# Re: Special Relativity

Ian Goddard (igoddard@netkonnect.net)
Tue, 23 Jun 1998 01:16:50 -0400

At 08:51 PM 6/22/98 -0400, Daniel Fabulich wrote:

>You just don't get it, do you? OK, try this on for size:
>
>B perceives A to be smaller than B. A perceives B to be smaller than A.
>Who perceives other to be larger than self? If the answer is "no one"
>(and it is!) thenthere is no positive sign on the identity chart. Period.

> In one line, tell me in what reference frame A gets larger.

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.

>> The fact that both observers witness
>> the same thing does not break this
>> symmetry of relational structure.
>> Both observers see themselves
>> as larger than the other:
>>
>> A B (how I appeared)
>> A 0 +
>> B + 0
>
>Did you make another error here? "Both observers see themselves as
>larger than the other..." 0 is self, and 0 is SMALLER than +, not
>larger.

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.
(Which is also what B observes,
that he (B) got larger than A.)

The first chart defines what happens to the
other guy's ruler relative to me as I see it
and the second describes what happened to
my ruler relative to other as I see it.

>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.

>> Because B was also size 1, it could
>> be stated now that A = 1.5, for no
>> point of size-reference is absolute.
>
>Except that this is true in no reference frame, for if you measure A from
>B's reference frame, you do NOT get 1.5: you get 0.5. If someone, ANYONE,
>measured that meter stick to be 1.5m long, I'd agree. Except A never
>measures any meter sticks to be longer than 1m, and neither does B. So,
>from what reference frame is A 1.5m long?

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.

>> IAN: There is no absolute size, you cannot have
>> "got smaller" free from "got larger." Observer
>> A will measure the situation and see that there
>> are two sides of the relative change: he himself
>> got larger than B because B got smaller than A.
>
>Relative to WHAT? A got larger relative to B? <BZZT> No, A got SMALLER
>relative to B. Try again.

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.

>Until you can provide a reference frame in which B grows (that is, from
>the perspective of observer X, B is 1.5m long) you haven't proved
>anything. And unfortunately, from A's perspective all sticks are <= 1m.
>Same for B. And with that, you're out of perspectives.

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.

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VISIT IAN WILLIAMS GODDARD --------> http://Ian.Goddard.net
______________________________________________________________

"A new scientific truth does not triumph by convincing its
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