Groups > sci.physics.relativity > #582438

Re: Annotated version of SRT

From	Thomas Heger <ttt_heg@web.de>
Newsgroups	sci.physics.relativity
Subject	Re: Annotated version of SRT
Date	2022-04-10 09:14 +0200
Message-ID	<jbfeeoFgs4lU1@mid.individual.net> (permalink)
References	(19 earlier) <6764db6a-256b-46c2-83ca-ab2d74811565n@googlegroups.com> <jbbeghFo9obU1@mid.individual.net> <t2qf3s$uqr$1@gioia.aioe.org> <jbcm7iFr8jU1@mid.individual.net> <t2sbk2$ka$1@gioia.aioe.org>

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Am 09.04.2022 um 18:18 schrieb Michael Moroney:
> On 4/9/2022 2:08 AM, Thomas Heger wrote:
>> Am 09.04.2022 um 01:05 schrieb Michael Moroney:
>>
>>>>>> Usually the author should say, how he likes his symbols to be
>>>>>> understood.
>>>>>
>>>>> It's completely specified in the paper.
>>>>>
>>>>>> But since Einstein did not define his variables,
>>>>>
>>>>> He did.
>>>>
>>>> Sure. Actually he did that occasionally.
>>>>
>>>> But he used the symbol 'Y' for different purposes and in case of the
>>>> electric field strength vectors he left the question open, how that
>>>> 'Y' should be interpreted.
>>>>
>>>> Meant was the y-component of the field strength vector at point
>>>> (x,y, z).
>>>>
>>>> But what he meant was most likely also a vector, but with only one
>>>> entry: something like (0, Y, 0).
>>>
>>> Again, to simplify the example of an object moving at right angles to a
>>> magnetic field, with axes defined appropriately (direction of motion
>>> along X axis, magnetic field along Y axis).  No need to involve
>>> complexity needing the cross product etc.
>>
>> Totally wrong!
>>
>> The effect on a moving charge by a magnetic field is usually described
>> by vectors and cross products.
>
> In the full 3 dimensional description.  Not for this simplified case
> where motion is along the x axis and the magnetic field is at a right
> angle to it.  The resulting force is trivially calculated, and is
> understood as being at right angles to both the x axis speed and the
> right angle magnetic field.

But Einstein had written about this case, where an electric field 
accelerates an electron along the x-axis of K in streight lateral motion.

This can be seen here:

[quote from page 22]
"If an electron moves from rest at the origin of co-ordinates of the 
system K along the axis of X under the action of an electrostatic force 
X, it is clear that the energy R withdrawn from the electrostatic ﬁeld 
has the value integral(Xdx). "

He had actually not written about a force, but about acceleration along 
the y-axis.

This can be seen in the second last equation on page 23

>> The cross product is also not such an advanced tool, that nobody can
>> actually use it.
>
> Yet it is more complex than the simplified case presented.  Remember,
> one can ALWAYS choose a system of coordinates such that motion is along
> the x axis and a field at a right angle is along the y axis.

Cross products are not very sophisticated constructs.

>>> You have been told this many times, yet you ignore this.
>>
>>
>> Sure, I ignored your useless statement, because it is totally wrong.
>
> The physicists of the time didn't consider my statement as wrong.  If
> they did, it would have been flagged and Einstein told to resubmit his
> paper using full blown 3d vectors and cross products.  No need.

I don't live in Einstein's time.

As you tried to convince me, I would apply my current understanding, not 
the historic one of 1905.

>>>> The symbol 'Y' could have other meanings, too:
>>>>
>>>> for instance the y-axis of the stationary system K had the name 'Y',
>>>> too.
>>>
>>> In a different part of the paper.  Here it is defined differently.
>>
>>
>> This is VERY BAD !!!! practise!.
>
> No, it is not.  Certain variable names (especially x and y, or symbols
> frequently associated with a type of unit, such as v for velocity) are
> used in papers, both early and modern, repeatedly.

Well, yes. But in math the symbol 'x' means usually 'independent 
variable', while 'y' means 'dependent variable'.

In physics x,y and z mean coordinates in Euclidean space.

That's something else, hence an author needs to decide, how he would 
like to use such symbols.

To mix both meanings would be just terrible.

>> You should NOT redefine used symbols within a scientific paper without
>> good reasons to do so.
>>
>> There are tons of possibilities to name things with symbols, which you
>> can maintain throughout the entire paper.
>>
>> E.g. sub- or superscripts are a possibility or  hooks, ~, *, ° or
>> other signs like arrows or under- or overlines, different fonts,
>> different alphabets, upper- and lower-case and so forth.
>
> Was any of those dingbats used by others during Einstein's time?  Other
> than the heavier use of Greek letters then, it is similar to modern papers.

E.g. you may look at publications from Maxwell or Tait, which were 
actually older than Einstein's paper,  and how they distinguished 
vectors from functions, for instance.

The older papers are actually much easier to read, once you understand 
the symbols.

I have often martered my brain, when I have tried to find out, what 
Einstein actually meant with a certain variable, becaue Einstein gave 
not hints whatever. The few hints he actually gave, were used 
inconsistently.

E.g. the text attribute 'italic' was used, but without identifiable reason.

E.g. some equations contain italic and normal font letters, but the 
reason to do so remains a riddle. (page 18, lower third)

>>
>> There is absolutely no need to reuse the same symbol for other
>> purposes somewhere later in the same text.
>
> If the earlier point was made and is finished, no.
> Go sit in on a modern algebra or geometry course.  You'll see the
> instructor use the same symbols over and over and over again.

Usually an author should write list of used symbols and their meaning.
This would exclude any reuse of variable names, because these defintions 
are usually written at the end of the paper, hence the definitions 
operate backwards throughout the entire paper.

...

TH

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Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-05 13:58 -0400
  Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-06 08:22 +0200
    Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-07 07:45 +0200
      Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-07 01:20 -0700
        Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-08 08:14 +0200
          Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-07 23:47 -0700
    Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-07 01:06 -0700
      Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-08 08:40 +0200
        Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-07 23:56 -0700
          Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-08 20:50 +0200
            Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-08 19:05 -0400
              Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-09 08:08 +0200
                Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-08 23:51 -0700
                Re: Annotated version of SRT Odd Bodkin <bodkinodd@gmail.com> - 2022-04-09 13:02 +0000
                Re: Annotated version of SRT Coke Hishikawa <uhva@blseummh.nm> - 2022-04-09 13:21 +0000
                Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-09 12:18 -0400
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-10 09:14 +0200
                Re: Annotated version of SRT Mikko <mikko.levanto@iki.fi> - 2022-04-10 11:29 +0300
                Re: Annotated version of SRT nospam@de-ster.demon.nl (J. J. Lodder) - 2022-04-10 12:28 +0200
                Re: Annotated version of SRT Mikko <mikko.levanto@iki.fi> - 2022-04-10 16:54 +0300
                Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-11 00:50 -0400
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-10 21:52 -0700
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-11 07:42 +0200
                Re: Annotated version of SRT Odd Bodkin <bodkinodd@gmail.com> - 2022-04-11 11:01 +0000
                Re: Annotated version of SRT Paparios <mrios@ing.puc.cl> - 2022-04-11 05:50 -0700
                Re: Annotated version of SRT nospam@de-ster.demon.nl (J. J. Lodder) - 2022-04-11 18:20 +0200
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-11 09:48 -0700
                Re: Annotated version of SRT Paparios <mrios@ing.puc.cl> - 2022-04-11 09:54 -0700
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-11 12:32 -0700
                Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-11 18:39 -0400
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-11 21:28 -0700
                Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-12 06:36 +0200
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-11 21:38 -0700
                Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-12 06:47 +0200
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-11 21:58 -0700
                Re: Annotated version of SRT Richard Hachel <r.hachel@tiscali.fr> - 2022-04-12 11:14 +0000
                Re: Annotated version of SRT Richard Hachel <r.hachel@tiscali.fr> - 2022-04-12 11:10 +0000
                Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-11 12:38 -0700
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-12 18:48 +0200
                Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-12 11:37 -0700
                Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-13 02:37 -0400
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-14 08:36 +0200
                Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-13 23:44 -0700
                Re: Annotated version of SRT Michael Moroney <moroney@world.std.spaamtrap.com> - 2022-04-14 04:16 -0400
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-14 01:34 -0700
                Re: Annotated version of SRT Odd Bodkin <bodkinodd@gmail.com> - 2022-04-14 12:47 +0000
                Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-10 13:06 +0200
            Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-09 07:48 +0200
        Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-09 14:36 +0200
          Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-09 06:18 -0700
          Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-10 08:49 +0200
            Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-09 23:52 -0700
              Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-10 12:54 +0200
            Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-10 12:51 +0200
              Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-10 05:02 -0700
              Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-10 21:04 +0200
                Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-10 22:08 +0200
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-10 21:20 -0700
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-11 07:48 +0200
                Re: Annotated version of SRT Reinhardt Behm <rbehm@hushmail.com> - 2022-04-11 08:43 +0000
                Re: Annotated version of SRT nospam@de-ster.demon.nl (J. J. Lodder) - 2022-04-11 13:55 +0200
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-11 21:09 +0200
                Re: Annotated version of SRT Reinhardt Behm <rbehm@hushmail.com> - 2022-04-12 02:52 +0000
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-13 07:49 +0200
                Re: Annotated version of SRT Reinhardt Behm <rbehm@hushmail.com> - 2022-04-13 07:41 +0000
                Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-14 08:21 +0200
                Re: Annotated version of SRT Python <python@example.invalid> - 2022-04-14 14:38 +0200
                Re: Annotated version of SRT Maciej Wozniak <maluwozniak@gmail.com> - 2022-04-14 07:47 -0700
                Re: Annotated version of SRT Reinhardt Behm <rbehm@hushmail.com> - 2022-04-14 15:26 +0000
                Re: Annotated version of SRT Odd Bodkin <bodkinodd@gmail.com> - 2022-04-14 15:42 +0000
  Re: Annotated version of SRT Coke Hishikawa <uhva@blseummh.nm> - 2022-04-09 11:33 +0000
    Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-09 13:08 -0700
      Re: Annotated version of SRT nospam@de-ster.demon.nl (J. J. Lodder) - 2022-04-10 11:54 +0200
        Re: Annotated version of SRT Thomas Heger <ttt_heg@web.de> - 2022-04-10 21:10 +0200
        Re: Annotated version of SRT JanPB <filmart@gmail.com> - 2022-04-11 12:43 -0700

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