"Spoonfed" wrote in message ups.com...

Dirk Van de moortel wrote:
"Spoonfed" wrote in message
Dirk, If I am not mistaken, you believe that beyond a certain length,
distance loses its meaning

No, I don't.
You are mistaken :-)

My error. You had a pretty explicit definition for length--only it was
different than mine, because we disagreed about which version of
"simultaneity" needed scare quotes.

http://groups.google.com/group/sci.p...e=source&hl=en

To understand your interpretation, I guessed that you calculated the
"current" distance to faraway galaxies by first, switching to their
reference frame and then calculating the distance to earth in their
reference frame at the time when earth reaches its current proper time
in their reference frame.

I remember the subthread.
It was not about distances to galaxies.
It was about whether it makes sense to wonder what time it is
now somewhere else (concerning Mike's program iirc).
Mike finds it an interesting question.
Ben was saying that it never makes sense.
I said something about it being totally useless when you are
accelerating and useful when you are at rest w.r.t the remote
location.
I recall that you brought into the thread a bunch of unrelated
technical issues in which I really wasn't interested, and so we
ended up talking past each other.
So I haven't really looked at what you write below about
"current" distances...

[skipping to the end]


Another method to do the same thing is by
plotting out locations at times by using rapidity (v/sqrt(1-(v/c)^2)
instead of velocity; multiplying the rapidity of the galaxy by the time
on earth to find the distance.

I'm not actually sure this is how you calculated the distances, but it
seemed like whatever you were doing was getting this result.

This makes some sense, because if we were to send them a message, they
would regard it to have been sent from the earth in their reference
frame, not in our reference frame, and it does create a nice infinite
but expanding model. The only problem with it is that it's not what we
see from here.


And the idea is not to get laughs.
I am *having* an incredible laugh over a statement like:

| "Other than the rod being light-years in length, the parameters are
| values that occur in our daily experience."

I think that David has another kind of sense of humour.

Dirk Vdm

Eh, 20 to 30 trillion kilometers? With length contraction, we can
bring that down to only a few hundred billion. No biggie. I grant
that it is humorous, but not necessarily a blunder.

This is not about lenght contraction of distances.
This is about someone who has lost his mind decades ago
over light-years long physical rods and manages to say
without blinking:

| "Other than the rod being light-years in length, the parameters are
| values that occur in our daily experience."

In my book it is exactly the same kind of blunder as:
"Your Honour, other than that bitchy wife of mine, I would never
kill anyone, so surely you're not going to put me behind bars?"

But YBMV :-)

Dirk Vdm