on a straight path throughout to eliminate the problem. We can put the source of our light beam over the track slightly higher than the train and send out a pulse of light exactly as the back of the train passes underneath. Further up the track we can have a detector, and what we want to do is get the light to hit that detector at the same moment as the front of the train passes underneath.

How far away from the source is the front of the train when the light is emitted? Is it one metre, or half a metre?. How far from the source is the back of the train when the light hits the sensor? Is it one metre, or half a metre? How far away from the source is the detector going to be placed? I'm not even going to give you a choice for this one - you're going to have to prove that you can actually do the necessary maths.

So, the challenge is set right there for you. Stop messing everyone around and provide us with some hard answers to demonstrate that you are actually sufficiently qualified to make your assertions and to ignore everything everyone else says. You're calling on the mods to get rid of me. I'm calling on you to show them that they shouldn't get rid of you.
« Last Edit: 02/11/2012 22:01:16 by David Cooper »
 

Offline JP

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Re: Evidence for large scale length contraction?
« Reply #257 on: 03/11/2012 16:07:36 »
Mods,
I need help (again) to shake this guy and his personal agenda "off my case."

The moderators aren't going to get involved here, since this is a legitimate discussion and well within site rules.  There is no ownership of threads on this forum: you may have started this thread to discuss your ideas, but other users have equal rights to post comments so long as it's civil, scientifically-based and a discussion.
« Last Edit: 03/11/2012 16:15:35 by JP »
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #258 on: 05/11/2012 19:06:40 »
David Cooper:
Quote
And no: you are not a realist. Realism requires you to take length contraction on board in order to account for the results of actual experiments which show your "realism" to be wrong, but you refuse to do that.
Yet again... Wiki:
"Realism... the belief that reality exists independent  of observers."

"Observers" include frames of reference as used in the context of lenght contraction.
In other words, realism denies that different observations of the same object or distance (from different frames of reference) reflect real differences in those objects and distances.
(Force is required to actually change the shape or length of a physical object, and length contraction posits no such applied force.)
This is quite obvious in the case of Earth's diameter and distance to the sun, neither of which actually contract, even if they could be observed to contract from extreme relativistic frames.
The same principle holds for other supposedly "contracted" objects like my "probe"* or arms of the MM apparatus, or your train.

* It was measured from Earth to be 10 meters, approaching at .866c, but at as the shuttle pulls alongside to capture it, it is seen as it is... 20 meters long, twice as long as the shuttle bay. You never did get that one, an expose of... a reality check on... the length contraction fallacy.

The operative phrase in length contraction is always some version of "for observer A vs for observer B... the length  is measured to be different."
Realism insists that the objects themselves do not change even if observed/measured to change. Observers seeing an object differently does not mean that the same object actually changes.

The latter is no different than classical idealism, which rejects "reality" as independent of observation. So, "for blind man A", an elephant is shaped like a tree trunk, while "for blind man B" it is shaped like a rope... etc. We all know that an elephant exists as a whole animal of its own intrinsic shape which neither of the above describes accurately. Yet we have length contraction "theory" insisting that an Earth with a 1000  mile diameter is equally accurate ("no preferred frame") with the "real animal" which is nearly spherical with a nearly 8000 mile diameter.

The same principle holds for "length contracted trains" and the MM apparatus arms.
No, David, different observations do not crreate different lengths for the same object.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #259 on: 05/11/2012 20:06:11 »
I take it the test questions were too hard for you, seeing as you don't even mention them. I suspect everyone else who has taken part in this thread is capable of answering them correctly, but the person who has the most need to do so is you because you are trying to lay down the law to everyone on what reality is despite not having a proper grasp of the maths of length contraction and why it is necessary for realism to take it into account.

David Cooper:
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And no: you are not a realist. Realism requires you to take length contraction on board in order to account for the results of actual experiments which show your "realism" to be wrong, but you refuse to do that.
Yet again... Wiki:
"Realism... the belief that reality exists independent  of observers."

That poses no problem for me, but it does for you because experiments show that length contraction is part of reality.

Quote
"Observers" include frames of reference as used in the context of lenght contraction.
In other words, realism denies that different observations of the same object or distance (from different frames of reference) reflect real differences in those objects and distances.

Realism is fully compatible with LET, and also with some interpretations of SR. It is not compatible though with a model which excludes length contraction altogether.

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(Force is required to actually change the shape or length of a physical object, and length contraction posits no such applied force.)

Repeating that over and over again doesn't make it true. The first bit is true, but in some interpretations of SR the shape isn't really changed, while in LET is isn't changed by observation but by movement through space, and the only forces required for the contraction are in action all the time (whether the thing's moving or not).

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This is quite obvious in the case of Earth's diameter and distance to the sun, neither of which actually contract, even if they could be observed to contract from extreme relativistic frames.

In LET it could be contracted without you knowing it, so there's nothing obvious about it.

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The same principle holds for other supposedly "contracted" objects like my "probe"* or arms of the MM apparatus, or your train.

When you think the train's moving at 0.866c it could actually be stationary for all you know, so you have no idea how long it really is.

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* It was measured from Earth to be 10 meters, approaching at .866c, but at as the shuttle pulls alongside to capture it, it is seen as it is... 20 meters long, twice as long as the shuttle bay. You never did get that one, an expose of... a reality check on... the length contraction fallacy.

If the shuttle is moving with the probe, it is length contracted to 5 metres while the probe remains contracted to 10m. You appear to be the only person here who doesn't "get" your own thought experiment.

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The operative phrase in length contraction is always some version of "for observer A vs for observer B... the length  is measured to be different."
Realism insists that the objects themselves do not change even if observed/measured to change. Observers seeing an object differently does not mean that the same object actually changes.

I have always agreed with you on that.

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Yet we have length contraction "theory" insisting that an Earth with a 1000  mile diameter is equally accurate ("no preferred frame") with the "real animal" which is nearly spherical with a nearly 8000 mile diameter.

No, we have one interpretation of SR insisting on that and you are right to attack it. Another interpretation of SR is close to your position, regarding the true shape of an object as the one you see when you are moving/stationary with it. In LET (which you presumably include in "length contraction theory") there is no measurement you can point to and claim to be the true one unless you have access to knowledge which is currently not available by any known method.

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The same principle holds for "length contracted trains" and the MM apparatus arms.

Are you claiming they don't contract then? Surely you can answer this simple question without doing any maths.

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No, David, different observations do not create different lengths for the same object.

How can you think you're disagreeing with me on that? The "No" at the start of that should be a "yes".
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #260 on: 06/11/2012 19:40:34 »
David,
I did not take your test because different observations do not make things change in length. Given that, your "test" is irrelevant. You said that you agree, as follows:
Me:
Quote
The operative phrase in length contraction is always some version of "for observer A vs for observer B... the length  is measured to be different."
Realism insists that the objects themselves do not change even if observed/measured to change. Observers seeing an object differently does not mean that the same object actually changes.
You:
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I have always agreed with you on that.
You contradict yourself.

"Realism... the belief that reality exists independent  of observers." (Wiki)
You:
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That poses no problem for me, but it does for you because experiments show that length contraction is part of reality.

There are no experiments showing length contraction outside of particle accelerators. There, subatomic particles are flattened ("pancaked") by overwhelming application of force accelerating them. It doesn't work with Planet Earth, distance to the Sun, or rigid objects on the scale of the examples discussed in this thread. The "contraction", for instance of one arm of the MM apparatus, depends on differences in observation (frame of reference). See again what you agreed to above.
Me:
Quote
* It (the probe) was measured from Earth to be 10 meters, approaching at .866c, but at as the shuttle pulls alongside to capture it, it is seen as it is... 20 meters long, twice as long as the shuttle bay. You never did get that one, an expose of... a reality check on... the length contraction fallacy.
You:
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If the shuttle is moving with the probe, it is length contracted to 5 metres while the probe remains contracted to 10m. You appear to be the only person here who doesn't "get" your own thought experiment.

The shuttle bay was built on Earth to be 10 meters long. It stays 10 meters long, even when it is traveling beside the probe, the bay now appearing 5 meters long from Earth. The probe was built 20 meters long, which is why it appears from Earth contracted to 10 meters because of its velocity relative to Earth. The shuttle when at rest with the probe sees it as it is, 20 meters. It is twice as long as the bay. Neither the probe nor the bay changed lengths.
Only appearences changed, (called length contraction) due to changes in relative velocity. You still don't get it.

Me:
"(Force is required to actually change the shape or length of a physical object, and length contraction posits no such applied force.)"
You:
"Repeating that over and over again doesn't make it true. The first bit is true,..."
You agree that "force is required to actually change the shape or length of a physical object" ("the first bit"), yet you say that repeating it doesn't make it true, implying that it is false. More self contradiction. It is true, and of course repeating it doesn't make it more true. Different observations do not make the same object change lengths. Believing that reality changes with observation is idealism, not realism. "For observer A", Earth, the probe appears to be 10 meters. "For observer B" (shuttle at rest with probe) the probe is as it is, 20 meters. It didn't actually ("really") change lengths during the shuttle's mission to capture it.
Do you get it yet?
Me:
Quote
Yet we have length contraction "theory" insisting that an Earth with a 1000  mile diameter is equally accurate ("no preferred frame") with the "real animal" which is nearly spherical with a nearly 8000 mile diameter.
You:
Quote
No, we have one interpretation of SR insisting on that and you are right to attack it.

The mods and those who run the show here insist on it, and the purpose of this thread is to argue against their "mainstream" position on length contraction. That is why it was moved to, essentially, the 'theories not to be taken seriously' section.

I am not interested in debating the alternative theory you call LET.
Start your own thread and make your argument there.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #261 on: 06/11/2012 22:15:03 »
David,
I did not take your test because different observations do not make things change in length. Given that, your "test" is irrelevant.

You didn't answer the two simple questions and the other question which required a little bit of maths because you know that it would destroy your position whether you got it right or wrong. That's why you'll never answer it, but you'll find an infinite supply of flimsy excuses instead, starting with this:-

Quote
You said that you agree, as follows:
Me:
Quote
The operative phrase in length contraction is always some version of "for observer A vs for observer B... the length  is measured to be different."
Realism insists that the objects themselves do not change even if observed/measured to change. Observers seeing an object differently does not mean that the same object actually changes.
You:
Quote
I have always agreed with you on that.
You contradict yourself.

I agree with the bit about observers seeing an object differently not changing the object. I assumed that was what you were talking about throughout the whole bit there, but if you're actually intending part of it to mean that the change in an object caused by its change of speed doesn't change the object, then I don't agree with that part.

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There are no experiments showing length contraction outside of particle accelerators.

You've missed out the Michelson Morley experiment - the one which disproves your "realism".

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There, subatomic particles are flattened ("pancaked") by overwhelming application of force accelerating them.

The pancaking has nothing whatsoever to do with acceleration forces on them - that is a complete misunderstanding of the physics on your part.

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It doesn't work with Planet Earth, distance to the Sun, or rigid objects on the scale of the examples discussed in this thread. The "contraction", for instance of one arm of the MM apparatus, depends on differences in observation (frame of reference). See again what you agreed to above.

You misunderstood what I was agreeing to: I was only agreeing to the part about the same thing being observed by different observers as having different dimensions not making any change to that object - their contradictory measurements cannot both be correct when it comes to the actual shape of the object.

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The shuttle bay was built on Earth to be 10 meters long. It stays 10 meters long, even when it is traveling beside the probe, the bay now appearing 5 meters long from Earth. The probe was built 20 meters long, which is why it appears from Earth contracted to 10 meters because of its velocity relative to Earth. The shuttle when at rest with the probe sees it as it is, 20 meters. It is twice as long as the bay. Neither the probe nor the bay changed lengths.
Only appearences changed, (called length contraction) due to changes in relative velocity. You still don't get it.

If you're trying to measure length contraction using a ruler which has been length contracted by its movement, you're on a fool's errand.

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Me:
"(Force is required to actually change the shape or length of a physical object, and length contraction posits no such applied force.)"
You:
"Repeating that over and over again doesn't make it true. The first bit is true,..."
You agree that "force is required to actually change the shape or length of a physical object" ("the first bit"), yet you say that repeating it doesn't make it true, implying that it is false. More self contradiction.

Again no contradiction. If you want to change the actual length, forces will be involved in that, but there is no extra compression force added to the mix for this - the forces which contract an object are the same ones which set the distances between its atoms all the time whether it's stationary, moving, accelerating or decelerating. The full quote should be:-

Quote
The first bit is true, but in some interpretations of SR the shape isn't really changed, while in LET is isn't changed by observation but by movement through space, and the only forces required for the contraction are in action all the time (whether the thing's moving or not).

That's fully clear and fully correct.

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It is true, and of course repeating it doesn't make it more true.

You're attacking a straw man - SR doesn't need the contraction to be real, and LET uses existing forces within the object to contract it simply by maintaining the balance of forces between atoms.

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Different observations do not make the same object change lengths. Believing that reality changes with observation is idealism, not realism.

Agreed.

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"For observer A", Earth, the probe appears to be 10 meters. "For observer B" (shuttle at rest with probe) the probe is as it is, 20 meters. It didn't actually ("really") change lengths during the shuttle's mission to capture it.
Do you get it yet?

You're the only one who hasn't got it. In LET it really did change length. In SR, it changed it's alignment in spacetime and hid some of its length in the time dimension.

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I am not interested in debating the alternative theory you call LET.
Start your own thread and make your argument there.

Every time you attack "length contraction theory", you're attacking LET. If you restrict yourself to attacking the camp within SR which you have an issue with, I won't have to keep setting the record straight, though you'll also have to stop laying claim to realism, because LET is realism.
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #262 on: 07/11/2012 20:11:18 »
Me:
Quote
I did not take your test because different observations do not make things change in length. Given that, your "test" is irrelevant.
D.C.:
Quote
You didn't answer the two simple questions and the other question which required a little bit of maths because you know that it would destroy your position whether you got it right or wrong
.

You still claim to know me and my motivations better than I know myself and my reason, as above. If you agree that that different observations do not create different realities (lengths of objects, etc.), then seeing the same object differently does not make it change. Your train does not get shorter with differing observations of it. The details are then moot.
You:
..."
Quote
but if you're actually intending part of it to mean that the change in an object caused by its change of speed doesn't change the object, then I don't agree with that part.

SR theory does not maintain that change of speed physically compacts an object, as a bullet compacts to shorter when fired. It is always, "For observer A," moving relative to an object, it IS shorter than "for observer B," at rest with the object. SR theory (which is the focus of my argument!) does not claim that application of force compacts the object to make it shorter. And, further, physical objects are not shrunken to shorter by the 'power of observation', which is not a force that can change physical objects.
You:
Quote
You've missed out the Michelson Morley experiment - the one which disproves your "realism".

No. It still depends on the usual "for observer A" vs "for observer B" definition of changing "reality." Again, the reality of physical objects (the length of the apparatus arms here) is not altered by differences in observation. That is idealism, not realism. (See the Wiki definition above... again.)

Regarding subatomic "pancaking" as length contraction:
You:
Quote
The pancaking has nothing whatsoever to do with acceleration forces on them - that is a complete misunderstanding of the physics on your part.
You are wrong. The machines are built to apply immense force to accellerate minute particles. In the process, they are observed to be flattened in the direction they are traveling. Denying that doesn't help your argument. No force is likewise applied to Earth, yet mainstream SR (my focus here!) claims that "for an observer" traveling past at near 'c', it is pancaked in diameter in the direction of the observer's travel. It doesn't work. It has a load of false assumptions which do not transfer from the empirical observation of contraction of particles with applied force in an accelerator.
You:
Quote
...their contradictory measurements cannot both be correct when it comes to the actual shape of the object.

The MM apparatus was built with arms of equal length. Seeing one arm as shorter under no circumstance makes the actual physical arm shorter.

Yet again, regarding my "alien probe retrieval project," you say:

Quote
If you're trying to measure length contraction using a ruler which has been length contracted by its movement, you're on a fool's errand.

You are stuck in the belief that physical objects change length when they move relative to an observer... the essence of SR's length contraction. The shuttle bay was built and remained 10 meters long, even when it joined the probe's frame and *appeared contracted* to 5 meters. The probe was built and remained 20 meters long, even as it approached Earth at .866c and *appeared* 10 meters long. As said above, the shuttle's launch and change of velocity relative to Earth did not make it shorter, "in the real world" even though it appeared to shrink as it joined the probes frame.
You:
Quote
The first bit is true, but in some interpretations of SR the shape isn't really changed, while in LET is isn't changed by observation but by movement through space, and the only forces required for the contraction are in action all the time (whether the thing's moving or not).
You:
"That's fully clear and fully correct."

I repeat, my argument here is with mainstream SR's version of length contraction as advocated by the authorities of this forum, in which there is no force applied to objects to compact/contract them. There is no force applied to Earth to flatten it, but the fly-by guy "sees" it as flattened, and there is no preferred frame, so a flattened Earth is equally valid, they say. I am not interested in what you say about LET. Movement doesn't make objects contract. Only the image of objects gets distorted. They still don't understand the difference.
You:
Quote
...LET uses existing forces within the object to contract it simply by maintaining the balance of forces between atoms.

Nonsense! "Maintaining the balance of forces between atoms" will maintain the object's shape and length. To change an object's shape/length, a force bust be applied to change the space between whaterver units, molecules or atoms, of which the object is composed.
You:
"...because LET is realism."

Nonsense, as exposed above. You really don't understand realism. Objects remain as they were formed or built until a force is applied to crush or compact them to a shorter length or to way out of spherical shape, in Earth's case.
In the real world, observation is not a force which changes physical things. That is my argument, and I've said all I have to say about your argument... yet again... hopefully.

Again, carry on with your LET argument in a thread of your own.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #263 on: 08/11/2012 21:05:23 »
You still claim to know me and my motivations better than I know myself and my reason, as above. If you agree that that different observations do not create different realities (lengths of objects, etc.), then seeing the same object differently does not make it change. Your train does not get shorter with differing observations of it. The details are then moot.

I'm still trying to get you to explain your exact position - it isn't yet clear what you believe based on your attacks on length contraction. I've tried to make it easy for you by pointing to two theories and two interpretations of one of them in the hope that you'll either pin yourself to one of them or put forward a clear fourth alternative which doesn't go against the results of experiments. It still looks as if you could fit into one of the camps within SR, and yet you repeatedly appear to reject that. If you answered the train questions it would maybe help to clear that up. It is perfectly possible to say that the metre-long train when moving at 0.866c fits into a space 50cm long while still remaining one metre long in its own frame where its true length is to be found.

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SR theory does not maintain that change of speed physically compacts an object, as a bullet compacts to shorter when fired.

I'm not clear as to your meaning there in relation to the bullet being made shorter. I can see three different ways in which the bullet length contracts: if it's soft enough, it could be slightly crushed by the force applied to it (that crushing remaining as the bullet slows down); it will have compression waves sent through it (but would rapidly bounce back from those to recover its full length shortly after leaving the gun); and it may be length contracted for relativistic reasons. I suspect the bullet is strong enough not to be crushed, so it's probably only affected by two of these kinds of contraction.

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It is always, "For observer A," moving relative to an object, it IS shorter than "for observer B," at rest with the object. SR theory (which is the focus of my argument!) does not claim that application of force compacts the object to make it shorter. And, further, physical objects are not shrunken to shorter by the 'power of observation', which is not a force that can change physical objects.

That is fine - it is clearly a problem for one camp within SR if they imagine that things are physically changed by being viewed from different frames.

Quote
Quote
You've missed out the Michelson Morley experiment - the one which disproves your "realism".

No. It still depends on the usual "for observer A" vs "for observer B" definition of changing "reality." Again, the reality of physical objects (the length of the apparatus arms here) is not altered by differences in observation. That is idealism, not realism. (See the Wiki definition above... again.)

You seem to be positioning yourself in one of the main SR camps there. If that's the case, then you simply need to accept length contraction as a phenomenon relating to the effective lengths of things in different frames. If that is your position, I don't know why you haven't made it clear that that was your position from the start.

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You are wrong. The machines are built to apply immense force to accellerate minute particles. In the process, they are observed to be flattened in the direction they are traveling. Denying that doesn't help your argument.

They are accelerated up to speed gradually and any compression from that acceleration is thrown off almost as soon as it is added. Even if they were accelerated in an instant, the resulting compression would be thrown off again a moment later. Length contraction is a totally different thing from compression, and you're mixing up the two.

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No force is likewise applied to Earth, yet mainstream SR (my focus here!) claims that "for an observer" traveling past at near 'c', it is pancaked in diameter in the direction of the observer's travel. It doesn't work. It has a load of false assumptions which do not transfer from the empirical observation of contraction of particles with applied force in an accelerator.

If you accept the length contraction of particles in an accelerator, you have to accept it in relation to the Earth too because it is not a different phenomenon. To avoid contradiction, you really ought to be denying that particles are length contracted in an accelerator because they are not compressed into a pancake shape by acceleration forces.

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The MM apparatus was built with arms of equal length. Seeing one arm as shorter under no circumstance makes the actual physical arm shorter.

You've made another assertion which goes against LET. If you don't intend your assertion to apply universally but are restricting it to SR, then for one camp within SR that is fine: the arm is effectively shorter in other frames, but not actually shorter.

Quote
Yet again, regarding my "alien probe retrieval project," you say:

Quote
If you're trying to measure length contraction using a ruler which has been length contracted by its movement, you're on a fool's errand.

You are stuck in the belief that physical objects change length when they move relative to an observer... the essence of SR's length contraction. The shuttle bay was built and remained 10 meters long, even when it joined the probe's frame and *appeared contracted* to 5 meters. The probe was built and remained 20 meters long, even as it approached Earth at .866c and *appeared* 10 meters long. As said above, the shuttle's launch and change of velocity relative to Earth did not make it shorter, "in the real world" even though it appeared to shrink as it joined the probes frame.

Your experiment is an attempt to prove that length contraction isn't real, but it tries to do that by accelerating a ruler up to the same speed as the thing it's going to measure, at which point any length contraction which has been applied to the thing being measured will also have been applied to the thing doing the measuring, rendering the experiment pointless.

Quote
I repeat, my argument here is with mainstream SR's version of length contraction as advocated by the authorities of this forum, in which there is no force applied to objects to compact/contract them. There is no force applied to Earth to flatten it, but the fly-by guy "sees" it as flattened, and there is no preferred frame, so a flattened Earth is equally valid, they say. I am not interested in what you say about LET. Movement doesn't make objects contract. Only the image of objects gets distorted. They still don't understand the difference.

If you are actually in a camp within SR and not writing off length contraction altogether, then I prefer your position to theirs. They don't actually agree that a force needs to be applied to length contract anything, so I'm guessing they see it more in the way of multiple realities all being true at the same time, and that's a kind of thinking encouraged by some interpretations of quantum mechanics. That is why their position isn't as mad as it may initially seem - it's just a different approach.

Quote
You:
Quote
...LET uses existing forces within the object to contract it simply by maintaining the balance of forces between atoms.

Nonsense! "Maintaining the balance of forces between atoms" will maintain the object's shape and length. To change an object's shape/length, a force must be applied to change the space between whaterver units, molecules or atoms, of which the object is composed.

Existing forces acting all the time between atoms will do the job automatically. Think about this illustration of how it works. Imagine two people who decide to maintain their distance from each other by shouting across a field, each one shouting back to the other as soon as they've heard the other one shout to them. They continually adjust their positions to try to keep the round trip of the sound to a fixed interval of time. On a windy day, they will automatically end up closer together than on a still day because of the extra distance the sound has to travel through the air, and the exact distance between them will vary in direct response to the speed of the wind. If the wind is moving at 86.6% the speed of sound, they would need to stand twice as close together as they do on a still day if their clocks were also affected by the wind speed, but because their clocks are actually governed by the speed of light they will instead end up standing four times as close together as on a still day. (Ignore the impossibility of standing up in such a strong wind.)

That is how it works in LET: the forces between atoms are actively maintaining the distances between them all the time, and normally that means the distances are constant, but if you move the body of which they are part at high speed through the vacuum, this slows down the communications of these forces between the atoms and results automatically in them settling closer together in their direction of travel. That is why no additional force need be applied, other than to accelerate the body to higher speed. The clue to the fact that no lasting compression has been added is the fact that if you then spin the body the length contraction remains in the direction of travel at all times. That happens to spinning particles in an accelerator too - the pancaking is always in the direction of travel, whereas a crushed bullet if it started to tumble would have that compression rotate along with the bullet. You also need to understand that the acceleration of particles in an accelerator is done as much by pulling them as by pushing, so if you're imagining them being squashed by pushing forces you're getting a warped view of things. Even if all the force was applied by pulling the particles up to speed though, they would still length contract and not be pulled out into long strings.

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"...because LET is realism."

Nonsense, as exposed above. You really don't understand realism. Objects remain as they were formed or built until a force is applied to crush or compact them to a shorter length or to way out of spherical shape, in Earth's case.

LET and SR are both developments of realism: they have taken length contraction onboard in different ways, and in different ways within SR too. Anything which hasn't taken length contraction into account is not realism.

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In the real world, observation is not a force which changes physical things. That is my argument, and I've said all I have to say about your argument... yet again... hopefully.

Fine, but I'm still trying to find out why/whether you think you aren't in an SR camp.

Quote
Again, carry on with your LET argument in a thread of your own.

I only bring LET into it when it is necessary. Your lack of interest in it doesn't give you the right to ban it being mentioned when you make absolute pronouncements which conflict with it.
 

lean bean

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Re: Evidence for large scale length contraction?
« Reply #264 on: 09/11/2012 13:24:16 »
I just see it as… if you want to interact with something travelling at relativistic speed relative to you, then you have to interact with it the way the laws of physics allows and dictates you to, because we know from the muon reaching earth’s surface without decaying that nature does that too. That is, time dilation and length contraction explain how nature works.

It seems this question of shuttle and probe is an artificial situation or question which would not occur naturally.
Does anyone know of a natural process or natural interaction between particles /fields whereby the particle ‘first’ observes something and then decides to interact with it?
I use the word natural and not intelligent as in… ‘man’ observes a probe and then decides to go and interact with it with a shuttle. An intelligence without knowledge of SR would lean the hard and slow way about chasing after fast moving probes and then matching their speed.
(Superposition, probabilities, SR,GR and quantum theory our models of something we agree to call nature).
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #265 on: 09/11/2012 21:11:04 »
Briefly... 'short' on "time":

Here again is the essence of my argument against length contraction:
"In the real world,(neither) observation (nor measurement from different frames) is a force which changes physical things."

It is ironic that denying that Earth changes shapes/diameters, as observed from different frames, is now considered a "new theory" not to be taken seriously, because it denies that Earth's diameter contracts, as SR insists.
This basic embrace of a "real physical Planet Earth" with intrinsic properties (size and shape) independent of how it is observed (not changing with changes in how it is observed) is still my answer to D.C."s query:

Quote
Fine, but I'm still trying to find out why/whether you think you aren't in an SR camp.

But I've said this dozens of times... yet you ask the above. SR says that reality depends on how it is observed, that there is no "real, unchanging Earth." They say that "for" a frame of reference flying by at near 'c', Earth is flattened, i.e., contracted in diameter. Re-read the thread if you have forgotten all the insistence by length contraction advocates that earth does change shape with changes in frame from which it might be measured.

The reason I use this as my signature example is because it is so obviously a denial of reality by SR. But the same principle applies to rulers, trains, the MM apparatus arms, my shuttle and probe... and the distance to the sun... which if severely "contracted" would result in Earth's incineration (as a "flattened" Earth would also be destroyed.)

lean bean,
If Earth ever develops near 'c' space travel, and if an "alien probe" were discovered approaching Earth at .866c, the true test of "length contraction" would be to determine the real, actual length of the probe in order to send a ship with long enough bay capacity to capture it. It would *appear to be* 10 meters long from earth, if the equations are correct (which I don't doubt.) However, sending out a shuttle with a 10 meter bay would be folly... a very stupid wast of resources... and perhaps fatal to life on Earth if the probe's mission were to kill all life on Earth. So the question, "How long is the probe, really" becomes one of vital importance.
Turns out it is not "really" 10 meters, as it appears. It is really 20 meters. A shuttle bay 20 meters long, not 10, will be required.
 

lean bean

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Re: Evidence for large scale length contraction?
« Reply #266 on: 10/11/2012 18:55:48 »
lean bean,
If Earth ever develops near 'c' space travel, and if an "alien probe" were discovered approaching Earth at .866c, the true test of "length contraction" would be to determine the real, actual length of the probe in order to send a ship with long enough bay capacity to capture it. It would *appear to be* 10 meters long from earth, if the equations are correct (which I don't doubt.) However, sending out a shuttle with a 10 meter bay would be folly... a very stupid wast of resources... and perhaps fatal to life on Earth if the probe's mission were to kill all life on Earth. So the question, "How long is the probe, really" becomes one of vital importance.
Turns out it is not "really" 10 meters, as it appears. It is really 20 meters. A shuttle bay 20 meters long, not 10, will be required.

Is that all your worried about …an evil alien probe.
Don’t worry old wrinkly, we on earth already know of SR and will know that what we observe travelling at high speeds is length contracted and so will allow for it when we send out a shuttle to retrieve the probe. As I said in my post…“An intelligence without knowledge of SR” will be the ones having your probe retrieval problem. Watch the skies…it may rain.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #267 on: 10/11/2012 23:09:38 »
Here again is the essence of my argument against length contraction:
"In the real world,(neither) observation (nor measurement from different frames) is a force which changes physical things."

That is not an argument against length contraction: it's a argument for (or against, depending on whether the brackets are there or not) the idea that observation changes things physically.

Quote
It is ironic that denying that Earth changes shapes/diameters, as observed from different frames, is now considered a "new theory" not to be taken seriously, because it denies that Earth's diameter contracts, as SR insists.

Don't attribute it to SR as a whole - you are only attacking one camp within SR.

Quote
This basic embrace of a "real physical Planet Earth" with intrinsic properties (size and shape) independent of how it is observed (not changing with changes in how it is observed) is still my answer to D.C."s query:

Quote
Fine, but I'm still trying to find out why/whether you think you aren't in an SR camp.

But I've said this dozens of times... yet you ask the above. SR says that reality depends on how it is observed, that there is no "real, unchanging Earth." They say that "for" a frame of reference flying by at near 'c', Earth is flattened, i.e., contracted in diameter. Re-read the thread if you have forgotten all the insistence by length contraction advocates that earth does change shape with changes in frame from which it might be measured.

Again you're attacking SR as a whole rather than just the specific camp within SR which holds that view. There are other ways of looking at things within SR where there is no physical change made to the thing being observed, and you may find that you belong there. So long as you keep attacking SR instead of finding out whether you fit within an SR camp, you're putting yourself in a position which either requires you to be wrong, to be in the LET camp (which you aren't interested in and don't understand), or to have an alternative theory which you aren't prepared to set out clearly enough to demonstrate that it isn't wrong. You've been doing this for eleven pages now in this thread and still haven't made your position clear. What makes you think you aren't in a mainstream SR camp which doesn't insist on things being physically changed by being observed from different frames?

Quote
The reason I use this as my signature example is because it is so obviously a denial of reality by SR. But the same principle applies to rulers, trains, the MM apparatus arms, my shuttle and probe... and the distance to the sun... which if severely "contracted" would result in Earth's incineration (as a "flattened" Earth would also be destroyed.)
meters long, not 10, will be required.

All the camps in SR (and LET) require you to build a >20m long container to hold a 20m long object when they are moving/stationary together. Length contraction only comes into it when calculating interactions between things that are moving relative to each other, so your signature example isn't addressing that issue.
 

Offline bizerl

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Re: Evidence for large scale length contraction?
« Reply #268 on: 11/11/2012 22:03:56 »
Old guy, I stopped responding when it became apparent that I don't know enough about this stuff to formulate a convincing argument. And since you ignore it all anyway in favour of a wiki definition of what philosphical realism is anyway, I didn't think it mattered.

Couple of points though...

If length contraction is indeed just an illusion created by an observer approaching the speed of light relative to another object, what is the reason for this optical illusion? How does it occur? Why should objects appear shorter if they are travelling really fast?

Also, in relation to this:
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OK, so bizerl and the team of length contraction "experts" here insist that an Earth with a 1000 mile diameter is just as valid a description as the well validated nearly 8000 mile diameter. Please correct me if I am wrong.

and this:
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The fact is that all the observational and experimental evidence that has been gathered so far, indirectly supports the fact that if a 20m spaceship flies through a 10m bay at 0.866c, it will (very briefly) fit exactly inside that bay.You, like almost everyone here misunderstood and/or misrepresented my "alien probe retrieval project." There was no ship (the probe) "flying through" the 10 meter bay of the shuttle. In order to retrieve the probe, the shuttle would by necessity need to match the probe's velocity (come to rest with the probe's frame.) The probe was measured from earth to be 10 meters as it approaced earth at .866c. However, as the shuttle pulled alongside the probe, it was then measured to be 20 meters long, so it would not fit in the 10 meter bay, which did not change after launch.
This was offered as a thought experiment (that's all we have to work with regarding lenght contraction on this scale) demonstrating that the "length contracted probe" as seen from earth was not *actually* contracted to 10 meters. Nor would the shuttle bay have *actually* contracted to 5 meters, as it would be measured from earth when traveling with the probe.


The point is, if you accept that when travelling at 0.866c, the ship will indeed fit very briefly inside the bay, then saying "the ship is 10m when travelling at 0.866c relative to the observer" is as equally valid description of it as saying "the ship is 20m at rest with the observer".
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #269 on: 12/11/2012 19:06:31 »
lean bean,
If Earth ever develops near 'c' space travel, and if an "alien probe" were discovered approaching Earth at .866c, the true test of "length contraction" would be to determine the real, actual length of the probe in order to send a ship with long enough bay capacity to capture it. It would *appear to be* 10 meters long from earth, if the equations are correct (which I don't doubt.) However, sending out a shuttle with a 10 meter bay would be folly... a very stupid wast of resources... and perhaps fatal to life on Earth if the probe's mission were to kill all life on Earth. So the question, "How long is the probe, really" becomes one of vital importance.
Turns out it is not "really" 10 meters, as it appears. It is really 20 meters. A shuttle bay 20 meters long, not 10, will be required.

Is that all your worried about …an evil alien probe.
Don’t worry old wrinkly, we on earth already know of SR and will know that what we observe travelling at high speeds is length contracted and so will allow for it when we send out a shuttle to retrieve the probe. As I said in my post…“An intelligence without knowledge of SR” will be the ones having your probe retrieval problem. Watch the skies…it may rain.
I'm not worried, skinny kid. The whole point was that the probe is not 10 meters long as it appears from earth, so the transformation formula must first be applied to get its true, actual, real length before going out to capture it.
This exposes the "for this frame (Earth) vs for that frame (at rest with the probe)" version of reality as a fallacy. The probe is and stays 20 meters, even as it *appears* contracted. The shuttle bay is and stays 10 meters. the probe will not fit into the bay, even for a theoretical instant.
 

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Re: Evidence for large scale length contraction?
« Reply #270 on: 12/11/2012 19:47:22 »
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Here again is the essence of my argument against length contraction:
"In the real world,(neither) observation (nor measurement from different frames) is a force which changes physical things."
D.C.:
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That is not an argument against length contraction: it's a argument for (or against, depending on whether the brackets are there or not) the idea that observation changes things physically.

Throughout this thread I have agrued against the length contraction  insistence that physical objects actually change shapes/lengths with differences in frames of reference from which they are observed. SR claims that "length is not invarient," i.e., denies that Earth (etc.) has an intrinsic property of diameter length, i.e., insisting that it IS flattened, as above, not just "appears flattened," based on the dictums, "length is not invarient" and "there is no preferred frame of reference." I've made this case many times and it is you who do not yet get it.

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Don't attribute it to SR as a whole - you are only attacking one camp within SR.
As above. I am not interested in your LET "camp" because it insists that physical objects actually do change shapes/lengths as their velocities change.
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...you're putting yourself in a position which either requires you to be wrong, to be in the LET camp (which you aren't interested in and don't understand), or to have an alternative theory...

See above re your misconception, which I bolded.

"My theory" is none of the above, mainstream SR or LET as you have presented it with objects physically changing with changes in velocity... and it is not "my theory." It is realism, which you do not understand, though I've explained it many times. The "elephant" has its own intrinsic shape as a real animal/object, independent of how it is observed. If you accellerate the elephant to .866c, it will not shrink to half its tail-to-trunk length. An "elephant compactor" would be required for that, and that would definitely kill the elepant.

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All the camps in SR (and LET) require you to build a >20m long container to hold a 20m long object when they are moving/stationary together. Length contraction only comes into it when calculating interactions between things that are moving relative to each other, so your signature example isn't addressing that issue.

My example addresses the SR claim that the probe is contracted to 10 meters as measured from Earth. It is not, and it doesn't grow twice as long after the shuttle enters its frame.
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #271 on: 12/11/2012 20:10:13 »
bizerl:
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If length contraction is indeed just an illusion created by an observer approaching the speed of light relative to another object, what is the reason for this optical illusion? How does it occur? Why should objects appear shorter if they are travelling really fast?

I am not an optics expert, but I do know that the image observed is not the object itself, and that all images are carried by light, so when one approaces light speed, one could expect some distortion. I also know that physical objects can not be compacted into shorter lengths without application of appropriate amounts of force, which would then crush the object. Assuming objects are not made of rubber, they could not then 'bounce back" to original length as frame of reference changes back.

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The point is, if you accept that when travelling at 0.866c, the ship will indeed fit very briefly inside the bay, then saying "the ship is 10m when travelling at 0.866c relative to the observer" is as equally valid description of it as saying "the ship is 20m at rest with the observer".
No, I do not "... accept that when travelling at 0.866c, the ship will indeed fit very briefly inside the bay..."

The bay is 10 meters long. The probe is 20 meters long. As repeated many times, the probe will not fit into the bay even for an instant. Its length does not actually," really" change even though it is observed to change due to changes in relative velocity as observed from different frames.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #272 on: 12/11/2012 23:55:37 »
Throughout this thread I have agrued against the length contraction insistence that physical objects actually change shapes/lengths with differences in frames of reference from which they are observed. SR claims that "length is not invarient," i.e., denies that Earth (etc.) has an intrinsic property of diameter length, i.e., insisting that it IS flattened, as above, not just "appears flattened," based on the dictums, "length is not invarient" and "there is no preferred frame of reference." I've made this case many times and it is you who do not yet get it.

That is just the view of one camp within SR. It is perfectly possible to have a view within SR that the shape of an object does not actually change and that the true shape is seen when stationary or moving with the object. It doesn't matter how many of the people within SR don't agree with that, it is still a viewpoint from within SR.

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Don't attribute it to SR as a whole - you are only attacking one camp within SR.
As above. I am not interested in your LET "camp" because it insists that physical objects actually do change shapes/lengths as their velocities change.

Now that's a strange reply! LET is not a camp within SR. Maybe you were writing in a hurry again and didn't have time to check and edit.

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...you're putting yourself in a position which either requires you to be wrong, to be in the LET camp (which you aren't interested in and don't understand), or to have an alternative theory...

See above re your misconception, which I bolded.

You clearly don't understand it because you never get the point that things are length contracted in LET without adding any crushing force.

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"My theory" is none of the above, mainstream SR or LET as you have presented it with objects physically changing with changes in velocity... and it is not "my theory." It is realism, which you do not understand, though I've explained it many times. The "elephant" has its own intrinsic shape as a real animal/object, independent of how it is observed. If you accellerate the elephant to .866c, it will not shrink to half its tail-to-trunk length. An "elephant compactor" would be required for that, and that would definitely kill the elepant.

And there we see again that you don't understand LET. Let me just walk you through a little of the history. Up to about a century ago, your theory was the only game in town. The Michelson Morley experiment then disproved it. Lorentz managed to recover the situation by working out how objects automatically become length-contracted in the direction of travel, so he created an improved version of Realism which corrected an incorrect assumption of the earlier kind of Realism. Einstein then came up with another kind of Realism which turned time into a dimension and so far as I know it is only LET and SR that can handle the Michelson Morley experiment - the older version or Realism clashed with it. Now, if there is another theory which can account for the results of MM, I'd like to see it. So far as I can tell, you're just pushing the old, broken version of Realism. If you don't like the idea of Spacetime, the only place you'll find where you've still got a leg to stand on is going to be LET. The advantage that SR has over LET is that GR can be built upon it to provide a startlingly accurate way of calculating the effects of gravity, but that doesn't mean that it's right - I suspect it's just tapping into something which could be accounted for in some other way, but that's another discussion. What matters is that there are two theories which can handle MM, and both of them are well worth getting your head around. If there's a viable third option, I want to get my head round it too because it may be the piece that unlocks the puzzle. I don't believe that you've got a viable third theory though: it looks exactly like the old, broken Realism to me, and the mistakes you keep making confirm that.

That paragraph was important - don't skip it.

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All the camps in SR (and LET) require you to build a >20m long container to hold a 20m long object when they are moving/stationary together. Length contraction only comes into it when calculating interactions between things that are moving relative to each other, so your signature example isn't addressing that issue.

My example addresses the SR claim that the probe is contracted to 10 meters as measured from Earth. It is not, and it doesn't grow twice as long after the shuttle enters its frame.

Ironically, you'd only have a vestage of a case if you were in a Realism camp within SR, using the nature of Spacetime to avoid the length contraction being real. You don't like Spacetime though, which leaves you with a straight choice between the old and new Realisms of OGVT and LET (V standing for vacuum). Without Spacetime complicating the issue, we can now state categorically that when the platform is stationary within the vacuum and the train is moving past at 0.866c, the train is length contracted to half its rest length, and this can be demonstrated by sending light along it as set out a few posts back (in the thought experiment which you're too scared to explore). If you don't like that, then you can jump into an SR camp and use Spacetime to escape from the clutches of LET. I don't care which way you jump, but I would like to see you make the leap of understanding necessary to recognise that you're standing in a position which is not viable. OGVT should make the train travel twice as far as it does in reality before the light from the back has reached the front. That is where OGVT falls.
 

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Re: Evidence for large scale length contraction?
« Reply #273 on: 13/11/2012 19:09:30 »
This exposes the "for this frame (Earth) vs for that frame (at rest with the probe)" version of reality as a fallacy.

No it doesn’t. if two things interact and one is travelling at a relativistic speed relative to the other, then you must treat the situation of time dilation and length contraction as real… how else does the muon reach earth’s surface without decaying, are you saying this is some kind of optical illusion, who is the observer in this case? The detection is only made when the muon reaches the detector at earth’s surface or below surface.
 
skinny



« Last Edit: 13/11/2012 19:13:05 by lean bean »
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #274 on: 13/11/2012 21:29:57 »
This exposes the "for this frame (Earth) vs for that frame (at rest with the probe)" version of reality as a fallacy.

No it doesn’t. if two things interact and one is travelling at a relativistic speed relative to the other, then you must treat the situation of time dilation and length contraction as real… how else does the muon reach earth’s surface without decaying, are you saying this is some kind of optical illusion, who is the observer in this case? The detection is only made when the muon reaches the detector at earth’s surface or below surface.
 
skinny
Me:
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The whole point was that the probe is not 10 meters long as it appears from earth, so the transformation formula must first be applied to get its true, actual, real length before going out to capture it.
This exposes the "for this frame (Earth) vs for that frame (at rest with the probe)" version of reality as a fallacy. The probe is and stays 20 meters, even as it *appears* contracted. The shuttle bay is and stays 10 meters. the probe will not fit into the bay, even for a theoretical instant.

"No, it doesn't"? In the real world both a shuttle bay and an alien ship are made of rigid metal and would require a crushing force to compact them to half their length-as-built. If you don't agree, then you must believe that observation from different frames, seeing them as half their actual length (in the case of .866c relative velocity) is an actual force which compacts them. If not, they stay the length they were built. The latter is realism. The former is the length contraction version of idealism, in which physical objects change with how they are observed. You believe that and I don't.

"Time dilation" is a misnomer (time is not an entity) for the observed fact that physical processes (like the ticking of clocks) slow down when they travel at higher velocities. Muons enter Earth's atmosphere at very high speed, so thier rate of decay is slowed down accordingly. Therefore they "live longer" and travel further than would be expected at a slower (edit: higher) rate of decay. This does not make Earth's atmosphere thinner (contracted.) Earth's atmosphere does not contract around mouns to accomodate the math that insists that length contraction is the reciprocal of "time dilation." SR insists that "they go hand in hand." SR also insists that Earth can be squished to a small fraction of its established diameter of nearly 8000 miles by the same principle, as observed by a fast fly-by frame. This is nonsense.
 Same for the distance to the sun. Never mind that Earth would be incinerated if it were actually a small fraction of the established average of 93 million miles or so from the Sun. SR assumes that math creates new distances between such bodies based on the slower clocks of theoretical high speed space travelers. Total nonsense.
Same applies to the "altered realities" of what D.C. calls LET. He says that the space between atoms in Earth varies with changes in velocity (of Earth relative to near 'c' travelers), thus giving it a 1000 mile diameter in the extreme case. More total nonsense.

Late edit regarding D.C.'s last post: It is trivial and irrelevant whether "LET" is a "camp" within SR. Earth's diameter does not actually change as its image is  viewed from various frames of reference. That is the point which D.C. is trying to obfuscate here with his pet project, promoting "LET." Why he doesn't promote it in his own thread, I do not know.
« Last Edit: 14/11/2012 18:53:30 by old guy »
 

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