Re: Does anyone really know the physical cause for time dilation and length contraction?

From	Odd Bodkin <bodkinodd@gmail.com>
Newsgroups	sci.physics
Subject	Re: Does anyone really know the physical cause for time dilation and length contraction?
Date	2016-05-19 07:48 -0500
Organization	Aioe.org NNTP Server
Message-ID	<nhkcm4$1f7r$1@gioia.aioe.org> (permalink)
References	(4 earlier) <0463f78b-c778-4ce6-8566-02316fe17a0c@googlegroups.com> <nhcu07$npp$4@gioia.aioe.org> <db7a76ae-4757-4ac5-8e12-9fcb1524b01e@googlegroups.com> <nhd78i$182t$1@gioia.aioe.org> <896bab90-0c7a-4bb0-a887-196e3f68fc51@googlegroups.com>

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On 5/19/2016 3:47 AM, Nicolaas Vroom wrote:
> Op maandag 16 mei 2016 21:32:40 UTC+2 schreef Odd Bodkin:
>> On 5/16/2016 2:17 PM, jay moseley wrote:
>>
>>> Temper temper. But you are wrong. Speed is not
>>> measured. Only assumed.
>>
>> Not true, Jay. Your ignorance of experimental procedures is not an
>> excuse to make up fictions instead.
>
> Let us try to stay with the facts
>
>> In the Advanced Photon Laboratory, for example, photons are created when
>> a charged particle beam passes a "wiggler" magnet, something that
>> happens in a very well-defined, narrow time window and something that is
>> actually recorded by monitors.
>
> This narrow time window indicates the inaccuracy in your measurement of
> individual photons

The narrower the window, the more precise the time-of-flight measurement.

>
>> Tangential to that location on the ring
>> and downstream quite a ways are photon detectors, which fire when the
>> photon or photons arrive, again in a very tight signal.
>
> Also here it is very difficult to link "creation" versus "destruction"
> of individual photons to measure its speed

No, it's not, the narrowness of the time window assures that.

>
>> Knowing the time
>> and location of the point the photons where created, and the time and
>> location of the point where they appear downstream, the time-of-flight
>> and of course the speed of the photons is measured in about the most
>> direct way possible.
>
> You are correct if you mean the best way possible.
>
>> Notice the speed of the photons is not assumed, it is directly MEASURED.
>
> That is the question.
> It is extremely difficult (impossible?) to measure the speed of individual
> photons.
> The question is what are the results?
> The link:
> http://www.aps.anl.gov/About/APS_Overview/insertion_devices.html
> does not supply this information.

Oh dear. I see you are trying to figure it out by looking at Overview 
web pages. How about you look up the published papers about the design 
of the APS.

> The link:
> http://www.aps.anl.gov/About/APS_Overview/linac.html
> tells you that c = 299792458 m/sec but not how this speed is measured.
> When I read the text, what they measure is the speed of electrons.

That's because you're not reading about the part of the accelerator 
where the photons are in flight. Good grief.

>
>> Likewise in time dilation experiments, the speed of the passing objects
>> is measured by time-of-flight between two recording locations along the
>> path of motion. Thus the speed is MEASURED, not assumed. The time
>> dilation is also MEASURED, not assumed. And so the correlation between
>> the time dilation and the speed is a MEASURED comparison with theory.
>
> It is an interesting discussion what the difference is between
> a measurement, a calculation, a calibration and a correlation.
>
>> Physicists do not have an obligation to come to you and teach you, to
>> correct your ignorance.
>
> Physicists have an obligation to listen to any question, to ask questions
> when the question is not clear and to try to answer the question
> the best they can, with always doubt in their mind.

Nicolaas, this is naive at best. Physicists have the obligation to 
answer questions if they have taken the job of teaching a class and the 
people asking the question have paid tuition to take that class. 
Physicists have the obligation to explain a subject if they have engaged 
with a publisher to write a book or an article on the subject. 
Physicists have the obligation to answer questions about their work from 
other physicists to whom they are communicating their research. 
Physicists do NOT have an obligation to hear and respond to questions 
from the interested amateur, any more than you can get free medical 
consultation from a doctor you meet at a dinner party. Grow up and do 
the work. Your options are to take a class, read books and articles on 
your own, or to hire a physicist as a tutor.

>
> Nicolaas Vroom
>

-- 
Odd Bodkin --- maker of fine toys, tools, tables

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