Re: Motion Through Space Is Meaningful

PD wrote:
>A postulate is something that is *assumed without proof*.

I assume that you meant "assumed to be true sans proof";
in that case, a physical postulate is a prediction
because it assumes to be true the outcome of some
experiment because only experiment can supply us with
the truth in physics.

But this is not the end of your problems.

Again, consider your definition that a postulate is
something that is assumed (to be true) without proof.
What could this possibly mean in the case of Einstein's
light postulate? Have you never asked yourself this
very important question?

To save you the time, I will tell you what it means:

It means simply that Einstein assumed one-way light speed
invariance and isotropy to be true.

But what does _this_ mean?

It means that Einstein assumed that whenever light's one-way
speed is experimentally measured between two clocks that the
result must be or should be or will be invariance/isotropy.

Got the picture so far?

Now let's really get down to business:

As Einstein himself pointed out very clearly, the _only_ way
to obtain one-way light speed invariance/isotropy on paper is
to manually preset the distant clock to read x/c after preset-
ting the origin clock to read zero. In other words, the only
way to obtain one-way invariance/isotropy on paper is via a
definition of clock "synchronization."

Clearly, a "result" beforehand does not qualify as an
experimental result. This is known as rigging the result.

But Einstein had to do it via definition because there is
no way to do it experimentally.

That is, no one can experimentally measure light's one-way
speed between two clocks without rigging the result by first
setting the clocks to cause a prechosen result, just as did
"Sir Albert."

So Einstein's light postulate - contrary to your belief -
cannot be "something that is assumed (to be true) without
proof" because it is something that can never happen.

This is why, to this day, no one has ever used two clocks
(which have not been transported and are not rotating) to
measure light's one-way speed. There is no such experiment.

Therefore, Einstein's light postulate is neither a prediction
nor an "axiom" in any sense of either word.

But PD went on re the light postulate, now calling it
"an assumption":
>However, no one has shown that the consequences of those
>assumptions are incorrect, and therefore there is no
>reason to believe that the assumptions are incorrect.

The consequences of this "assumption" are:

A. Relative time (asynchronous clocks)
B. All of the consequences of using asynchronous clocks
(such as apparent rod shrinkage, apparent clock
slowing, etc., etc.)

PD wrote:
>Let me give you an example. In one experiment where I am
>watching muons decay, [etc.]

>Show me specifically how you know the speed through space
>of either me or the muons in each case.

I have already told you. You simple obtain a pair of
absolutely synchronous clocks, and go from there. Such
clocks can tell you your speed through space, and such
clocks can also tell you a muon's speed through space.
If a muon is really moving (i.e., is moving through
space) at half light speed, then it will live longer
by a given amount of time per an unslowed clock. If
your clocks are moving through space, then you of
course must correct for it slowness.

PD wrote:
>This tells me nothing about how I measure the length
>of a rod. Suppose I don't know its speed, though I can
>see it flying by. How do I measure its length?

Must I tell you every little step for every case?
Using absolutely synchronous clocks (the only kind
of _synchronous_ clocks), you locate (absolutely)
simultaneously the rod's end points. Then you know
that it truly fits between the two clocks. You then
correct for your own intrinsic ruler shrinkage, and
you get the rod's (physical) length.

>>The space-time interval has no physical meaning,
>>so it is irrelevant to physics.

>This is an assertion without basis.
>... The interval is *experimentally* verified to be an
>invariant quantity and therefore it is a quantity with
>presumably physical meaning.

Let's look at a time-like interval; this is of course
really just the proper time between the two events, but
is this the time per a physically unslowed clock? Only
if it is is it physically meaningful, and useful, but
can you prove that the clock is unslowed?

>>>3. Velocities do not add algebraically ....

>>You apparently forgot that SR's composition of velocities
>>equation is based entirely on Einstein's light postulate,
>>which you yourself (above) agreed was a mere triviality
>>as far as physics goes, and, indeed, was not even important
>>to SR. Circularities and trivialities abound in SR!

>The fact that it is based on a postulate does not mean that
>it is a postulate itself. It is a nontrivial prediction
>that is experimentally testable and in fact experimentally
>confirmed.

All one-way velocity measurements use two Einsteinian clocks,
which, of course, are clocks related per his light "postulate,"
or his definition of "synchronization," which, of course, rigs
the outcome to be one-way light speed "invariance." This is
not an experimentation; it is a circularity at its worst.

--
2nd Postulate Dude

.

Relevant Pages

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