# Re: Special Relativity

Daniel Fabulich (daniel.fabulich@yale.edu)
Tue, 23 Jun 1998 03:11:40 -0400 (EDT)

On Tue, 23 Jun 1998, Ian Goddard wrote:

> IAN: A gets larger with reference to B: A
> observes that B is smaller and therefore
> he himself is larger than B. B observes
> that A is smaller and therefore that
> he is larger than A. Pretty simple.
>
>
> This is what A sees, his ruler and B's:
>
> ___________
> Their ruler: |||||||||||
> |_________|
> ____________________
> My ruler: | | | | | | | | | | |
> |___________________|
>
>
> Please notice that "my" ruler is larger.
> B also sees "my" (i.e., his) ruler larger.

No, it doesn't. Because your "larger" rulers are not larger than "self"
within any reference frame; from BOTH reference frames the "larger" ruler
is not positive; it is zero, because it is self.

A cannot measure A to be non-zero. B can, but B measures A to be smaller,
not larger. Similarly, B cannot measure B to be non-zero. A can, but A
measures B to be smaller.

Larger is not the same as +. Larger can be 0. Unfortunately, summing
negatives and zeroes does not get you back to zero, it just makes you more
negative.

> IAN: This is what the charts say
> for A, which is reading down from A:
>
> A B
> ______
> A | 0 - |
> | |
> B | - 0 |
> --------
>
> A: I stayed the same size to me
> (0), and B got smaller (-) to me.
>
> A B
> ______
> A | 0 + |
> | |
> B | + 0 |
> --------
>
> A: I stayed the same size to me,
> but I got larger relative to B.

A did not get larger relative to B. Ask B. He'll tell you. A got
SMALLER. That's what it means when you say "A gets larger relative to B:"
B measures A to be larger. B does NOT measure A to be larger, however.
You keep falling back on this completely false presumption and claiming
that you've answered my point already. So long as you continue to insist
that A is large relative to B, you make it clear that you have no clear
grasp of the situation at hand.

> >When they get moving, B's meter stick looks to be 0.8m long. So, you want
> >to say A's meter stick is growing? Relative to what? Not B: B perceives
> >A's meter stick to be SHRINKING, not growing. What is A growing relative
> >to?
>
> IAN: A is growing relative to B. You
> see, A observes B to be smaller, but
> has A gotten larger than B? The only
> way for A to know is look at B. If B
> is smaller, then A has gotten larger.
> This is because size is relative.

When you say A has gotten larger, then that means that in some frame of
reference, the A-0 partial difference is greater than before. This isn't
true, so this argument is unsound.

> IAN: From A's reference frame his ruler
> is as long as (actually) 2 of B's rulers,
> if A's rulers is twice as long as B's.

Here you're getting yourself confused. A is 0 to A, because A does not
use B's ruler. *B* uses B's ruler. When we make up these charts, we
write down the partial difference between each relevant entity *as
measured by one entitiy* on the row in question. B's ruler is not used on
A's row. B's ruler is used on B's row. See the difference?

> IAN: A sees B, A measures A relative
> to A's observation of B, A does NOT
> measure A relative to how B sees A.

So now we're back to

A B
A + 0
B 0 +

A measures itself in terms of B's ruler, and finds itself large. Oops...
Oh, wait, no.. that's not it, B measures A and finds A large. Wait, no,
that's flat out wrong. B measures A and finds A SMALL compared to 0.
What was it again? *I* know! A measures A in terms of ITSELF ONLY and
gets 0, remember? This is why you have that diagonal line of zeros down
all your identity charts. A does not measure itself in terms of B until
after we have written out the whole chart. The individual values on the
chart are PARTIAL differences, for which A uses only A's ruler, and not
B's. A will eventually find the NET identity in terms of A, B, C, etc.
but the partial differences which are summed do not use multiple
perspectives. A measures A in terms of itself, and gets 0. It measures B
in terms of itself, and gets -C. B does the same, getting 0 for itself
and -C for A. B does not create a partial difference of itself in terms
of A; this only takes place when we sum the chart.

A is larger than B only in A's perspective, but in A's perspective A is
always 0.

Yes, and wrongly every time, which is why I continue to press the point.
A is not large according to A: A is 0 relative to A. You cannot say that
A is larger than 0 according to either A or B. Therefore, any chart you
grows relative to anything, it DOES shrink relative to B. This special
case violates your principles, which is why I propose it.

> The implicit phrasing of the charts is a
> little confusing. But this is cleared up.
> As we can see, if A appears larger than
> B, then A is said to be larger than B.

Nice use of the passive voice. A says that it is larger than B, but only
in that A is 0 and B is negative. B says the same thing about A. So
nobody claims to observe any positive numbers at all: A is 0 to A and
negative to B, B is 0 to B and negative to A. No positive numbers means
no way to add back up to zero.

Now, try this again, and this time remember that just because A is larger
than B according to itself does NOT make it positive in its own
reference frame, and that it is NEGATIVE is B's reference frame.