From: Daryl McCullough on
Thomas Smid says...

>I did point it out to you above:
>
>Your original equations for the coefficients were
>
>x' - c t' = lambda (x - ct) + tau (x + ct)
>x' + c t' = mu (x + ct) + sigma (x - ct)
>
>Then you found that tau=0 under the provision that x' and x are
>positive and sigma=0 under the provision that x' and x are negative.

And I pointed out to you that tau and sigma are *constants*.
If they are equal to 0 in some particular case, then they
are *always* equal to zero.

So, no, you have not pointed out any mistakes.

--
Daryl McCullough
Ithaca, NY

From: Thomas Smid on
Daryl McCullough wrote:
> Thomas Smid says...
>
> >Your original equations for the coefficients were
> >
> >x' - c t' = lambda (x - ct) + tau (x + ct)
> >x' + c t' = mu (x + ct) + sigma (x - ct)
> >
> >Then you found that tau=0 under the provision that x' and x are
> >positive and sigma=0 under the provision that x' and x are negative.
>
> tau and sigma are *constants*, independent
> of x and t. So if they can be proved to be
> 0 in the special cases x=ct and x=-ct, then
> they must be zero in *all* cases.
>
> Suppose A and B are constants, and I tell you
>
> 1. forall x, A*x = 2*B*x
> 2. forall x, if x is a prime number, then A*x = 0.
> Do you come to the conclusion that A=0 only when x is prime?

Your example is inappropriate as the prime numbers are contained in all
numbers, but positive and negative numbers are mutually exclusive.

Your example should read in fact like this:

For all x positive A*x=2*B*x
For all x negative A*x=0

So can you conclude that B=0? Not as far as I am concerned (it's not
about the mere appearance of constants here but about the validity of
equations).


>
> Let's make everything more explicit.
>
> 1. For all events e,
> x'(e) - c t'(e) = lambda (x(e) - ct(e)) + tau (x(e) + ct(e))
> 2. For all events e,
> x'(e) + c t'(e) = mu (x(e) + ct(e)) + sigma (x(e) - ct(e))
> 3. For all events e such that
> x(e) = c t(e),
> then x'(e) = c t'(e).
> 4. For all events e such that
> x(e) = - c t(e),
> then x'(e) = -c t'(e).
>
> Putting 3 and 1 together, we get
>
> For all events e such that x(e) = ct(e), then
> x'(e) = ct'(e) (from 3) and
> x'(e) - c t'(e)
> = lambda (x(e) - ct(e)) + tau (x(e) + ct(e)) (from 1)
>
> which simplifies to
>
> For all events e such that x(e) = ct(e), then
> tau = 0.
>
> But since tau is a *constant*, independent of e, then
> if tau = 0 in a particular case, it is *always* 0.
>
> Similarly, we prove that sigma is always 0. Therefore,
> 1 and 2 simplify to
>
> 1' forall events e, (x'(e)-ct'(e)) = lambda (x(e)-ct(e))
> 2' forall events e, (x'(e)+ct'(e)) = mu (x(e)+ct(e))

If all the equations always apply, I should also have been entitled to
make the transformation ct'(x2,t)=ct'(-x1,t)=-(B+A)x1 above. Not
allowing me to do this means that you are applying double standards
here.

But why don't you make life easier for yourself and avoid negative
x-coordinates in the first place (as I suggested above already). If you
split x into x1 and x2 there is no point anyway having x2 negative. As
the sign of the measuring unit is only a convention, you can just take
x1(t)=ct and x2(t)=ct (imagine you have two rulers going into opposite
directions, one with a scale entitled x1 and one with x2).

Thomas

From: Daryl McCullough on
Thomas Smid says...

>Your example should read in fact like this:
>
>For all x positive A*x=2*B*x
>For all x negative A*x=0
>
>So can you conclude that B=0?

Of course you can.

>Not as far as I am concerned

Well, I don't know what to say, except that
this is elementary algebra. If you're having
trouble with it, it isn't Einstein's fault.

Why don't you tell me what value of the constants
A and B can make both of these statements true:

For all x positive A*x=2*B*x
For all x negative A*x=0

other than the choice A=0, B=0?

--
Daryl McCullough
Ithaca, NY

From: Dirk Van de moortel on

"Thomas Smid" <thomas.smid(a)gmail.com> wrote in message news:1126464875.087754.309620(a)o13g2000cwo.googlegroups.com...
> Daryl McCullough wrote:
> > Thomas Smid says...
> >
> > >Your original equations for the coefficients were
> > >
> > >x' - c t' = lambda (x - ct) + tau (x + ct)
> > >x' + c t' = mu (x + ct) + sigma (x - ct)
> > >
> > >Then you found that tau=0 under the provision that x' and x are
> > >positive and sigma=0 under the provision that x' and x are negative.
> >
> > tau and sigma are *constants*, independent
> > of x and t. So if they can be proved to be
> > 0 in the special cases x=ct and x=-ct, then
> > they must be zero in *all* cases.
> >
> > Suppose A and B are constants, and I tell you
> >
> > 1. forall x, A*x = 2*B*x
> > 2. forall x, if x is a prime number, then A*x = 0.
> > Do you come to the conclusion that A=0 only when x is prime?
>
> Your example is inappropriate as the prime numbers are contained in all
> numbers, but positive and negative numbers are mutually exclusive.
>
> Your example should read in fact like this:
>
> For all x positive A*x=2*B*x
> For all x negative A*x=0
>
> So can you conclude that B=0? Not as far as I am concerned (it's not
> about the mere appearance of constants here but about the validity of
> equations).

For all x negative A*x=0
==> A*(-1) = 0 (taking x = -1)
==> A = 0


For all x positive A*x=2*B*x
==> For all x positive 0=2*B*x (since A = 0)
==> 0 = 2*B*1 (taking x = 1)
==> B = 0

Dirk Vdm


From: Thomas Smid on
Daryl McCullough wrote:
> Thomas Smid says...
>
> >Your example should read in fact like this:
> >
> >For all x positive A*x=2*B*x
> >For all x negative A*x=0
> >
> >So can you conclude that B=0?
>
> Of course you can.
>
> >Not as far as I am concerned
>
> Well, I don't know what to say, except that
> this is elementary algebra. If you're having
> trouble with it, it isn't Einstein's fault.
>
> Why don't you tell me what value of the constants
> A and B can make both of these statements true:
>
> For all x positive A*x=2*B*x
> For all x negative A*x=0
>
> other than the choice A=0, B=0?

>

Sorry, I had already deleted my corresponding post as I intended to
re-edit it. I wanted to write originally 'So can you conclude that B=0
*if x<0*?'. In this case the first equation is simply not defined and B
could have any value.

Thomas