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Author Topic: Evidence for large scale length contraction?  (Read 56800 times)

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #50 on: 07/09/2012 20:19:16 »
The idea of absolutes in time and space, of a universal reference frame, of immutability have been shown to be incorrect.

They haven't all been shown to be incorrect, but length contraction certainly must happen in one way or another, as has been demonstrated by the Michelson Morley experiment. Anyone who wants to deny length contraction would really be better off joining the Einstein camp rather than attacking it, because SR at least provides a way for the contraction to be apparent rather than actual, even if it then leads to endless arguments about whether the contraction then counts as an illusion or not.
 

Offline flr

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Re: Evidence for large scale length contraction?
« Reply #51 on: 07/09/2012 21:11:34 »
This particular thread was so interesting to me, because for such a long time I tried to train my intuition to see the length contraction. And I visited this forum (and some others) specifically because I could find some line of thinking different from text-book, and some freedom of users to express whatever they wanted.

You have decided - on the basis of zero evidence - that earth has an essential, absolute shape that forms part of a natual universal truth;

To be honest, my intuition tells me that objects deserve an absolute shape, and I find it hard to train my intuition to believe otherwise. Maybe from here arise my difficulty in accepting the relativity of lengths. 
Why should not some real object have a form of itself? Why an object cannot be something by itself?

the products of special relativity threaten your preconceptions therefore you reject the proven science and embrace your intuitions
It is not that I reject proven science, actually I really want to get there but myself and in my own way.
In this process I asked myself many of the questions you have seen in this thread or in other related threads.

I hope @imatfaal will not close this topic. Why should be closed? Isn't special relativity an interesting topic?
 

Offline flr

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Re: Evidence for large scale length contraction?
« Reply #52 on: 07/09/2012 21:22:01 »
..  SR at least provides a way for the contraction to be apparent rather than actual.

To me looks quite "actual", otherwise how could muon decay so little while passing through atmosphere? The little decay of muon is quite actual and not apparent. Note that In muon frame it has to travel a smaller distance that the observer on Earth measure.
 

Offline JP

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Re: Evidence for large scale length contraction?
« Reply #53 on: 07/09/2012 21:30:07 »
To be honest, my intuition tells me that objects deserve an absolute shape, and I find it hard to train my intuition to believe otherwise. Maybe from here arise my difficulty in accepting the relativity of lengths. 
Why should not some real object have a form of itself? Why an object cannot be something by itself?

That's a good point, flr.  The problem is that intuition only works when you're so familiar with something that it becomes intuitive!  It can also be very misleading in science, since many effects are counterintuitive.  A far better guide in science is logic.  Once you know something is true (by observing or measuring it), you can logically figure out its consequences. 

That's the case in special relativity.  Length contraction is very counterintuitive, but we know that the speed of light is constant for all observers from experiments.  Once you know that's true, you can logically work through the consequences, and find that lengths have to contract.  Our intuition fails because we hardly ever experience relativistic effects in daily life.  You can definitely train your intuition by studying something thoroughly, but it takes a lot of effort to actually learn a subject so well that it becomes intuitive, especially when its as abstract as relativity theory.
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #54 on: 08/09/2012 00:07:44 »
This thread is now continued in the New Theories section, by order of imatfaal.
 

Offline damocles

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Re: Evidence for large scale length contraction?
« Reply #55 on: 08/09/2012 00:27:07 »
At this point I will repeat my previous message.

SR does not rob an object of its intrinsic properties.

The properties that we measure and ascribe to an everyday object: its mass, size and shape, are its intrinsic properties. The Earth is an oblate spheroid of revolution, with minor radius 6353 km and major radius 6379 km, and mass 5.98 E 24 kg. Those are absolute and immutable properties.

If a traveller moving at speeds where SR effects exceed the precision of measurement makes observation of the Earth's properties, then s/he will observe a set of properties different to this, and different to those observed by another such observer moving at a different speed and direction. But none of this directly reflects the Earth, which can blissfully retain its intrinsic properties.

When we refer to such observations, it is quite usual to use the term "rest mass". Perhaps the logic of the situation would become clearer if we were also to use terms like "rest shape" for the other intrinsic properties of an object.

If, however, the Earth interacts with another object moving at such speeds, then the interaction will, from the point of view of the other object, be determined by the "distorted" properties of the Earth, as measured in its own reference frame. From an Earthbound point of view, though, the interaction will be governed by the intrinsic properties of the Earth and the "distorted" properties of the other object as observed from the Earthbound frame of reference. And the mathematical detail of the SR formulation will ensure that both observers will get the same result when the actual consequences of the interaction are calculated -- relative to the particular frame of each observer, of course.

The other laws of physics are likely to ensure that neither of these observers is still around to make the actual measurements, of course ;D
 

Offline yor_on

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Re: Evidence for large scale length contraction?
« Reply #56 on: 08/09/2012 15:37:52 »
This particular thread was so interesting to me, because for such a long time I tried to train my intuition to see the length contraction. And I visited this forum (and some others) specifically because I could find some line of thinking different from text-book, and some freedom of users to express whatever they wanted.

You have decided - on the basis of zero evidence - that earth has an essential, absolute shape that forms part of a natual universal truth;

To be honest, my intuition tells me that objects deserve an absolute shape, and I find it hard to train my intuition to believe otherwise. Maybe from here arise my difficulty in accepting the relativity of lengths. 
Why should not some real object have a form of itself? Why an object cannot be something by itself?

the products of special relativity threaten your preconceptions therefore you reject the proven science and embrace your intuitions
It is not that I reject proven science, actually I really want to get there but myself and in my own way.
In this process I asked myself many of the questions you have seen in this thread or in other related threads.

I hope @imatfaal will not close this topic. Why should be closed? Isn't special relativity an interesting topic?

It's no illusion friend :) And I like the way you think btw, but neither will you ever see it locally. The only way a length contraction can be expressed is in a measurement between 'frames of reference'. If you use what I call 'locality' as your guiding principle OG is right. A object has the form you find it to have being at rest with it and the proofs for that is simple. Just become 'at rest' relative whatever you want to measure. Damocles hit the nail spot on with that one.

To further the discussion :) All of this has to do with what you think you observe. A 'whole undivided SpaceTime', or 'frames of reference' mediated by and through 'radiation'. Using your own unique frame you can define yourself and your closest environment as, loosely speaking again :) unchanging, aka 'invariant', no matter where you are or how 'fast' you go.

I believe in 'frames of reference' and 'locality', and there you will find things to have a consistency. Using a 'undivided SpaceTime the concept becomes trickier to me in that, what we have, still must relate to those 'frames of reference' 'joining it up'. Then defining it as 'one reality', the degrees of freedom we find it to have (dimensions) becomes 'unbreakable definitions´, defining a 'bubble' of sorts called SpaceTime. It's not like that to me, SpaceTime is a (very) partial 'bit' of something more/less, and it all coexists. What we see use radiation.
=

Can you see what I mean there? That when we find those length contractions contradict common sense. we all assume that 'one SpaceTime to bind us all'? ahem. If we let locality define a SpaceTime it will use frames of reference, radiations constant, 'gravity/mass', 'energy'. And we can leave the 'space' as it is, 'empty', at least classically, locally definable as 'invariant' too. Our problems arise with our preconceptions of how 'things always have been, and always must be'. Those change with knowledge, but each generation somehow still presume that their 'level' defines 'what is', don't they :)

When it comes to the question of 'motion' as uniform/accelerations?
That's tricky, but in locality all (uniform) motion must by definition become relative. Although we still have that constant frame radiation binding together 'locality', to measure a 'motion' against, using lights blue/red shifts. Accelerations will then be equivalent to 'gravity' as I think.
===

Sorry, I write too slow, and my brain seems to assume that my fingers have brains of their own, as I keep missing those letters and small binding words. Also, you can always polish it a bit, can't you ::))
=

And OG, please stop being so hard on the mods. It's definitely not easy being one, and? I find Imatfaal a quite good one.
« Last Edit: 08/09/2012 16:37:42 by yor_on »
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #57 on: 08/09/2012 19:50:56 »
..  SR at least provides a way for the contraction to be apparent rather than actual.

To me looks quite "actual", otherwise how could muon decay so little while passing through atmosphere? The little decay of muon is quite actual and not apparent. Note that In muon frame it has to travel a smaller distance that the observer on Earth measure.

That's a different aspect of it - it travels further through our frame, but it itself appears to be (or is) shortened in length. You're now talking about it travelling further in our frame due to time dilation making it longer-lived in our frame. To make sense of it without SR, the internal mechanical mechanisms of the muon would have to be slowed down by its movement through the fabric of space such that it lasts longer. Alternatively, to make sense of that in SR you have to eliminate all ideas of Newtonian time such that the most genuine length of time for the muon to last is the one as measured in its own frame, while in any other frames where the measurement is different it will appear to last for longer than that.

What this means is that both the shape and time are probably best measured from the same frame as the thing being measured, while other frames may contract the apparent length in one direction and extend the apparent lifespan of the thing in question. But we're always trying to describe things in terms which shouldn't be applied to a universe with Newtonian time removed from it. If we attempt to remove Newtonian time properly, everything in the universe ends up being effectively simultaneous (because you end up with an eternal block universe) and there is no longer any speed of anything - not even a speed of light. Time is transformed into a kind of distance instead, and the future was never generated out of the past in cause-and-effect order.

Those are the necessary consequences of removing Newtonian time, and I hope there's no one here who wants to have their cake and eat it by smuggling a Newtonian time back in by the back door to try to make SR sound more compatible with common sense, because it won't fit.
 

Offline lightarrow

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Re: Evidence for large scale length contraction?
« Reply #58 on: 08/09/2012 23:24:47 »
Lightarrow said:
Quote
Physics concerns measures; if an object's measure changes, then the object changes.
(Also):You always have to specify a frame of reference, it *doesn't exist* a "lenght" independent of it.

This claims that things have no length (shape, etc.) on their own, intrinsically, independent of measurement.
Me:
"Does this claim that Earth changes shape as it is measured from different frames of reference?"
Lightarrow:
Quote
Certainly. In a frame of reference which is still with respect of our planet, the Earth is spherical...; in another, moving, frame, it's not (and of course every human being is flattened too). Where is the problem?

The "problem" is that, "in the real world" Earth does not change shape with every different possible measurement of it. It is in fact nearly spherical. As I said: "This, of course, is impossible and has never been empirically observed." (A flattened Earth, for instance.)
When you say "in the real world" you are actually saying "in the Earth's frame of reference".
Do you want to postulate the existence of a preferred frame of reference in relativity (that is, the "proper" frame, which in this case is the Earth frame )? Then you should explain how could Einstein base his theory on the fact that a preferred frame doesn't exist.
Quote
Quote
You're wrong for both assertion. Maybe you still haven't totally grasped what "measure of lenght" means, read again my first post. A measure of lenght *is* frame-dependent, and so is, as consequence, an object's shape.

I grasped it just fine. You are wrong to assert that an object's shape (like Earth) depends on how it is observed/measured, as if it had no reality, no intrinsic properties of its own.
Say 1000 ships pass by Earth going 1000 different (but near 'c') velocities, all going in 1000 different directions. Does Earth change into 1000 different shapes with its diameter contracting variously in all those directions? Of course not!
See up. You are still talking of the Earth's shape in a preferred one of the frames.
Quote
Wiki on Realism (my bold):
Quote
In philosophy, Realism, or Realist or Realistic, are terms that describe manifestations of philosophical realism, the belief that reality exists independently of observers.
"Observers" here in the context of this thread includes abstract points of view, all possible "frames of reference... no living "subject" required.
You asked me to define "actual." That would be that "reality exists independently of observers."
Earth is actually nearly spherical. AC is actually 4.37 light years from Earth. The distance to the Sun is actually about 93 million miles, which would not change if it were measured by a ship flying by very fast. The probe in my example is not actually 10 meters long, as observed from Earth's frame. Proof: It will not fit in the shuttle's 10 meter cargo bay. (Much too long, actually.)
In all of those cases we refer to distances and dimensions in the "proper" frame, because is the simpler one; but is it always possible to find such a frame?
Imagine a massive neutron star, which is composed of two concentric parts spinning along a same axis but in opposite directions, so that the outer edges of these parts are moving at relativistic speeds.
1. Which would be the measured radius of the star?
2. Which would be its "intrinsic" radius?
« Last Edit: 08/09/2012 23:28:25 by lightarrow »
 

Offline damocles

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Re: Evidence for large scale length contraction?
« Reply #59 on: 08/09/2012 23:55:39 »
From Lightarrow:
Quote
Imagine a massive neutron star, which is composed of two concentric parts spinning along a samr axis but in opposite directions, so that the outer bords of these parts are moving at relativistic speeds.
1. Which would be the measured radius of the star?
2. Which would be its "intrinsic" radius?

We would have to imagine something a little different to that, because in SR length contraction operates only in the direction of motion, and rotation only describes motion perpendicular to the radius. So the intrinsic radius would be easily and unambiguously determined in an inertial frame that is stationary relative to the centre-of-mass of the neutron star.

Nevertheless it is possible to think of an "intrinsic" property that is ill-defined for a complex object -- in fact such properties are legion. What is the rest mass of the solar system? If we try to measure it in the frame of the centre-of-mass of the solar system, the orbital motion of each of the planets would ascribe to it a mass slightly greater than its own rest mass. So we are faced either with an object that has a mass somewhat greater than the sum of the parts or a mass that cannot be directly measured.

For a physicist, this creates a contradiction and a crisis, that can only be ultimately resolved with a denial that anything has "intrinsic" properties. For a chemist, though, there is no problem. We are forever ascribing an "intrinsic" weight to an atom which (for quite different reasons) is quite significantly different to the sum of masses of its protons, neutrons, and electrons.

Even in a Newtonian universe, the solar system does not have a shape. The concept of "intrinsic" properties does not collapse as a result. A house or a raindrop still has an intrinsic shape. In the chemist's world an object may or may not have a particular intrinsic property. A benzene molecule has an intrinsic shape, a butane molecule does not.
 

Offline flr

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Re: Evidence for large scale length contraction?
« Reply #60 on: 09/09/2012 02:31:58 »
A benzene molecule has an intrinsic shape, a butane molecule does not.

 Note that, although in benzene is no free rotation of some chemical group(at  room T), the benzene also changes its [instantaneous] shape (on fs time-scale) due to all sort of  vibrations/deformations. But that has nothing to do with Lorentz contraction.
 

Offline damocles

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Re: Evidence for large scale length contraction?
« Reply #61 on: 09/09/2012 09:10:47 »
You are quite right of course flr. I had wandered a long way from the original topic. The point that I was trying to establish in my post was that the fact that some objects did not have some intrinsic properties was not an argument against rest properties (Lorentz contraction) as genuinely intrinsic properties.
 

Offline lightarrow

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Re: Evidence for large scale length contraction?
« Reply #62 on: 09/09/2012 11:56:02 »
From Lightarrow:
Quote
Imagine a massive neutron star, which is composed of two concentric parts spinning along a samr axis but in opposite directions, so that the outer bords of these parts are moving at relativistic speeds.
1. Which would be the measured radius of the star?
2. Which would be its "intrinsic" radius?

We would have to imagine something a little different to that, because in SR length contraction operates only in the direction of motion, and rotation only describes motion perpendicular to the radius. So the intrinsic radius would be easily and unambiguously determined in an inertial frame that is stationary relative to the centre-of-mass of the neutron star.
Yes, you're right. Then we could substitute "radius" with "circumference", even if this quantity it's not so immediate to measure...
Quote
Nevertheless it is possible to think of an "intrinsic" property that is ill-defined for a complex object -- in fact such properties are legion. What is the rest mass of the solar system? If we try to measure it in the frame of the centre-of-mass of the solar system, the orbital motion of each of the planets would ascribe to it a mass slightly greater than its own rest mass. So we are faced either with an object that has a mass somewhat greater than the sum of the parts or a mass that cannot be directly measured.
I have written a lot of times that the term "rest mass" is misleading and you have found now a perfect example of this (apart  the case of a massless object as a photon).
The right concept is "invariant mass" m, and it's very easy to compute it: you find a frame of ref. where the total momentum p is zero, then m = E/c2 where E is the total energy of the system. Of course invariant mass is not additive: the solar system's mass is not the sum of the planets masses (as for an atom, as for a nucleus, as for a gas in a box).
Quote
For a physicist, this creates a contradiction and a crisis, that can only be ultimately resolved with a denial that anything has "intrinsic" properties. For a chemist, though, there is no problem. We are forever ascribing an "intrinsic" weight to an atom which (for quite different reasons) is quite significantly different to the sum of masses of its protons, neutrons, and electrons.

Even in a Newtonian universe, the solar system does not have a shape. The concept of "intrinsic" properties does not collapse as a result. A house or a raindrop still has an intrinsic shape. In the chemist's world an object may or may not have a particular intrinsic property. A benzene molecule has an intrinsic shape, a butane molecule does not.
 

Offline simplified

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Re: Evidence for large scale length contraction?
« Reply #63 on: 09/09/2012 12:14:49 »
To be honest, my intuition tells me that objects deserve an absolute shape, and I find it hard to train my intuition to believe otherwise. Maybe from here arise my difficulty in accepting the relativity of lengths. 
Why should not some real object have a form of itself? Why an object cannot be something by itself?

That's a good point, flr.  The problem is that intuition only works when you're so familiar with something that it becomes intuitive!  It can also be very misleading in science, since many effects are counterintuitive.  A far better guide in science is logic.  Once you know something is true (by observing or measuring it), you can logically figure out its consequences. 

That's the case in special relativity.  Length contraction is very counterintuitive, but we know that the speed of light is constant for all observers from experiments.  Once you know that's true, you can logically work through the consequences, and find that lengths have to contract.  Our intuition fails because we hardly ever experience relativistic effects in daily life.  You can definitely train your intuition by studying something thoroughly, but it takes a lot of effort to actually learn a subject so well that it becomes intuitive, especially when its as abstract as relativity theory.
Our logic should use what laws of measurement of speeds?
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #64 on: 10/09/2012 20:41:35 »
imatfaal, post 44:
Quote
OK - Enough.  This is a semi-official note that we either return to accepted ideas or the thread gets closed.

There have been 18 posts here since this warning. Are they all based on “accepted ideas” or are my criticisms of mainstream large scale length contraction the only ones censored?
I tried to move the discussion to “New theories,” as you demanded, but none but one joined in there, and it continues here.
I have replies to many of those posts since your warning, but I am gagged while no one else is. I need some guidance here, preferably from a moderator not so prejudiced against me.
imatfaal:
Quote
It is clear that many of you regard Special Relativity and/or its implications as a convenient fiction - This thread is rapidly descending into a melange of arguments from personal incredulity and ignorance of the subject and that is against the ethos of this Q&A forum.


No, I do not regard SR as a “convenient fiction.” You continue to intentionally misrepresent me. Clocks do slow down when accelerated to higher velocities, and adjustments to the GPS system (and other applications) compensate for the differences precisely and effectively. Yet there is still no empirical evidence for large scale length contraction, and insisting that it is a logical consequence of the math, as a reciprocal of “time dialation” still doesn’t make earth’s diameter or the distance to the sun contract.

Imatfaal From post 49:
Quote
Frame dependence, special and general relativity, and a privileging of observation, modelling, and mathematics mean that your false division into intrinsic and extrinsic is meaningless.

That division is the core of the issue, as far from "meaningless" as it gets.
Yet you have not replied to any of the very cogent arguments by others here, let alone mine, here or in “New Theories,” explaining the central relevance of the internal vs external properties distinction to the difference between actual, real, naturally occurring properties and the differences among observational effects due to differences in frames of reference.

I am bound and gagged here and need of some help from someone who is willing to address these issues on behalf of the forum admin and let me speak freely in reply.
 

Offline JP

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Re: Evidence for large scale length contraction?
« Reply #65 on: 10/09/2012 22:15:32 »
Hi Old Guy,

Hopefully I count as a less prejudiced moderator.  :)

First, the moderators did discuss this as a team, and we support Imatfaal's decision. 

The reason why is that this forum is primarily a science Q&A and discussion forum to answer questions and foster follow-up discussion about mainstream science.  Unfortunately, if we regularly allowed posts on non-mainstream science, we would confuse the many users who come to the site to get answers in terms of the main stream!

'Mainstream' in terms of length contraction is Einstein's special relativity, which does predict length contraction.  Criticisms of that idea should be kept to New Theories, as mentioned above. 

As you note, the New Theories forum is not an incredibly active part of this site.  This is probably because our primary purpose as a forum is science Q&A.  While we're happy to accommodate non-mainstream ideas in 'New Theories', if your primary goal on the site is to discuss outside-the-mainstream ideas, then you might find it more productive to seek out another forum.

Finally, I've posted this publicly because you've posted your complaint publicly.  If you don't find this a satisfactory response, please PM me or another moderator, but please do not post your response here so that this thread stays on topic.

Thanks!

JP moderator
 

Offline flr

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Re: Evidence for large scale length contraction?
« Reply #66 on: 11/09/2012 00:13:16 »

But how came the moun finds a shorter path in its way through atmosphere? By which mechanism its path is shorter than what I observe from Earth?
Is our universe made of multiple "realities" that are superimposed? In each such "reality" length is shorter or longer and time "flow" faster or slower? 
 

Offline old guy

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Re: Evidence for large scale length contraction?
« Reply #67 on: 11/09/2012 00:28:20 »

But how came the moun finds a shorter path in its way through atmosphere? By which mechanism its path is shorter than what I observe from Earth?
Is our universe made of multiple "realities" that are superimposed? In each such "reality" length is shorter or longer and time "flow" faster or slower?
Good questions, fir. I hope you get some answers. So far, I haven't.
 

Offline imatfaal

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Re: Evidence for large scale length contraction?
« Reply #68 on: 11/09/2012 16:10:08 »
It is as if Skulls in the Stars were reading this thread!  His latest blog addresses this question with spooky accuracy
http://skullsinthestars.com/2012/09/10/relativity-ten-minutes-to-alpha-centauri/

Quote
This warping of space and time is the most shocking part of special relativity when one encounters it for the first time.  It is important to note that I use words like “perceive”, “observe” and “point-of-view” to describe the changes in time and space, but these are real changes — no physical experiment or measurement of any kind will disagree with the results.
 

Offline JP

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Re: Evidence for large scale length contraction?
« Reply #69 on: 11/09/2012 17:24:12 »

But how came the moun finds a shorter path in its way through atmosphere? By which mechanism its path is shorter than what I observe from Earth?
Is our universe made of multiple "realities" that are superimposed? In each such "reality" length is shorter or longer and time "flow" faster or slower? 

Now you're venturing into philosophy, flr.  What physics can tell you, as imatfaal said, is that distance is something we measure.  We know that for the same Newtonian (non-relativistic) path, from the sun to the earth, the distance measured does in fact depend on how fast the observer is moving along that path.  This is what the theory of special relativity tells us and is in accordance with experiments and observations.

Science restricts itself to predicting the results of measurements, however.  If you want to ask about what it means for two observers going from the sun to the earth to measure two different distances, that's getting into philosophy.  Science can guide your inquiries by telling you that any philosophical interpretation you come up with has to match validated theories, but building some reality that exists beyond those theories is beyond science.
 

Offline flr

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Re: Evidence for large scale length contraction?
« Reply #70 on: 11/09/2012 17:24:49 »
The relativity of lengths and time on the frame of reference is barely a reformulation of "speed of light is invariant to observer".
In my opinion the invariance of "c" does not explain the length contraction and time dilation just - because they are 2 sentences with the same meaning but put in different wording.

I am not sure I found a satisfactory answer to the question: "what makes space and time be relative?" or its equivalent "what makes c be invariant?"
Instead I found in many places the argument that the invariance of c is immediately equivalent with relativity of space and time.
 

Offline JP

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Re: Evidence for large scale length contraction?
« Reply #71 on: 11/09/2012 17:32:12 »
I am not sure I found a satisfactory answer to the question: "what makes space and time be relative?" or its equivalent "what makes c be invariant?"
Instead I found in many places the argument that the invariance of c is immediately equivalent with relativity of space and time.

I don't think there is a satisfactory answer to why the speed of light is constant.  It's a postulate of special relativity, which means we take it as a fact.  We have plenty of measurements that establish it as a fact, but we don't have some deeper theory that tells us why it is.  The other postulate of special relativity is that the laws of physics are the same for all observers in inertial (constant velocity) reference frames.
(See: http://en.wikipedia.org/wiki/Postulates_of_special_relativity#Postulates_of_special_relativity)

Once you take those two to be true (and we do so based on observations) then special relativity follows.  You can further validate special relativity by checking its specific predictions against reality, which has also been done.  So we're pretty sure it's true because the postulates have been checked, and the theory follows from those, and the theory itself has been checked.

As for why the postulates are true, we don't know.  Some deeper theory may come along to explain that, or it may be something we never know.  The fact that we don't know means there's plenty of future work to be done.
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #72 on: 11/09/2012 22:30:33 »
There is a clear divide here between two sides, one of them being mainstream (physics) and the other being mainstream (common sense). Each side frequently claims things to be facts when they are not facts at all, but merely assumptions made by the theory they have already aligned themselves with. For example, if a theory says that there is no preferred frame of reference, then that is a "fact" within that theory, but not a real fact. A rival theory which assumes that there is a preferred frame of reference could likewise have the existence of a preferred frame as one of its "facts", but it is not a real fact either. People on both sides here are promoting "facts" as facts, and that is simply not moral. If you want to educate people, you have absolutely no right to indoctrinate them by pushing "facts" as facts while doing so on the basis of any kind of authority (such as being some variety of mainstream, whether that be of the physics or common sense variety).

Here's an example of the problem:-

Quote
I don't think there is a satisfactory answer to why the speed of light is constant.  It's a postulate of special relativity, which means we take it as a fact.  We have plenty of measurements that establish it as a fact, but we don't have some deeper theory that tells us why it is.

So, we take something as a fact because it is a postulate of a theory. That does not make it a real fact - it's only a "fact" within a theory. This is then backed up by a claim about measurements establishing it as a fact, but there are no measurements that can be made which can do anything of the kind - the speed of light can only be measured on a round trip, thereby completely hiding any actual variation that may be there. To call things facts when they are not facts is wrong, and it's absolutely wrong to mislead the public in this way.

Special Relativity is a theory and not a fact. The things taken as facts within SR are not automatically facts outside of SR. I had to take my questions about relativity to another forum because I was not allowed to ask them here as I was daring to question Einstein's relativity. You are not supposed to be a church defending a religion here by excluding people who ask awkward questions which challenge your own beliefs. Your job is to explain theories and to word things carefully so as not to make claims which go beyond what can be justified.

On the other side we have a claim that there's no real length contraction, but ironically that could only be true in any absolute sense if Einstein's Special Relativity is true - any other way of interpreting the Michelson Morley experiment requires actual length contraction to account for the only real fact which can be measured here (that light always completes the journeys along the arms of the MM apparatus and back in the same length of time [assuming they're exactly the same length - they don't actually have to be, but that's a detail that doesn't need to be explored]).

I myself made some assertions here a while back when asking a question about the mechanism behind time dilation and was banned from posting here for ten days on the basis that I was evangelising. I could have backed up those assertions and demonstrated them all to be correct, but I wasn't allowed to. The moderators, however, are allowed to make assertions without backing them up, and they refuse to engage in any discussions which are in danger of showing them to be false - it all gets pushed into a backwater instead where they can ignore it and where no one will see it.

I've arranged for some people at a couple of radio stations to watch what happens to this post because the way it is dealt with will be very revealing to them about the nature of a certain forum which they promote through their connections with a certain person who has already failed to deal with my fully-reasonable complaints about the way I've been treated here. I want to discuss science, and science has to be open to question. If this is actually a Church of Einstein, it should say so at the top and not claim to be a science forum.
 

Offline JP

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Re: Evidence for large scale length contraction?
« Reply #73 on: 11/09/2012 22:58:01 »
David, you're right that you can't prove anything is 100% fact.  Fortunately, science doesn't work that way, or we'd be in serious trouble doing it!  It's a fascinating subject how theories get accepted as mainstream, but its also well beyond the scope of this forum. 

Our scope is, as I said above, science Q&A and discussion in terms of mainstream theories.  We're a site staffed mostly by volunteer moderators and provided freely to our members as a place to do just this.  Your previous posts were moved because they were simply beyond the limited scope of this forum.  As I mentioned to Old Guy, we're not trying to stifle your ideas--we just have a very limited scope: science Q&A and discussion in terms of mainstream science.  Topics that stray too far from that are moved to the appropriate sub-fora (generally new theories for non-mainstream science). 

If you are eager to discuss non-mainstream ideas, we do provide the New Theories forum for this.  However, as you can see it's a small part of this forum and not our focus.  If you would like an in-depth discussion of non-mainstream theories, there are other science fora on the net which are far broader in scope and content that might generate livelier discussions. 

Again, due to our limited scope and time, and to keep this thread on topic, I'll be moving all further off-topic posts to the appropriate sub-fora.

Thanks,
JP moderator
 

Offline David Cooper

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Re: Evidence for large scale length contraction?
« Reply #74 on: 12/09/2012 00:31:02 »
Discussing Einstein's SR and trying to help people understand it properly is not something that can be classed as non-mainstream ideas. Most ordinary people find SR downright weird, and that automatically makes it interesting to them and well worthy of serious discussion on any science forum. It isn't beyond them either. Having explored it extensively myself, I now understand why physicists make the claims they do about it, and it actually makes a lot of sense in many places where I previously thought it was completely barking. Most, if not all of the apparent contradictions disappear when you completely eliminate Newtonian time from the model. This ultimately leads though to a point where the cause-and-effect pattern of events which is written through everything that happens in the universe cannot have taken place in order of cause followed by event because that would automatically bring back in a Newtonian kind of time which is not allowed in SR, so that means that within SR events are not caused by their causes. There is a rival interpretation (that of Lorentz) which fits the actual facts every bit as well as SR while lacking the cause-and-effect problem, so we are clearly dealing with "facts" here which aren't anywhere near to being 100% fact and which may not even be 50%, and that's why it's so important that people aren't given a misleading impression as to what is a fact. [There is a problem for the Lorentz theory too in that its preferred frame of reference cannot be detected, though it is also the case that it shouldn't be possible to detect it through any of the experiments which have ever been carried out.] I cannot see how it is acceptable for anyone to push one theory while banning discussion of the other given that the banned one is arguably at least as likely to be true as the allowed one. If the mainstream common sense theory of Lorentz is not to be allowed here in discussions, the only fair thing to do would be to be even-handed and ban all discussion of SR from this forum as well so that the public is not misled by any bias. I don't see any need to do that though - the subject is well within the capability of ordinary people to follow the arguments and it's just a matter of stamping on anyone who makes an assertion of any kind and demanding that they either back it up or shut up. Relativity is one of the most interesting aspects of science, and I think it ought to be possible to handle it here fairly.
 

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Re: Evidence for large scale length contraction?
« Reply #74 on: 12/09/2012 00:31:02 »

 

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