Re: Is the speed of light really constant ?
From: Pax (pax1_at_whitesweb.com)
Date: 11/02/04
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Date: Tue, 02 Nov 2004 15:03:18 GMT
"Bill Rowe" <readnewscix@earthlink.net.invalid> wrote in message
news:readnewscix-C0AA4B.18161501112004@news1.west.earthlink.net...
> In article <Jpthd.11415$bP2.2375@newssvr12.news.prodigy.com>,
> "Pax" <pax1@whitesweb.com> wrote:
>
> > "Bill Rowe" <readnewscix@earthlink.net.invalid> wrote in message
> > news:readnewscix-05BD6E.22100230102004@news1.west.earthlink.net...
> > > In article <48tgd.5866$bP2.4141@newssvr12.news.prodigy.com>,
> >> [BR]
> >> This quote is really nothing more than a statement of the limitations
of the technology of the time. Specifically about the possibility of planes
exceeding the speed of sound. It really isn't a statement that the speed of
sound cannot be exceeded.
>
> >> In fact, at the time such statements were being made there were
examples of things exceeding the speed of sound such as the tip of a bull
whip when it is cracked.
> > [Pax]
> > Oh, you mean like the light from the headlights of two cars approaching
each other on a dark road? Or two gold ions heading at each other then
colliding with each other when each are both traveling at all but the speed
of light? (Note: 1st example is light/light; 2nd example is mass/mass.)
> [BR]
> No, these are not equivalent to the example of the bullwhip I gave. In the
case of the bullwhip, there is something physical (the tip of the whip)
moving faster than the speed of sound. In the examples you give, the rate of
closure exceeds c, but there is no physical thing moving faster than c.
[Pax]
And what frame of reference are you using to decide this? The local frame of
either of the light emitting vehicles or the local frame of one or the other
gold ion, or are you using a third frame external to all of them? If you're
using a third external frame... which you are... why do you consider your
conclusion valid, since Relativity addresses c wrt local frames?
Using local frames for the light of the oncoming vehicles, c is c; but,
using local frames for the ions approaching each other the answer's not that
simple. Those ions hit each other with a collision force equal to almost 2c.
You can't get around that, Bill. As far as either of those ions are
concerned, an object of mass closing on them at all but 2c is a very real
reality.
> >> [BR]
> >> It follows mathematically from the two principles Einstein used to
formulate special relativity. That is the principle of relativity and the
constancy of the speed of light. And as I've pointed out before, assumptions
about the constancy of the speed of light are not needed to derive c as a
maximum limit
>
> >> But note the difference in both. The quote you chose regarding sound
talks about planes and limited power of piston engines. That is it is
technology based . The idea c is a maximum speed comes from first principles
with no reference to any technology. Do you not see the difference?
> > [Pax]
> > No.
> [BR]
> Really? That is you do not see a difference between saying using current
technology such and such is not possible and reasoning from first principles
that such and such is not possible regardless of technology?
[Pax]
I understand that global statements of absolutes are and have always been
unjustifiably made with expected-to-be unquestioned authority based upon
current limitations as construed from current observations.
Going on your question of either/or above, one must conclude that, since
exactly such statements have always been made by experts in the past, Man
can't fly. Ignoring the actual present, far previous to the assertions of
those experts, and oblivious to the existence of any such irrefutable canon
of "actual facts", primitive Peruvians had been assembling large expanses of
cloth, oiling them, attaching a basket with ropes to the four corners,
trapping the hot air rising from a fire in the billows and floating away to
look at the pretty giant pictures they'd scratched out on the plains.
> > [Pax]
> > And from what I've gathered from what Einstein wrote, he really didn't
draw that distinction either.
> [BR]
> I've no idea whether Einstein made the distinction above or not in his
writings. Nor do I have any way to determine what Einstein would have
thought one way or the other.
[Pax]
Why do make such statements? Of course you have a way. Einstein wrote a lot
of books, and they are brimming with his thoughts on just about everything.
> [BR]
> What Einstein may or may not have written/thought on this issue is really
unimportant.
[Pax]
And why is that? Has Relativity been "put in the dust" as Einstein so often
said it might be "except..."? Or is it simply Einstein when you need him,
but to heck with him when it gets uncomfortable to hang with him? As far as
you're concerned, either Einstein was right or he was wrong... which is it?
> > [Pax]
> > He said Lorentz used it and Lorentz didn't make sense if you plugged in
v>c. He constantly refers to the fact that c should be taken as infinite for
all human considerations, since we could never attain it anyway.
>
> > Why? Because, if we tried to push anything of mass to c, it would take
all the energy in the universe. Sound familiar?
> [BR]
> Yes, this chain of logic follows many popular accounts of relativity. But
it doesn't represent Einstein's logic at all.
[Pax]
Of course it does. He said it in the quote you cut: "Of course this feature
of the velocity c as a limiting velocity also clearly follows from the
equations of the Lorentz transformation, for these become meaningless if we
choose values of v greater than c."
Bill, have you read _Relativity The Special and General Theory_ by Einstein?
> [BR]
> Einstein started with two very reasonable postulates. A direct
mathematical consequence of these two postulates is c must be a maximum
possible velocity.
[Pax]
No. He stated the velocity of light must be *constant* in vacuo wrt all
local frames. The Principle of Relativity and the constancy of the speed of
light in vacuo wrt all local frames are what he based his Special Theory on,
coupled with the work of Lorentz.
> [BR]
> In fact, one can reach this conclusion directly from the Lorentz transform
making no mention of mass or energy at all.
[Pax]
When did I bring in mass and energy with regard to the above?
> > [Pax]
> > All the energy in the universe = infinite energy. How much energy does
it take to push a gold ion to all but c? Is it "all but" all the energy in
the universe? In his box-on-a-rope thought experiment, Einstein stated that
constant acceleration could go on indefinitely.
>
> > There's a clash of principles going on. On one hand the laws of nature
must remain "normal" within all local frames, regardless of velocity,
> [BR]
> Huh??? What do you mean by "normal"? This certainly doesn't look to me
like a correct statement of the principle of relativity.
[Pax]
What I meant was exactly what Einstein meant by "general laws of nature". Is
that not also what we would consider "normal"? The following progresses from
the Special Theory to the General Theory:
[Open quote]
Part I: The Special Theory of Relativity
XIV. The Heuristic Value of the Theory of Relativity
http://www.bartleby.com/173/14.html
OUR train of thought in the foregoing pages can be epitomised in the
following manner. Experience has led to the conviction that, on the one
hand, the principle of relativity holds true, and that on the other hand the
velocity of transmission of light in vacuo has to be considered equal to a
constant c. By uniting these two postulates we obtained the law of
transformation for the rectangular co-ordinates x, y, z and the time t of
the events which constitute the processes of nature. In this connection we
did not obtain the Galilei transformation, but, differing from classical
mechanics, the Lorentz transformation.
The law of transmission of light, the acceptance of which is justified by
our actual knowledge, played an important part in this process of thought.
Once in possession of the Lorentz transformation, however, we can combine
this with the principle of relativity, and sum up the theory thus:
Every general law of nature must be so constituted that it is transformed
into a law of exactly the same form when, instead of the space-time
variables x, y, z, t of the original co-ordinate system K, we introduce new
space-time variables x', y', z', t' of a co-ordinate system K'. In this
connection the relation between the ordinary and the accented magnitudes is
given by the Lorentz transformation. Or, in brief: General laws of nature
are co-variant with respect to Lorentz transformations.
This is a definite mathematical condition that the theory of relativity
demands of a natural law, and in virtue of this, the theory becomes a
valuable heuristic aid in the search for general laws of nature. If a
general law of nature were to be found which did not satisfy this condition,
then at least one of the two fundamental assumptions of the theory would
have been disproved. [...]
Part II: The General Theory of Relativity
XVIII. Special and General Principle of Relativity
Albert Einstein
http://www.bartleby.com/173/18.html
In contrast to this we wish to understand by the "general principle of
relativity" the following statement: All bodies of reference K, K', etc.,
are equivalent for the description of natural phenomena (formulation of the
general laws of nature), whatever may be their state of motion.
XXVIII. Exact Formulation of the General Principle of Relativity
http://www.bartleby.com/173/28.html
[...] The following statement corresponds to the fundamental idea of the
general principle of relativity: "All Gaussian co-ordinate systems are
essentially equivalent for the formulation of the general laws of nature."
[...] ...by application of arbitrary substitutions of the Gauss variables
x1, x2, x3, x4, the equations must pass over into equations of the same
form; for every transformation (not only the Lorentz transformation)
corresponds to the transition of one Gauss co-ordinate system into another.
[...] This non-rigid reference-body, which might appropriately be termed a
"reference-mollusk," is in the main equivalent to a Gaussian
four-dimensional co-ordinate system chosen arbitrarily. That which gives the
"mollusk" a certain comprehensibleness as compared with the Gauss
co-ordinate system is the (really unqualified) formal retention of the
separate existence of the space co-ordinate. Every point on the mollusk is
treated as a space-point, and every material point which is at rest
relatively to it as at rest, so long as the mollusk is considered as
reference-body. The general principle of relativity requires that all these
mollusks can be used as reference-bodies with equal right and equal success
in the formulation of the general laws of nature; the laws themselves must
be quite independent of the choice of mollusk.
[Close quote]
> > [Pax]
> > on the other, the laws of nature break down at c... which is exactly
what insisting c is the universal speed limit says.
> [BR]
> Nothing in relativity says "the laws of nature break down at c".
[Pax]
True, Relativity doesn't say that, it says what can only be deduced to be
just the opposite, in fact.
Please explain how c as a definite, unattainable, impassable speed limit can
be maintained while at the same time maintaining the requirement of the
Principle of Relativity that "the formulation of the general laws of nature"
[...] "must be quite independent of the choice of mollusk."
> [BR]
> Relativity does predict nothing with non-zero rest mass can ever attain a
local velocity of c.
[Pax]
How would you go about testing that?
[Open quote]
Part II: The General Theory of Relativity
XX. The Equality of Inertial and Gravitational Mass as an Argument for the
General Postulate of Relativity
http://www.bartleby.com/173/20.html
Albert Einstein
[...] The chest together with the observer then begin to move "upwards" with
a uniformly accelerated motion. In course of time their velocity will reach
unheard-of values-provided that we are viewing all this from another
reference-body which is not being pulled with a rope.
[...] Even though it is being accelerated with respect to the "Galileian
space" first considered, we can nevertheless regard the chest as being at
rest. We have thus good grounds for extending the principle of relativity to
include bodies of reference which are accelerated with respect to each
other, and as a result we have gained a powerful argument for a generalised
postulate of relativity.
[Close quote]
> [BR]
> Also, it is non-sensical in relativity to try and formulate a description
of any physical process with reference to something moving at c. That is it
makes no sense to speak of a rest frame for a photon.
[Pax]
How about the rest frame of a gold ion? Two of them, in fact? Two heavy gold
ions about to kill each other nearly head-on at almost 2c? Those are
particles of mass, and they attest to an observation from either of their
local frames of some other particle of mass coming at them at almost twice
the speed of light... (local frames Einstein stated must nonetheless be
regarded as being at rest from the point-of-view of an observer within that
frame, whatever may be the local frame's actual state of motion).
> > [Pax]
> > So, which is it?
> [BR]
> The conflict here is between two things you've invented. It isn't between
relativity and the rest of physics or natural laws.
[Pax]
I haven't invented anything, I've just restated... and backed-up my
statements with quotes from Relativity.
> > [Pax]
> > Re-adding what has a *lot* to do with the speed of light and relativity:
> >
> > So, in this Brave New Old World of Physics, light rides itself and is a
massless thing with mass, gravity is removed to a less "disturbing"
dimension, and random, constant dimensional collisions construct and
destruct what's here and not here.
> [BR]
> OK, let me be more explicit as to why I don't see this as meaningful.
Start with what do you mean be "light rides itself".
[Pax]
How is it commonly accepted that light gets from one place to another? If
you run from one place to another on your feet, are you carrying yourself
(as opposed to another person or a vehicle carrying you)? As it now stands,
it is said photons are created as particles without mass that are fired into
space carrying a fair amount of energy with them, which they then proceed to
carry until they are intercepted.
> [BR]
> Light is not a "massless thing with mass".
[Pax]
How else would you describe a thing that has no mass but carries energy?
What is the Mass of a Photon?
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html
Energy and mass are the same thing. Actually, you're right though, the
photon itself doesn't have mass, but "light", which is the electromagnetic
wave energy, does have mass.
> [BR]
> Photons are massless, or if you prefer have 0 rest mass. In modern physics
massless is exactly equivalent to 0 rest mass. But do note, photons have
nothing to do with relativity.
[Pax]
uhhuh. Maybe not photons, but "light" seems to show up repeatedly everywhere
you read. In fact, Relativity was based on discoveries concerning
electrodynamics.
[Open quote]
XVI. Experience and the Special Theory of Relativity
http://www.bartleby.com/173/16.html
[...] The special theory of relativity has crystallised out from the
Maxwell-Lorentz theory of electromagnetic phenomena. Thus all facts of
experience which support the electromagnetic theory also support the theory
of relativity.
[Close quote]
> [BR]
> Gravity is not removed from relativity. It is from special relativity. But
general relativity is a theory of gravity.
[Pax]
Of course it is! Have seen posts on here that try to say differently though.
Wonder if they just haven't read GR.
When did I say gravity was removed from Relativity? You'd have to remove
General Relativity. What I said was it "is removed to a less 'disturbing'
dimension," the 11th to be exact... by M-theorists. That sort of circumvents
Relativity... or maybe not... I don't know...
> [BR]
> And as for the rest of what you posted, it seems to me to be random
thoughts with no clear relationship to physics much less relativity.
[Pax]
That, Bill, must be considered to be your personal opinion.
To clarify: random as it sounded, my previous closing statements were *all*
based on an arm-chair version the "New Physics", which strikes me as
disturbingly ambiguous in some instances... at least as it's been presented
to the general populace.
Be well - Pax
._..~*~.._..~*~.._..~*~.._..~*~.._..~*~.._..~*~.._..~*~.._..~*~.._..~*~.._.
The true value of a human being is determined primarily
by the measure and the sense in which he has attained
to liberation from the self. - Albert Einstein
We have met the enemy and he is us! - Pogo Possum
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