Groups > sci.physics.relativity > #599859

Re: Kinetic Energy formula check - a series of short burn rockets, and see how the velocity adds up.

From	Thomas Heger <ttt_heg@web.de>
Newsgroups	sci.physics.relativity
Subject	Re: Kinetic Energy formula check - a series of short burn rockets, and see how the velocity adds up.
Date	2023-01-19 09:28 +0100
Message-ID	<k2sd92Fud77U1@mid.individual.net> (permalink)
References	(10 earlier) <1c40752b-50d6-4c70-98ea-3ad0bfde5ad0n@googlegroups.com> <k2kbehFn2nnU1@mid.individual.net> <tq6nuu$3b8ve$1@dont-email.me> <k2poiiFi1jiU1@mid.individual.net> <tq9ojl$12dv7$1@dont-email.me>

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Am 18.01.2023 um 22:33 schrieb Volney:
> On 1/18/2023 3:22 AM, Thomas Heger wrote:
>> Am 17.01.2023 um 19:04 schrieb Volney:
>>
>>>> Such inertial frames require absense of gravity, which we earthlings
>>>> obviously cannot provide.
>>>
>>> As usual in physics, especially then, things are tested to within an
>>> error limit, where it can be shown the error from the existence of
>>> gravity or whatever is smaller than measurement errors or outcome error.
>>>
>>> Secondly, this is theoretical, it's what happens when there is no
>>> gravity even if such a situation is difficult or impossible to reproduce
>>> in real life. Just like Einstein's trains, moving at a substantial
>>> fraction of c, with observers able to time flashes from lightning bolts
>>> as a train passes an embankment aren't real.
>>>
>>>> But in such a dark and gravity free inertial frame, you have abolutely
>>>> nothing, which could eventually help you to measure absolute velocity.
>>>
>>> And Einstein doesn't try to use any absolute velocity. He says simply
>>> here's a frame where the equations of Newton's mechanics hold good. Are
>>> you going to complain that Einstein didn't discuss moving objects around
>>> and accelerating them to test Newton's mechanics?
>>>>
>>>> In that scenario you always need something, where you could base your
>>>> position vectors on.
>>>
>>> You, the observer, say "Here's the origin".
>>
>> That would be actually correct, but was not, what Einstein said.
>
> He defined a frame in which 'equations of Newton hold good'. Period. He
> defined the origin. No other reference frame necessary.
>>
>> I personally use a concept I call 'subjectivism', which states, that
>> all observers would naturally take the own position and base
>> observations upon that.
>
> Thus, Einstein use the perspective of an unnamed observer and called
> this frame "the stationary frame". That's really just a name, it has no
> special features like being "absolutely stationary" in some way.

What Einstein had in mind is not important, but what he wrote in his text.

I wrote a critique about 'On the electrodynamics of moving bodies' and 
didn't attempt to read his mind in a psychoanalysis.

It is simply irrelevant, what Einstein really wanted, if he didn't write 
that in his paper.

Also subsequent papers are irrellevant for a review, because at the time 
of the article those didn't exist.

That's why I'm allowed to ignore Einstein's real intentions, if they 
were not put into words and those into the text.

Sure, 'the perspective of an unnamed observer' would make sense, but I 
cannot find such a statement in the text.

Contrary to your view, Einstein gave the impression, that he wanted to 
measure velocity against a static and well defined universe.

This was actually a self-contradicting statement, because Einstein also 
wrote, that Newton's absolute space would not exist.

This would require some specualtions about what else would replace 
Newton's universe and 'the perspective of an unnamed observer' would be 
in fact an option, but Einstein left that question to the reader.

And I, as a reader, interpreted Einstein's statements, that he wanted to 
refer to the universe in the sense of the space of fixed stars, but 
erronously also declared that space for noexistent.

This is self-contradicting, because that space of the fixed stars was 
also Newton's 'absolute space', which Einstein said wouldn't exist.

TH

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