On May 15, 8:27Â*pm, rbwinn wrote:
On May 15, 2:30Â*pm, PD wrote:



On May 15, 7:27Â*am, rbwinn wrote:

On May 15, 2:24�am, PD wrote:

On May 14, 11:31�pm, rbwinn wrote:

� � However, it defies all of the laws of physics and mathematics for
a train to shrink to a fraction of its length just because it is
moving.

What laws of physics and mathematics would that be?

In the interest of foreshortening the conversation, note that neither
the Galilean nor Lorentz transforms are laws of physics. Perhaps you
could start by listing a few laws of physics you know, and then select
out of that pool the ones you think are defied by having length be a
frame-dependent quantity.

While you're at it, note that kinetic energy of an object is a frame-
dependent quantity, even in Galilean physics. And note that energy
conservation is one of the laws you're looking for. This would be a
good opportunity to point out also why no laws of physics are violated
by this frame-dependence.

PD

Well, according to Einstein's interpretation of the Lorentz equations,
and also Lorentz's, one frame of reference actually shrinks relative
to the other.

Nice little fantasy. Would you like to cite where you read that, or
are you willing to acknowledge that there are pieces of your reality
you just make up as you go?

Â*Not only that, but the one that shrinks is also its own
size in its own frame of reference, and the other frame of reference
is shrinking.

See, this is the kind of nonsense that results when you make stuff up
as you go along.

Â*So there are several things going wrong at once here.
Scientists at one time maintained that no laws of science were
violated by the Ptolemaic system of astronomy because it could
accurately predict the positions of planets with its complicated
mathematics of epicycles.

Actually, no, it *post-dicted* those positions. It had very poor
predictive power. Those folks didn't even call themselves scientists
in that day and age. "Scientist" is a more recent term, and what they
practice (and in fact what they practice defines what science is) is
much different that what they practiced then. More emphasis on
experimental verification, more emphasis on prediction rather than
postdiction.

Tycho Brahe was not a scientist? Â*Kepler thought he was one. Â*That is
why he went to work for him so he could have access to his mathematics
and experimental data.

He was an observational astronomer and a very careful measurer. By the
modern definition of "science", he did not practice much in the way of
science. There were no *pre*dictions of observations, though there
were plenty of *post*dictions. It is in fact interesting to note the
difference between empirical rules (which is what Kepler's laws are)
and a physical theory (which is what Newton added). This distinction
is carefully drawn out in introductory science courses in the first
week, where the details of the scientific method are drawn out, and
these distinctions which really define science are made.

It doesn't surprise me that your eyebrows go up a little about this.
It's these subtleties that are important to those who have immersed
themselves in the subject and completely unimportant to casual
observers.

PD

Robert B. Winn