Evidence for large scale length contraction?

  • 302 Replies
  • 58026 Views

0 Members and 1 Guest are viewing this topic.

*

Offline JP

  • Neilep Level Member
  • ******
  • 3366
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #200 on: 02/10/2012 00:22:14 »
I've moved this thread to New Theories as it's continued down it's metaphysics path.

*

Offline lightarrow

  • Neilep Level Member
  • ******
  • 4586
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #201 on: 02/10/2012 18:17:10 »
If we all agree that the laws of physics (gravity here) form planets as near spherical, by what stretch of imagination is that not reality?
1. Laws of physics say that a planet forms as spherical in their proper frame.
2. Laws of physics say that a planet forms as a deformed sphere in a moving frame.
Did you get it now?

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #202 on: 02/10/2012 20:00:19 »
If we all agree that the laws of physics (gravity here) form planets as near spherical, by what stretch of imagination is that not reality?
1. Laws of physics say that a planet forms as spherical in their proper frame.
2. Laws of physics say that a planet forms as a deformed sphere in a moving frame.
Did you get it now?
Do you understand that the phrases "in their proper frame" and "in a moving frame" define the shapes of planets by how they are observed, denying that they have shapes independent of how variously they are observed?
Do you think that planets change shapes as they are observed differently? What then causes them to change shape with no application of force, or is it the magical power of different observations that alters massive physical objects?

Everyone but extremist SR theorists like yourself understands that planets and stars are in fact nearly spherical, and that their original formation as such does not depend on from what frame of reference they are observed.

Do you understand that "for this observer" vs "for that observer" makes reality observer dependent, as if Earth's shape depended on who is looking at it from what frame?
Do you get that this is idealism? Do you know what that means? Do you think that a falling tree makes no sound unless there is an "observer" present to hear it?
Do you have any idea how absurd that denial of reality is, or is the difference between idealism and realism beyond your comprehension?

Do as yet undiscovered galaxies simply not exist until they are observed?
How far would you like to carry this obvious absurdity. Is an elephant's shape a rope, because a blind man is feeling its tail. How about claiming that a tree trunk shape is equally valid, as "observed" by the blind man holding a leg? "No, an elephant is like a fire hose," says the one holding the trunk. Or does the whole elephant have a shape of its own independent of observation from limited perspective?
Yes, it does, and so does the Earth. Try to get over your idealism-based misconception about that. Science knows Earth's shape, and SR did not reinvent it.

*

Offline lightarrow

  • Neilep Level Member
  • ******
  • 4586
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #203 on: 03/10/2012 11:24:26 »
If we all agree that the laws of physics (gravity here) form planets as near spherical, by what stretch of imagination is that not reality?
1. Laws of physics say that a planet forms as spherical in their proper frame.
2. Laws of physics say that a planet forms as a deformed sphere in a moving frame.
Did you get it now?
Do you understand that the phrases "in their proper frame" and "in a moving frame" define the shapes of planets by how they are observed,
You insist on using the term "observed" but it's incorrect.
The right term is "measured".
At high speeds what you would "observe" is different from what you would measure.
Quote
Science knows Earth's shape.
Indeed: science *knows* that Earth's shape is not spherical in a moving frame.
Science doesn't work according to what *you think*, but according to what *everyone measures*.
And this is the last answer of me.
« Last Edit: 03/10/2012 11:29:30 by lightarrow »

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #204 on: 03/10/2012 18:46:34 »
lightarrow,
I don't blame you for quitting, since there are no good answers to the questions/challenges i posed in my last post to you.
You say:
Quote
You insist on using the term "observed" but it's incorrect.
The right term is "measured".
At high speeds what you would "observe" is different from what you would measure.
Your last statement is a false dichotomy.
Most SR advocates use the terms 'observed' and 'measured' interchangeably, as "measured" is just the formal quantification of what is observed; and we all know that a 'frame of reference' can be abstract, not literally requiring a personal observer, as I have said here before.
Quite a lame criticism.
You say:
Quote
Indeed: science *knows* that Earth's shape is not spherical in a moving frame.
Science doesn't work according to what *you think*, but according to what *everyone measures*.

See... Earth is a "real" solid physical planet. It doesn't change shape to accommodate all possible differences in how it might be observed/measured. So observing/measuring it "in a moving frame" does not make it flatten out into a very oblate spheroid, even though it my appear so distorted from a high speed frame. That is the source of your continuing confusion, and that of all SR theorists in this forum who agree with you. You fail to distinguish appearance (the image of the object) from the object itself. The elephant is not, in fact, shaped like a rope.

*

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • 12188
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #205 on: 03/10/2012 19:47:03 »
There is one frame from what you say is (approximately) true OG. The local one where you are 'at rest' with what you measure. But then it becomes a philosophical question which frame is 'more true' than another, if you want a indivisible universe? Because then all frames of reference must be as 'true', as they all need to be in-cooperated in this universe.

Just exchange each 'point' in our universe with a 'observer' but keep 'gravity', to see why I state it this way.

Or you can take a stand in where you define the 'truth' of 'reality' as belonging solely to the 'local description', meaning where you are in space and time, as you observe/measure. From a relativistic point of view that is what I see you try for here, but to do so you now will need to define how all those different 'local definitions' can exist, and all be true for those observing? Because you still have this universe consisting of 'observers', although you now made each one a 'creator' of their own unique universe, as all observations still must differ if compared,  if you see my drift there?

What is good with such a reasoning is that it gives us a 'preferred frame of reference' which actually is how it is treated practically as I think, considering the validity and importance we give 'repeatable experiments'. Aways done locally, then tested/compared in equivalent (relativistically seen) frames of reference (measured in uniform motion mostly). '

But it still need to answer how this can be possible? If so?
And that is one tricky subject OG.
=

When it comes to 'simultaneity', in a indivisible universe you must need it, or else assume that 'time and its arrow' must be a illusion. But then you by necessity have to do the same with a LorentzFitzGerald contraction, as I see it, as they are a symmetry. And if you allow contractions to 'exist' then you've failed anyway, no matter what you think of 'time'. But we have 'frames of reference gravitationally, on Earth, with time dilations :) so it exist as we can measure it.

In a 'local' definition of reality a time dilation becomes slightly simpler as I think of it as they all become unique descriptions, describing unique universes, slightly shifted out of place/focus from your neighbors. Then there is only one time keeping, and that is the one decided by your wristwatch. And the same will hold true for contractions, meaning that you can treat your local clock and ruler as approximately 'invariant'. But then the next question becomes, if it is so, what is the scale of a 'frame of reference', is it enough with being 'at rest' with what you measure? And there i think one have to answer, no. 'At rest' can only be seen as a approximation as we have gravity as the metric of space. Superimposing light/radiation though can be seen as being 'at rest'. Though we have 'point particles', the Pauli exclusion principle stops them from superimposing, normally treated at least. Anyway, the one thing joining them (when comparing between different frames of reference) is something we only can measure as having a 'beginning', as in a recoil, and a 'end', as in a annihilation, but doesn't exist in between?


Radiation.
« Last Edit: 03/10/2012 20:29:41 by yor_on »
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #206 on: 03/10/2012 22:01:06 »
yor_on:
Quote
There is one frame from what you say is (approximately) true OG. The local one where you are 'at rest' with what you measure. But then it becomes a philosophical question which frame is 'more true' than another, if you want a indivisible universe? Because then all frames of reference must be as 'true', as they all need to be in-cooperated in this universe.

The universe is filled with bodies which were formed by various laws. Gravity is the one which makes stars and planets form as nearly spherical. There is no philosophy involved in that. It is the physics of how cosmic dust and debris is formed into planets and stars.
Enter length contraction theory: "For a frame of reference" flying by at near 'c', such objects may appear very oblate, nothing close to spherical.
That does not change the law of physics (gravity) that made them spherical in the first place.
If you are a scientist of the future charged with measuring and describing planets and stars in far away solar systems, flying there at near 'c', what will be your report?... that they are all extremely flattened, or that they are pretty much like our local system?
I would suggest that you slow down and then "park" in the orbit of all objects to be measured to get the most accurate measure. But if that is inconvenient and an inefficient use of rocket power, you could always apply the Lorentz formula to account for your velocity as a factor distorting the images of the bodies your are zipping past. But in no case will you be telling "mission control" that all those bodies are somehow strangely "pancaked" in shape.
Is that clear enough?
(Out of time... More later as "it permits.")

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #207 on: 04/10/2012 00:14:13 »
Just another piece added to last post.
yor-on:
Quote
Because you still have this universe consisting of 'observers', although you now made each one a 'creator' of their own unique universe, as all observations still must differ if compared,  if you see my drift there?

SR theory made each "observer" a "creator" of each frame-specific version of each resulting, as measured, unique universe.
My argument is exactly the opposite.... that the universe and all its objects are "as they were formed by the laws of physics," totally independent of differences in observation. Why is this concept so hard to communicate clearly?

*

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • 12188
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #208 on: 04/10/2012 13:39:02 »
It's not hard to communicate OG. It's just that you have to refute relativity, both versions I presented, to make that statement true. And if you can't do that then is will be a dreamers position, what should have been, but what isn't.
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #209 on: 04/10/2012 18:37:44 »
It's not hard to communicate OG. It's just that you have to refute relativity, both versions I presented, to make that statement true. And if you can't do that then is will be a dreamers position, what should have been, but what isn't.
So.... Nothing specifically in reply to my last two posts?

I'll walk you through the last point where you had my position exactly opposite.
(The reason I commented on the lack of communication.)
You:
Quote
    Because you still have this universe consisting of 'observers', although you now made each one a 'creator' of their own unique universe, as all observations still must differ if compared,  if you see my drift there?
Me:
Quote
SR theory made each "observer" a "creator" of each frame-specific version of each resulting, as measured, unique universe.
My argument is exactly the opposite.... that the universe and all its objects are "as they were formed by the laws of physics," totally independent of differences in observation.

SR, not I, makes each observer "a creator of their own unique universe." "For observer A" Earth is nearly spherical, while "for observer B" Earth is nearly flattened. Is there a "real Earth" with an intrinsic shape of its own, as originally formed by gravity, or does each different observer (frame of reference) create his/its own unique version of Earth?
Do you understand "my drift" now? Are you willing to answer honestly?

Do you disagree with this, from 206:...
Quote
The universe is filled with bodies which were formed by various laws. Gravity is the one which makes stars and planets form as nearly spherical. There is no philosophy involved in that. It is the physics of how cosmic dust and debris (ed: and gasses) (are) formed into planets and stars.

Enter length contraction theory: "For a frame of reference" flying by at near 'c', such objects may appear very oblate, nothing close to spherical.
That does not change the law of physics (gravity) that made them spherical in the first place.
...If so, how, specifically?

Ps; as I said to lightarrow above:
Quote
Earth is a "real" solid physical planet. It doesn't change shape to accommodate all possible differences in how it might be observed/measured. So observing/measuring it "in a moving frame" does not make it flatten out into a very oblate spheroid, even though it my appear so distorted from a high speed frame. That is the source of your continuing confusion, and that of all SR theorists in this forum who agree with you. You fail to distinguish appearance (the image of the object) from the object itself. The elephant is not, in fact, shaped like a rope.
... nor Earth like a pancake.
« Last Edit: 04/10/2012 18:58:49 by old guy »

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #210 on: 04/10/2012 21:42:11 »
Just a piece at the core of the argument, from yor_on in post 4:

"So to invalidate it (edit: length contraction) one will have to redefine 'c' as a variable instead of a constant.

So are we then left with an impossible choice: To redefine 'c' as a variable or to redefine Earth's diameter as a variable?
How could the latter vary, given that Earth is in fact a solid, immutable (but for trivially) object?

This challenge has consistently been ignored and then the whole thread was moved to where the question will not be noticed.

Maybe the answer is in the difference between the image of an object, obviously conveyed by light, and the solid ("immutable") object itself. (The image could be distorted while the object stays the same.)

We can probably agree that the Earth's diameter does not physically change to 1000 miles under any circumstance... which makes it a serious question of "what changes?"
If this question is allowed in the Physics section, I will start a thread there on the question of what is variable in this case. If the question is still forbidden, this is not science. Please advise.

I am asking you, JP, to allow me to move this question back to the physics section for serious debate by physicists.
Suggested title:
"Does invariant 'c' require a variable Earth diameter?"

 

*

Offline JP

  • Neilep Level Member
  • ******
  • 3366
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #211 on: 04/10/2012 22:40:49 »
Yes, you can start a new thread.

If you use it to evangelize (push the same arguments you've been making and are making in this post that the earth must "really" be invariant), then given the number of warnings you've gotten, you may face a temporary or permanent ban.

*

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • 12188
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #212 on: 04/10/2012 22:43:53 »
Ahh JP. i have a suspicion it is this thread OG was referring to, which I just finished, and planning to answer, finding your new reply as I was going to post.

"No OG, this is philosophy, maybe 'philosophy of relativity' but nowhere near science. If you could suggest a experiment in where it could be proved that a length contraction doesn't exist, as defined relative some other frame of reference, then is would close in on science though.

Can you do that?"
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #213 on: 05/10/2012 18:36:11 »
Yes, you can start a new thread.

If you use it to evangelize (push the same arguments you've been making and are making in this post that the earth must "really" be invariant), then given the number of warnings you've gotten, you may face a temporary or permanent ban.
This sounds like, if I started a new thread on the very specific question, "Does invariant 'c' require a variable Earth diameter?", it  would automatically be locked and I would be banned. ... but, "Yes, you can." Thanks.

I would (still) settle for a straight answer right here in this thread to these questions, as above:
Quote
So are we then left with an impossible choice: To redefine 'c' as a variable or to redefine Earth's diameter as a variable?
How could the latter vary, given that Earth is in fact a solid, immutable (but for trivially) object?
This challenge has consistently been ignored. "For this frame" vs "for that frame" does not answer it. It only addresses how it might me observed and measured variously... which is not the question.
Science must not cop out and claim that what we know about Earth (its precise shape) varies with how we look at it. Physics tells us that a change in shape would require application of force, and length contraction theory does not claim to apply any forces.

If only these challenges were directly addressed, no new thread would be needed.

Same for my “suggested title” for a new thread in the Physics section.

So, JP, does Earth’s diameter as a solid object vary with how it is measured or not? If you insist that it  would BE contracted if measured from a very high speed frame, how can physics account for such a shrinkage in a solid, rigid planet? This remains a very sincere and reasonable question requiring an explanation from physics besides “It would appear flattened from  the extreme frame.” (No doubt it would.)

Also, my "probe," measured to be 10 meters long from Earth as it approached at .866 c,(edit) would not fit into a 10 meter shuttle bay sent to retrieve it. Its "contacted length" was 10 meters, but its actual length (what better adjective, I do not know) was 20 meters.
Why is this NOT a conclusive example proving my point? Traveling at .866 c (edit) did not change its length but only its apparent length. How is this wrong?
Ps; yor_on:
Quote
If you could suggest a experiment in where it could be proved that a length contraction doesn't exist, as defined relative some other frame of reference, then is would close in on science though.

Can you do that?

My above thought experiment did just that. Since we can not travel at relativistic speeds... upon which "length contraction" depends,... such experimental "proof" (evidence, anyway) must depend on thought experiments, as do most "examples" of large scale length contraction from its advocates. Both "sides" are allowed such thought experiments. There is no way a 20 meter probe will fit in a 10 meter bay. What more proof could you ask for?
« Last Edit: 06/10/2012 18:57:51 by old guy »

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #214 on: 06/10/2012 19:02:21 »
Does invariant 'c' require a variable Earth diameter?
If so, how does physics explain the latter... or would it simply appear to vary from and extreme frame?

*

Offline wolfekeeper

  • Neilep Level Member
  • ******
  • 1092
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #215 on: 07/10/2012 00:12:29 »
There is no way a 20 meter probe will fit in a 10 meter bay. What more proof could you ask for?
Yes it will... and no it won't!

(Surprisingly, both are true!):

http://en.wikipedia.org/wiki/Ladder_paradox

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #216 on: 07/10/2012 03:36:56 »
If the probe fits in the bay when they are both at relative rest, the probe will always fit in the bay.

The reason is that there better not be a relativistic difference in velocity – which would cause appreciable length contraction - as the probe enters the bay.

So with the relative velocities of the bay and probe near zero, there is no length contraction to consider.
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #217 on: 08/10/2012 21:59:07 »
There is no way a 20 meter probe will fit in a 10 meter bay. What more proof could you ask for?
Yes it will... and no it won't!

(Surprisingly, both are true!):

http://en.wikipedia.org/wiki/Ladder_paradox
You can not have it both ways. That is why I set it up as I did.
The probe *appeared to be* 10 meters long from Earth. Since it was approaching Earth at .866c, it was *measured to be* 10 meters, "length contracted" by 1/2 at that velocity. Of course, to retrieve any object in space, the shuttle must match velocities with the object... come alongside. Then the *actual length* of the probe was found to be 20 meters. So it simply will not fit. I have repeated this at least a dozen times. Do you get it yet?

Butchmurray:
Quote
If the probe fits in the bay when they are both at relative rest, the probe will always fit in the bay.
See above. It was measured to be 10 meters at a velocity relative to Earth which made it appear contracted to 10 meters. The "proof" that it would not fit is found when the shuttle enters the same frame as the probe. "Ooopse!" It is actually 20 meters long!

Quote
The reason is that there better not be a relativistic difference in velocity – which would cause appreciable length contraction - as the probe enters the bay.
It is as given for any retrieval project that the object and the retrieval craft must be traveling at the same velocity. I've repeated that at least a dozen times.

Quote
So with the relative velocities of the bay and probe near zero, there is no length contraction to consider.

Right, but the question was, will it fit in our 10 meter bay? We better know the answer before we send out our shuttle to capture it. (No.)

The same holds true for Earth's diameter as measured from a fast fly-by.
Here is a quick review of that argument from two recent posts:   

Quote
    So are we then left with an impossible choice: To redefine 'c' as a variable or to redefine Earth's diameter as a variable?
    How could the latter vary, given that Earth is in fact a solid, immutable (but for trivially) object?

This challenge has consistently been ignored. "For this frame" vs "for that frame" does not answer it. It only addresses how it might me observed and measured variously... which is not the question.
Science must not cop out and claim that what we know about Earth (its precise shape) varies with how we look at it. Physics tells us that a change in shape would require application of force, and length contraction theory does not claim to apply any forces.
Also:
If you insist that it  would BE contracted if measured from a very high speed frame, how can physics account for such a shrinkage in a solid, rigid planet? This remains a very sincere and reasonable question requiring an explanation from physics besides “It would appear flattened from  the extreme frame.” (No doubt it would.)
Or in 214; here it is in a nutshell, but none of the length contraction experts here dare address the challenge:
[quote]Does invariant 'c' require a variable Earth diameter?
If so, how does physics explain the latter... or would it simply appear to vary from an extreme frame? [/quote]


*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #218 on: 09/10/2012 05:53:18 »
Quote
Quote
So with the relative velocities of the bay and probe near zero, there is no length contraction to consider.

Right, but the question was, will it fit in our 10 meter bay? We better know the answer before we send out our shuttle to capture it. (No.)


Absolutely!

Exercise due diligence. You know its relative velocity. You know its measurements judged from your frame. Crunch the numbers. You will know if it will fit or not. NO PROBLEM.
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #219 on: 09/10/2012 18:27:30 »
Quote
Quote
So with the relative velocities of the bay and probe near zero, there is no length contraction to consider.

Right, but the question was, will it fit in our 10 meter bay? We better know the answer before we send out our shuttle to capture it. (No.)


Absolutely!

Exercise due diligence. You know its relative velocity. You know its measurements judged from your frame. Crunch the numbers. You will know if it will fit or not. NO PROBLEM.
"Absolutely!", what? The example clearly shows the difference between the probe's "contracted length" as measured from Earth and its *actual length* as measured from traveling right beside it, as required to retrieve it. Its velocity relative to Earth is .866 c. That makes it *appear to be* 10 meters long. My point, over and over, is that its *apparent, "contracted" length* is only half of its *actual length*, and the proof of this difference is that it is twice as long as our cargo bay.
It was not "really, actually" 10 meters after all but 20. No way! The proof that its "contracted length" is half of its "actual length."

The length contraction "experts" here refuse to acknowledge that "length contraction" is only an "appearance" due to observing it approaching at high speed, whereas is "actual length" remains twice as long.
OK?
What is your answer to the question no one here will touch (for good reason... to avoid making an absolutely absurd claim):
Quote
Does invariant 'c' require a variable Earth diameter?
(Edit: The claim is that " because 'c' is invariant, length is not invariant.")
If so, (ed: if Earth's diameter changes) how does physics explain the latter... or would it simply appear to vary from an extreme frame?
My answer: Yes, it would only appear contracted from the extreme frame. Earth does not change diameters, "actually."

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #220 on: 11/10/2012 13:43:14 »
Quote
You can not have it both ways. That is why I set it up as I did.
The probe *appeared to be* 10 meters long from Earth. Since it was approaching Earth at .866c, it was *measured to be* 10 meters, "length contracted" by 1/2 at that velocity. Of course, to retrieve any object in space, the shuttle must match velocities with the object... come alongside. Then the *actual length* of the probe was found to be 20 meters. So it simply will not fit. I have repeated this at least a dozen times. Do you get it yet?

I think I understand now.

The shuttle bay can accommodate a 10m probe.

The relative velocity of the probe is .866c.

At relative velocity .866c, the probe is 10m judged from relative rest.

If you know the relative velocity is .866c and you know the length is 10m judged from relative rest, then you know the “at rest” or “proper” length is 20m. You also know the probe will not fit in the 10m cargo bay of the shuttle because when the shuttle’s relative velocity is also .866c the cargo bay will only accommodate a 5m probe judged from relative rest.

In other words your measurements for BOTH the probe and the shuttle bay must be either “rest” length OR contracted length because they will be in the same frame (the same relative velocity or difference in velocity close to zero) as the probe is recovered.
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #221 on: 11/10/2012 18:24:34 »
butchmurray,
Finally... someone 'gets it!' Thank you for paying attention to the example *as I presented it.*
If length contraction advocates did not insist that "proper" length and "contracted" length were equally valid (all frames being equal) the whole example would be very simple.

We recognize the difference between "contracted length" as mere appearance due to observing something traveling at high velocity relative to the observer and  the *actual length* of something as it was either naturally formed (Earth's diameter does not change) or, in this case, built... its "proper length" as measured in its own frame.

So we see a probe approaching Earth at .866c, plug in the formula, and know immediately that it is *actually* 20 meters long. We will not send out a 10 meter cargo bay to retrieve it, because it is not *really* 10 meters long.

It is really very simple when the dogma of "all frames are equal" is removed.

Just one clarification... you said:
Quote
You also know the probe will not fit in the 10m cargo bay of the shuttle because when the shuttle’s relative velocity is also .866c the cargo bay will only accommodate a 5m probe judged from relative rest.

As seen from Earth, the shuttle, now traveling with the probe, will *appear to have* a bay 5 meters long, "contracted" to half its actual length, as the probe also appears. The shuttle bay did not shrink. It was 10 meters on Earth and remains 10 meters as it approaches with the probe. Just because it now "looks" 5 meters long from Earth did not make it shrink to half its length.
This is an extremely persistent misconception among those advocating length contraction.

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #222 on: 11/10/2012 20:18:01 »
I truly understand your misgivings about “is” and “appears to be”.

The way I reconciled it was, “It ‘is’ when judged from relative rest”.

Here is something else to ponder:

Suppose inside of the probe there is a constant light projected from one end to the other end of the probe in the direction of motion. What is the difference in that light when judged from the shuttle, which is moving at the same relative velocity as the probe (.866c) and when judged from relative rest?
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #223 on: 11/10/2012 21:46:48 »
butchmurray:
Quote
I truly understand your misgivings about “is” and “appears to be”.

I think it would bring much needed clarity to the SR conversation if everyone understood the difference and did not insist that Is = Appears to Be.
Quote
The way I reconciled it was, “It ‘is’ when judged from relative rest”.

I agree. Scientists must "put it under a microscope" or at least be at rest (same frame) with 'it' to study and measure 'it' accurately.

Quote
Here is something else to ponder:

Suppose inside of the probe there is a constant light projected from one end to the other end of the probe in the direction of motion. What is the difference in that light when judged from the shuttle, which is moving at the same relative velocity as the probe (.866c) and when judged from relative rest?

Yes, I've pondered that a lot over the years.
Seems as if it makes no difference whether the light source or the observer(s) or whatever frames of reference are moving or how fast. They all observe light to travel at the constant speed 'c.' I can't argue with that. The experiments are very conclusive.

My concern is that what is "observed" is an image reflected or projected from an object or light source, not the object itself. So there could be an appearance of contraction due to the medium of light itself as carrier of the image. I don't pretend to know the specifics of how that all that might work. I just know that the image is not the object, and light carries the image.

Btw, thanks for understanding my "probe" example.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #224 on: 13/10/2012 18:46:54 »
Regarding this from yesterday: "I just know that the image is not the object"...
I also know that a possible image of a flattened Earth (say with a 1000 mile diameter in the direction of an observer's very high speed travel) would/could only be an appearence, an image of a flattened Earth. We all know that Earth's diameter is not, has never been and will never be 1000 miles.

I can not get the "SR experts" here to address this challenge. Since you, butchmurray, win the prize for understanding my probe illustration of "actual vs apparent" length, maybe you would give the shrunken Earth diameter challenge a shot too.

Ps; btw, we are now even on number of posts at 112. Here is your chance to move ahead!
« Last Edit: 13/10/2012 18:52:14 by old guy »

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #225 on: 15/10/2012 16:17:12 »
Quote
I can not get the "SR experts" here to address this challenge.

Please restate exactly what the “challenge” is.

Thanks,
Butch
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #226 on: 15/10/2012 18:53:45 »
Quote
I can not get the "SR experts" here to address this challenge.

Please restate exactly what the “challenge” is.

Thanks,
Butch
As in my last post... The "challenge" now bolded:
Quote
Regarding this from yesterday: "I just know that the image is not the object"...
SR experts have the image and the object as the same, claiming that how it appears is how it is. You seemed to know what I meant earlier. The challenge for SR is to recognize and distinguish the difference. The "all frames are equal" dictum grants equal validity to a shrunken Earth diameter, as I said here:

Quote
I also know that a possible image of a flattened Earth (say with a 1000 mile diameter in the direction of an observer's very high speed travel) would/could only be an appearence, an image of a flattened Earth. We all know that Earth's diameter is not, has never been and will never be 1000 miles.

My challenge to the SR experts is to admit/clarify that Earth's diameter does not change even  if it appeared to becontracted to 1000 miles, as above.

Same with the probe example, which you seemed to understand. The shuttle's 10 meter bay would appear to be (from Earth) contracted to 5 meters long as it approaced earth with (same frame as) the probe. But it did not magically shrink after it left Earth to retrieve the probe. Same for the probe, appearing to be 10 meters long from earth, but actually being 20 meters long, as it is, in "reality," in its own frame.
I hope this clarifies the challenge.

Again, I hope you will give "the shrunken Earth diameter challenge a shot too."
Thanks.


*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #227 on: 16/10/2012 01:23:01 »
While I'm waiting for Butch's reply, I'd like to clarify that I am not a "crank" trying to debunk all of relativity or an "evangelist" for anything but a nearly spherical Earth which doesn't change shape with how you might look at it passing by at relativistic speeds. (Same for other solid objects.)
The thing is that the theory of length contraction depends on the concept of 4-D "spacetime", which in turn depends on non-Euclidean geometry and cosmology.
So first, to "get to the bottom of it" we must ask what space is and what time is and what the coalescence of the two into one is supposed to be.

The point of departure for non-Euclidean geometry is the denial of Euclid's fifth postulate, i.e., the assertion that parallel lines do indeed intersect. Who here agrees with that? Please explain. Also, how is that the shortest distance between two points is no longer a straight line?

I know that it all depends on the concept of curved space. There are at least three choices of what shapes space is curved into, but nobody bothers to explain how 3-D volume (space) became a malleable medium, an entity rather than the void in which all things exist and move.

So we have a curved surface (of what?... empty volume?) on which the shortest line between two points *on that surface* is a curved line. But the shortest distance is still straight through, not "on the surface." And parallel lines finally intersect "in infinity" by the magic of math. Never mind that if they intersect, they are no longer parallel.

So... back to length contraction. It is said that "... as you approach the speed of light, you're increasingly looking at the four-dimensional fabric of space and time "edge-on", causing space and time to mix." (Citation available but not handy.)

So two non-entiies "mix" and that makes objects contract. Its too bad that ontology is not allowed in the physics section, being as it is mere philosophy, but it would certainly help to sort out all of the above and maybe even help to clarify how Earth's diameter gets relativistically contracted... and how thaqt might differ from the planet actually getting squished.
Open for deiscussion... if anyone cares. This is an honest inquiry, folks. Is that not the essence of science?
« Last Edit: 16/10/2012 01:30:31 by old guy »

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #228 on: 16/10/2012 04:46:06 »
Examples:
There are 4 ships. All of these measurements occur at roughly the same time on earth.

For 2 bodies with one in motion in relationship to the other, either one can be considered to be at relative rest compared to the other. For these examples the ships will be considered to be at relative rest.

One is on earth so the velocity of that ship relative to earth is zero.
The velocity of one ship in flight is .436c relative to earth.
The velocity of another ship in flight is .866c relative to earth.
The velocity of yet another ship in flight is .977c relative to earth.

The relative velocity of earth for the ship on earth is zero. The diameter of the earth in the direction of impending motion IS 100% of its “proper” or “at rest” judged from the ship at relative rest.
For the ship in flight at .436c relative to earth, the diameter of the earth in the direction of motion IS 90% of its “proper” or “at rest” diameter judged from that ship at relative rest.
For the ship in flight at .866c relative to earth, the diameter of the earth in the direction of motion IS 50% of its “proper” or “at rest” diameter judged from that ship at relative rest.
For the ship in flight at .977c relative to earth, the diameter of the earth in the direction of motion IS 20% of its “proper” or “at rest” diameter judged from that ship at relative rest.

It is obvious that the diameter of the earth cannot have all these values at the same time. The fact of the matter is that those diameters ARE the diameters JUDGED FROM REST for those various relative velocities. It is not that the earth appears to have those diameters, those are the ACTUAL diameters JUDGED from those rest frames.

The rest frame can be reversed, with the earth at relative rest, for all of the examples. In that case it is the length of the ships in the direction of motion that is contracted by the corresponding amount and not the diameter of the earth.

Thank you for the vote of confidence.

Butch

I generally like to “sleep on” whatever I post but I didn’t want to keep you waiting unnecessarily.
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #229 on: 16/10/2012 19:27:47 »
I've run this one before, to no avail:
A thousand different ships fly by Earth in 1000 different directions at 1000 different relativistic velocities. They all measure the diameter differently in all different directions.
 You are correct to say,
 "It is obvious that the diameter of the earth cannot have all these values at the same time. " But then you say, "The fact of the matter is that those diameters ARE the diameters JUDGED FROM REST for those various relative velocities. It is not that the earth appears to have those diameters, those are the ACTUAL diameters JUDGED from those rest frames.
Forget for a moment about the "as judged from" relativistic psuedo-reality depending on how observer A sees it vs how observer B sees it vs how all the other 998 observers see it.
EARTH DOES NOT CHANGE DIAMETERS. It is a relatively solid planet. Do you understand that? Do you agree?

You seemed to agree earlier that there is a difference between "IS" and "APPEARS TO BE." Must I now revoke my "vote of confidence?"
The "ACTUAL" diameter of Earth is nearly 8000 miles... a little shorter through the poles than through the equator. Earth science KNOWS this very precisely from measurements taken at rest with Earth... which is the "preferred frame" for accurate measurements of anything, as we discussed earlier.
Do you also think that the aforementioned cargo bay magically shrinks from its 10 meters at launch from Earth to the 5 meters it APPEARS TO BE as it approaches Earth at .866 c in the frame with the probe (as required to capture it?)
I would certainly appreciate a straightforward answer. Thanks.

Ps: Any comments, anyone, on my post 227 above... say on "intersecting" parallel lines or on how a curved line is now imagined to be be the shortest distance between two points... or how 3-D volume became a malleable medium... other than in imatinative minds?
« Last Edit: 16/10/2012 19:55:31 by old guy »

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #230 on: 16/10/2012 21:07:08 »
Look at it this way:

If you are on any of those ships, the “judged from” diameter is what you will see.

I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #231 on: 16/10/2012 22:05:09 »
Look at it this way:

If you are on any of those ships, the “judged from” diameter is what you will see.
I see that you are still missing the whole point of this thread.
The point is that EARTH DOES NOT CHANGE SHAPE.
So, even if a fast flying observer SAW  an Earth with, say a 1000 mile diameter, that would not make its ACTUAL diameter 1000 miles. It remains always nearly 8000 miles, and its shape remains nearly spherical, not extremely flattened.
Will you acknowledge this fact?

You said, "It is not that the earth appears to have those diameters, those are the ACTUAL diameters JUDGED from those rest frames." "Judged from" different frames does not make the actual diameter change. Do you see that?

Do you not, after all, know the difference between "IS" and "APPEARS TO BE?"... the difference between "ACTUAL" length and a contracted APPEARENCE due to high speed... the difference between an IMAGE of an object conveyed by light and the OBJECT ITSELF?

Did the cargo bay "ACTUALLY" shrink from its 10 meters as constructed and as launched to 5 meters AS OBSERVED approaching with the probe at .866 c?
Please explain.
Ps, I said:
Quote
Forget for a moment about the "as judged from" relativistic psuedo-reality depending on how observer A sees it vs how observer B sees it vs how all the other 998 observers see it.
EARTH DOES NOT CHANGE DIAMETERS. It is a relatively solid planet. Do you understand that? Do you agree?
Do you think that different observations create different shaped objects, that observation dictates reality... that objects have no intrinsic reality of their own?
« Last Edit: 16/10/2012 22:20:09 by old guy »

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #232 on: 16/10/2012 23:34:52 »
Here is another one:

A rocket takes off.

It finally disappears.

Does it really disappear? If you are on the ground, yes, of course it does.
Does it really disappear? If you are in the rocket, no, of course it doesn't.

It’s largely semantics. Don’t give yourself a headache!

May I have my “vote of confidence” back, PLEASE?
I have already told everyone!

Thanks,
Butch
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #233 on: 17/10/2012 00:05:09 »
Butch,
You refuse to engage in conversation with me after several attempts on my part. The whole point of this thread is that different observations/measurements do not create different lengths or shapes of  the objects/distances observed, as length contraction claims.
Last question of my last post as a case in point:
"Do you think that different observations create different shaped objects, that observation dictates reality... that objects have no intrinsic reality of their own?"
Of course when someting disappears from the sight of one observer it doesn't cease to exist.
How about answering even one of my length contraction challenges?
Does the cargo bay change from 10 meters to 5 meters after it enters the frame at rest with the probe? (Does it "actually" shrink to half its length-as-built-and-launched?)
Does Earth change shape/diameter when it is observed to contract from relativistic frames.
Do "things" have intrinsic shapes/lengths of their own, as formed by gravity (like Earth) or as built (like the probe and shuttle?)... or does observation make things change shape/length.

 JP stuck this thread here to avoid  scrutiny of these challenges, I must presume. Now you are doing the same dance of avoidance.
Please answer the above questions, and I will restore my vote of confidence in you, as if you really cared!

I do care. The issue is not semantics. It is the very core of "length contraction."
If a solid planet does get squished or a rigid craft get shrunken, what laws of physics, what forces cause the physical changes?
Seriously.

*

Offline JP

  • Neilep Level Member
  • ******
  • 3366
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #234 on: 17/10/2012 02:14:53 »
JP stuck this thread here to avoid  scrutiny of these challenges, I must presume. Now you are doing the same dance of avoidance.

Actually, I've explained several times why I moved this thread here.  If you'd like to us it keep making accusations about us censoring you, I'd be happy to lock the thread, though.  :) 

Please keep it a discussion, not a complaint thread.

*

Offline bizerl

  • Sr. Member
  • ****
  • 279
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #235 on: 18/10/2012 05:59:11 »
Old guy, You don't seem to question the impact of time dilation and the well known idea that time passes differently for observers based on how close to c they are travelling.

Why should space be any different? It is just as intangible as time when you consider what length actually is. You've asked me to make definitions of abstract concepts in another thread, and I put it to you to define "length".

If time can slow down for someone on a spaceship travelling at .866c, yet remain constant for the "stationary" observer on Earth, I think that's incredible and goes against the logic that has been ingrained in our human psyche that time is constant. Yet if it is true, it follows that anything that we once held to be "solid", may in fact be as fluid as time.

I've always thought that the diameter of the Earth remains at 8000kms, it's just that 8000kms becomes 1000kms long when you are travelling at speed.

But that's just more semantics I'm afraid.  [:P]

*

Offline bizerl

  • Sr. Member
  • ****
  • 279
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #236 on: 18/10/2012 06:17:56 »
I haven't made my way through all 234 replies so I apologise if I am doubling up on comments, but I think the original problem in the post is that travelling at .866c would make the Earth appear squashed by half, and if you could zoom in you would see people that were also squashed holding lengths of wood that they called "one metre lengths" but you could see clearly that they were actually half metre lengths, measuring a diameter (through the hole they've bored through the centre of the Earth  [;)]) which was 8,000,000 of these "one metre lengths" that you know are half a metre and therefore they measure 8000kms which is correct for them, but you measure 4000kms which is correct for you.

Therefore, the Earth gets squashed for the traveller - including the atmosphere etc, but the humans on the Earth also get squashed so they don't notice.

They move at double the speed as well...

I think...

*

Offline butchmurray

  • Sr. Member
  • ****
  • 194
  • If I had my druthers, I would have druthers
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #237 on: 18/10/2012 15:14:55 »
Overheard on a plane before takeoff:
The 4-year-old girl said, “I can’t wait to go into the sky so we can be small.”

A passenger jet is at the terminal.
An identical jet is 30,000 ft. above.
Which one is larger?

Are the jets the same size? Yes.
When you are at the terminal is the jet at the terminal larger? Yes.
When you are in the jet at 30,000 ft. is the jet you are in larger? Yes.
I was not smart enough to know it was impossible to do what I did.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #238 on: 18/10/2012 19:38:06 »
Wiki:
"Philosophical realism is the belief that reality exists independently of observers."

Is anyone here besides me a realist? Does anyone else here 'real-ize' that the "real" Earth stays the same shape (has the same diameter(s) independently of how it is observed?

Does anyone else 'real-ize' that a shuttle cargo bay built 10 meters long wouls stay that length even if it were possible to observe it approaching Earth at .866 c, then appearing to be 5 meters long... alongside a 20 meter alien probe which appears to be 10 meters long from Earth? (Practical test of length contraction: The probe, appearing 10 meters long from Earth will not fit into a 10 meter bay sent to capture it.)

Does anyone here 'real-ize' that the distance between stars as they are formed and distributed in space (by the laws of phyics, including gravity) would not get shorter (stars would not move closer together) if it were possible for intersteller observers to travel near 'c' between them?
(Note: I did not say "would not appear shorter" but "would not get shorter".)
Again, would stars actually move closer to each other if so obseved by high speed travelers? What amazing power that would grant to mere observation!!
Does anyone here get my point, the whole point of this thread?

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #239 on: 18/10/2012 19:57:34 »
bizerl:
Quote
Old guy, You don't seem to question the impact of time dilation and the well known idea that time passes differently for observers based on how close to c they are travelling.

I've said this quite a few times already, so it would indeed be helpful if you had read the thread.
Empirically we observe that clocks "tick" more slowly at higher velocities (and "deeper in a gravity well.") Time is the concept of the duration of physical processes, that which elapses as things move. That does not make it an entity which "slows down."

A clock on a future high speed spacecraft traveling to Alpha Centauri (4.37 light years away) will show much less elapsed time than those on Earth. But Earth will have orbited the Sun many more than 4+ times during the journey. More than four years will have passed, as a year remains a standardized Earth orbit of the Sun. The craft has mass, so it can not travel at 'c', therefore it will take more than 4.37 years for the craft to reach AC. Relativity has not changed that fact. Saying that "for the spacecraft less that four years have passed" does not alter fact that more than four years would have passed by the standard reckoning of what "a year" means. It wouldn't make Earth move closer to AC either.

*

Offline bizerl

  • Sr. Member
  • ****
  • 279
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #240 on: 19/10/2012 06:00:54 »
Okay. Now I have read the entire thread. It's been a slow day.

It got me thinking about a lot of things. Firstly, if a ship is coming directly towards Earth, how can we measure it's length? - but that's a side issue.

If two ships were coming towards Earth in tandem at .866c, both lengths would appear contracted from Earth. If a tether was placed between them, the tether would also appear contracted. If the tether was then taken away, the distance between the ships would still be the contracted distance.

This makes me think that the length contraction has nothing to do with the physical properties of what is travelling, but of space itself. The only way I can see it working is if, like time, space is actually distorting in the direction of travel.

Because it is space distorting and not any physical matter, whatever exists in that space also distorts.

If someone was travelling at .866c towards Earth, they would see a flattened disc facing them. Now the Earth rotates, but the rotation would follow only the surface of the Earth, the "disc" would never actually be edge on to anyone observing it.

I think that to address some recurring questions you've had, old guy, an intrinsic measure of the properties of the Earth is possible, only if stated as a function of relative speed. For instance you can say that the instrinsic diameter of the Earth is 8000km0c which is equal to 4000km0.866c etc.

I don't see why it can't be "real" for space and therefore length to distort when one is travelling at speed, and therefore "real" that the Earth is 8000 x 4000km if you're travelling towards it at .866c.

In regards to
Quote
EARTH DOES NOT CHANGE DIAMETERS. It is a relatively solid planet.

What is solid? "Solid" is made of sub-atomic particles. Lots of them in the case of the Earth. They exist in "space". Three dimensions of it (that we know of so far...[:D]) and time. If "length" is defined as the shortest amount of space that separates two points (I don't know if it IS defined as that, but I don't know how else to define it) then if space is contracted relativisticly, it is "real" that "length" should "contract" too.


*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #241 on: 21/10/2012 21:08:15 »
bizerl,
So... no comment on realism, top of post 248 or "time" in post 249 or what space is, if anything besides 3-D volume, the void in which things and forces exist and move,i.e., NOT a malleable medium.

You simply assume that reality changes as it is differently observed, including that Earth changes shape as seen from a fast fly-by and that Earth moves closer to Alpha Centauri, as reckoned by a ship with a slowed down clock.

Neat trick, moving stars and panets closer to each other and changing their shapes/diameters simply by the magical power of observation/measurement.

So objects have no intrinsic properties of their own, huh? It all depends on how you look at them? No "reality" per se. Each observer creates his own unique reality.
Does the falling tree make no sound if it is not heard? Idealists say sound doesn't exist unless it is heard. What do you say?

At this point, you are not responding to what I am posting...  not a conversation.

*

Offline bizerl

  • Sr. Member
  • ****
  • 279
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #242 on: 21/10/2012 22:20:43 »
bizerl,
So... no comment on realism, top of post 248 or "time" in post 249 or what space is, if anything besides 3-D volume, the void in which things and forces exist and move,i.e., NOT a malleable medium.

Sorry OG, I must be seeing a different thread to you. As far as I can see, this reply is only 242, so not sure what aspects of these you'd like a reply to.

You simply assume that reality changes as it is differently observed, including that Earth changes shape as seen from a fast fly-by and that Earth moves closer to Alpha Centauri, as reckoned by a ship with a slowed down clock.

Yes, I'm afraid I do, as I pointed out in a previous post. I don't have the luxury of understanding all the nitty gritty details of relativity but I do believe that it has been extensively tested and has not yet been adequately disproven. Length contraction is an integral part of this theory and since the theory seems so well fitted to all our (I say "our", I mean scientists) observations, it stands to logical reason that length contraction is true too.

I find it interesting that you "assume" that length contraction doesn't exist on large scales and I'm yet to hear a convincing argument in your favour, other than "the Earth is solid". You've stated previously that
Quote
The "ACTUAL" diameter of Earth is nearly 8000 miles... a little shorter through the poles than through the equator. Earth science KNOWS this very precisely from measurements taken at rest with Earth... which is the "preferred frame" for accurate measurements of anything, as we discussed earlier.

Earth science also KNOWS that this value changes depending on how fast you are travelling, relative to the Earth.

Neat trick, moving stars and panets closer to each other and changing their shapes/diameters simply by the magical power of observation/measurement.

The world is an incredible place. A great many things that are common knowledge would have been ridiculed as "magic" in more ignorant times.

So objects have no intrinsic properties of their own, huh? It all depends on how you look at them? No "reality" per se. Each observer creates his own unique reality.
Does the falling tree make no sound if it is not heard? Idealists say sound doesn't exist unless it is heard. What do you say?

Yes, everything has intrinsic properties of their own. The properties are governed by strict laws of physics. A 10m (at rest) cargo bay will always be 5m long when travelling at .866c. That is an intrinsic property.

Your definition (or rather, wiki's definition) of realism - "Philosophical realism is the belief that reality exists independently of observers." is not one I follow. It is a philosophical viewpoint that does not have any grounding in science. It conveniently contains "reality" in it's definition which leaves everything open to interpretation.

Unfortunately (for some), science has shown that in fact, what we experience as "reality", changes depending on how it is observed.

At this point, you are not responding to what I am posting...  not a conversation.

I am stating my viewpoint. I apologise if you feel I am not trying to address your queries.
« Last Edit: 22/10/2012 05:35:58 by bizerl »

*

Offline bizerl

  • Sr. Member
  • ****
  • 279
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #243 on: 22/10/2012 05:40:38 »
Perhaps on a science forum, this is a better definition of "realism".

Quote from: http://en.wikipedia.org/wiki/Scientific_realism
Scientific realism is, at the most general level, the view that the world described by science (perhaps ideal science) is the real world.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #244 on: 22/10/2012 22:32:37 »
Me:
" So... no comment on realism, top of post 248 or "time" in post 249 or what space is, if anything besides 3-D volume, the void in which things and forces exist and move,i.e., NOT a malleable medium."
You:
"Sorry OG, I must be seeing a different thread to you. As far as I can see, this reply is only 242, so not sure what aspects of these you'd like a reply to."

Sorry. I meant post 238, quoting Wiki:
"Philosophical realism is the belief that reality exists independently of observers."
If you don't think there is a "real world/cosmos" with real things in it with intrinsic properties of their own and distances between things determined by how they were distributed in space when they were formed... independent how they are observed....
And that Earth's diameter varies between 1000 and nearly 8000 miles...
And that Earth/Sun moves a lot closer to Alpha Centauri if a fast ship so observes...
And that, likewise Earth moves much closer to the Sun  (ditto above)... without getting incinerated...
Then you live in a length contraction fantasy world where variations in observation cause variations in physical objects and distances between them.... where each observer creates his own unique "reality."

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.
 The above is subjective idealism, not objective science.
There were quite a few questions/challenges left unanswered, (time and space assumptions, sound with no one to hear it... but if you believe that an Earth with a 1000 mile diameter is an accurate description of it we have nothing left to say. A squished Earth is fiction, not science. Observation does not alter physical things or distances between them.


*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #245 on: 24/10/2012 20:55:53 »
bizerl,
Maybe you haven't had time to reply... or maybe it's that we have nothing left to say, as in,
... "but if you believe that an Earth with a 1000 mile diameter is an accurate description of it we have nothing left to say. A squished Earth is fiction, not science. Observation does not alter physical things or distances between them."

Do you really believe that Earth's diameter changes drastically with how it is observed?... no "real world" at all?

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #246 on: 25/10/2012 19:02:36 »
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.

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.


This will be my last attempt to communicate in this thread if no one cares about the above enough to answer.
Thanks.

*

Offline bizerl

  • Sr. Member
  • ****
  • 279
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #247 on: 26/10/2012 01:17:31 »
Okay. I wasn't going to bother, but out of courtesy I'll sign off on this thread with one last post.

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.

I can't speak for length contraction "experts" as I am not one of them, but yes. I believe that both measurements are equally valid depending on the observers velocity relative to the Earth. I believe this because it is an integral part of a theory that is continually tested and proven, and furthermore, has been continually contested and has thus far failed to be disproven. I am willing to change my belief if the observed and/or experimental evidence says otherwise.

Quote
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.


This will be my last attempt to communicate in this thread if no one cares about the above enough to answer.
Thanks.

I don't agree with this statement. In my view, the job of science is to understand how the world works through observation and experimentation, and to come up with theories and models that reflect those observations, regardless of how counter-intuitive their implications may seem.

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.

Also, all the observational and experimental evidence that has been gathered so far, has failed to disprove that this is the case.

I wish you well on your journey to obtain observational and/or experimental evidence which dis-proves length contraction. It will surely be a guaranteed ticket to Stockholm.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #248 on: 26/10/2012 21:10:53 »
bizerl,
Thank you for your reply. I asked if an Earth with a 1000 mile diameter was  equally valid with the Earth science measure of nearly 8000 miles. You said, "yes." Please explain by what law of physics the nearly spherical Earth gets squished to nearly flattened, or in lieu of that, how the physical "world" changes by virtue of different observations, or is it just the observations which change?
Do you know of any empirical observations confirming large scale length contraction? I know that, so far, no one has ever observed Earth's diameter to shrink, yet you insist that it does or would "for" a relativistic fly-by frame. Do you see any difference between "Earth as it is" and "Earth as seen from" such a fly-by? Would it change into 1000 diferent shapes if observed from 1000 different frames, do you think?

I said:
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.

You replied:
Quote
I don't agree with this statement. In my view, the job of science is to understand how the world works through observation and experimentation, and to come up with theories and models that reflect those observations, regardless of how counter-intuitive their implications may seem.

Do you disagree that it is the job of science is to study and accurately describe things as they are?
 Do you think that it is the legitimate task of science to re-create "the world" (whatever is being measured) as subjective versions of an infinite number of "realities" depending on who is measuring whatever from all varieties of different frames of reference?
You said:
Quote
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.

I hope you will reply to all of the above before quitting the thread.

*

Offline old guy

  • Sr. Member
  • ****
  • 165
    • View Profile
Re: Evidence for large scale length contraction?
« Reply #249 on: 29/10/2012 19:16:21 »
One repeat of my invitation (post 246) before I too sign off from this thread...

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.