Re: Imagine



*** rD wrote:
> "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> news:1117996316.266782.194800@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> |
> |
> | *** rD wrote:
> | > "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> | > news:1117925965.059533.257450@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> | > |
> | > |
> | > | destiny wrote:
> | > | > i waste my time with you
> | > | >
> | > | > its sad for a guy having a phd trying to
> | > | > play smart avoiding to answer simple questions
> | > | >
> | > | > good bye
> | > |
> | > | I thought you'd say something like that...
> | > |
> | > | PD
> | > |
> | >
> | > Well it is to some extent true as you don't seem to have addressed
> except
> | > perhaps by mantra the fact that SS3 is in fact perhaps breaking the
> rules of
> | > SR by going at 1.5 c as far as the information passed back to SS1 is
> | > concerned.
> |
> | I said no such thing. If you'll look again, I said the following:
>
> I did not say that *you* did

That's right. That's what I just said: *I* said the following...

> I was just stating the physical facts that the
> statement that c is constant in frame implies that, if you cascade up you
> arrive at a point were the frame itself exceeds c

No, it does NOT! That's the whole point.

> never mind what's
> happening in it unless you introduce contraction and inversely proportional
> dilation as limiting factors
>
> Some statements\suggestions from Albert's 1905 paper (abbreviated)
> i) no properties corresponding to the idea of absolute rest.
> ii) valid for all frames of reference
> iii) light is always propagated in empty space at c which is independent of
> the motion of the body.
> iv) The introduction of a "luminiferous ether" will prove to be superfluous
> inasmuch as the view here to be developed will not require an "absolute
> stationary space" provided with special properties, nor assign a
> velocity-vector to a point of empty space in which electromagnetic processes
> take place.
>
> This appears to be the words that have somehow been bent by those who
> perhaps should know better.
>
> iii) Implies if not explicitly states that empty space has a velocity of
> zero with respect to c and the motion of bodies can have a velocity in
> relation to the zero of empty space unless you resort to the balistic red
> herring..

No, it does NOT say that. (iii) says "light is always propagated *IN*
empty space at c...". It does NOT say "light is always propagated *WITH
RESPECT TO* empty space at c..." There is no implication whatsoever
about what the speed of empty space is, nor for that matter whether
empty space can even have a speed. What (iii) is implying is that the
speed of light *WITH RESPECT TO ANY MATERIAL OBSERVER* will be c, as
long as that light is traveling in empty space. Note what the reference
for c is -- it is a material observer, not empty space.

> iv) States "L. ether" is not required and the zero of empty space is not
> "absolute stationary space" and the last which imposes a sever limitation on
> the use of the frames he is developing in that they can only be referenced
> to an object. I have no idea what he or the translator would have meant by
> "luminiferous ether" a 100 years ago and it seems academic as its something
> that we don't have and most probably don't want {:-) So he makes a start at
> defining the properties of empty space in relation to his system of
> reference. It appears that some people with the conceptual and imaginative
> breadth of a stone have perverted an interesting idea into a piece of mental
> idiocy to beat others with.

It means there is no need to reference light speed with respect to a
dielectric of empty space. Luminiferous ether would be an example of
something that exhibits a dielectric quality of empty space. When you
are positing that c is with respect to a local dielectric, you are in
fact positing the very same luminiferous ether that Einstein says is
not necessary at all!

>
> |
> | >> Note that relative velocity is not a quantity that is frame-independent
> | >> in the "usual" way. That is, you can't sit in frame A, see S2 and S3
> | >> both go whizzing by and deduce that their relative velocity is
> | >>(0.93-0.8)c = 0.13 c. Relative velocity between a pair of objects is
> | >> customarily defined in a frame of reference where one of the objects is
> | >> at rest.
>
> Yes SR frames have to be referenced to objects and if the origin is not at
> an object then it must be defined as an offset from an object as per SR
> definition. ? You seem a bit muddled here, I have a frame and in it is the
> earth and the origin of the frame is your house for example, a spaceship
> shoots off and gets to 0.5 c relative to your house then another spaceship
> shoots off from the first and gets to 0.5 c relative to the first ship

Stop right there. When you say the second spaceship shoots off from the
first with a relative velocity of 0.5c, that is a statement that can
ONLY be made from a reference frame in which one of those objects,
either the first spaceship or the second spaceship is at rest. You can
NOT make the same statement viewing it from the Earth, because neither
spaceship is at rest in that frame. That's a key point. Relative
velocity is ONLY defined from a frame of reference where one of the
objects in the pair is at rest. You *can* make this statement from the
frame of reference riding along with the first spaceship for example,
because in that frame the first spaceship is stationary, but you can
NOT make that statement from the Earth.

> and
> the velocity of the second ship is not c relative to your house ignoring
> contraction\dilation adjustments. ?

No, it is NOT! You see what you're doing? You're *assuming* that you
simply add 0.5 c and 0.5 c to get 1 c with respect to the Earth. But
velocities don't add that way!
In the frame of reference where the first spaceship is at rest, the
second spaceship is traveling at 0.5 c.
But in the frame of reference where the Earth is stationary, the first
spaceship is traveling at 0.5 c, and the second spaceship is traveling
at 0.8 c!

I know this seems odd. It seems unnatural. It seems counter to logic.
But it is nevertheless true. You can't just add velocities
algebraically.


[snip]

PD

.

Relevant Pages

  • Re: Imagine
    ... statement that c is constant in frame implies that, ... valid for all frames of reference ... velocity-vector to a point of empty space in which electromagnetic processes ... Implies if not explicitly states that empty space has a velocity of ...
    (sci.physics.relativity)
  • Re: Imagine
    ... > |> statement that c is constant in frame implies that, ... velocity addition formula, you'll see that c remains constant in any ... > |> iii) light is always propagated in empty space at c which is independent ... Note what the reference ...
    (sci.physics.relativity)
  • Re: Imagine
    ... |> statement that c is constant in frame implies that, ... |> iii) light is always propagated in empty space at c which is independent ... Note what the reference ...
    (sci.physics.relativity)
  • Re: Rel. Speed
    ... Certainly it would have speed zero relative to another spaceship ... Then the ship sends a pulse of light to the same direction as of the ship. ... The ship has zero velocity with respect to its own frame of reference. ...
    (sci.physics.relativity)
  • Re: Galilean transformation explanation of MMX
    ... Cartesian coordinates S to represent the frame of reference of the ... where it is reflected by the mirror. ... Nobody knows the essence of the physics they are talking ...
    (sci.physics.relativity)
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