Re: For Seto: Theories incompatible with relativity
Dirk Van de moortel
<schoenf...@gmail.com> wrote in message news:1167477840.8...@s34g2000cwa.googlegroups.com...
> Sam Wormley wrote:
> > For Seto: Theories incompatible with relativity
> > http://en.wikipedia.org/wiki/Status_of_special_relativity#Theories_incompatible_with_relativity
>
> That article needs to be cleaned up and its sources corrected.
>
> > Special relativity is not compatible with the physical existence of the
> > following objects, forces, or laws (except in the nonrelativistic limit
> > in which all speeds are much less than c):
> >
> > 1. Infinitely rigid rods, or any other object which transmits forces at
> > infinite speeds. Note that this would require the existence of a new
> > force which is not currently explained by any of the laws of physics.
>
>
> I don't see how SR prohibits the existence of a 'rigid rod', from its
> axioms.
Rigidity implies that when you push the rod on one end,
it either
- instantaneously starts moving as a whole, which requires
the disturbance to move at infinite velocity, or
- it never moves at all, which contradicts experience.
> That considering such objects causes contradictory results in
> the theory is insufficient to conclude that the theory prohibits such
> objects. Maybe the theory has a 'bug' (using computer jargon)
Maybe you don't understand the theory.
>
> For example:
>
> [1] Suppose there is a rod 1m long, with respect to its own frame.
Yes, that is the proper lenght of the rod, by definition.
>
> [2] Suppose that an instantaneous acceleration is applied
> *simultaneously* everywhere on that rod, with respect to the rods
> initial frame.
>
> The kinematics of the rod allows it to be classified as 'rigid'.
>
> The problem with this scenario is:
>
> [3] Suppose the end velocity of the rod is 0.866c with respect to the
> rods initial coframe.
>
> [4] Relative to the rods initial coframe,
> *Proper* length of Rod before acceleration = 1m
> *Proper* length of Rod after acceleration = 1 /
> sqrt(1-(0.866c)^2/c^2) = 2m
The transformation equation
Dx' = gamma ( Dx - v Dt )
reduces to your
Dx' = gamma Dx
provided
Dt = 0
i.o.w. provided the distances difference Dx between the endpoints
is measured in the rod's rest-frame. So Dx is the proper length here,
and the quantity
Dx' = gamma Dx
is useless because it is the distance difference between the end
points at different times
Dt' =/= 0 .
When you measure the front and the back of a train at different
times and calculate the difference between these distances, you
get a useless quantity.
Common error. Marcel Luttgens' specialty.
> Thus the rod has doubled in physical size after the accelartion, and
> this violates the supposed invariance of proper length. It would seem
> that Special Relativity admits a contradictory result.
Actually, in this case it would seem that you haven't understood
special relativity.
Dirk Vdm
schoenf...@gmail.com
Dirk Van de moortel wrote:
> <schoenf...@gmail.com> wrote in message news:1167477840.8...@s34g2000cwa.googlegroups.com...
>
> > Sam Wormley wrote:
> > > For Seto: Theories incompatible with relativity
> > > http://en.wikipedia.org/wiki/Status_of_special_relativity#Theories_incompatible_with_relativity
> >
> > That article needs to be cleaned up and its sources corrected.
> >
> > > Special relativity is not compatible with the physical existence of the
> > > following objects, forces, or laws (except in the nonrelativistic limit
> > > in which all speeds are much less than c):
> > >
> > > 1. Infinitely rigid rods, or any other object which transmits forces at
> > > infinite speeds. Note that this would require the existence of a new
> > > force which is not currently explained by any of the laws of physics.
> >
> >
> > I don't see how SR prohibits the existence of a 'rigid rod', from its
> > axioms.
>
> Rigidity implies that when you push the rod on one end,
> it either
> - instantaneously starts moving as a whole, which requires
> the disturbance to move at infinite velocity, or
> - it never moves at all, which contradicts experience.
See below.
You have misunderstood the scenario.
Let's make it simpler. Suppose that we care only about the two end
points of the rod, labeled A and B below.
With respect to our coordinate system, suppose that A and B are
accelerated instantaneously and simultaneously. That is, suppose both A
and B experience an acceleration at time 0.
|
T |
I | A B
M | A B
E | A B
| A B
0----A-----B--------
| A B
| A B
| A B
SPACE
Before acceleration, the frame observes
- length of rod = 1 m { note: this is coordinate length =
proper length }
- velocity of rod = 0 m/s
After acceleration, the frame observes
- length of rod = 1 m { note: this is new coordinate
length }
- velocity of rod = 0.866c m/s
To see the proper length of the rod, we need to transform into the rods
frame which is now travelling at 0.866c. When you do that, you get
proper length of rod = sqrt(1-(0.866c)^2/c^2) = 2m
THE ROD HAS CHANGED PROPER LENGTH = VIOLATION OF INVARIANCE, ENERGY
CONSERVATION, ETC
The solution to this problem is to not apply the acceleration
simultaneously everywhere. That is, we need to delay the acceleration
of 'B' such that
|
T | A B
I | A B
M | A B
E 2 A B
| A B
0----A-----B--------
| A B
| A B
| A B
Now we see that the coordinate length of the rod changed - it
contracted by just the right amount such that the proper length does
not change, but remains 1.
The 'delay' between A's and B's acceleration had to be fixed such that
invariance remains preserved. This sort of acceleration profile is
called a Born rigid acceleration.
The problem is that we can't force all physical situations to be Born
rigid accelerations. In fact, out of all the infinite possibile ways
the rod could be accelerated, the Born rigid profile is merely one of
them..
So, how does SR prevent non-"Born rigid accelerations" other than
denying them because they violate SR?
[...]
[I AM AWARE GOOGLE GROUPS MAY HAVE SKEWED THE SPACETIME DIAGRAMS]
Dirk Van de moortel
<schoenf...@gmail.com> wrote in message news:1167494743....@a3g2000cwd.googlegroups.com...
Marcel Luttgens' and John Schoenfeld's specialty.
Dirk Vdm
Tom Roberts
> Suppose that we care only about the two end
> points of the rod, labeled A and B below.
>
> With respect to our coordinate system, suppose that A and B are
> To see the proper length of the rod, we need to transform into the rods
> frame which is now travelling at 0.866c. When you do that, you get
> proper length of rod = sqrt(1-(0.866c)^2/c^2) = 2m
> THE ROD HAS CHANGED PROPER LENGTH = VIOLATION OF INVARIANCE, ENERGY
> CONSERVATION, ETC
No, there is no such violation. You have implicitly assumed that in
performing that acceleration of the two ends of the rod that you impart
the same force to both ends. In fact, you do not -- you must pull harder
on the front than on the back in order to make the two accelerations
equal, and the difference is just the strain in the rod. That is, in
order to make those two accelerations equal in the inertial frame you
must stretch the rod.
This was originally posed as "Bell's paradox" involving two spaceships
and a string between them. For identical rockets the force is the same,
but the string breaks.
> The solution to this problem is to not apply the acceleration
> simultaneously everywhere. That is, we need to delay the acceleration
> of 'B'
This is not a complete solution, because the delay must vary over time.
Even then I don't think you can accurately maintain the proper length of
the rod.
> The 'delay' between A's and B's acceleration had to be fixed such that
> invariance remains preserved. This sort of acceleration profile is
> called a Born rigid acceleration.
Not quite. To really obtain Born rigid motion one must apply different
_proper_ accelerations to the ends of the rod (and all along it). Using
different proper accelerations solves the variable delay problem
mentioned above.
> The problem is that we can't force all physical situations to be Born
> rigid accelerations. In fact, out of all the infinite possibile ways
> the rod could be accelerated, the Born rigid profile is merely one of
> them..
Sure.
> So, how does SR prevent non-"Born rigid accelerations" other than
> denying them because they violate SR?
They don't "violate SR", they just behave differently.
The usual case for Born rigid motion of an object made up of ordinary
matter is to apply a small acceleration to a single point of the object,
and to rely on the inter-atomic forces to maintain the shape of the
object; an example is an ordinary rocket. Here "small" must be small
enough so the inter-atomic forces of the material can maintain the
inter-atomic distances to sufficient accuracy; for all human-made
rockets this is reasonably accurate.
Tom Roberts
schoenf...@gmail.com
Dirk Van de moortel wrote:
What you misunderstood was that the acceleration was applied
_simultaneously_ everywhere on the rod with respect to the initial
frame. The *coordinate length* of the rod remains the same before the
acceleration and after the acceleration w.r.t to the initial frame. A
transformation into the rods frame at 0.866c gives a new proper length
of 2.
The solution is to avoid accelerations which are simultaneous
everwhere, but delayed from point to point (w.r.t to initial coframe)
such that the coordinate length contracts but the proper length remains
invariant.This special type of proper-length preserving acceleration
profile is called a Born rigid acceleration. In SR, the only types of
accelerations which don't break the theory are Born rigid
accelerations. But, out of the infinite possible ways to physically
accelerate an object, a Born rigid acceleration is only of them. That
the theory is violated by other types of acceleration profiles is
insufficient to show that the theory only admits Born rigid
accelerations - the other types must be ruled out axiomatically, but
they can't be.
schoenf...@gmail.com
You have misunderstood. The acceleration was _instantaneous_ and
_simultaneous_ everywhere on the rod with respect to the rods initial
frame. This means that the length of the rod is the same *before* the
acceleration and *after* the acceleration, with respect to the initial
coframe. A transformation into the rods accelerated frame gives a
proper length of 2, which violates invariance.
The solution is to invoke a special type of acceleration profile called
a Born rigid acceleration - prevent *simulaneous* acceleration
everywhere but time them in such a way that the proper-length remains
invariant (the coordinate length contracts). However, there is no axiom
in SR that all accelerations must be Born rigid, and out of all the
infinite physical ways one could accelerate an object, a Born rigid
acceleration is only one of them.
> Dirk Vdm
[GOOGLE APPEARS TO HAVE LOST PREVIOUS REPLIES. THEY HAVE NOT SHOWN UP
AT TIME OF THIS WRITING]
schoenf...@gmail.com
schoenf...@gmail.com
Tom Roberts wrote:
[...]
> No, there is no such violation. You have implicitly assumed that in
> performing that acceleration of the two ends of the rod that you impart
> the same force to both ends.
Yes.
> In fact, you do not -- you must pull harder
> on the front than on the back in order to make the two accelerations
> equal, and the difference is just the strain in the rod.
>That is, in
> order to make those two accelerations equal in the inertial frame you
> must stretch the rod.
Yes, but the instantaneous and simultaneous acceleration *caused* the
rod to stretch. That it _caused_ the stretching *is* the problem:
Consider:
[1] The lab-frame and the rods initial frame are the same.
[2] The simultaneity planes of the lab-frame and rod initial-frame are
the same
[3] The acceleration was applied _instantaneously_ and _simultaneously_
w.r.t lab-frame (and transtively, rod initial-frame)
[4] Due to [2] with [3], coordinate acceleration = proper acceleration
[5] Rod length remains invariant in lab-frame, which means proper
length changed.
That all this results in the stretching in [5] *IS* the problem - that
_only one_ special acceleration profile (i.e. born rigid) preserves
proper unit invariance *IS* the problem.
IMPORTANT:
If the acceleration was NOT instantaneous, then the
Born rigid acceleration is recovered because the Rod's
simultaneity plane begins to rotate as the acceleration is
applied.
The instantaneous property of the acceleration profile is
key to this 'bug'. I guess you can dismiss it as 'unphysical'
or whatever, but computer models still throw exceptions
irrespective!
> This was originally posed as "Bell's paradox" involving two spaceships
> and a string between them. For identical rockets the force is the same,
> but the string breaks.
Thanks for pointing out the name. There is no point really discussing
this much more since it turns out to be a semi-well-known 'paradox':
http://math.ucr.edu/home/baez/physics/Relativity/SR/spaceship_puzzle.html
> This is not a complete solution, because the delay must vary over time.
> Even then I don't think you can accurately maintain the proper length of
> the rod.[...]
> Not quite. To really obtain Born rigid motion one must apply
different
> _proper_ accelerations to the ends of the rod (and all along it). Using
> different proper accelerations solves the variable delay problem
> mentioned above.[...]
Sure.
> > So, how does SR prevent non-"Born rigid accelerations" other than
> > denying them because they violate SR?
>
> They don't "violate SR", they just behave differently.
I don't debate the validity of SR, generally. I just contend that an
acceleration characterized by being _instantaneous_ and _simultaneous_
everywhere blows up the rod, when it shouldn't.
Tom Roberts
> Tom Roberts wrote:
>> No, there is no such violation.
> rod to stretch. That it _caused_ the stretching *is* the problem:
> w.r.t lab-frame (and transtively, rod initial-frame)
Make unphysical assumptions, get unphysical results. No surprise.
It is well known that for sensible accelerations there is no problem.
But the accelerations to maintain the proper length of the rod must be
different.
> The instantaneous property of the acceleration profile is
> key to this 'bug'.
The bug is yours, not SR's.
Tom Roberts
schoenf...@gmail.com
Tom Roberts wrote:
> schoenf...@gmail.com wrote:
> > Tom Roberts wrote:
> >> No, there is no such violation.
> > Yes, but the instantaneous and simultaneous acceleration *caused* the
> > rod to stretch. That it _caused_ the stretching *is* the problem:
> > [3] The acceleration was applied _instantaneously_ and _simultaneously_
> > w.r.t lab-frame (and transtively, rod initial-frame)
>
> Make unphysical assumptions, get unphysical results. No surprise.
You cannot simply dismiss a result from a theory because "Tom Roberts"
naively decides the result is "unphysical".
That SR violates proper unit invariance when an acceleration is applied
instantaneously and simultaneously derives as trivially as its
implication that SR fails as a fully consistent kinematical theory
(unless the Born rigidity is given as an additional constraint).
> It is well known that for sensible accelerations there is no problem.
> But the accelerations to maintain the proper length of the rod must be
> different.
>
>
> > The instantaneous property of the acceleration profile is
> > key to this 'bug'.
>
> The bug is yours, not SR's.
If that is the case you should be able to show why Born rigidity
applies to _all_ accelerated objects in SR (use an axiomatic
foundation, not your naive notions on what should or should not be
physical).
> Tom Roberts
Tom Roberts
> Tom Roberts wrote:
>> Make unphysical assumptions, get unphysical results. No surprise.
>
> You cannot simply dismiss a result from a theory because "Tom Roberts"
> naively decides the result is "unphysical".
Infinite accelerations, such as the ones you discuss, are unphysical to
every thinking physicist. <shrug>
>> The bug is yours, not SR's.
>
> If that is the case you should be able to show why Born rigidity
> applies to _all_ accelerated objects in SR (use an axiomatic
> foundation, not your naive notions on what should or should not be
> physical).
But it doesn't. Born rigid motion only applies to objects to which an
accelerating force is properly coupled throughout their volume.
Tom Roberts
schoenf...@gmail.com
Tom Roberts wrote:
> schoenf...@gmail.com wrote:
> > Tom Roberts wrote:
> >> Make unphysical assumptions, get unphysical results. No surprise.
> >
> > You cannot simply dismiss a result from a theory because "Tom Roberts"
> > naively decides the result is "unphysical".
>
> Infinite accelerations, such as the ones you discuss, are unphysical to
> every thinking physicist. <shrug>
Fine, just don't say your pet *theory* is "mathematically consistent"
because it's not.
To be clear, my contention is NOT that SR is empirically false. Merely
that the theoretical model suffers from problems I classify as "bugs".
For example, such a 'bug' in Newton's law' is
- two point particles A and B of same mass collide at point x
- A exerts force F on B at x
- B exerts force -F on B at x
- Resulting force at x is F + (-F) = 0
- A and B remain stationary at x = violation of momentum conservation
You would probably dismiss that as "unphysical", but you wouldn't be
able to show why it is "unphysical" within the axiomatic framework
(Newton's laws) being considered.
You would probably say "physicists don't consider point particles or
contact forces". But if I used inverse-square force I would get even
more serious "bugs" which include singularities in the field which blow
up integrals over that field.
Then you would probably say "serious physicists use quantum mechanics"
which introduces an abominable host of new bugs requiring processes
(i.e. renormalization) to 'explain them away' and 'fix' them up.
The continuation of this process leads one down the yellow brick road
to fantasy land where multi-dimensional unobservable strings flip and
flip, according to "serious physicists", and construct 97% of the
unobservable unobservable universe with the 3% of observable reality as
its mere consequence..
Tom Roberts
> Tom Roberts wrote:
>> Infinite accelerations, such as the ones you discuss, are unphysical to
>> every thinking physicist. <shrug>
>
> Fine, just don't say your pet *theory* is "mathematically consistent"
> because it's not.
It has been proved that Minkowski geometry is as consistent as is
Euclidean geometry. And also as consistent as is real analysis.
Neither Euclidean geometry or real analysis admit such infinities,
either. <shrug>
Tom Roberts
schoenf...@gmail.com
Tom Roberts wrote:
> schoenf...@gmail.com wrote:
> > Tom Roberts wrote:
> >> Infinite accelerations, such as the ones you discuss, are unphysical to
> >> every thinking physicist. <shrug>
> >
> > Fine, just don't say your pet *theory* is "mathematically consistent"
> > because it's not.
>
> It has been proved that Minkowski geometry is as consistent as is
> Euclidean geometry. And also as consistent as is real analysis.
And how does that prove that Special Relativty, the _kinematical
theory_ containing Minkowski geometry as a subset, always preserves
proper units under *all* kinematical cases?
Sorcerer
<schoenf...@gmail.com> wrote in message news:1167804258.4...@48g2000cwx.googlegroups.com...
|
| Tom Roberts wrote:
| > schoenf...@gmail.com wrote:
| > > Tom Roberts wrote:
| > >> Infinite accelerations, such as the ones you discuss, are unphysical to
| > >> every thinking physicist. <shrug>
| > >
| > > Fine, just don't say your pet *theory* is "mathematically consistent"
| > > because it's not.
| >
| > It has been proved that Minkowski geometry is as consistent as is
| > Euclidean geometry. And also as consistent as is real analysis.
|
| And how does that prove that Special Relativty, the _kinematical
| theory_ containing Minkowski geometry as a subset, always preserves
| proper units under *all* kinematical cases?
Remind Roberts that he said:
"This is PHYSICS, not math or logic, and "proof" is completely irrelevant."
Why you bother with the idiot is your business, but he's got more
screws loose than Hammond. Maybe taunting the afflicted is funny...
schoenf...@gmail.com
Sorcerer wrote:
> Remind Roberts that he said:
> "This is PHYSICS, not math or logic, and "proof" is completely irrelevant."
> Why you bother with the idiot is your business, but he's got more
> screws loose than Hammond. Maybe taunting the afflicted is funny...
To prove a scientific theory one is required to _verify_ the theory at
_all_ events in spacetime - that is impossible.
To disprove a scientific theory one is required to _falsify_ the theory
at _one_ event in spacetime - that is possible.
Sorcerer
<schoenf...@gmail.com> wrote in message news:1167881898.4...@s34g2000cwa.googlegroups.com...
Yeah, but the theory itself isn't "scientific" to begin with. It is
mathematical drivel.
http://www.androcles01.pwp.blueyonder.co.uk/PoR/PoR.htm
http://www.androcles01.pwp.blueyonder.co.uk/DominoEffect.GIF
http://www.androcles01.pwp.blueyonder.co.uk/Rocket/Rocket.htm
http://www.androcles01.pwp.blueyonder.co.uk/Smart/Smart.htm
http://www.androcles01.pwp.blueyonder.co.uk/Algol/Algol.htm
http://www.androcles01.pwp.blueyonder.co.uk/Cepheid/cepheid.htm
http://www.androcles01.pwp.blueyonder.co.uk/GPS/GPS.htm
I don't need to prove there are no bright green flying elephants,
burden of proof is always upon the claimant.
That simple logic had Roberts defeated every time, which is why
he staggers and reels and shrugs when his wild claims are challenged.
Science is the observation, investigation and explanation of
natural phenomena, not the invention of black holes or bright green
flying elephants and then go looking for them, saying "I have a
theory, so they ought to exist".
"I can't believe that!" said Alice.
"Can't you?" the queen said in a pitying tone. "Try again, draw a long breath, and shut your eyes."
Alice laughed. "There's no use trying," she said. "One can't believe impossible things."
"I dare say you haven't had much practice," said the queen. "When I was your age, I always did it for half an hour a day. Why, sometimes I've believed as many as six impossible things before breakfast."
"Tom Roberts" <tjrobe...@sbcglobal.net> wrote in message
news:GMFSg.17769$Ij....@newssvr14.news.prodigy.com...
| Yes, physicists are notoriously loose; but if you claim
| to display a "contradiction", _YOU_ must be precise.
|
|
| Tom Roberts
On Tue, 02 Jan 2007 20:01:13 GMT, Tom Roberts wrote:
"the basic equations of SR are only APPROXIMATELY valid."
and he should know, he wrote a lot in the FAQ's.
The basic equations of NM are what the basic equations
of SR approximate to.
"Tom Roberts" <tjrobe...@sbcglobal.net> wrote in message
news:7hQah.16667$6t....@newssvr11.news.prodigy.com...
| fitz wrote:
| > When can we use special relativity?
|
| SR is strictly valid only in a flat Lorentzian manifold with the
| topology of R^4. This of course is a very poor model of the world we
| inhabit.
|
| But physics is not math, and we often use approximations. SR is
| approximately valid when the curvature of the manifold is negligible
| over the region of interest compared to one's measurement accuracy.
Read between the lines, Roberts KNOWS his garbage is nonsense.
He's troll, all troll and nothing but the troll.