On Feb 27, 5:23 pm, HW@....(Henri Wilson) wrote:
On 27 Feb 2007 07:11:36 -0800, "PD" wrote:

On Feb 26, 6:53 pm, HW@....(Henri Wilson) wrote:
On 26 Feb 2007 13:12:25 -0800, "PD" wrote:

Depends on what you mean by a physical entity. Is momentum a physical
entity?

Yes. A frame dependent one...but you don't know what that means Draper.

Sure I do, and on this small point we're in agreement.
So tell me, what makes momentum a physical entity and spacetime not?

Momentum has physical rammifications. Spacetime is just a method of viewing a
physical situation.

Which "physical rammifications" do you have in mind for momentum.
Do you think that 3D space has "physical rammifications"? Does
Euclidean geometry count as a "physical rammification"?


A reference frame is no more or no less a physical entity than
spacetime.

Nobody claimed it was.

Then I'm not sure what your point was. I described what a frame of
reference in part by using the term "spacetime events" and you
commented that spacetime is not a physical entity. But since a frame
of reference is no less a physical entity than spacetime, I'm not sure
why that's important.

I don't wish to discuss your imaginary 'spacetime'. We were defining 'frame'.

Ah, OK, then you didn't have a point. That's not unusual.


You blundewred...now you want to change the subject....a typical SRian ploy.

"Blundewred"? What "blundewr" was that, Henri?


In the maths construction known as space/time, there is no movement.

That's why I included the word "or" between "spacetime events" and
"spatial positions". Reading comprehension problems, Henri? Is this
why you don't like to read books about relativity? Or books at all,
for that matter?

Draper, spacetime is completely static. There are no 'events'. Everything that
ever happened is laid out permanently in 4D. Static!!!!!
Even the future is static.... just not plotted yet.

A spacetime event, Henri, is something at a location (x, y, z, t) that
is distinguishable from neighboring locations. The snapping of fingers
is something that happens at a particular place and a particular time
and so marks a location in spacetime, called an "event".

Oh crap Draper.
You blokes like to rave about this 'spacetime' when you haven't a clue what you
are even talking about.

Try plotting the snapping of fingers in a 4D representation Draper.

Sure. It's a little blot on a 4D space, kind of like the period at the
end of this sentence.

Better still, try something simple like a ball falling to ground. You can plot
that in 2D.

That's not a spacetime event, Henri. That's a sequence of spacetime
events. Now, the ball *landing* on the ground, that's a spacetime
event.

There is NO movement in the 2D representation. It is hardly an 'event'.


....unless of course you want to agree with me that at least two orthogonal
time dimensions exist....

I asked you, where did you get the idea that a frame is everything at
rest with respect to a defined point?

Because it is Draper...including Wilsonian nort-holes.
Anything at rest wrt the defined point also defines the frame.

That doesn't tell me where you got the idea, Henri. You can also tell
me you got the idea that mammals all give live birth to their young
"because they do", but it wouldn't answer the question where you got
that ridiculous notion.

Draper, I have told you before, I'm not going to waste my time teaching YOU
elementary physics.
GO BACK TO SCHOOL... like geesey has.

Then tell me in which school, and under what professor, using which
textbook, you got the idea that a frame is everything at rest with
respect to a defined point.

Everything at rest wrt a particular point or frame is in that frame and can
define that frame.
Other objects can move wrt that frame but are not in it.

And that's ridiculous, Henri.

See? You can't answer a simple question. I asked you where you got
this notion, and all you can do is repeat it.
HW: "2+2=7.43"
PD: "Why Henri, wherever did you get that idea?"
HW: "Don't be an idiot, PD. 2+2=7.43"


Are you under the misguided impression that my definition precludes the
possibility that objects can move wrt a reference frame.

I didn't relate any impression, Henri. I asked you a question, which
you have yet to answer. You asked me a question about my definition,
and I answered that.

....with drivel...

Now once again: Where did you get the idea that a frame is everything
that is at rest with respect to a defined point?

You really can't answer a simple question, Henri? This isn't about me
going to school, it's about where YOU got this idea.

stop raving Draper. You are a waste of time...

Every time I ask you a question you don't want to answer (or you can't
remember what the answer is), you say it's raving.

Every time you say something stupid and I point it out to you, you say
that any "real physicist" understands what you are talking about and
agrees with it, and then when I ask you what "real physicist" that is,
you suddenly say I am raving. It's like a little pattern with you. I
can ring a little bell and you'll salivate.


I answered your question. Now you answer mine. Are you an idiot or a
liar, Henri?

Learn some physics Draper..... you simply don't have any idea at present..

Happy to. Tell me what reference I should read about reference frames
that shows your definition, Henri.

Any real physicist knows what a reference frame is.

Sure they do. I just don't think it's the same as what you think it
is. The reason is that I can go to any reference written by "any real
physicist" and find a definition that doesn't have anything to do with
what you say it is. Unless of course, you've got an "any real
physicist" in mind that agrees with your definition. That is, unless
YOU are the only "any real physicist" you know....

A reference frame is simply something that can be used to compare velocities.

Really? How can a reference frame be something that can be used to
compare velocities, if the only things that are in the frame are
things that are mutually at rest?

Or are you saying that the only way to compare the velocity of a stop
sign and a truck is to find the two reference frames in which each of
these things is at rest and then compare the two reference frames?
Sort of a "Have your people talk to my people" kind of thing?

Are you really this dense?

And what "real physicist" says that a reference frame is defined as
everything that is at rest with respect to a defined point? And which
"real physicist" says that a reference frame is simply something that
can be used to compare velocities? You still haven't answered either
of these questions.


IT'S A BLOODY REFERENCE FOR VELOCITIES.
EVERYTHING THAT IS MUTUALLY AT REST IS IN THE SAME FRAME.

As well as everything that is not mutually at rest -- all in the same
frame. Do you disagree with that?

You are a moron Draper. Are you thinking of an ant walking across a framed
picture?

Objects that are moving wrt a frame ARE NOT in that frame. The ant is NOT in
the frame of the picture.


Of course the ant is not in the frame of the picture. The frame of a
picture forms a boundary around a picture. What does this have to do
with a reference frame, Henri? Were you thinking that a reference
frame is a box around a collection of objects?

PD