Re: Relativity and Clocks


"Curious" <anthonyroseuk-curious@xxxxxxxxxxx> wrote in message
news:1117824257.155400.95920@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
>
>
> [Please excuse the delayed response, I'm moving house.]
>
> Well, I was waiting to see what the times on the clocks would be in
> frame 2. Before anyone answered that I realised that they must be
> unsynchronised (in frame 2) by exactly the time difference of the two
> photons' arrival (again as timed in frame 2). This is the only way the
> bomb could go off as per frame 2. *
>
> [In fact since then I now understand more clearly that time has become
> a variable co-ordinate in the transformation of co-ordinates for any
> space-time point between the two frames, and thus the different times
> showing on the clocks and the different arrival times of the two
> photons (different times as per frame 2) are simply results of the
> *same* transformation for those points of space-time - the photon's
> arrival and the clock's time shown are calculated by the same function
> and must therefore undergo the same deviation by definition of the
> transformation function. The only question left is, can frame 2 really
> have a different set of real times for frame 1's space at time x or is
> there another explanation. I don't want this answered for me as I'm am
> still working through the alternative explanation technically (or
> rather, semi-tech!).]
>
> * But at that stage I thought you said something to the effect of, Hang
> on, you don't understand something, we need to discuss xyz first.
> So I expected us to get back to the bomb later and see what happens
> from frame 2 and what the clocks say. Now I realise we are done with
> it. And I'm fine with that.
>
> >
> > I take it by 'we' you mean you and me on this group.
> > There is plenty of evidence for SR. Have you looked at:
> > http://www.physics.adelaide.edu.au/~dkoks/Faq/Relativity/SR/experiments.html
>
> I may be upsetting quite a few people here but they can console
> thesmelves with the thought that I'm just an idiot, I've browsed a lot
> on that site and I think it's terrible. It assumes, it skims, it
> skips... as an intro for someone who doesn't want to think things
> through deeply it's fine, but as a defense for SR I think it's poor.

That page just refers to the experiments that support SR.
Obviously if you want the details you will have to look at
the original papers.


> By 'we' I meant the entire world scientific community: I realise SR is
> entrenched and practically effective but it is not the only viable
> theory.

SR is the only theory in use anywhere in the world. What
other viable theory did you have in mind.


> Furthermore, we are still getting to grips with understanding
> relativity, are we not? There are some elements to SR/GR predictions
> that do not quite fit observations??

No. There is no more reason to doubt SR than there is to
doubt any other theory of physics. For any theory there is
always the odd result that does not agree. Nearly always
a reason such as experimental error or a wrong analysis
is found to account for the discrepancy.

If reproducible experiments find serious discrepancies
between theory and observation than the theory needs to be
changed. This is exactly what happened to Newtonian
physics at the start of the twentieth century. It is not the
case with SR or GR.


> One memory that surfaces here from
> a skim I did was that the planetary orbits have some minor
> quirks/deviations/angle adjustments (I forget the word/exact concept)
> and the author claimed that SR/GR did not account for them nearly as
> well as it fitted that of Mars (or was it Mercury), so in fact rather
> than supporting evidence it was challenging evidence.

The net is full of crackpots.

In the link that I gave you Tom Roberts discusses that results that
seem to disagree with relativity. There really is nothing serious.


> Back to the point: we cannot assume that because a model's predictions
> fit with observational experiment, that the model's underlying
> postulates and deductions are correct.

There is no such thing as 'correct' in physics. Physics is about finding
a quantitative model that agrees with experiment. It is not about finding
the 'real' rules by which the universe operated, we can not even be sure
that there are any.

> When arriving at such a weird
> conclusion that time is altered under motion, I'd keep looking, because
> the idea that every moving body in the universe is under the influence
> of its own unique time frame is, frankly, ridiculous, although barely
> possible.

I am not sure that there are degrees of possibility in this context.
It is possible - it happens.

> I'd much rather assume *for example* that a moving body's
> *'experience'* of time is altered - that moving atoms oscillate slower
> - and see if this can account for the same observations.

Of course it can.

We can either say that all clocks (meaning everything that measures,
or senses time) are changed or that time itself is changed. What is
the difference.

If you really want a theory to look at you should study
Minkowski's geometric interpretation of SR (which is
the mainstream theory).

Let me ask you this question, I would be interested
in your answer: do things really get smaller when
they are further away from you?

> And keep
> stretching my assumptions and worldview in lateral ways to see if there
> is another less impossible model to account for things. Like the world
> moving through the aether by translation rather than 'transvection' if
> there is such a word. But I'm out of my depth on reviewing let alone
> justifying such hypotheses of course.

You really have to try to imagine how many really clever
people over the last century have studied and analysed
relativity and found no fault or viable alternative (no doubt
you have been told about LET).


> But as a result of our being reluctant to assume or to rely on a
> postulate unnecessarily, I'd rather not depend our experiments on
> something which we are still measuring. To put it another way, if light
> is always measured at c regardless of the motion of the detector, we
> should really look more closely at how the detector is being affected
> by its motion - and if we rely on something which travels at
> relativistic speeds, such as light, we may inadvertently deny ourselves
> the window through which we need to look. Furthermore, we may need to
> examine light itself further.

There is nothing special about light except that it moves
at the maximum possible speed. All the relativity experiments
could have been done using something else that moves quickly.
Basically the faster things move the greater the discrepancies
with Newtonian physics are.

> So I'd rather just move the clocks slowly
> for now - this doesn't guarantee anything but it doesn't add another
> layer of assumption. Admittedly I don't have the physics and this is
> just intuitive but you did ask me to raise a flag on any issue.
>
> >
> > In other words Einstein's method and the assumption that slowly
> > transported clocks remain synchronised both give the same result.
>
> One-way speed of light measured is subject to some assumptions,
> including:
> a) measured = reality i.e. that our instruments are not affected in
> some way

Scientists are always checking for ways in which their instruments
may be in error but if absolutely every type of clock is always
affected in exactly the same way you have to listen to the results.


> b) circumstance of experiments cover all circumstances which can affect
> light speed
> There are others I can think of but these will do.
> Why bother with using light when we have a means already?

You may see yourself as having a free and independent mind
that can see through things that other might have missed but in
reality you are limiting your mind and your imagination.

I say this not to insult you nor because I think I am so clever
myself, but I have studied a small fraction of the works of
others on this subject and I have some idea just how much
thought has gone into this subject.

Maybe it just needs some time to sink in. While you are waiting
have a look at Minkowsi spacetime.

Martin Hogbin


.

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