Closing speed vs relative speed for dummies
Uncle Ben
<Headmas...@Hogwarts.physics> wrote:
> Snivelling relativistic lying bastard trolls claim that c+v is not the
> speed of anything or is a "closing speed", accusing mathematicians
> of not being able to distinguish a "closing speed" from a "relative
> speed" (which, with all honesty, I readily own that I cannot -'
Poor Androcles, stuck in the 19th century, cannot understand how
Albert Einstein, writing in the 20th, can write an equation containing
the factors (c+v) and (c-v) and yet claim that the speed c is a
universal constant. Thus in his delicate and tactful manner,
Androcles suggests that Einstein violates the 2nd Postulate of SR,
when actually Einstein is merely calculating the time of closure
between a light wave with speed c and a target moving at speed v. If
the target is moving away from the oncoming light beam, the distance
betweem them decreases at the rate c-v; if it is moving towards the
oncoming beam, the closing rate is c-v.
Some of us have used the term "closing speed" for the factors quoted
above, and this has mystified Androcles. Closing speed is the rate of
change of the distance between two objects as they both move. Closing
speed is certainly a rate of change of a distance, but in the given
frame of reference, there is no material object nor even a photon that
moves with that speed.
Relative speed, the speed of one object relative to another, is a
different matter. In Galilean physics, there is no difference between
closing speed and relative speed, because distance and time are on the
same scale regardless of motion between the two frames of reference.
Relative speed, in short, is the speed of one object with respect to a
frame of reference in which the other object is at rest.
Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
Androcles behind, and Einstein is theorizing that distance and time
change their scales with motion so as to preserve the speed of light
between frames. This is where the difference between closing speed
and relative speed arises.
Consider two light beams aimed at each other, each travelling at speed
c. The distance between their light fronts decreases at the rate 2c,
and this is the closing speed.
To compute their relative speed starting with a Lorentz transformation
with frame speed c is complicated by a singularity in the
transformation. But the general result for sub-luminal speeds u and
v
(u+v) / (1 + uv/c^2)
does not have that singularity. The resulting formula for relative
speed in this case is
(c+c)/(1 + c*c/c^2), which simplfies easily to c.
Androcles has recently omitted his signature complaint about
Einstein's calculations. Maybe the penny in the slot has finally
dropped. But don't count on it yet.
Uncle Ben
harry
> On Feb 13, 2009, 9:51 am (EST), "Androcles"
> <Headmas...@Hogwarts.physics> wrote:
>
>> Snivelling relativistic lying bastard trolls claim that c+v is not
>> the speed of anything or is a "closing speed", accusing
>> mathematicians
>> of not being able to distinguish a "closing speed" from a "relative
>> speed" (which, with all honesty, I readily own that I cannot -'
>
> Poor Androcles, stuck in the 19th century, cannot understand how
> Albert Einstein, writing in the 20th, can write an equation containing
> the factors (c+v) and (c-v) and yet claim that the speed c is a
> universal constant.
The Newspeak you refer to has been invented in or around the 50ties of the
twentieth century - Einstein did NOT take participate in that. However, you
are of course quite right that Andro got confused by the simple terms such
as c-v, but this appears to have happened WITHOUT the introduction of such
jargon. On the other hand, it is possible of course that he FIRST got
confused by that jargon, and next the reading of Einstein's paper was done
with confused eyes, and so the damage was irreversible...
> Thus in his delicate and tactful manner,
> Androcles suggests that Einstein violates the 2nd Postulate of SR,
> when actually Einstein is merely calculating the time of closure
> between a light wave with speed c and a target moving at speed v. If
> the target is moving away from the oncoming light beam, the distance
> betweem them decreases at the rate c-v; if it is moving towards the
> oncoming beam, the closing rate is c-v.
Me thinks you surely mean:
" If the target is moving away from the oncoming light beam, the distance
betweem them decreases at the rate c-v; if it is moving towards the oncoming
beam, the closing rate is c+v." ;-)
Moreover, if the target is moving away from a retreating lightbeam, the
distance betweem them increases at the rate c+v; if it is following the
retreating beam, the opening rate is c-v.
> Some of us have used the term "closing speed" for the factors quoted
> above, and this has mystified Androcles. Closing speed is the rate of
> change of the distance between two objects as they both move. Closing
> speed is certainly a rate of change of a distance, but in the given
> frame of reference, there is no material object nor even a photon that
> moves with that speed.
>
> Relative speed, the speed of one object relative to another, is a
> different matter. In Galilean physics, there is no difference between
> closing speed and relative speed, because distance and time are on the
> same scale regardless of motion between the two frames of reference.
> Relative speed, in short, is the speed of one object with respect to a
> frame of reference in which the other object is at rest.
Not quite, see your own text just above; as you correctly stated initially,
*relative speed* is the speed of one object relative to another; and the
other object may be either a small object or a reference frame (even a
virtual one).
However, *speed* generally means the relative speed of one object wrt a
frame of reference.
> Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
> Androcles behind, and Einstein is theorizing that distance and time
> change their scales with motion so as to preserve the speed of light
> between frames. This is where the difference between closing speed
> and relative speed arises.
Not quite: "closing speed" is merely Newspeak for "relative speed", and some
good textbooks still correctly define "relative speed" without being
influenced by new jargon. Poor Androcles, I can understand that he got
confused! If you like to read more about it, I can give you a very good
reference from the Aus.J.P.
> Consider two light beams aimed at each other, each travelling at speed
> c. The distance between their light fronts decreases at the rate 2c,
> and this is the closing speed.
In my and Einstein's words: "relative speed".
> To compute their relative speed
In my and Einstein's words: "speed" (or, in the old English translation of
his 1905 paper, "velocity").
> starting with a Lorentz transformation
> with frame speed c is complicated by a singularity in the
> transformation. But the general result for sub-luminal speeds u and
> v
>
> (u+v) / (1 + uv/c^2)
>
> does not have that singularity. The resulting formula for relative
> speed in this case is
> (c+c)/(1 + c*c/c^2), which simplfies easily to c.
Note: this only refers to the 1-dimensional case for aligned velocities.
> Androcles has recently omitted his signature complaint about
> Einstein's calculations. Maybe the penny in the slot has finally
> dropped. But don't count on it yet.
I don't think so. ;-)
Cheers,
Harald
Edward Green
<...>
> If the target is moving away from the oncoming light beam, the distance
> betweem them decreases at the rate c-v; if it is moving towards the
> oncoming beam, the closing rate is c-v.
>
> Some of us have used the term "closing speed" for the factors quoted
> above, and this has mystified Androcles. Closing speed is the rate of
> change of the distance between two objects as they both move.
In a particular reference frame. Yes.
Not only Androcles is confused by this. Sometimes perfectly straight
relativists wax wroth when such expressions are used, insisting that
it is not correct relativistic velocity addition. Indeed it is not,
but in the correct context, neither is relativistic velocity addition
what one wants. In a fixed reference frame, calculation of time until
collision proceeds perfectly straightforwardly with purely Gallilean
concepts.
Uncle Ben
Thanks for your comment, Harry, and for catching the typo.
I find it much more confusion to use the same term for two results so
different as c and 2c ! But to each his own definition.
Uncle Ben
Androcles
"Uncle Ben" <b...@greenba.com> wrote in message
news:518f5f95-8385-49c7...@r24g2000vbp.googlegroups.com...
On Feb 13, 2009, 9:51 am (EST), "Androcles"
<Headmas...@Hogwarts.physics> wrote:
> Snivelling relativistic lying bastard trolls claim that c+v is not the
> speed of anything or is a "closing speed", accusing mathematicians
> of not being able to distinguish a "closing speed" from a "relative
> speed" (which, with all honesty, I readily own that I cannot -'
Poor Androcles, stuck in the 19th century, cannot understand how
Albert Einstein, writing in the 20th, can write an equation containing
the factors (c+v) and (c-v) and yet claim that the speed c is a
universal constant. Thus in his delicate and tactful manner,
Androcles suggests that Einstein violates the 2nd Postulate of SR,
when actually Einstein is merely calculating the time of closure
between a light wave with speed c and a target moving at speed v. If
the target is moving away from the oncoming light beam, the distance
betweem them decreases at the rate c-v; if it is moving towards the
oncoming beam, the closing rate is c-v.
===============================================
Which of these two gifs shows the closing speed and which shows
the relative speed, clever Uncle Bonehead Ph.D. physics 1956 and
big mouth almighty?
http://www.androcles01.pwp.blueyonder.co.uk/Doppler/ship2star.gif
http://www.androcles01.pwp.blueyonder.co.uk/Doppler/star2ship.gif
Now put up or shut up, fuckhead.
Uncle Ben
There is a spaceship, a planet, and some light from the planet.
Choose any two of them. If both are moving, you can see only the
closing speed. If either is at rest, you can see both closing and
relative speed in that frame.
No charge, sweetheart.
Uncle Ben
Androcles
On Feb 16, 12:14 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
The one showing both objects moving shows closing speed only.
The one showing the ship at rest shows relative speed, which is the
same as closing speed in that frame of reference.
No charge, dear one.
Uncle Ben
Cool. So the observer in the ship "at rest" both sees, and measures
using Doppler, the light approaching at c+v.
Now, fuckhead,
What kind of lunacy prompted the fuckin' moron Einstein, prince of
bullshit, to say
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same, you ignorant fuckin' pervert?
PS. I expect Harald Van Lintel would like you to blow and kiss him,
at least you've found a fellow boneheaded poofter to suck up to, deer one.
Androcles
=============================================
Sane people would say that was light from a star, but no matter.
Well done! You can read pictures. Next study "See Spot Run".
=============================================
Choose any two of them. If both are moving, you can see only the
closing speed. If either is at rest, you can see both closing and
relative speed in that frame.
=============================================
The speed being c+v.
No charge, sweetheart.
Uncle Ben
=============================================
For your next stage, you useless fuck,
What kind of lunacy prompted Einstein to say
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same so that he could derive magic gamma?
Answer that correctly and I might let you kiss my arse.
harry
: Uncle Ben
Hi Ben please read it again: in that example we use "speed"
(Geschwindigkeit) for c and "relative speed" for 2c; moreover, those who
don't use the new definition understand that it is in principle NOT very
different. In general we can always use the vectorial relative velocity
(c-v) which simply equals c for v=0 (in which case the "relative velocity"
or "closing velocity" equals "velocity", since our coordinate system happens
to be co-moving with the object).
To introduce a superfluous word that gives the impression that a relative
speed is somehow not relative or not a speed or something that obeys special
rules or logic (as Androcles thinks, and he is not the only one) is simply
misleading. Although in this case a word was added instead of removed, its
reducing effect on thinking is similar as with Newspeak, see
http://en.wikipedia.org/wiki/Newspeak.
Cheers,
Harald
Uncle Ben
Albert Einstein, writing in the 20th, can write an equation
containing
the factors (c+v) and (c-v) and yet claim that the speed c is a
universal constant. Thus in his delicate and tactful manner,
Androcles suggests that Einstein violates the 2nd Postulate of SR,
when actually Einstein is merely calculating the time of closure
between a light wave with speed c and a target moving at speed v. If
the target is moving away from the oncoming light beam, the distance
betweem them decreases at the rate c-v; if it is moving towards the
Androcles
Poor Uncle Bonehead, still making silly assertions not commensurate
with the simple fact of relative motion, which he calls opening and
closing motion.
Einstein's theory of Special Closing and Opening Motion is an acceleration
free form of General Opening and Closing Motion.
Koobee Wublee
> Poor Androcles, stuck in the 19th century,
Andro is stuck in the 18th century. In the meantime, the emission
theory of light was already appealed by electromagnetism in the 19th
century. <shrug>
> cannot understand how
> Albert Einstein, writing in the 20th,
Einstein the nitwit, the plagiarist, and the liar did not write
anything, and you do not understand the stuff credited to Einstein the
nitwit, the plagiarist, and the liar as well. The proof is that you
have not gone beyond that and identify all the fallacies involved as
yours truly did.
> [...]
>
> Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
> Androcles behind, and Einstein is theorizing that distance and time
> change their scales with motion so as to preserve the speed of light
> between frames.
It was not Einstein the nitwit, the plagiarist, and the liar who first
made the postulate on the constancy in the speed of light instead of
the constancy in the wavelength. It was Voigt who had this insight.
In doing so, he applied it, and the result becomes the Voigt
transform. <shrug>
> This is where the difference between closing speed
> and relative speed arises.
Introducing extra terminology does not improve your understanding.
<shrug>
> Consider two light beams aimed at each other, each travelling at speed
> c. The distance between their light fronts decreases at the rate 2c,
> and this is the closing speed.
>
> [...]
The Voigt transform gives identical velocity transformation as well.
<shrug>
> Androcles has recently omitted his signature complaint about
> Einstein's calculations. Maybe the penny in the slot has finally
> dropped. But don't count on it yet.
Remember that Andro is still stuck in the 18th century, and Uncle Ben
appears to have stuck in the early 20th century when mysticism
prevailed in the development of physics. <shrug>
Androcles
"Koobee Wublee" <koobee...@gmail.com> wrote in message
news:4febd995-f64c-4445...@b38g2000prf.googlegroups.com...
> On Feb 16, 6:32 am, Uncle Ben wrote:
>
>> Poor Androcles, stuck in the 19th century,
>
> Andro is stuck in the 18th century. In the meantime, the emission
> theory of light was already appealed by electromagnetism in the 19th
> century. <shrug>
Kinky Wobbly is incapable of reason, you two should get along well
together. Perhaps Uncle Bonehead will kiss and blow you, Kinky.
I told him I'd cut his balls off if he tried that on me.
Uncle Ben
Thanks for the information about the Voigt Transform. Voigt didn't
get as much attention as Einstein, and one of the reasons may be the
following, taken from the Wikipedia article about him and his
transform:
"In 1887 Voigt[1] formulated a form of the Lorentz transformation
between a rest frame of reference and a frame moving with speed v in
the x direction. However, as Voigt himself declared the transformation
was aimed for a specific problem and did not carry with it the ideas
of a general coordinate transformation, as is the case in relativity
theory."
Uncle Ben
Androcles
=================================================
It's not call "relativity theory" anymore, it's "opening and closing motion
theory".
Remember that Kinky Wobbly is as crazy as you but has a different faith.
Where you believe in magic gamma he believes in magic aether, otherwise
there is no difference between you. Go on, kiss and blow him, pervert.
Neither one of you can explain Sagnac.
Koobee Wublee
> On Feb 16, 3:42 pm, Koobee Wublee wrote:
> > It was not Einstein the nitwit, the plagiarist, and the liar who first
> > made the postulate on the constancy in the speed of light instead of
> > the constancy in the wavelength. It was Voigt who had this insight.
> > In doing so, he applied it, and the result becomes the Voigt
> > transform. <shrug>
>
> > The Voigt transform gives identical velocity transformation as well
> > [to the Lorentz transform]. <shrug>
>
> Thanks for the information about the Voigt Transform. Voigt didn't
> get as much attention as Einstein, and one of the reasons may be the
> following, taken from the Wikipedia article about him and his
> transform:
>
> "In 1887 Voigt[1] formulated a form of the Lorentz transformation
Whoever wrote that Wikipedia article did not know what he is talking
about. <shrug> Both the Voigt and the Lorentz transforms are
believed to satisfy the null results of the MMX. The difference is
that the Voigt transform does not satisfy the principle of relativity
while the Lorentz transform does. Since the Voigt transform does not
satisfy the principle of relativity, it does not have a symmetric
reciprocal form and thus does not manifest the twin’s paradox. Unlike
the Lorentz transform where the transverse direction is not
contracted, the Voigt transform has its transverse direction
contracted by sqrt(1 – B^2) where (B c) is the speed of the experiment
moving relative to the stationary background of the Aether. In the
longitudinal direction, the Voigt transform has its length contracted
by (1 – B^2) while the Lorentz transform has sqrt(1 – B^2).
> between a rest frame of reference and a frame moving with speed v in
> the x direction.
Since the MMX is designed with the stationary background of the Aether
in mind, the stationary background of the Aether must be taken into
the derivation. It is fine if you can show the stationary background
of the Aether does not enter the derived equations, but the Lorentz
transform does not indicate so. In fact, the Lorentz transform does
not seem to satisfy the null results of the MMX although widely to
have been believed so. <shrug>
> However, as Voigt himself declared the transformation
> was aimed for a specific problem and did not carry with it the ideas
> of a general coordinate transformation, as is the case in relativity
> theory."
Yes, the only postulate Voigt made was the invariance in the speed of
light. Since dealing with the stationary background of the Aether, it
is not wise to also make the assumption in the validity of the
principle of relativity. Einstein’s reverse engineering of the
Lorentz transform added such a constraint that has no absolute merit.
What do you expect from a nitwit, a plagiarist, and a liar anyway?
harry
And that is even an understatement. Strangely enough most (or all?!)
commentators never read his paper, for when you read it you will notice that
his transformation (which is NOT a Lorentz transformation) was nothing else
but a linear mapping tool in order to solve the classical problem of a
moving source - for both light waves AND sound waves. He could just as well
have used a Lorentz transformation (as modern books on sound theory do); the
exact form is irrelevant as it is back transformed for the answer in
physical coordinates.
Regards,
Harald
Uncle Ben
>
> - Show quoted text -
I wrote my original post for dummies. I don't think I know how to
write one for idiots.
Uncle Ben
Androcles
"harry" <harald.NOTT...@epfl.ch> wrote in message
news:1234858...@sicinfo3.epfl.ch...
Hey Bozo!
Why don't you teach Uncle Bonehead how to derive magic gamma?
Begin with
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same
and get to
gamma = 1/ sqrt( (c+v) * (c-v) /c^2)
so that t-vx/c^2 * magic gamma = tau.
Show us all how smart you are, fuckhead. Silly grinning ape symbol -->
:-)
"Easy: he did NOT say that. " -- cretin harald.vanlin...@epfl.ch
Uncle Ben
> "harry" <harald.NOTTHISvanlin...@epfl.ch> wrote in message
>
> - Show quoted text -
Nobody not already institutionalized can be a stupid as Androcles. He
is just being obstinate, looking for attention. Is that not the
definition of a troll?
Uncle Ben
Androcles
==============================================
Sure you do, Harald van lintel is hanging on your every word.
Why don't you teach the grinning ape how to derive magic gamma?
Begin with
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same
and get to
gamma = 1/ sqrt( (c+v) * (c-v) /c^2)
so that t-vx/c^2 * magic gamma = tau, which is not a vector.
Show us all how smart you are, fuckhead.
"Easy: he did NOT say that. " -- cretin harald.vanlin...@epfl.ch
Androcles
=============================================
So you can't do it and want to change the subject when cornered,
creating a flame war.
That's defines a troll, you useless fucking pervert. Go on, kiss and
blow van lintel, I'll cut your balls off if you try that with me.
Daryl McCullough
>Not quite, see your own text just above; as you correctly stated initially,
>*relative speed* is the speed of one object relative to another; and the
>other object may be either a small object or a reference frame (even a
>virtual one).
>However, *speed* generally means the relative speed of one object wrt a
>frame of reference.
>
>> Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
>> Androcles behind, and Einstein is theorizing that distance and time
>> change their scales with motion so as to preserve the speed of light
>> between frames. This is where the difference between closing speed
>> and relative speed arises.
>
>Not quite: "closing speed" is merely Newspeak for "relative speed", and some
>good textbooks still correctly define "relative speed" without being
>influenced by new jargon.
What you are saying is not correct. "relative speed" is not the
same as "closing speed". If a textbook treats them the same, then
it is *not* a good textbook. It's a sloppy textbook.
Uncle Ben explained why not: In problems involving the
motion of two objects, A and B, there is a distinction between
(1) The rate of change of the distance between A and B, as
measured in some coordinate system S unrelated to the motion
of A and B. (This is what Ben called "the closing speed" between
A and B, as measured in coordinate system S).
(2) The rate of change of the distance between A and B, as
measured in a special coordinate system S in which A is at
rest. (This is what Ben called "the relative speed" between
A and B.)
(2) is a special case, and it's a very important special case.
In a collision between two cars, the important consideration
is the speed of one car as measured in the frame in which the
other car is at rest.
It is not Newspeak to introduce terminology that allows
*distinctions* to be made that could not be made otherwise.
*Failing* to make precise distinctions is the source of
very many crackpot errors. And the point of the inventors
of Newspeak in Orwell's novel was to *block* reasoning
by taking away the precision of language necessary to
conduct that reasoning. Using the same word, "relative speed"
to mean two different things is the sort of sloppy thinking
that Newspeak encouraged.
--
Daryl McCullough
Ithaca, NY
jonas.t...@hotmail.com
To be honest Uncle Ben some of us actualy know that speed not only
take on relative timelike behaviour, but more important relative
spacelike behaviour in any inertial frame. So please rephrase your
question in a way that at least make sense, spit out that d/t is frame
variant and alot of people will stop bother you, and just conclude
that your pointlike behaviour do not apply to cosmic eventology. You
see the dream factory stops just outside your little bubble, the
galactic void doesn't care and the spatial magnitudes remain
indifferent to any try of con and scam.
Reality does not care about measure *THEOLOGY* it remain indifferent
to your scam, it only work observing reality from a single doppler
distorted point. That is the truth about closing speed a term that i
sold on the scientific community to finally disprove you spouting
bullshit all day long.
JT
Androcles
Androcles
JT
===========================================
Uncle Bonehead is complaining that he hasn't answered my question.
The penny is stuck in his craw and he's choking on it.
Ref:
http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img22.gif
What kind of lunacy prompted Einstein to say
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same?
Uncle Bonehead Green Ph.D. physics 1956 Johns Hopkins man of
science and pervert that wants to kiss and blow me on Valentine's
day, whines:
It's a closing velocity and you don't understand it!
Keep slamming the silly bastard, JT.
harry
: JT
Hey Jonas,
"Closing speed" may be superfluous and potentially misleading (as I assert),
but mere jargon like that doesn't imply a scam and regretfully such minor
disagreements distract from the real issues. BTW what is "cosmic
eventology?! - http://dictionary.reference.com/browse/eventology : "No
results found".
And for sure, "Doppler distorted points" won't help us much to "observe
reality". What we observe is a kind of projection of reality onto our
senses, and SRT intentionally ducks reality (except for one thing, which is
that light propagates like a wave). Thus, while accepting the observational
laws of SRT we may differ about our ideas of reality - it's only a theology
if one of a number of possible interpretations is pushed as gospel.
Cheers,
Harald
Uncle Ben
>
> - Show quoted text -
JT, take your thorazine and get some rest.
Uncle Ben
kenseto
> On Feb 13, 2009, 9:51 am (EST), "Androcles"
>
> <Headmas...@Hogwarts.physics> wrote:
> > Snivelling relativistic lying bastard trolls claim that c+v is not the
> > speed of anything or is a "closing speed", accusing mathematicians
> > of not being able to distinguish a "closing speed" from a "relative
> > speed" (which, with all honesty, I readily own that I cannot -'
>
> Poor Androcles, stuck in the 19th century, cannot understand how
> Albert Einstein, writing in the 20th, can write an equation containing
> the factors (c+v) and (c-v) and yet claim that the speed c is a
> universal constant. Thus in his delicate and tactful manner,
> Androcles suggests that Einstein violates the 2nd Postulate of SR,
> when actually Einstein is merely calculating the time of closure
> between a light wave with speed c and a target moving at speed v. If
> the target is moving away from the oncoming light beam, the distance
> betweem them decreases at the rate c-v; if it is moving towards the
> oncoming beam, the closing rate is c-v.
So you are saying that an observer can move wrt light....right? In
that case how does the observer can measure the speed of light in his
frame is isotropic?
Ken Seto
PD
> On Feb 16, 9:32 am, Uncle Ben <b...@greenba.com> wrote:
>
>
>
> > On Feb 13, 2009, 9:51 am (EST), "Androcles"
>
> > <Headmas...@Hogwarts.physics> wrote:
> > > Snivelling relativistic lying bastard trolls claim that c+v is not the
> > > speed of anything or is a "closing speed", accusing mathematicians
> > > of not being able to distinguish a "closing speed" from a "relative
> > > speed" (which, with all honesty, I readily own that I cannot -'
>
> > Poor Androcles, stuck in the 19th century, cannot understand how
> > Albert Einstein, writing in the 20th, can write an equation containing
> > the factors (c+v) and (c-v) and yet claim that the speed c is a
> > universal constant. Thus in his delicate and tactful manner,
> > Androcles suggests that Einstein violates the 2nd Postulate of SR,
> > when actually Einstein is merely calculating the time of closure
> > between a light wave with speed c and a target moving at speed v. If
> > the target is moving away from the oncoming light beam, the distance
> > betweem them decreases at the rate c-v; if it is moving towards the
> > oncoming beam, the closing rate is c-v.
>
> So you are saying that an observer can move wrt light....right? In
> that case how does the observer can measure the speed of light in his
> frame is isotropic?
>
Ken, here is the important thing. Please pay attention. The first
question you need to ask is NOT "how can this happen?".
The first question is "Does this in fact happen?"
The answer to that question does not come from logic or argument. It
comes from experimental measurement.
The answer to that question is "Yes. For an observer moving with
respect to the light, the speed of light is measured to be isotropic."
THEN you can ask the question, "How can this happen?" while knowing
with certainty that it DOES happen.
The problem you have is that you try to answer the "How can this
happen?" question first. Then you get stuck, not able to think of a
way that it can happen, and then you feel forced to jump to the second
question "Does this in fact happen?" by answering it with "No, it
cannot happen, because I can't think of a way that it happens." But
this is obviously the wrong answer, because experiment shows that it
DOES happen.
You have the order of your questions reversed.
PD
Androcles
"harry" <harald.vanlin...@epfl.ch> wrote in message
news:499b3...@news.bluewin.ch...
The real issue is
What kind of lunacy prompted Einstein to say
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same?
According to Cretin harald.vanlin...@epfl.ch
Easy: he did NOT say that.
According to cretin van lintel, Einstein did not write the equation he
wrote.
You are merely stupid.
Uncle Bonehead Green Ph.D. physics 1956 Johns Hopkins
troll of science and pervert that wants to kiss and blow me is
troll, the whole troll and nothing but the troll.
Androcles
Uncle Ben, troll, the whole troll and nothing but the troll.
Androcles
"kenseto" <ken...@erinet.com> wrote in message
news:9e29235a-c5cc-458d...@m16g2000vbp.googlegroups.com...
On Feb 16, 9:32 am, Uncle Ben <b...@greenba.com> wrote:
> On Feb 13, 2009, 9:51 am (EST), "Androcles"
>
> <Headmas...@Hogwarts.physics> wrote:
> > Snivelling relativistic lying bastard trolls claim that c+v is not the
> > speed of anything or is a "closing speed", accusing mathematicians
> > of not being able to distinguish a "closing speed" from a "relative
> > speed" (which, with all honesty, I readily own that I cannot -'
>
> Poor Androcles, stuck in the 19th century, cannot understand how
> Albert Einstein, writing in the 20th, can write an equation containing
> the factors (c+v) and (c-v) and yet claim that the speed c is a
> universal constant. Thus in his delicate and tactful manner,
> Androcles suggests that Einstein violates the 2nd Postulate of SR,
> when actually Einstein is merely calculating the time of closure
> between a light wave with speed c and a target moving at speed v. If
> the target is moving away from the oncoming light beam, the distance
> betweem them decreases at the rate c-v; if it is moving towards the
> oncoming beam, the closing rate is c-v.
So you are saying that an observer can move wrt light....right? In
that case how does the observer can measure the speed of light in his
frame is isotropic?
============================================
He does can by using Doppler. Or perhaps he can does.
Wavelength is directly proportional to velocity, frequency is constant.
closing or opening speed = \lambda * \nu
kenseto
> Poor Androcles, stuck in the 19th century, cannot understand how
> Albert Einstein, writing in the 20th, can write an equation
> containing
> the factors (c+v) and (c-v) and yet claim that the speed c is a
> universal constant. Thus in his delicate and tactful manner,
> Androcles suggests that Einstein violates the 2nd Postulate of SR,
> when actually Einstein is merely calculating the time of closure
> between a light wave with speed c and a target moving at speed v. If
> the target is moving away from the oncoming light beam, the distance
> betweem them decreases at the rate c-v; if it is moving towards the
> oncoming beam, the closing rate is c+v.
ou can have closing speed between two macroscopic objects. But you
can't have clocsing speed between an object and light. Why Because the
speed of light in any frame is constant and isotropic and the idea of
closing speed contradicts this SR postulate.
Ken Seto
PD
> On Feb 16, 3:11 pm, Uncle Ben <b...@greenba.com> wrote:
>
> > Poor Androcles, stuck in the 19th century, cannot understand how
> > Albert Einstein, writing in the 20th, can write an equation
> > containing
> > the factors (c+v) and (c-v) and yet claim that the speed c is a
> > universal constant. Thus in his delicate and tactful manner,
> > Androcles suggests that Einstein violates the 2nd Postulate of SR,
> > when actually Einstein is merely calculating the time of closure
> > between a light wave with speed c and a target moving at speed v. If
> > the target is moving away from the oncoming light beam, the distance
> > betweem them decreases at the rate c-v; if it is moving towards the
> > oncoming beam, the closing rate is c+v.
>
> ou can have closing speed between two macroscopic objects. But you
> can't have clocsing speed between an object and light. Why Because the
> speed of light in any frame is constant and isotropic and the idea of
> closing speed contradicts this SR postulate.
What do you think the "idea of closing speed" is?
kenseto
> On Feb 17, 5:25 pm, kenseto <kens...@erinet.com> wrote:
>
>
>
>
>
> > On Feb 16, 3:11 pm, Uncle Ben <b...@greenba.com> wrote:
>
> > > Poor Androcles, stuck in the 19th century, cannot understand how
> > > Albert Einstein, writing in the 20th, can write an equation
> > > containing
> > > the factors (c+v) and (c-v) and yet claim that the speed c is a
> > > universal constant. Thus in his delicate and tactful manner,
> > > Androcles suggests that Einstein violates the 2nd Postulate of SR,
> > > when actually Einstein is merely calculating the time of closure
> > > between a light wave with speed c and a target moving at speed v. If
> > > the target is moving away from the oncoming light beam, the distance
> > > betweem them decreases at the rate c-v; if it is moving towards the
> > > oncoming beam, the closing rate is c+v.
>
> > ou can have closing speed between two macroscopic objects. But you
> > can't have clocsing speed between an object and light. Why Because the
> > speed of light in any frame is constant and isotropic and the idea of
> > closing speed contradicts this SR postulate.
>
> What do you think the "idea of closing speed" is?
As observed by a third party two macroscopic objects can have a
closing speed of almost 2c. But a third party observer cannot assert
that an observed object can have a closing speed of c+v or c-v wrt
light. Why? Because the speed of light in the rest frame of the object
is constant and isotropic.
Ken Seto
>
>
>
>
>
> > Ken Seto
>
> > > Some of us have used the term "closing speed" for the factors quoted
> > > above, and this has mystified Androcles. Closing speed is the rate
> > > of
> > > change of the distance between two objects as they both move.
> > > Closing
> > > speed is certainly a rate of change of a distance, but in the given
> > > frame of reference, there is no material object nor even a photon
> > > that
> > > moves with that speed.- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
jonas.t...@hotmail.com
> <jonas.thornv...@hotmail.com> wrote in message
> results found".
> And for sure, "Doppler distorted points" won't help us much to "observe
> reality". What we observe is a kind of projection of reality onto our
> senses, and SRT intentionally ducks reality (except for one thing, which is
> that light propagates like a wave). Thus, while accepting the observational
> laws of SRT we may differ about our ideas of reality - it's only a theology
> if one of a number of possible interpretations is pushed as gospel.
>
> Cheers,
>
> - Visa citerad text -
Well what is a cosmic event, it sure doesn't care about measure
theology. So cosmic eventology must be separated from measure
theology. My best guess is that a cosmic event is based on event
casuality, and since SR seems to escape casuality the theory must be
incompatible with cosmic eventology. I am fully aware that quantum
philosophy says that events on the micro scale is nonedetermant
however that is on the scale of quantum philosophy, on the macroscopic
scale events are decided by causality.
That simply mean that spatial magnitude do not care about measure
theology they remain same between frames of reference. Reality do not
behave and have the pointlike structure of Lorentz transform and
Minkowsky spacetime. Spatial magnitudes isn't direction sensitive.
Only the theory of relativity use direction sensitive spatial
magnitudes, i call it scam or con if someone try to tell me that the
distance as measured from an inertial frame, with restcordinates A ->
B is not the as same from B -> A.
It is a cheap scam for the mathematical inclined but the logical
disabled. Space does not care about relative speed, when it come to
spatial magnitudes. They remain nonevariant, relativists led us to
beleive that spatial magnitudes somehow was frame dependent, they are
not, in fact they never told us that the spatial magnitudes according
to relativity was direction sensitive in one and the same frame.
Because if they had put forward such a stupid and logically insane
argument special relativity would had been abondoned long time ago. My
guess is noone bothered to check because they were spellbound by the
Lorentz transform and Minkowsky space times cheap tricks that Einstein
AdHoc put togehter to create a reality full of misteries. They just
sat there with their calculators applied Lorentz transform to get
their doppler distorted magnitudes between spacelike points,
starstrucked and spellbound by both theory and Einstein.
So have anyone yet managed to actually count the red and blue flashes
in my example so we can discuss the possibility of variant spatial
magnitudes between two points in a frame?
Or maybe you want do discuss the possibility that light travels
variant thru space?
JT
PD
You did not answer my question. What do you think the "idea of closing
speed" is?
>
jonas.t...@hotmail.com
>
> - Visa citerad text -
The light travel invariant thru space never happen bubbleboy. You have
not counted the number of blue and red flashes in each direction and
calculated the lightspeed yet?
JT
harry
"Daryl McCullough" <stevend...@yahoo.com> wrote in message
news:gnen4...@drn.newsguy.com...
> harry says...
>
>>Not quite, see your own text just above; as you correctly stated
>>initially,
>>*relative speed* is the speed of one object relative to another; and the
>>other object may be either a small object or a reference frame (even a
>>virtual one).
>
>>However, *speed* generally means the relative speed of one object wrt a
>>frame of reference.
>>
>>> Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
>>> Androcles behind, and Einstein is theorizing that distance and time
>>> change their scales with motion so as to preserve the speed of light
>>> between frames. This is where the difference between closing speed
>>> and relative speed arises.
>>
>>Not quite: "closing speed" is merely Newspeak for "relative speed", and
>>some
>>good textbooks still correctly define "relative speed" without being
>>influenced by new jargon.
>
> What you are saying is not correct. "relative speed" is not the
> same as "closing speed". If a textbook treats them the same, then
> it is *not* a good textbook. It's a sloppy textbook.
Indeed "relative speed" is not the same as "closing speed", instead, closing
speed is a form of relative speed. Sorry if I wasn't clear!
(Note: if I say that a Toyota is a car, it does NOT mean that a car is a
Toyota!)
> Uncle Ben explained why not: In problems involving the
> motion of two objects, A and B, there is a distinction between
> (1) The rate of change of the distance between A and B, as
> measured in some coordinate system S unrelated to the motion
> of A and B. (This is what Ben called "the closing speed" between
> A and B, as measured in coordinate system S).
Indeed, and as I pointed out: Einstein, good textbooks and myself call that
"relative speed".
> (2) The rate of change of the distance between A and B, as
> measured in a special coordinate system S in which A is at
> rest. (This is what Ben called "the relative speed" between
> A and B.)
Indeed, and as I pointed out: Einstein, good textbooks and myself call that
form of relative speed simply "speed".
> (2) is a special case, and it's a very important special case.
> In a collision between two cars, the important consideration
> is the speed of one car as measured in the frame in which the
> other car is at rest.
Not necessarily: other important considerations can be for example the frame
in which the total centre of mass is in rest.
> It is not Newspeak to introduce terminology that allows
> *distinctions* to be made that could not be made otherwise.
Indeed. Apprently like Ben you did not understand my clarification that the
distinction already existed, nor did you read my pointing this out to him.
> *Failing* to make precise distinctions is the source of
> very many crackpot errors.
Yes indeed, sorry to see that you are misguided this time.
> And the point of the inventors
> of Newspeak in Orwell's novel was to *block* reasoning
> by taking away the precision of language necessary to
> conduct that reasoning.
Yes indeed, as I also explained to Ben in the next posting which you forgot
to read before jumping on this. :-)
> Using the same word, "relative speed"
> to mean two different things is the sort of sloppy thinking
> that Newspeak encouraged.
Yes indeed, and not applicable here - as already explained.
Good luck,
Harald
harry
> On 17 Feb, 23:13, "harry" <harald.vanlintelButNotT...@epfl.ch> wrote:
>> <jonas.thornv...@hotmail.com> wrote in message
>>
>> news:a20115b0-2117-453a...@q9g2000yqc.googlegroups.com...
>> On 16 Feb, 15:32, Uncle Ben <b...@greenba.com> wrote:
>>> Androcles has recently omitted his signature complaint about
>>> Einstein's calculations.
I overlooked that: note that Einstein did not use the term "closing speed"
with his calculations, that term is just an additional distraction provided
by newcomers in the field. :-)
causality perhaps? ;-)
> and since SR seems to escape casuality
No, not at all. Perhaps you mean QM? ;-)
> the theory must be
> incompatible with cosmic eventology.
Hmm as I pointed out, eventology doesn't seem to exist yet. :-)
> I am fully aware that quantum
> philosophy says that events on the micro scale is nonedetermant
> however that is on the scale of quantum philosophy, on the macroscopic
> scale events are decided by causality.
>
> That simply mean that spatial magnitude do not care about measure
> theology they remain same between frames of reference.
"Special magnitude", what is that? Sorry but you appear to give striking
examples of the kind of (not-exactly) Newspeak that I find counterproductive
(and no, I didn't invent jonas.thornvall to make my point!).
> Reality do not
> behave and have the pointlike structure of Lorentz transform and
> Minkowsky spacetime. Spatial magnitudes isn't direction sensitive.
> Only the theory of relativity use direction sensitive spatial
> magnitudes, i call it scam or con if someone try to tell me that the
> distance as measured from an inertial frame, with restcordinates A ->
> B is not the as same from B -> A.
According to standard definitions, the distance between "rest"coordinates
A -> B is *the as same* as from B -> A.
Apart of that, SRT merely describes the laws of observations that correspond
to measurements such as done in labs but also in consumer applications. And
from even before SRT this was already explained with a model of reality
according to which spatial magnitudes are not really direction sensitive but
can be apparently so in certain situations of measurement. Thus if you try
to make sense of it, you have no excuse except that you didn't know (in
contrast , QM does not yet have a sufficiently good realist explanation).
> It is a cheap scam for the mathematical inclined but the logical
> disabled. Space does not care about relative speed, when it come to
> spatial magnitudes. They remain nonevariant, relativists led us to
> beleive that spatial magnitudes somehow was frame dependent, they are
> not, in fact they never told us that the spatial magnitudes according
> to relativity was direction sensitive in one and the same frame.
You are obviously mistaken - they didn't tell you because it isn't so!
> Because if they had put forward such a stupid and logically insane
> argument special relativity would had been abondoned long time ago. My
> guess is noone bothered to check because they were spellbound by the
> Lorentz transform and Minkowsky space times cheap tricks that Einstein
> AdHoc put togehter to create a reality full of misteries.
You never got the idea that perhaps you made a calculation error? ;-)
Note that, as I already mentioned to you, there is no reason at all to think
that there is something "mysterious" about SRT - it's just a theory of
observations without an explanation. Different kinds of explanations have
been given by different people and you should study those first before
jumping to conclusions.
> They just
> sat there with their calculators applied Lorentz transform to get
> their doppler distorted magnitudes between spacelike points,
> starstrucked and spellbound by both theory and Einstein.
Haha no the theory already existed in a rudimentary form before Einstein,
and there was nothing "spellbound" about it. :-)
> So have anyone yet managed to actually count the red and blue flashes
> in my example so we can discuss the possibility of variant spatial
> magnitudes between two points in a frame?
I have not seen that but see below.
> Or maybe you want do discuss the possibility that light travels
> variant thru space?
No sorry as the saying goes, a madman can ask more questions than all the
wise in the world can ever answer (not meaning that you are necessarily a
madman - but there are a few lurking around here!).
If you want to get understanding, it's better to use such groups as these to
ask people for good literature on the topic (e.g. there have been many
papers about how to calculate Doppler complete with detailed examples) and
to ask clarification if you don't understand a specific point.
Success,
Harald
kenseto
Hey idiot I already said what the idea of closing speed is.
Ken Seto
PD
Hmmm... let me try a different tack.
Give me your *definition* of "closing speed".
Note that a definition is not a description of what you can and cannot
do with it.
If you need an illustration of what a definition is, you can look in a
dictionary for examples.
kenseto
Hey idiot you give me your definition of closing speed.
kenseto
You give me your definition of closing speed.
My point is: In Einstein's train gedanken the track observer M cannot
assert that M' has a closing speed between the light fronts from A and
B. M' must determine if the light fronts arrive at him simultaneously
based on his own measurements.
PD
So when you say "the idea of closing speed contradicts this SR
postulate," you don't even know what "closing speed" MEANS?
How do you manage to say whether this contradicts that when you don't
even know what the terms mean?
Don't you think your pretense is obvious?
kenseto
Hey idiot I gave you examples of closing speed. It is you who don't
know what closing speed mean.
Ken Seto
PD
Let's work on what a definition is.
If I asked you define "mammal", your listing "cat, dog, horse" would
not serve as a definition of what a mammal is. If you listed "cat,
dog, horse" as the definition of mammal, then how could one judge
whether a whale or a bat or a platypus is also a mammal? None of those
are cat, dog, horse.
Tell me what your *definition* of "closing speed" is. Not examples.
kenseto
The reasons I said that you don't know what closing speed are as
follows:
1. You and Einstein said that M' has a closing speed wrt the light
fronts from A and B of c+v and c-v.
2. The SR postulate says that the speed of light in the M' frame is
isotropic and therefore there is no closing speed between M' and the
light fronts from A and B.
Ken Seto
PD
Not quite. What was said that the train observer, as seen in M (not
M'), has a closing speed wrt the light fronts from A and B of c+v and
c-v.
> 2. The SR postulate says that the speed of light in the M' frame is
> isotropic
This is *relative* speed, not closing speed. This is why I asked you
for your definition of "closing speed". You don't seem to know the
difference between closing speed and relative speed.
Secondly, note that this is relative speed as seen in the M' frame,
not the closing speed as seen in the M frame. See my comment for your
point 1.
> and therefore there is no closing speed between M' and the
> light fronts from A and B.
What on earth gives you the impression that if light speed is
isotropic then there is "no closing speed" at all? This is why I asked
you for your definition of "closing speed". You don't seem to know
what the term means.
I don't know how you can attempt to criticize something if you don't
know what the terms mean. Does that seem unfair to you?
kenseto
That's the point: M does not see or predict M' to have a closing speed
wrt the light fronts from A and B. M predicts that the speed of light
in the M' frame is isotropic.
Ken Seto
jonas.t...@hotmail.com
Well SR certainly escape causuality you have not read the paradoxes
incorporated in SR, events is not causuality driven in SR, and is easy
to construct examples where events between two objects is simultaneous
although one object seised to exist.
> > the theory must be
> > incompatible with cosmic eventology.
>
> Hmm as I pointed out, eventology doesn't seem to exist yet. :-)
Well maybe it should replace measure theology.
> > I am fully aware that quantum
> > philosophy says that events on the micro scale is nonedetermant
> > however that is on the scale of quantum philosophy, on the macroscopic
> > scale events are decided by causality.
>
> > That simply mean that spatial magnitude do not care about measure
> > theology they remain same between frames of reference.
>
> "Special magnitude", what is that? Sorry but you appear to give striking
> examples of the kind of (not-exactly) Newspeak that I find counterproductive
> (and no, I didn't invent jonas.thornvall to make my point!).
You can not even quote spatial magnitude correct? How do you expect me
to keep an intelligent conversation with you.
You seem to have a sore thumb also since you can not use wikipedia...
======================
In elementary mathematics, physics, and engineering, a vector
(sometimes called a geometric[1] or spatial vector[2]) is a geometric
object that has both a magnitude (or length), direction and sense,
i.e., orientation along the given direction.[3] A vector is frequently
represented by a line segment with a definite direction, or
graphically as an arrow, connecting an initial point A with a terminal
point B,[4] and denoted by
->AB
The magnitude of the vector is the length of the segment and the
direction characterizes the displacement of B relative to A: how much
one should move the point A to "carry" it to the point B.[5]
=================================
Is this incomprhensible for you? I can see you find it confusing.
> > Reality do not
> > behave and have the pointlike structure of Lorentz transform and
> > Minkowsky spacetime. Spatial magnitudes isn't direction sensitive.
> > Only the theory of relativity use direction sensitive spatial
> > magnitudes, i call it scam or con if someone try to tell me that the
> > distance as measured from an inertial frame, with restcordinates A ->
> > B is not the as same from B -> A.
>
> According to standard definitions, the distance between "rest"coordinates
> A -> B is *the as same* as from B -> A.
Now you resort to dreaming now you go calculate, number of flashes
counted in my examples of spatial separation. And you tell me the
numbers of flashes counted in each direction.
You tell me if the directional discrepancy depends on
A. SR using directional sensitive magnitudes of spatial vectors in SR.
B. The light travel invariant in frame X.
C. Any silly explanation you can come to think of.
> Apart of that, SRT merely describes the laws of observations that correspond
> to measurements such as done in labs but also in consumer applications. And
> from even before SRT this was already explained with a model of reality
> according to which spatial magnitudes are not really direction sensitive but
> can be apparently so in certain situations of measurement. Thus if you try
> to make sense of it, you have no excuse except that you didn't know (in
> contrast , QM does not yet have a sufficiently good realist explanation).
You resort to dreaming again spatial vector magnitudes is well
explored you can not have longer way to work than home. You see cosmic
spatial vector magnitudes, neither care or is dependent on measure
*THEOLOGY*, they just are what they are and direction invariant in any
theory except for SR. If you doubt the direction dependent component
of SR simply do the most simple calculation counting numbers of
flashes in each direction for observer P in inertial frame X in my
example, P stands for punked, Einstein punked you all and got away
with it.
> > It is a cheap scam for the mathematical inclined but the logical
> > disabled. Space does not care about relative speed, when it come to
> > spatial magnitudes. They remain nonevariant, relativists led us to
> > beleive that spatial magnitudes somehow was frame dependent, they are
> > not, in fact they never told us that the spatial magnitudes according
> > to relativity was direction sensitive in one and the same frame.
>
> You are obviously mistaken - they didn't tell you because it isn't so!
Well i am not. you only have to count the number of flashes in each
direction, to tell you were punked to begin with of Einstein. And
that's a fact, another fact is that so far noone in the to simply add
the numbers of flashes P register in each direction, and they never
will since it simply put invalidate Special Relativity.
> > Because if they had put forward such a stupid and logically insane
> > argument special relativity would had been abondoned long time ago. My
> > guess is noone bothered to check because they were spellbound by the
> > Lorentz transform and Minkowsky space times cheap tricks that Einstein
> > AdHoc put togehter to create a reality full of misteries.
>
> You never got the idea that perhaps you made a calculation error? ;-)
No it never occured and you never applied your on the problem, and you
never will because it invalidate SR. Many strawmen will though because
it such a simple measurement of counting. And they will conclude that
either Einstein had some logical disabilities or simply was a charming
conman, i have my idea pretty solid of which do apply in this case.
> Note that, as I already mentioned to you, there is no reason at all to think
> that there is something "mysterious" about SRT - it's just a theory of
> observations without an explanation. Different kinds of explanations have
> been given by different people and you should study those first before
> jumping to conclusions.
You do not want to count the number of flashes P register in each
direction, because you know that it invalidates SR. This is the truth,
even bot Sue know it making fun of you, she just cant spit it out.
Maybe they throw her out of the university computer.
> > They just
> > sat there with their calculators applied Lorentz transform to get
> > their doppler distorted magnitudes between spacelike points,
> > starstrucked and spellbound by both theory and Einstein.
>
> Haha no the theory already existed in a rudimentary form before Einstein,
> and there was nothing "spellbound" about it. :-)
Well you tell that to the bubbleboys, i think they will disagree.....
> > So have anyone yet managed to actually count the red and blue flashes
> > in my example so we can discuss the possibility of variant spatial
> > magnitudes between two points in a frame?
>
> I have not seen that but see below.
No you go count the flashes, and you comeback when you learned how to
perform a logical evaluation using simple *ADD*
> > Or maybe you want do discuss the possibility that light travels
> > variant thru space?
>
> No sorry as the saying goes, a madman can ask more questions than all the
> wise in the world can ever answer (not meaning that you are necessarily a
> madman - but there are a few lurking around here!).
> If you want to get understanding, it's better to use such groups as these to
> ask people for good literature on the topic (e.g. there have been many
> papers about how to calculate Doppler complete with detailed examples) and
> to ask clarification if you don't understand a specific point.
You simply talk alot of nonsense and is unable to perform a simple
operation of ADD, i already disproved invariant lightspeed you are
just to slow to get it. When i did this i solely disproved the dream
factory of SR.
> Success,
Well you only did succe keeping your own charade going to be honest,
dance for Einstein puppet.
JT
PD
This is not what Einstein said. You were making a statement about what
Einstein said. You mistakenly stated what Einstein said.
> M predicts that the speed of light
> in the M' frame is isotropic.
Science is about measurements, Ken. The truth of science is based not
on the sensibility of predictions, but on how well predictions match
measurement. This seems to completely elude you. It's how science
works, Ken.
jonas.t...@hotmail.com
So how is the adding coming along Harald to hard for you?
JT
kenseto
So einstein didn't say that M' rush toward the front light front and
receding away from the light front from the rear? You are an idiot
runt of the SRians.
Ken Seto
PD
This does NOT mean: M' has a closing speed wrt the light fronts from A
and B of c+v and c-v.
It DOES mean: The train observer, as seen in M (not M'), has a closing
speed wrt the light fronts from A and B of c+v and c-v.
This, you'll note, is what I told you earlier.
You do not understand the meaning of the terms being used. Do you find
this unfair?
Daryl McCullough
>"Daryl McCullough" <stevend...@yahoo.com> wrote
>> Uncle Ben explained why not: In problems involving the
>> motion of two objects, A and B, there is a distinction between
>> (1) The rate of change of the distance between A and B, as
>> measured in some coordinate system S unrelated to the motion
>> of A and B. (This is what Ben called "the closing speed" between
>> A and B, as measured in coordinate system S).
>
>Indeed, and as I pointed out: Einstein, good textbooks and myself call that
>"relative speed".
I disagree. I think it is bad terminology and very confusing.
The fact that Einstein called it that was, in my opinion, because
he was addressing an audience that only knew Galilean relativity,
in which "closing speed" and "relative speed" are the same.
>> (2) The rate of change of the distance between A and B, as
>> measured in a special coordinate system S in which A is at
>> rest. (This is what Ben called "the relative speed" between
>> A and B.)
>
>Indeed, and as I pointed out: Einstein, good textbooks and myself call that
>form of relative speed simply "speed".
That doesn't make any sense. If there are two cars that are both
moving, and I say "The speed of the first car is 100 kilometers
per hour", I *DON'T* mean "The speed of the first car, as measured
in a frame in which the other car is at rest." Nobody uses that
terminology. It doesn't make any sense.
If I say "the speed of the first car", I mean the speed as measured
in an implicit "lab frame". If it's just a physics problem ("A car
with a mass of 1000 kilograms moving 120 kilometers
per hour collides with a car of mass 1200 kilograms moving in the
opposite direction at 80 kilometers per hour") it doesn't matter
exactly what the "lab frame" is. For a real experiment, it is
often implicitly the frame in which the lab is at rest (which
is why it is called the "lab frame").
Besides "speed" (which is dependent on an implicit "lab frame"),
there are two other concepts: (1) The rate at which the distance
between the objects changes, as measured in the "lab frame", and
(2) the rate at which the distance between the objects changes,
as measured in the rest frame of one of the objects.
What do you call those two quantities? You want to call the
first one "relative speed", but then what do you call the
second quantity? It *ISN'T* "speed". Speed means "the rate
at which the distance of the car from the origin of the
lab coordinate system changes".
--
Daryl McCullough
Ithaca, NY
Daryl McCullough
>I overlooked that: note that Einstein did not use the term "closing speed"
>with his calculations, that term is just an additional distraction provided
>by newcomers in the field. :-)
You are completely wrong about that. It isn't a distraction.
It's an important distinction. Einstein did not make that distinction,
and you can see the consequence: poor Androcles has been confused
for decades.
There are three different concepts: (1) the rate of change of the
position of an object, as measured in the implicit "lab frame", (2)
the rate of change of the distance between two objects, as measured
in the "lab frame", and (3) the rate of change of the distance between
two objects, as measured in a frame in which one of the objects is
at rest.
Three concepts, three terms: (1) speed, (2) closing speed, (3) relative
speed.
You are wanting to use *two* phrases ("relative speed", "closing speed")
to mean concept (2), and one phrase, "speed" to mean both concepts (1)
and (3). That is a misallocation of terminology.
YBM
> harry says...
>
>> I overlooked that: note that Einstein did not use the term "closing speed"
>> with his calculations, that term is just an additional distraction provided
>> by newcomers in the field. :-)
>
> You are completely wrong about that. It isn't a distraction.
> It's an important distinction. Einstein did not make that distinction,
> and you can see the consequence: poor Androcles has been confused
> for decades.
That's true. But have you ever seen anyone being confused by this but
Androcles? Even other first class cranks here haven't, as far as I can
say.
harry
> harry says...
>
>>"Daryl McCullough" <stevend...@yahoo.com> wrote
>
>>> Uncle Ben explained why not: In problems involving the
>>> motion of two objects, A and B, there is a distinction between
>>> (1) The rate of change of the distance between A and B, as
>>> measured in some coordinate system S unrelated to the motion
>>> of A and B. (This is what Ben called "the closing speed" between
>>> A and B, as measured in coordinate system S).
>>
>>Indeed, and as I pointed out: Einstein, good textbooks and myself call
>>that
>>"relative speed".
>
> I disagree. I think it is bad terminology and very confusing.
Sorry I didn't carefully read what you wrote, and now it becomes more
interesting. Indeed it is only the same for 1D problems (which appeard to be
the topic of this thread, but the general case must not be forgotten!).
However the speed as you define here above is again something different, and
perhaps the term "closing speed" would be appropriate for it, see below.
> The fact that Einstein called it that was, in my opinion, because
> he was addressing an audience that only knew Galilean relativity,
> in which "closing speed" and "relative speed" are the same.
Probably the term "closing speed" was not yet invented. I don't recall
having ever come across that term in any publication of before 1950.
>>> (2) The rate of change of the distance between A and B, as
>>> measured in a special coordinate system S in which A is at
>>> rest. (This is what Ben called "the relative speed" between
>>> A and B.)
>>
>>Indeed, and as I pointed out: Einstein, good textbooks and myself call
>>that
>>form of relative speed simply "speed".
>
> That doesn't make any sense.
It's correct for the 1D problems of this thread, but not in general - sorry
for the glitch. However evidently you are confused in more than one way, see
below.
> If there are two cars that are both moving,
Which means that you consider both cars with reference to a frame in which
both are measured as moving, as in your example 1.
> and I say "The speed of the first car is 100 kilometers
> per hour"
That means in standard language: wrt your coordinate system in which both
cars are moving...
> , I *DON'T* mean "The speed of the first car, as measured
> in a frame in which the other car is at rest." Nobody uses that
> terminology. It doesn't make any sense.
Nor do I. See my reply to your example 1 as well as further below.
> If I say "the speed of the first car", I mean the speed as measured
> in an implicit "lab frame".
Quite so; more generally, it's the speed as measured in our inertial
coordinate system of choice.
> If it's just a physics problem ("A car
> with a mass of 1000 kilograms moving 120 kilometers
> per hour collides with a car of mass 1200 kilograms moving in the
> opposite direction at 80 kilometers per hour") it doesn't matter
> exactly what the "lab frame" is. For a real experiment, it is
> often implicitly the frame in which the lab is at rest (which
> is why it is called the "lab frame").
>
> Besides "speed" (which is dependent on an implicit "lab frame"),
> there are two other concepts: (1) The rate at which the distance
> between the objects changes, as measured in the "lab frame", and
> (2) the rate at which the distance between the objects changes,
> as measured in the rest frame of one of the objects.
The rest frame of one of the objects is according to both classical physics
and SRT just another valid reference frame (if it is a sufficiently good
approximation of a Newtonian frame); a material "lab frame" is not preferred
for the description of physics (the PoR).
> What do you call those two quantities?
Personally I call them both Doppler speeds, and I specify the used reference
frame if not already implicit from the description. I don't know if a
generally accepted term for a change-of-distance rate exists but I think
that "closing speed" would be a good term for such a speed. Anyway, in 3D,
NEITHER of your cases is generally equal to the absolute value of the vector
subtraction (c-v) which appeared to be the subject of this thread.
> You want to call the
> first one "relative speed", but then what do you call the
> second quantity?
I don't "want" to call anything; instead I'm happy with the standard
textbook definitions that I learned and know how to apply.
> It *ISN'T* "speed". Speed means "the rate
> at which the distance of the car from the origin of the
> lab coordinate system changes".
No, that is erroneous: textbooks define speed as ds/dt, as measured in a
coordinate system of choice. As speed is the derivative of the object's
position over time, the position of the origin is irrelevant for the
determination of speed.
Moreover, in 3D problems there is a big difference between the definition
you use and the one of textbooks: when an object passes at a distance by a
point such as the origin in your reference system, at the instant that the
velocity is perpendicular to the origin the distance doesn't change (thus
you would say that its speed is zero!) even if its speed ds/dt is constant.
And as a reminder: textbooks define "relative velocity" as the vector
subtraction of two velocities V_ba = V_b - V_a ; Einstein also correctly
applied that definition in 1905.
Best regards,
Harald
Androcles
"harry" <harald.NOTT...@epfl.ch> wrote in message
news:1235043...@sicinfo3.epfl.ch...
Pathetic!
You two dozy bastards don't know how to knot two ropes together
without a text book and a lab frame, and McCullough has his head
so far up his arse he doesn't want to find out.
Real lab frame:
http://nellore.ap.nic.in/images/rc5.jpg
va...@icmf.inf.cu
> Uncle Ben wrote:
> > On Feb 13, 2009, 9:51 am (EST), "Androcles"
> > <Headmas...@Hogwarts.physics> wrote:
>
> >> Snivelling relativistic lying bastard trolls claim that c+v is not
> >> the speed of anything or is a "closing speed", accusing
> >> mathematicians
> >> of not being able to distinguish a "closing speed" from a "relative
> >> speed" (which, with all honesty, I readily own that I cannot -'
>
> > Albert Einstein, writing in the 20th, can write an equation containing
> > the factors (c+v) and (c-v) and yet claim that the speed c is a
> > universal constant.
>
> twentieth century - Einstein did NOT take participate in that. However, you
> are of course quite right that Andro got confused by the simple terms such
> as c-v, but this appears to have happened WITHOUT the introduction of such
> jargon. On the other hand, it is possible of course that he FIRST got
> confused by that jargon, and next the reading of Einstein's paper was done
> with confused eyes, and so the damage was irreversible...
>
> > Thus in his delicate and tactful manner,
> > Androcles suggests that Einstein violates the 2nd Postulate of SR,
> > when actually Einstein is merely calculating the time of closure
> > between a light wave with speed c and a target moving at speed v. If
> > the target is moving away from the oncoming light beam, the distance
> > betweem them decreases at the rate c-v; if it is moving towards the
>
> Me thinks you surely mean:
> " If the target is moving away from the oncoming light beam, the distance
> betweem them decreases at the rate c-v; if it is moving towards the oncoming
>
> Moreover, if the target is moving away from a retreating lightbeam, the
> distance betweem them increases at the rate c+v; if it is following the
> retreating beam, the opening rate is c-v.
>
> > Some of us have used the term "closing speed" for the factors quoted
> > change of the distance between two objects as they both move. Closing
> > speed is certainly a rate of change of a distance, but in the given
> > frame of reference, there is no material object nor even a photon that
> > moves with that speed.
>
> > different matter. In Galilean physics, there is no difference between
> > closing speed and relative speed, because distance and time are on the
> > same scale regardless of motion between the two frames of reference.
> > Relative speed, in short, is the speed of one object with respect to a
> > frame of reference in which the other object is at rest.
>
> *relative speed* is the speed of one object relative to another; and the
> other object may be either a small object or a reference frame (even a
> virtual one).
> However, *speed* generally means the relative speed of one object wrt a
> frame of reference.
>
> > Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
> > Androcles behind, and Einstein is theorizing that distance and time
> > change their scales with motion so as to preserve the speed of light
> > between frames. This is where the difference between closing speed
> > and relative speed arises.
>
> Not quite: "closing speed" is merely Newspeak for "relative speed", and some
> good textbooks still correctly define "relative speed" without being
> confused! If you like to read more about it, I can give you a very good
> reference from the Aus.J.P.
>
> > Consider two light beams aimed at each other, each travelling at speed
> > c. The distance between their light fronts decreases at the rate 2c,
> > and this is the closing speed.
>
>
> > To compute their relative speed
>
> his 1905 paper, "velocity").
>
> > starting with a Lorentz transformation
> > with frame speed c is complicated by a singularity in the
> > transformation. But the general result for sub-luminal speeds u and
> > v
>
> > (u+v) / (1 + uv/c^2)
>
> > does not have that singularity. The resulting formula for relative
> > speed in this case is
> > (c+c)/(1 + c*c/c^2), which simplfies easily to c.
>
>
> > Androcles has recently omitted his signature complaint about
> > dropped. But don't count on it yet.
>
>
> Cheers,
> Harald
Daryl McCullough
>"Daryl McCullough" <stevend...@yahoo.com> wrote
>> If there are two cars that are both moving,
>> and I say "The speed of the first car is 100 kilometers
>> per hour"
>
>That means in standard language: wrt your coordinate system in which both
>cars are moving...
Right. It does *not* mean
>>> (2) The rate of change of the distance between A and B, as
>>> measured in a special coordinate system S in which A is at
>>> rest. (This is what Ben called "the relative speed" between
>>> A and B.)
But, you implied that this was simply "speed":
>>Indeed, and as I pointed out: Einstein, good textbooks and myself call
>>that form of relative speed simply "speed".
>> Besides "speed" (which is dependent on an implicit "lab frame"),
>> there are two other concepts: (1) The rate at which the distance
>> between the objects changes, as measured in the "lab frame", and
>> (2) the rate at which the distance between the objects changes,
>> as measured in the rest frame of one of the objects.
>
>The rest frame of one of the objects is according to both classical physics
>and SRT just another valid reference frame (if it is a sufficiently good
>approximation of a Newtonian frame); a material "lab frame" is not preferred
>for the description of physics (the PoR).
Yes, of course the frame in which one particle is at rest is
a perfectly valid frame. Of course, the lab frame isn't preferred.
You can use whatever frame you like. But the point is to
be clear which one you are using, especially if you are switching
from the description in one frame to the description in another.
>> What do you call those two quantities?
>
>Personally I call them both Doppler speeds,
Well, my point is that you have different concepts, it is confusing
to use the *same* term. And why introduce new terminology when
it doesn't resolve any ambiguities?
>and I specify the used reference frame if not already implicit
>from the description.
Well, I'm saying that's what "relative to A" or "relative to the
lab" is for. If I say the speed relative to A, I mean the speed
as measured in a frame in which A is at rest.
>I don't know if a generally accepted term for a change-of-distance
>rate exists but I think that "closing speed" would be a good term
>for such a speed.
The use of "closing speed" clarifies that you are not talking
about speed as measured in the rest frame of one of the objects.
>Anyway, in 3D, NEITHER of your cases is generally equal to the
>absolute value of the vector subtraction (c-v) which appeared
>to be the subject of this thread.
What do you mean? c-v is the closing speed between an object
traveling at speed v and a light signal traveling at speed c
in the same direction.
>> You want to call the
>> first one "relative speed", but then what do you call the
>> second quantity?
>
>I don't "want" to call anything; instead I'm happy with the standard
>textbook definitions that I learned and know how to apply.
When there is confusion (and there *is* in this case), it is
reasonable to introduce new terminology to help clarify the
confusion. That's exactly what is going on with the introduction
of the terminology "closing speed" and "relative speed".
>And as a reminder: textbooks define "relative velocity" as the vector
>subtraction of two velocities V_ba = V_b - V_a ; Einstein also correctly
>applied that definition in 1905.
Yes, some people do use that convention, but it is a bad
convention, and the use of "closing speed" or "closing velocity"
is better. Why is it better? Because the use of "relative velocity"
is *confusing*. The word "relative" is already overloaded to mean
"relative to a coordinate system". Look at the name of the theory: the theory of
*RELATIVITY*. Where does that word come from? From the word "relative".
Some quantities, such as velocity, simultaneity, the length of
objects, etc. are relative to the coordinate system, or frame,
in which they are measured.
So someone learning relativity would expect that the use of the
word "relative" means "relative to some coordinate system". But
that is *not* what the vector subtraction V_ba means. It's not
velocity relative to any coordinate system. So it is misleading
and confusing to use the word "relative" here.
You don't actually have a counter-argument as to why the word
"relative velocity" is appropriate, other than the fact that
people have used that terminology in the past. So WHAT? Who
cares? As time goes on, terminology gets adjusted to become
more regularized. Definitions get tightened up. New terminology
is introduced to make distinctions that are awkward to make
with previous terminology. There is nothing sacred about original
terminology.
Daryl McCullough
Yes. I have seen non-cranks confused about when it is appropriate
to use the relativistic "velocity addition formula", and when good
old vector addition is appropriate.
kenseto
The point is: This assertion of M is wrong. M does not see M' to have
a closing velocities of c+v and c-v wrt the light fronts from A and B.
What M sees must be based on the SR postulate that the speed of light
in the M' frame is isotropic. Also what M sees must agree with the LT
which says that the light fronts from A and B arrive simultaneously at
M' at a transit time of gamma*L/c.
Ken Seto
va...@icmf.inf.cu
> Uncle Ben wrote:
> > On Feb 13, 2009, 9:51 am (EST), "Androcles"
> > <Headmas...@Hogwarts.physics> wrote:
>
> >> Snivelling relativistic lying bastard trolls claim that c+v is not
> >> the speed of anything or is a "closing speed", accusing
> >> mathematicians
> >> of not being able to distinguish a "closing speed" from a "relative
> >> speed" (which, with all honesty, I readily own that I cannot -'
>
> > Albert Einstein, writing in the 20th, can write an equation containing
> > the factors (c+v) and (c-v) and yet claim that the speed c is a
> > universal constant.
>
> twentieth century - Einstein did NOT take participate in that. However, you
> are of course quite right that Andro got confused by the simple terms such
> as c-v, but this appears to have happened WITHOUT the introduction of such
> jargon. On the other hand, it is possible of course that he FIRST got
> confused by that jargon, and next the reading of Einstein's paper was done
> with confused eyes, and so the damage was irreversible...
>
> > Androcles suggests that Einstein violates the 2nd Postulate of SR,
> > when actually Einstein is merely calculating the time of closure
> > between a light wave with speed c and a target moving at speed v. If
> > the target is moving away from the oncoming light beam, the distance
> > betweem them decreases at the rate c-v; if it is moving towards the
>
> Me thinks you surely mean:
> betweem them decreases at the rate c-v; if it is moving towards the oncoming
>
> Moreover, if the target is moving away from a retreating lightbeam, the
> distance betweem them increases at the rate c+v; if it is following the
> retreating beam, the opening rate is c-v.
>
> > above, and this has mystified Androcles. Closing speed is the rate of
> > change of the distance between two objects as they both move. Closing
> > speed is certainly a rate of change of a distance, but in the given
> > frame of reference, there is no material object nor even a photon that
>
> > Relative speed, the speed of one object relative to another, is a
> > different matter. In Galilean physics, there is no difference between
> > closing speed and relative speed, because distance and time are on the
> > same scale regardless of motion between the two frames of reference.
> > Relative speed, in short, is the speed of one object with respect to a
> > frame of reference in which the other object is at rest.
>
> Not quite, see your own text just above; as you correctly stated initially,
> *relative speed* is the speed of one object relative to another; and the
> other object may be either a small object or a reference frame (even a
> virtual one).
> However, *speed* generally means the relative speed of one object wrt a
> frame of reference.
>
of "(inertial) reference frame" (IRF) here. You identify an IRF with a
"small object"? If that were the case, you associate a mass with an
IRF? Can you clear to me what do you mean by "virtual IRF" and "non-
virtual IRF"? At the end, in what I am really interested, is to know
about if every specific IRF (for example, the ECI one of the GPS) can
be used or not to describe the movement with respect to it of ANY
object of the whole Universe (for example, the Sun). As maybe you can
remember, since many years I am claiming here that a specific IRF can
be only the centre of mass one corresponding to some determined body
set (for the ECI of the GPS, the Earth and its operating artificial
satellites), and I am also claiming that the UNIQUE bodies whose
movement can be described using some specific IRF are the ones
belonging to its associated body set, the unique ones taken into
account when determining the centre of mass.
RVHG (Rafael Valls Hidalgo-Gato)
harry
> harry says...
>
>>"Daryl McCullough" <stevend...@yahoo.com> wrote
>>> If there are two cars that are both moving,
>>> and I say "The speed of the first car is 100 kilometers
>>> per hour"
>>
>>That means in standard language: wrt your coordinate system in which both
>>cars are moving...
>
> Right. It does *not* mean
>
>>>> (2) The rate of change of the distance between A and B, as
>>>> measured in a special coordinate system S in which A is at
>>>> rest. (This is what Ben called "the relative speed" between
>>>> A and B.)
>
> But, you implied that this was simply "speed":
>
>>>Indeed, and as I pointed out: Einstein, good textbooks and myself call
>>>that form of relative speed simply "speed".
Yes and you said:
">>> "The speed of the first car is 100 kilometers
">>> per hour"
Thus Einstein, good textbooks and both of us call that form of relative
speed simply "speed" - without the need to add "relative". Do you have a
problem with that?
>>> Besides "speed" (which is dependent on an implicit "lab frame"),
>>> there are two other concepts: (1) The rate at which the distance
>>> between the objects changes, as measured in the "lab frame", and
>>> (2) the rate at which the distance between the objects changes,
>>> as measured in the rest frame of one of the objects.
>>
>>The rest frame of one of the objects is according to both classical
>>physics
>>and SRT just another valid reference frame (if it is a sufficiently good
>>approximation of a Newtonian frame); a material "lab frame" is not
>>preferred
>>for the description of physics (the PoR).
>
> Yes, of course the frame in which one particle is at rest is
> a perfectly valid frame. Of course, the lab frame isn't preferred.
> You can use whatever frame you like. But the point is to
> be clear which one you are using, especially if you are switching
> from the description in one frame to the description in another.
The point for me is that when you are NOT switching, there is no need to
specify that you are not switching.
>>> What do you call those two quantities?
>>
>>Personally I call them both Doppler speeds,
>
> Well, my point is that you have different concepts, it is confusing
> to use the *same* term. And why introduce new terminology when
> it doesn't resolve any ambiguities?
I agree, maybe you forgot to correct your question?
>>and I specify the used reference frame if not already implicit
>>from the description.
>
> Well, I'm saying that's what "relative to A" or "relative to the
> lab" is for. If I say the speed relative to A, I mean the speed
> as measured in a frame in which A is at rest.
And I mean that when I say "as measured in frame that is co-moving with A".
As I don't have the habit to jump frames like a madman (just as I don't have
the habit to switch between cm and inches every 10 secs), that isn't a
burden.
>>I don't know if a generally accepted term for a change-of-distance
>>rate exists but I think that "closing speed" would be a good term
>>for such a speed.
>
> The use of "closing speed" clarifies that you are not talking
> about speed as measured in the rest frame of one of the objects.
Please specify if you think that "closing speed" means:
A. The rate at which the distance between two objects closes
or
B. The absolute value of the vectorial difference of the velocities of two
objects
or
C. (?)
>>Anyway, in 3D, NEITHER of your cases is generally equal to the
>>absolute value of the vector subtraction (c-v) which appeared
>>to be the subject of this thread.
>
> What do you mean? c-v is the closing speed between an object
> traveling at speed v and a light signal traveling at speed c
> in the same direction.
I could not find a definition of "closing speed" in my textbooks. However,
it would be a great coincidence if objects travel exactly in the same
direction as a light signal - a physics term that is only applicable in 1D
would be of extremely limited use. Please specify above.
>>> You want to call the
>>> first one "relative speed", but then what do you call the
>>> second quantity?
>>
>>I don't "want" to call anything; instead I'm happy with the standard
>>textbook definitions that I learned and know how to apply.
>
> When there is confusion (and there *is* in this case), it is
> reasonable to introduce new terminology to help clarify the
> confusion. That's exactly what is going on with the introduction
> of the terminology "closing speed" and "relative speed".
"Relative speed" and "speed" already existed and were perfectly well
defined. I now concede that "closing speed" would be useful - as you suggest
above - to specify the rate of change of distance between two objects, in
particular for Doppler topics. Such a rate of distance change is however in
general (3D) NOT the same as the difference in velocities c-v.
>>And as a reminder: textbooks define "relative velocity" as the vector
>>subtraction of two velocities V_ba = V_b - V_a ; Einstein also correctly
>>applied that definition in 1905.
>
> Yes, some people do use that convention, but it is a bad
> convention, and the use of "closing speed" or "closing velocity"
> is better. Why is it better? Because the use of "relative velocity"
> is *confusing*. The word "relative" is already overloaded to mean
> "relative to a coordinate system".
We must be precise especially about the choice of reference, but that is in
SRT a common problem - the introduction of new jargon can be
counterproductive, as in this case it evidently is:
- Already, and as you show yourself here above, "speed" was and still is
*defined* as implying "relative to a coordinate system". To alter the
meaning of one term in order to make it mean the same as an already existing
term is either madness or Newspeak.
- See Ben's postings in this thread, while promoting "closing speed" he
explains "Relative speed, the speed of one object relative to another" AND
"Relative speed, in short, is the speed of one object with respect to a
frame of reference in which the other object is at rest."
- See your postings here, you seem to think that a term that stands for "a
rate of change of distance" correctly conveys the general meaning of a
difference of two velocities - which is plainly ERRONEOUS...
> Look at the name of the theory: the theory of
> *RELATIVITY*. Where does that word come from? From the word "relative".
> Some quantities, such as velocity, simultaneity, the length of
> objects, etc. are relative to the coordinate system, or frame,
> in which they are measured.
Sure. Many of them already were relative since Newton, and the physics terms
have been well defined, as explained.
> So someone learning relativity would expect that the use of the
> word "relative" means "relative to some coordinate system".
Not if that person had received basic physics at secondary school...
> But
> that is *not* what the vector subtraction V_ba means. It's not
> velocity relative to any coordinate system. So it is misleading
> and confusing to use the word "relative" here.
A DIFFERENCE between velocities is commonly called RELATIVE velocities,
while a common velocity in physics is ALWAYS relative to a coordinate
system. Thus there is nothing "confusing" or "misleading" about it.
Anyway, I feel no need to defend common standards, I'm happy with them. What
do you think of Seto's wish to introduce a certain "ratio" instead of a
speed, because he finds "lightspeed" misleading?
> You don't actually have a counter-argument as to why the word
> "relative velocity" is appropriate, other than the fact that
> people have used that terminology in the past.
Nonsense and you just gave me one additional argument: if as you think, (and
something else would be misleading), "closing speed" means the rate at which
a distance between two objects closes, than that term can NOT be used to
replace "relative velocity" - the velocity of one object relative to another
as measured in a reference frame of choice.
> So WHAT? Who
> cares? As time goes on, terminology gets adjusted to become
> more regularized. Definitions get tightened up. New terminology
> is introduced to make distinctions that are awkward to make
> with previous terminology. There is nothing sacred about original
> terminology.
True I don't care much - only I feel sorry for those who got confused.
As I don't really care, and you certainly have access to good textbooks -
over and out! :-)
Harald
PD
Why yes, yes he does. Closing velocity is not the speed of light
measured in M.
It would help if you knew what the term "closing speed" means, BEFORE
you decide whether a sentence involving "closing speed" is wrong.
Don't you think so? Or is that being unfair?
> What M sees must be based on the SR postulate that the speed of light
> in the M' frame is isotropic.
Yes, indeed, and it is perfectly consistent with that. It would help
if you knew what "closing speed" means, don't you think so?
> Also what M sees must agree with the LT
> which says that the light fronts from A and B arrive simultaneously at
> M' at a transit time of gamma*L/c.
Actually, no, the Lorentz transform does NOT say that. You've done the
calculation incorrectly. Now, if you have a *different* transform that
yields that result, then please do not call it the Lorentz transform.
harry
> YBM says...
>>
>>Daryl McCullough a écrit :
>>> harry says...
>>>
>>>> I overlooked that: note that Einstein did not use the term "closing
>>>> speed"
>>>> with his calculations, that term is just an additional distraction
>>>> provided
>>>> by newcomers in the field. :-)
>>>
>>> You are completely wrong about that. It isn't a distraction.
>>> It's an important distinction. Einstein did not make that distinction,
>>> and you can see the consequence: poor Androcles has been confused
>>> for decades.
I suspect just the inverse: without that new term he would have been less
confused... but likely it wouldn't have made much difference anyway!
>>That's true. But have you ever seen anyone being confused by this but
>>Androcles? Even other first class cranks here haven't, as far as I can
>>say.
>
> Yes. I have seen non-cranks confused about when it is appropriate
> to use the relativistic "velocity addition formula", and when good
> old vector addition is appropriate.
Such people don't understand that the "velocity addition formula" concerns a
coordinate system transformation... thus they think that mathemagically for
some kinds of speeds one has to use the one formula, and for other kinds of
speeds one has to use the other formula...
Harald
jonas.t...@hotmail.com
> "Daryl McCullough" <stevendaryl3...@yahoo.com> wrote in message
>
> news:gnidk...@drn.newsguy.com...
>
>
>
>
>
> > harry says...
>
> >>"Daryl McCullough" <stevendaryl3...@yahoo.com> wrote
Hello Harry nice to see you still vigorus trying to find solutions to
a SR problem, i am not sure you tackle them the right way though.
In Sweden we have the expression painting oneself into a corner and i
have the feeling that is what you are doing, in your attempt knoting
bananas together.
For us who are reasonably intelligent and logically inclined, we know
that your concept of doppler speed is simply good ol Newtonian c-v and
c+v, but you are a relativist and can not use those terms, because of
your beleif system based on measure theology.
Do you know how stupid doppler speed really sound, the term is
relative speed in the Newtonian vocabulary and it is c+v and c-v.
The way i see it *NOW* SRian slowly turn to accept the Newton laws of
motion. The problem is on they way they have to invent a terminology
that do not resemble of relative speed, so they will invent things
like doppler speed and start to try knot bananas together unfortunatly
it will not work that good.
Because as anyone knows a spatial magnitude is the same in both
direction, A->B = B->A. And their theory says it is not, so now they
will try to find away to climb that hinder.
>I don't know if a
> generally accepted term for a change-of-distance rate exists but I think
> that "closing speed" would be a good term for such a speed.
Here you can see Harry trying real hard to think up new terminology,
like change of distance rate, a reasonably intelligent person can now
see Harry's next move.
He will introduce the term doppler distorted spatial magnitudes within
his theory, this is all to confuse for the reader from the fact that
he have Newton's background space, but still want to play the SR game,
using doppler speed, doppler magnitudes instead of good ol c+v and c-v
because as everyone knows there is no such thing as a doppler
distorted length in Newtons theory, only plain doppler effect things
remain what they are regardless *APPEARANCE*.
So now we most conclude how Harry wont to go on keep playing his game
first he must somehow get rid of length contraction *OUCH* that one
really did hurt. What about the time dilation looks like he can keep
playing the bubbleboy game there i think.
But now to the critical issue that relativity totally is dependent on.
It seem *OH MY GOSH* that Harry have abandoned the invariance of light
travel thru space, *GEESH THAT ONE REALLY HURT*.
Androcles is it really so that they finally accepted there is more
lightpulses in one direction than the other?
Did they really accept c+v and c-v but trying to come up with new
terminology to escape the shame and their embarresment, we should
really cork up a bottle and celebrate those bold relativists who
travelled so far noone travelled before.
To boldly go where someone gone before, cheers Newton cheers
Androcles.
JT
But as anyone read anyone of my thread
Anyway, in 3D,
> NEITHER of your cases is generally equal to the absolute value of the vector
> subtraction (c-v) which appeared to be the subject of this thread.
>
> > You want to call the
> > first one "relative speed", but then what do you call the
> > second quantity?
>
> I don't "want" to call anything; instead I'm happy with the standard
> textbook definitions that I learned and know how to apply.
>
> > It *ISN'T* "speed". Speed means "the rate
> > at which the distance of the car from the origin of the
> > lab coordinate system changes".
>
> No, that is erroneous: textbooks define speed as ds/dt, as measured in a
> coordinate system of choice. As speed is the derivative of the object's
> position over time, the position of the origin is irrelevant for the
> determination of speed.
>
> Moreover, in 3D problems there is a big difference between the definition
> you use and the one of textbooks: when an object passes at a distance by a
> point such as the origin in your reference system, at the instant that the
> velocity is perpendicular to the origin the distance doesn't change (thus
> you would say that its speed is zero!) even if its speed ds/dt is constant.
>
> And as a reminder: textbooks define "relative velocity" as the vector
> subtraction of two velocities V_ba = V_b - V_a ; Einstein also correctly
> applied that definition in 1905.
>
> Best regards,
harry
> On 16 feb, 10:11, "harry" <harald.NOTTHISvanlin...@epfl.ch> wrote:
>> Uncle Ben wrote:
>>> Relative speed, the speed of one object relative to another, is a
>>> different matter. In Galilean physics, there is no difference
>>> between closing speed and relative speed, because distance and time
>>> are on the same scale regardless of motion between the two frames
>>> of reference. Relative speed, in short, is the speed of one object
>>> with respect to a frame of reference in which the other object is
>>> at rest.
>>
>> Not quite, see your own text just above; as you correctly stated
>> initially, *relative speed* is the speed of one object relative to
>> another; and the other object may be either a small object or a
>> reference frame (even a virtual one).
>> However, *speed* generally means the relative speed of one object
>> wrt a frame of reference.
> Hello Harald. I am very interested in the way you handle the concept
> of "(inertial) reference frame" (IRF) here.
Hi Rafael,
In fact I did not define "inertial" here; tha should be specified or clear
from the context.
For example, a geostationary satellite is moving in a standard reference
frame such as the ECI frame (which is only truly "inertial" in GRT language)
but stationary in a co-rotating frame.
> You identify an IRF with a
> "small object"?
No, for example the ECI is identified with a big object (the Earth), but
nothing on the Earth is at rest in it. In the context of SRT, an "inertial
reference frame" is in reality a Newtonian frame, which is operationally
defined as non-rotating relative to the distant stars.
> If that were the case, you associate a mass with an
> IRF?
No, certainly not!
> Can you clear to me what do you mean by "virtual IRF" and "non-
> virtual IRF"?
A piece of matter that does not rotate relative to the stars is a real
frame.
> At the end, in what I am really interested, is to know
> about if every specific IRF (for example, the ECI one of the GPS) can
> be used or not to describe the movement with respect to it of ANY
> object of the whole Universe (for example, the Sun).
As hinted at above, for SRT the ECI frame is not an accurate reference
frame, certainyl not for long-term and long-distance measurements. Note that
all this is entirely besides the topic and I think we have discussed this in
the past.
> As maybe you can
> remember, since many years I am claiming here that a specific IRF can
> be only the centre of mass one corresponding to some determined body
> set (for the ECI of the GPS, the Earth and its operating artificial
> satellites), and I am also claiming that the UNIQUE bodies whose
> movement can be described using some specific IRF are the ones
> belonging to its associated body set, the unique ones taken into
> account when determining the centre of mass.
I know, and you surely remember that I don't think so. :-)
Thus I'm sorry but I won't discuss this again.
Best refgards,
Harlad
Daryl McCullough
>
>
>"Daryl McCullough" <stevend...@yahoo.com> wrote in message
>news:gnjla...@drn.newsguy.com...
>> harry says...
>>
>>>"Daryl McCullough" <stevend...@yahoo.com> wrote
>>>> If there are two cars that are both moving,
>>>> and I say "The speed of the first car is 100 kilometers
>>>> per hour"
>>>
>>>That means in standard language: wrt your coordinate system in which both
>>>cars are moving...
>>
>> Right. It does *not* mean
>>
>>>>> (2) The rate of change of the distance between A and B, as
>>>>> measured in a special coordinate system S in which A is at
>>>>> rest. (This is what Ben called "the relative speed" between
>>>>> A and B.)
>>
>> But, you implied that this was simply "speed":
>>
>>>>Indeed, and as I pointed out: Einstein, good textbooks and myself call
>>>>that form of relative speed simply "speed".
>
>Yes and you said:
>">>> "The speed of the first car is 100 kilometers
>">>> per hour"
>
>Thus Einstein, good textbooks and both of us call that form of relative
>speed simply "speed" - without the need to add "relative". Do you have a
>problem with that?
Just the fact that it contradicts your use of the word "speed"
to mean "The rate of change of the distance between A and B,
as measured in a special coordinate system S in which A is at
rest".
>> Yes, of course the frame in which one particle is at rest is
>> a perfectly valid frame. Of course, the lab frame isn't preferred.
>> You can use whatever frame you like. But the point is to
>> be clear which one you are using, especially if you are switching
>> from the description in one frame to the description in another.
>
>The point for me is that when you are NOT switching, there is no need to
>specify that you are not switching.
Right. If you are keeping to one frame, then you don't need to
use the phrase "relative to", because everything is implicitly
relative to the "lab frame". On the other hand, if you mean
relative to a *different* frame, *then* you use the phrase
"relative to".
The convention of calling the vector difference of two
velocities "relative velocity" is confusing because you
*aren't* switching a new frame, as the word "relative"
would imply.
"Velocity of B relative to a frame in which A is at rest"
is perfectly well-defined and unambiguous. "Velocity of B
relative to A" is a completely natural shortening of that
phrase. It's very bizarre for "Velocity of B relative to
A" *not* to mean "Velocity of B relative to the rest frame
of A".
>> Well, I'm saying that's what "relative to A" or "relative to the
>> lab" is for. If I say the speed relative to A, I mean the speed
>> as measured in a frame in which A is at rest.
>
>And I mean that when I say "as measured in frame that is co-moving with A".
But if you say "velocity of B relative to A", it *sounds* like that's
what you mean.
>As I don't have the habit to jump frames like a madman
You're being silly. You pick whatever frame is easiest
to analyze whatever it is that you want to analyze. A
complex problem may very involve more than one frame.
Your point about the ambiguity of "closing speed" is perfectly
correct. I was indeed making a stupid mistake. The time derivative
of the distance between objects is not the same thing as the
absolute value of the vectorial difference of the velocities.
Calling the latter "closing velocity" only makes sense for problems
along a straight line.
So I do have to thank you for pointing that out. However, I
think that it still makes sense to use "relative velocity"
to mean "velocity of one object relative to the frame in which
the other object is at rest". That leaves no good term for
"the vectorial difference between two velocities". You have
convinced me that "closing velocity" is not an appropriate
term.
>> But
>> that is *not* what the vector subtraction V_ba means. It's not
>> velocity relative to any coordinate system. So it is misleading
>> and confusing to use the word "relative" here.
>A DIFFERENCE between velocities is commonly called RELATIVE velocities
But I'm saying that in the context of Special Relativity, that
terminology is misleading and confusing. In the context of
Galilean Relativity, there is no difference between "The
vectorial difference between two velocities" and "The
velocity of one object as measured in a coordinate system
in which the other object is at rest". So the one term,
"relative velocity" is perfectly fine. In special relativity,
the two concepts diverge, so you must choose which one to call
"relative velocity".
>Thus there is nothing "confusing" or "misleading" about it.
I explained why it is confusing. In Special Relativity, the
word "relative" means, in all other contexts, relative to a
*coordinate system*. For "relative velocity" *not* to mean that
is confusing.
Edward Green
wrote:
...
> Yes, some people do use that convention, but it is a bad
> convention, and the use of "closing speed" or "closing velocity"
> is better. Why is it better? Because the use of "relative velocity"
> is *confusing*. The word "relative" is already overloaded to mean
> "relative to a coordinate system". Look at the name of the theory: the theory of
> *RELATIVITY*. Where does that word come from? From the word "relative".
> Some quantities, such as velocity, simultaneity, the length of
> objects, etc. are relative to the coordinate system, or frame,
> in which they are measured.
>
> So someone learning relativity would expect that the use of the
> word "relative" means "relative to some coordinate system". But
> that is *not* what the vector subtraction V_ba means. It's not
> velocity relative to any coordinate system. So it is misleading
> and confusing to use the word "relative" here.
>
> You don't actually have a counter-argument as to why the word
> "relative velocity" is appropriate, other than the fact that
> people have used that terminology in the past. So WHAT? Who
> cares? As time goes on, terminology gets adjusted to become
> more regularized. Definitions get tightened up. New terminology
> is introduced to make distinctions that are awkward to make
> with previous terminology. There is nothing sacred about original
> terminology.
I claim I understand this issue perfectly well, but I kind of like
"relative velocity" for the simple vector subtraction nonetheless.
It's simply a frame dependent concept. "Velocity" itself is frame
dependent. So what?
The problem seems to be in conventional SR pedagogy the utility of
this concept is underplayed, and indeed many people reject it outright
(in my experience). But there is no need: vector velocity difference
is what you use to calculate a number of kinematic things in a given
frame.
Daryl McCullough
>I claim I understand this issue perfectly well, but I kind of like
>"relative velocity" for the simple vector subtraction nonetheless.
>It's simply a frame dependent concept. "Velocity" itself is frame
>dependent. So what?
My point is not that it is frame dependent, but that "relative to A"
usually means, in relativity theory, "as measured in A's rest frame".
So keeping with that convention, "velocity of B relative to A" would
mean "the velocity of B, as measured in A's frame".
harry
Wind back time, I wrote:
> However, speed generally means the relative speed of one object wrt a
> frame of reference.
However - and as I already acknowledged - I erroneously copied your and
Ben's description of closing speed to mean the same as "relative speed"
while that is erroneous, and I even elaborated quite a lot on that topic. I
hope that important point to be useful for many others.
>>> Yes, of course the frame in which one particle is at rest is
>>> a perfectly valid frame. Of course, the lab frame isn't preferred.
>>> You can use whatever frame you like. But the point is to
>>> be clear which one you are using, especially if you are switching
>>> from the description in one frame to the description in another.
>>
>> The point for me is that when you are NOT switching, there is no
>> need to specify that you are not switching.
>
> Right. If you are keeping to one frame, then you don't need to
> use the phrase "relative to", because everything is implicitly
> relative to the "lab frame". On the other hand, if you mean
> relative to a *different* frame, *then* you use the phrase
> "relative to".
More generally: relative to another object.
But as I don't want to waste more time on such fruitless discussions about
personal preference of which convention to follow and in which you even
started name calling, I will not comment further on that aspect. Note that I
generally reward name calling tactics with No Reply.
[...]
> Your point about the ambiguity of "closing speed" is perfectly
> correct. I was indeed making a stupid mistake. The time derivative
> of the distance between objects is not the same thing as the
> absolute value of the vectorial difference of the velocities.
Good that we clarified that!
> Calling the latter "closing velocity" only makes sense for problems
> along a straight line.
> So I do have to thank you for pointing that out. However, I
> think that it still makes sense to use "relative velocity"
> to mean "velocity of one object relative to the frame in which
> the other object is at rest". That leaves no good term for
> "the vectorial difference between two velocities".
You finally discovered why I call it Newspeak: it suppresses a very useful
concept (although in a more subtle way than Orwell's Newspeak). However I
had misidentified "closing speed" as the cause - a special term for "rate of
change of distance" is certainly useful.
[...]
For you it is confusing and misleading while for me it is clarifying and
even enlightening.
Well, different brains are wired differently. :-)
Regards,
Harald
harry
Maybe in your book, but not in mine...
As Edward already wrote:
"The problem seems to be [that] in conventional SR pedagogy the utility of
this concept is underplayed".
But in fact it's worse: it's not just underplayed but - like in Orwell's
theme - one attempts to *suppress* a useful concept by an unnecessary change
of language (it's misleading to call that "keeping").
That's all.
Harald
Daryl McCullough
>As Edward already wrote:
>"The problem seems to be [that] in conventional SR pedagogy the utility of
>this concept is underplayed".
>But in fact it's worse: it's not just underplayed but - like in Orwell's
>theme - one attempts to *suppress* a useful concept by an unnecessary change
>of language (it's misleading to call that "keeping").
You are being ridiculous. There are two concepts, (1) the vector
difference of two velocities, as measured in the same frame, and (2)
the velocity of one object, as measured in the frame of the other
object. If it is "Orwellian" to have only a phrase meaning (2),
and no convenient phrase meaning (1), then why isn't the other way
around "Orwellian", as well?
To say that "relative velocity" always meant (1) is not very
persuasive, since (1) and (2) mean the same thing in Galilean
physics.
harry
> harry says...
>
>> As Edward already wrote:
>> "The problem seems to be [that] in conventional SR pedagogy the
>> utility of this concept is underplayed".
>
>> But in fact it's worse: it's not just underplayed but - like in
>> Orwell's theme - one attempts to *suppress* a useful concept by an
>> unnecessary change of language (it's misleading to call that
>> "keeping").
>
[snip namecalling]
Harald
ken...@erinet.com
It is a huge waste of time talking to a SR religion fanatic like you.
It is you who don't know what closing speed means. Closing speeds of c
+v and c-v by M' wrt the light fronts from A and B is contradictory
with the isotropy of the speed of light in the M' frame.
Ken Seto
> > > > > > > > > > > > > > > - Show quoted text -- Hide quoted text -- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -...
>
> read more »
Sue...
[...]
>
> It is a huge waste of time talking to a SR religion fanatic like you.
> It is you who don't know what closing speed means. Closing speeds of c
> +v and c-v by M' wrt the light fronts from A and B is contradictory
> with the isotropy of the speed of light in the M' frame.
< where epsilon_0 and mu_0 are physical
constants which can be evaluated by performing two
simple experiments which involve measuring the force
of attraction between two fixed charges and two fixed
parallel current carrying wires. According to the
relativity principle, these experiments must yield
the same values for epsilon_0 and mu_0 in all inertial
frames. Thus, the speed of light must be the same
in all inertial frames. >>
http://farside.ph.utexas.edu/teaching/em/lectures/node108.html
See also:
http://nobelprize.org/nobel_prizes/physics/articles/ekspong/
http://espg.sr.unh.edu/ism/what1.html
http://en.wikipedia.org/wiki/Free_space
Sue...
>
> Ken Seto
PD
It's a waste of time talking with someone who bothers to point out
that you don't even know the meaning of the terms you are using?
Yes, I know, you only want to spend time with people who will support
you and endorse what you are doing.
I can imagine how lonely that existence is.
> ...
>
> read more »
Dr. Henri Wilson
>On Feb 13, 2009, 9:51 am (EST), "Androcles"
><Headmas...@Hogwarts.physics> wrote:
>
>Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
>Androcles behind, and Einstein is theorizing that distance and time
>change their scales with motion so as to preserve the speed of light
>between frames. This is where the difference between closing speed
>and relative speed arises.
>
>Consider two light beams aimed at each other, each travelling at speed
>c. The distance between their light fronts decreases at the rate 2c,
>and this is the closing speed.
Consider a light beam that is 'closing' on a moving observer at c+v.
Consider a second light beam from another source that is closing on the same
observer at c+u.
Does this mean that one beam is 'closing' on the other at v-u?
Harry Wilson. ASTC,BSc,DSc(T)
www.users.bigpond.com/hewn/index.htm.
.....
YBM
> On Mon, 16 Feb 2009 06:32:43 -0800 (PST), Uncle Ben <b...@greenba.com> wrote:
>
>> On Feb 13, 2009, 9:51 am (EST), "Androcles"
>> <Headmas...@Hogwarts.physics> wrote:
>>
>
>> Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
>> Androcles behind, and Einstein is theorizing that distance and time
>> change their scales with motion so as to preserve the speed of light
>> between frames. This is where the difference between closing speed
>> and relative speed arises.
>>
>> Consider two light beams aimed at each other, each travelling at speed
>> c. The distance between their light fronts decreases at the rate 2c,
>> and this is the closing speed.
>
> Consider a light beam that is 'closing' on a moving observer at c+v.
> Consider a second light beam from another source that is closing on the same
> observer at c+u.
ahem.
You talk about closing velocity of c+whatever for a moving observer wrt
to light so you're considering the closing speed as observed by *you* of
these observer wrt the light fronts, aren't you? (if you aren't you just
understand nothing about what closing velocities).
> Consider a light beam that is 'closing' on a moving observer at c+v
-> so observer is moving at speed v wrt you
> Consider a second light beam from another source that is closing on
> the same observer at c+u.
-> so observer is moving at speed u wrt you
u=v
Dr. Henri Wilson
>Dr. Henri Wilson a écrit :
>> On Mon, 16 Feb 2009 06:32:43 -0800 (PST), Uncle Ben <b...@greenba.com> wrote:
>>
>>> On Feb 13, 2009, 9:51 am (EST), "Androcles"
>>> <Headmas...@Hogwarts.physics> wrote:
>>>
>>
>>> Gaileo's big year was 1605. Jump forward 300 years to 1905, leaving
>>> Androcles behind, and Einstein is theorizing that distance and time
>>> change their scales with motion so as to preserve the speed of light
>>> between frames. This is where the difference between closing speed
>>> and relative speed arises.
>>>
>>> Consider two light beams aimed at each other, each travelling at speed
>>> c. The distance between their light fronts decreases at the rate 2c,
>>> and this is the closing speed.
>>
>> Consider a light beam that is 'closing' on a moving observer at c+v.
>> Consider a second light beam from another source that is closing on the same
>> observer at c+u.
>
>ahem.
>
>You talk about closing velocity of c+whatever for a moving observer wrt
>to light so you're considering the closing speed as observed by *you* of
>these observer wrt the light fronts, aren't you? (if you aren't you just
>understand nothing about what closing velocities).
Well let's do it another way.
Let there be TWO light sources and two observers. O1 moves inertially at v
towards S1 and O2 moves at v wrt S2.
We have:
...............(S1-------------------------------v<-O1)
(S2-------------------------------v<-O2)
Irrespective of how each system moves wrt a third observer, the 'closing speed'
of S1's light on O1 is c+v, as is that of S2's light on O2.
Now let the S2 system be moving inertially at v wrt S1.
...............(S1-------------------------------v<-O1)
...............(S2-------------------------------v<-O2)->v
When O1 and O2 are adjacent, we have a situation where S2's light is closing on
O2 at c+v but S1's light is closing on O2 at c...because O2 is now at rest wrt
S1.
How would a typical moron explain how light from different sources can be
simultaneously 'closing' at different speeds?
> > Consider a light beam that is 'closing' on a moving observer at c+v
>-> so observer is moving at speed v wrt you
>
> > Consider a second light beam from another source that is closing on
> > the same observer at c+u.
>-> so observer is moving at speed u wrt you
>
>u=v
You know, I had a feeling some idiot would say that.
YBM
>
> Let there be TWO light sources and two observers. O1 moves inertially at v
> towards S1 and O2 moves at v wrt S2.
>
> We have:
> ...............(S1-------------------------------v<-O1)
> (S2-------------------------------v<-O2)
>
> Irrespective of how each system moves wrt a third observer, the 'closing speed'
> of S1's light on O1 is c+v, as is that of S2's light on O2.
Ralph, Ralph... Closing velocity of two objects is always defined by a
given observer who simply add the velocities of both objects with
respect to him.
Dr. Henri Wilson
wrong.
0/10
YBM
> On Mon, 23 Feb 2009 01:48:05 +0100, YBM <ybm...@nooos.fr> wrote:
>
>> Dr. Henri Wilson a écrit :
>>> Well let's do it another way.
>>>
>>> Let there be TWO light sources and two observers. O1 moves inertially at v
>>> towards S1 and O2 moves at v wrt S2.
>>>
>>> We have:
>>> ...............(S1-------------------------------v<-O1)
>>> (S2-------------------------------v<-O2)
>>>
>>> Irrespective of how each system moves wrt a third observer, the 'closing speed'
>>> of S1's light on O1 is c+v, as is that of S2's light on O2.
>> Ralph, Ralph... Closing velocity of two objects is always defined by a
>> given observer who simply add the velocities of both objects with
>> respect to him.
> wrong.
You do exactly the same error you've been doing with all your stupid
Visual Basic programs for years: you assume a absolute space
background...
PD
I'm sorry, but that's not wrong, Hank. It's in fact the *definition*
of closing speed. You might have found that out if you'd looked it up
before opening your yap.
Dr. Henri Wilson
What a moron. All the speeds in the above experiment are specified as relative.
Dr. Henri Wilson
Why don't YOU tell me all about it.
YBM
> On Mon, 23 Feb 2009 12:45:18 +0100, YBM <ybm...@nooos.fr> wrote:
>
>> Dr. Henri Wilson a écrit :
>>> On Mon, 23 Feb 2009 01:48:05 +0100, YBM <ybm...@nooos.fr> wrote:
>>>
>>>> Dr. Henri Wilson a écrit :
>>>>> Well let's do it another way.
>>>>>
>>>>> Let there be TWO light sources and two observers. O1 moves inertially at v
>>>>> towards S1 and O2 moves at v wrt S2.
>>>>>
>>>>> We have:
>>>>> ...............(S1-------------------------------v<-O1)
>>>>> (S2-------------------------------v<-O2)
>>>>>
>>>>> Irrespective of how each system moves wrt a third observer, the 'closing speed'
>>>>> of S1's light on O1 is c+v, as is that of S2's light on O2.
>>>> Ralph, Ralph... Closing velocity of two objects is always defined by a
>>>> given observer who simply add the velocities of both objects with
>>>> respect to him.
>>> wrong.
>> You do exactly the same error you've been doing with all your stupid
>> Visual Basic programs for years: you assume a absolute space
>> background...
>
> What a moron. All the speeds in the above experiment are specified as relative.
Really?
" *Irrespective of how each system moves wrt a third observer*, the
'closing speed' of S1's light on O1 is c+v "
What would be the closing speed between S1's light and O1 for:
- an observer comoving with O1
- an observer comoving with S1
Are they the same?
PD
> On Mon, 23 Feb 2009 05:38:32 -0800 (PST), PD <TheDraperFam...@gmail.com> wrote:
> >On Feb 23, 4:57 am, hw@..(Dr. Henri Wilson) wrote:
> >> On Mon, 23 Feb 2009 01:48:05 +0100, YBM <ybm...@nooos.fr> wrote:
> >> >Dr. Henri Wilson a écrit :
> >> >> Well let's do it another way.
>
> >> >> Let there be TWO light sources and two observers. O1 moves inertially at v
> >> >> towards S1 and O2 moves at v wrt S2.
>
> >> >> We have:
> >> >> ...............(S1-------------------------------v<-O1)
> >> >> (S2-------------------------------v<-O2)
>
> >> >> Irrespective of how each system moves wrt a third observer, the 'closing speed'
> >> >> of S1's light on O1 is c+v, as is that of S2's light on O2.
>
> >> >Ralph, Ralph... Closing velocity of two objects is always defined by a
> >> >given observer who simply add the velocities of both objects with
> >> >respect to him.
>
> >> wrong.
> >> 0/10
>
> >I'm sorry, but that's not wrong, Hank. It's in fact the *definition*
> >of closing speed. You might have found that out if you'd looked it up
> >before opening your yap.
>
> Why don't YOU tell me all about it.
>
I just did, to the extent that is warranted, short of you taking the
LEAST bit of trouble to look it up.
PD
Dr. Henri Wilson
That's what my question is all about.
YBM
Funny. You're question assume, absurdly, that "Irrespective of how each
system moves wrt a third observer, the 'closing speed' of S1's light on
O1 is c+v, as is that of S2's light on O2.".
So your question is about how a quantity it assume invariant could be
variant. It's not very sane from you, no surprise.
Hint: they are not the same.
Dr. Henri Wilson
How could a relatively moving observer affect the time taken by light to travel
the length of a rod attached to its source?
Uncle Ben
>
> - Show quoted text -
Henri, Henry, or Ralph, closing speed is a simple concept. How fast
are two things approaching each other? Thing 1 is going West at 10 m/
sec, and thing 2 is going East on the same line at 12 m/sec? A bright
high school sudent will get the right answer. The separation between
them is decreasing at 22 m/sec. It is simply u+v w.r.t. the FoR in
which the problem is stated. It is simply the Galileian relative
speed.
The relative speed is the same per Galileio but different per
Einstein. Since you don't accept Einstein, I'll stop right there.
Hint: If it is two light fronts approaching each other, the closing
speed is 2c, but the relative speed is c. But that is SR.
Fuggedaboudit!
Uncle Ben
Androcles
"Uncle Ben" <b...@greenba.com> wrote in message
news:b59a2f6f-00bc-4b59...@n30g2000vba.googlegroups.com...
=============================================
Yep, Wilson v Green travelling in opposite directions on the
same track. How hard can it be to understand a train wreck?
And shit-for-brains Green is actually going to explain it to sheep-shagger
Wilson.
I can't watch...
Dr. Henri Wilson
wrote:
One wonders if they actually believe the crap they write......
YBM
Waouh! After ten years Ralph Rabbidge aka Henri Wilson is about to
discover that light speed invariance implies that relative motion
affects lenght and time.