Re: A little lesson for sqrt(144) year olds.

From: Androcles (androc1es_at_nospamblueyonder.co.uk)
Date: 07/03/04 

Date: Sat, 03 Jul 2004 13:43:15 GMT

"Jesper Pedersen" <jesper@befunk.com> wrote in message
news:cc66ej$ia7$1@news.net.uni-c.dk...
| "Androcles" <androc1es@nospamblueyonder.co.uk> wrote in message
| news:sQuFc.2591$aJ5.21906626@news-text.cableinet.net...
| >
| > "Jesper Pedersen" <jesper@befunk.com> wrote in message
| > news:cc3ues$vpd$1@news.net.uni-c.dk...
| > | "Androcles" <androc1es@nospamblueyonder.co.uk> wrote in message
| > | news:UReFc.1932$xl6.16431206@news-text.cableinet.net...
| > | <snip>
| > | > Let's move on. Work on this "Definition" for me, please.
| > | >
| > | > "If we place x'=x-vt, it is clear that a point at rest in the system
k
| > | must
| > | > have a system of values x', y, z, independent of time. We first
define
| > tau
| > |
| > | I am assuming that your system k
| > | is moving along the positive x-axis with
| > | constant velocity v>0, since this will make the sentence make sense.
| >
| > Assumptions are not wise. It is Einstein's system k. Otherwise your
guess
| > was correct.
| > | The
| > | fact that you don't bother telling me these vital details already
hints
| at
| > | the fact that you will end up drawing a false conclusion.
| >
| > The fact that you have somehow poked your nose into
| sci.physics.relativity,
| > probably because somebody I was replying to added sci.math in the list
of
| > newsgroups, is the most probable cause of your lack of understanding.
| > Newsgroups are not scientific papers where all references are indicated
| with
| > footnotes. However, since you are not familiar with the author's work, I
| > will cite: http://www.fourmilab.ch/etexts/einstein/specrel/www/
|
| This makes no sense at all. I haven't poked my nose into
| sci.physics.relativity. I only monitor psi.physics.

I only post my own material to sci.physics.relativity. When somebody I'm
responding to includes sci.physics and sci.math, I have no idea which the
originator of the message is monitoring. You have sent your missive to
sci.physics.relativity,sci.physics,sci.math, and that is where I'm replying.

I do not know (or particularly care) who changed the cross posting to three
newsgroups, but you have perpetuated it as much as I. If that makes no sense
to you, then try thinking about it.

| The reason I responded
| to your message was that I wanted to help you out in understanding the
| definitions of sqrt(x). And though I certainly understand that newsgroups
| are not scientific papers, I would expect that if someone wants to
challenge
| special relativity they should at least make clear all the specifics of
| their derivations.

That has been done frequently and often. If you respond to my posts, I
expect you to understand that I'm responding primarily to
sci.physics.relativity, whereas your claim to monitor only sci.physics has
lead you to post to sci.physics.relativity and sci.math as well. Why did you
do that? Same reason as I, I'm sure.

| And I am familiar with Einstein's work on special
| relativity.

If that had any ring of truth to it, you might have recognised the passage
I quoted.

| Seems like you have a bit of learning to do though.

Seems like you have a bit of lying to do.

| "Einstein's
| system k" for one makes no sense at all.

For someone that cannot figure out which newsgroup he is posting to, I doubt
very much anything makes sense to you.

| In which direction is it moving, IS
| it moving at all, is it accelerated, etc? These are quite vital specifics.

Read Einstein, since you claim you are "familiar with Einstein's work on
special relativity", but are clearly not.
|
| > So we have v > 0
| > | and k moving with constant velocity v along the x-axis.
| >
| > Very good.
|
| Thank you.
|
| > | <snip intermediates>
| > | > See that "IF" at the beginning?
| > | > Does that mean
| > | > xi really is equal to (x-vt)*gamma,
| > | > or does it depend on the "If"?
| > | > What IF we place x' = x+vt?
| > | > Androcles
| > |
| > | If you choose x'=x+vt, then a point at rest in system k no longer has
| > values
| > | x', y, z independent of time.
| >
| > What does it have values of, then?
|
| Well, x' is no longer independent of time, which should be painfully
obvious
| to anyone who has ever studied physics.

You really are arrogant, aren't you?

| Look at time t. The system has now
| moved v*t along the positive x-axis.

Well, well. So it has. How painfully obvious.

| Thus a point at rest in k which was
| originally at (x, y, z)=(x1, y1, z1) is now at (x, y, z)=(x1+v*t, y1, z1).
| The coordinate system of your choice,

Einstein's choice.

 (x', y, z), then places this same
| point in (x', y, z)=(x1+2v*t, y1, z1) which is by no means independent of
| time.

Really?

| This is the reasoning behind choosing x'=x-vt, since this effectively
| eliminates the time dependence of the x' coordinate.

Explain "effectively". Here, I'll give you a diagram. One that should be
painfully obvious to anyone who has ever studied physics.
t0 x'------------x---x''-------
t1 ----x'--------x-------x''---
t2 ---------x'---x------------x''
> vt >

Which is also
t0 ---------x'------------x---x''
t1 ---------x'--------x-------x''
t2 ---------x'---x------------x''
> vt >
Now tell me how choosing x' = x-vt makes it "effectively" independent of
time and chosing x'' = x+vt does not.

|
| > | For this to be true you would have to invert
| > | the direction of movement of k along the x-axis, meaning that you new
v'
| > | = -v, in which case you end up with the same expression that you get
| > | choosing x'=x-vt.
| >
| > Are you telling me that the RHS of the equation which you carefuly
snipped
| > to deliberately induce confusion doesn't change?
|
| I did not snip anything to induce confusion. If anything, I am trying very
| hard to avoid confusing you. But yes, I am saying that the entire equation
| stays the same.

Really. Proof, please.
½[tau(0,0,0,t)+tau(0,0,0,t+x'/(c-v)+x'/(c+v))] = tau(x',0,0,t+x'/(c-v))"
is the same as
½[tau(0,0,0,t)+tau(0,0,0,t+x'/(c-v)+x'/(c+v))] = tau(x',0,0,t+x'/(c+v))"
because
tau(x',0,0,t+x'/(c+v)) = tau(x',0,0,t+x'/(c-v))
Yes, I suppose it is if v = 0, which is trivial.
Conclusion: special relativity is valid for all values of v that are equal
to zero.

|
| > | Sounds like you have not understood the fundamental
| > | reasoning behind the choice of x'=x-vt. It is not arbitrary, given the
| > | initial movement of k.
| >
| > Is that what is "sounds like"?
| > It sounds to me as if you are guesser and a snipper, ignoring what you
| have
| > no answer for, and certainly you have not understood the fundamental
| > reasoning behind (2/3 + 1/3)/2 = 1/3, or that cars may be driven
forwards
| as
| > well as backwards, in which case (2/3 + 1/3)/2 = 2/3.
|
| I have throughout this "debate" tried to maintain a sober tone of writing.

"Sounds like you have not understood..." is arrogance, not "tried to
maintain a sober tone". If you want to discuss physics, keep the personal
crap out of it, sonny, or you'll find I retaliate in like manner. Try a
little harder. "x' is no longer independent of time, which should be
painfully obvious to anyone who has ever studied physics". Who do you think
you are bamboozling?

| You are the one who has ignored several of my questions, and who has now
| lowered yourself to name-calling.

What "name" have I called you? You were the first to use the word "troll".

| I have clearly indicated where I snipped
| your original text, and it has been done only to ensure that any casual
| readers could more easily find their way around the posts. I even
indicated
| that I snipped intermediate steps in your derivation,

What do you mean, MY derivation?

| to make it sure that
| noone believed that you jumped even faster to your false conclusion.

Well done. You've made it very clear that you consider Einstein's false
conclusion was jumped to. Make sure you tell that to "noone" so they'll
believe you when you say are "familiar with Einstein's work on special
relativity".
|
| As for the rest of this sentence...(2/3+1/3)=1/3? I am hoping that this is
| either a joke or a typo. In either case, the entire thing makes no sense.

But

½[tau(0,0,0,t)+tau(0,0,0,t+x'/(c-v)+x'/(c+v))] = tau(x',0,0,t+x'/(c-v))

does, I suppose, since you are "familiar with Einstein's work on special
relativity".

|
| > Or am I discussing special relativity with a troll?
| > Androcles
|
| I have had just a single course on special relativity in my physics
| education, and since then only met it briefly in various other courses.
| Special relativity isn't really that vital in the branch of physics I have
| chosen.

It isn't vital to anything, my friend, unless poppy*** is vital.

| However, even with that slight introduction to the field, I feel
| quite capable of discussing the theory with you.

We'll see.

| I wonder if you have any
| physics background at all.

Back to the personal crap again. You are boring me with your arrogance.
I wonder if you have any background at all.

| The notion of a non-time-dependent coordinate
| system (x', y', z') = (x' - vt, y', z') is not something related solely to
| special relativity.

It isn't related to anything at all.
Since when did x' = x'-vt? When t = 0 or v = 0, I suppose. Heck, if you
can't even get your notation right, it's little wonder nothing makes sense
to you. Spelling mistakes I can tolerate, but that (X, y', z') = (X - vt,
y', z') is a monumental gaff.

| If you have not caught on to the fundamental reasoning
| behind this choice of coordinates, then you would have had a hard time
| grasping basic mechanics as well.

Personal crap again? Blustering gets you nowhere.
|
| I think if you could swallow enough of your pride you might be able to
| actually learn something from all of this.

Good advice. Take it yourself. Start with losing some of that arrogance, cut
out the personal crap and maintain a sober tone of writing.

Androcles.

| / Jesper P