From: Daryl McCullough on
Thomas Smid says...
>
>Daryl McCullough wrote:

>> For any event e, let x(e), t(e) be the location and time of e
>> in the first frame, and let x'(e) and t'(e) be the location
>> and time as measured in the other frame. We assume that these
>> coordinates are linearly related:
>
>What is the justification for such an assumption?

The principle of relativity. Consider an object moving
in the absence of any forces. Then the object must travel
at a constant velocity. So the relationship between the
two coordinate systems must be such that constant-velocity
motion transforms to constant-velocity motion. That implies
that the transformation is linear.

>>There is some parameters
>> A,B,D,E that are functions of the relative velocity between
>> the two frames such that for all events e
>>
>> x'(e) = A x(e) + B ct(e)
>> ct'(e) = D x(e) + E ct(e)

[stuff deleted]

>> Because light travels at speed c, we know, in the first frame:
>>
>> x(e1) = c * t(e1)
>>
>> or
>>
>> (1) x(e1) - c t(e1) = 0
>>
>>
>> But light *also* travels at speed c in the second frame. So
>> we have:
>>
>> x'(e1) = c * t'(e1)
>
>OK, with x'(e1) = ct'(e1) your original equations
> x'(e1) = A x(e1) + B ct(e1)
> ct'(e1) = D x(e1) + E ct(e1)
>result therefore in
> A x(e1) + B ct(e1) = D x(e1) + E ct(e1)
>and since this must for all times t

No, it's not for all times! It's for one specific
time, which is the time of event e1.

You are confusing constants with variables.

--
Daryl McCullough
Ithaca, NY

From: Daryl McCullough on
Thomas Smid says...

>result therefore in
> A x(e1) + B ct(e1) = D x(e1) + E ct(e1)
>and since this must for all times t
> D=A
> E=B

No. Since x(e1) = ct(e1), it follows that

A ct(e1) + B ct(e1) = D ct(e1) + E ct(e1)

which implies that

A + B = D + E

--
Daryl McCullough
Ithaca, NY

From: Thomas Smid on
Todd wrote:
> "Thomas Smid" <thomas.smid(a)gmail.com> wrote in message
> news:1125762269.196256.173470(a)z14g2000cwz.googlegroups.com...
> > Daryl McCullough wrote:
>
> >>There is some parameters
> >> A,B,D,E that are functions of the relative velocity between
> >> the two frames such that for all events e
> >>
> >> x'(e) = A x(e) + B ct(e)
> >> ct'(e) = D x(e) + E ct(e)
>
> > OK, with x'(e1) = ct'(e1) your original equations
> > x'(e1) = A x(e1) + B ct(e1)
> > ct'(e1) = D x(e1) + E ct(e1)
> > result therefore in
> > A x(e1) + B ct(e1) = D x(e1) + E ct(e1)
>
> Yes, as long as you're considering events where x'(e1) = ct'(e1).
>
> > and since this must for all times t
> > D=A
> > E=B
>
> No, this is an incorrect conclusion.

Yes, I noticed this already and I had already deleted my post before
you posted it. I shall be posting a revised version of this.

Thomas

From: Ken S. Tucker on

Daryl McCullough wrote:
> Ken S. Tucker says...
>
> >Bilge (potato head) wrote:
> >> Do you believe the coordinate transformation,
> >>
> >> x' = x cos(A) - y sin(A)
> >> y' = y cos(A) + x sin(A)
> >>
> >> is mathematically inconsistent? If not, then your argument against
> >> the transformation,
> >>
> >> t' = t cosh(A) - x sinh(A)
> >> x' = x cosh(A) - t sinh(A)
> >>
> >> is inconsistent.
> >
> >Ding-bat, x and x' are defined parallel, no
> >relative rotation occurs.
>
> Bilge is talking about a generalized spacetime rotation,
> using hyperbolic trigonometric functions instead of ordinary
> trigonometric functions. His equations explain the analogy
> very well. The parameter A is defined by tanh(A) = v/c. Then
> cosh(A) = square-root(1/(1-tanh^2(A))) = gamma.
> sinh(A) = tanh(A) cosh(A) = gamma v/c. So his
> "rotation" equations are equivalent to the usual
> Lorentz transformations.
> Daryl McCullough

>From Androcles post...quote AE,

"let a spherical wave be emitted therefrom, and be propagated with the
velocity c in system K. If (x, y, z) be a point just attained by this
wave, then

x2+y2+z2=c2t2.

Transforming this equation with the aid of our equations of
transformation we obtain after a simple calculation"...
AE

Why use an incorrect complex analogy if the simple
physics is sufficient. Setting x and x' in differing
directions has bugged me since HS, because it's WRONG,
it's a crumby theoretical inventions that fucks
reality. AE's spherical wave gives,

0 = ds^2 = (cdt)^2 - dr^2

and then generalized to,

0 = g_uv dx^u dx^v .

See that, evolved from SR threw Minkowski SpaceTime
to GR, - no silly x vs x' rotations analogy's -
it's the Lorentz Transform in a nutshell.

Regards
Ken S. Tucker

PS: Androcles, thanks for the link.

From: Dirk Van de moortel on

"Daryl McCullough" <stevendaryl3016(a)yahoo.com> wrote in message news:dfcnps02504(a)drn.newsguy.com...
> Thomas Smid says...
> >
> >Daryl McCullough wrote:
>
> >> For any event e, let x(e), t(e) be the location and time of e
> >> in the first frame, and let x'(e) and t'(e) be the location
> >> and time as measured in the other frame. We assume that these
> >> coordinates are linearly related:
> >
> >What is the justification for such an assumption?
>
> The principle of relativity. Consider an object moving
> in the absence of any forces. Then the object must travel
> at a constant velocity. So the relationship between the
> two coordinate systems must be such that constant-velocity
> motion transforms to constant-velocity motion. That implies
> that the transformation is linear.
>
> >>There is some parameters
> >> A,B,D,E that are functions of the relative velocity between
> >> the two frames such that for all events e
> >>
> >> x'(e) = A x(e) + B ct(e)
> >> ct'(e) = D x(e) + E ct(e)
>
> [stuff deleted]
>
> >> Because light travels at speed c, we know, in the first frame:
> >>
> >> x(e1) = c * t(e1)
> >>
> >> or
> >>
> >> (1) x(e1) - c t(e1) = 0
> >>
> >>
> >> But light *also* travels at speed c in the second frame. So
> >> we have:
> >>
> >> x'(e1) = c * t'(e1)
> >
> >OK, with x'(e1) = ct'(e1) your original equations
> > x'(e1) = A x(e1) + B ct(e1)
> > ct'(e1) = D x(e1) + E ct(e1)
> >result therefore in
> > A x(e1) + B ct(e1) = D x(e1) + E ct(e1)
> >and since this must for all times t
>
> No, it's not for all times! It's for one specific
> time, which is the time of event e1.
>
> You are confusing constants with variables.

Actually, I think he is confusing the contents of
his skull with brains :-)

Dirk Vdm