Re: Twin paradox revisited ll

On Jul 24, 6:55 pm, "Martin Hogbin" <goatREMOVETHIS...@xxxxxxxxxx>
wrote:
"bill" <cosmo...@xxxxxxxxxxxxxxx> wrote in messagenews:1185235954.440484.53780@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I agree that the travelling twin will see that the earth clock
*appears* to be running slower than his own clock but if he insists
that it *is* physically ticking...

You continue to try to understand what happens in terms of
the normal meaning of English words. This cannot be done.
There is no parallel to this situation in everyday life and no
English words to fully describe what happens. If you cannot
understand this point you will never make any progress.

If something that happens cannot be described in everyday language
then in my opinion that 'thing' or 'event' does not take place. If it
can only be 'described' in mathematical 'language' or propositions I
agree with Einstein that it has no place in the real world.

over at a slower rate than his own
clock he is denying Einstein's 1918 article by insisting that he,
having experienced the force of acceleration, is *not* the moving
twin.

I understand that the 'twin paradox' resulted from questions raised by
people such as Dingle asking 'which is the *moving* clock? and that
Einstein attempted to overcome this paradox by pointing out that it is
the clock that experiences a force of acceleration which is, in
response to *that* question, *the* moving clock and that it is this
*moving* clock that incurs time dilation.

Most people seem to be ignoring this factor, making no response to
same.

It is the fact that one twin accelerates and one does not that
makes the situation non-symmetrical.

Thank you, simple everyday language that most people can understand.

Do you accept that in *Einstein's* opinion it is the accelerated clock
that incurs time dilation *not* that the other clock incurs time
*contraction*? I'm not referring to what some physicists now believe
but what *Einstein* believed!

I cannot possible answer the question as to what Einstein believed
any particular moment and neither can anyone else. It is quite
unimportant anyway. Einstein was a great physicist who proposed
and developed his theories of relativity; he was not a prophet
and to try to construe the meaning of is every word is pointless.

I did not ask if you can "answer the question as to what Einstein
believed at any particular moment" but if you accepted Einstein's
opinion *as expressed in his 1918 article*?

Einstein showed that a clock that is made to travel in a circular path
around another clock ticks over at a slower rate than the stationary
clock. He did not, and would not, have written that the stationary
clock is then physically ticking over at a faster rate than it was
*before the other clock went into orbit* around it.

For a person accompanying that orbiting clock to insist that the
stationary clock is *physically* ticking over at a faster rate than it
was *before he went into orbit around it* is a ludicrous solipsist,
philosophical concept that has no place in *reality*.

In SR, a clock made to travel on a circular path is not in an inertial
frame. Making measurements from a non-inertial frame is
complex and bizarre. Even in Newtonian mechanics, measurements
from non-inertial frames are significantly more complicated.

The Hafele-Keating experiment as well as information garnered from
global positioning satellites and from particle acceleration
experiments have *all* involved non-inertial frames yet they are *all*
cited providing confirmation of SR.

A version of the traveler's journey whereby he does not take a
straight out and return journey but travels in a circular path
provides the same argument as the former example but - as you point
out - this is *not* an 'inertial frame' journey.

He *can* say that the stationary clock *IS* ticking over at a faster
rate than his clock but to insist that this has *physically* occurred
- that the rate of operation of the stationary clock has *physically*
increased rather than the fact that the rate of operation of *his*
clock - as the result of its rate of travel with respect to the
stationary clock - has decreased, is solipsist nonsense!

You really must try to understand the point I am making about
use of the English language. You _must_ define exactly what you
mean by each of your emphasised words.

Anybody who suggests that during the first leg of the Hafele-Keating
experiment the laboratory clocks physically started ticking over at a
faster rate than the clocks in the aircraft and that during the second
leg the laboratory clocks physically started ticking over a slower
rate than the flying clocks is sprouting solipsist nonsense and if
that's what 'physics' shows the somebody should have a good look at
the subject of reality.

That is not what I asked. Which of the orbiting clocks told
the right time?

And I answered that - each of them told the time *in their reference
frame*.

I very much doubt that Hafele or Keating, during the first leg of the
experiment , insisted that they were not moving, that it was the
planet's axial spin that had slowed down.

Of course not.

Thank you, that's precisely my point. A traveler who insists that the
earth's axial spin decreases or increases on the basis that what he
sees is, from his point of view reality, would also insist that Hafele
or Keating *would* have concluded that it was the planet's axial spin
that had slowed down.

We could move the HKX to the abovementioned off-earth circular
trajectory journey where the astronaut commences his trip from a
geostationary location. This is precisely the same as Einstein's
reference to a clock that is made to travel in a circular path around
another clock but the traveler's course (clock's path) is eccentric to
the earth (Einstein's central clock).

For that astronaut to insist that during his trip the earth's axial
spin alternately increased and decreased is just as nonsensical as
Hafele or Keating insisting that the earth's axial spin physically
decreased during the first part of the experiment and that it
increased during the second part of their experiment.

Thirdly, we can try to come up with forms of words which
describe the situation You might say that the mutual slowing
of clocks is a consequence of measurement in the world
in which we live.

On the other hand, *I* would say that the mutual slowing of clocks is
a solipsist nonsense which introduced a paradox that Einstein,
apparently unsuccessfully, attempted to solve.

This is not what all the world's physicist's would say.

I am of the opinion that at least *some* of the world's physicists
might agree with Hafele and Keating that the laboratory clocks did
*not* tick over at a faster rate than their own clock during the first
leg of the experiment because for this to take place they would also
have to believe that the earth's axial spin had increased and that the
earth's axial spin decreased during the second leg of that experiment.
Seemingly you do not believe that either Hafele or Keating would have
insisted that this actually took place.

I assume that you mean that *all* of the world's physicists would say
that a clock that is moving past another clock would physically tick
over at slower rate than the latter and that the latter would
physically tick over at a slower rate than the former which is *not*
what Einstein wrote in his 1918 article where he insisted that it is
*only* the clock that experiences the force of acceleration as it
moves to the other clock's location *which is the one that has
incurred time dilation*. Of course, all the world's physicists might
not agree with Einstein.

Although the Hafele-Keating experiment did not involve SR's required
inertial reference frames I presume that *some* of the world's
physicists would agree that the flying clocks ticked over at a slower
rate than the laboratory clocks during the first leg of the experiment
thus that they agree with Hafele and Keating's (assumed) decision that
the earth's axial spin did not slow down.

This would be acceptable to most
physicists. A more personal view is that physics is all
about measurement, so the slowing is real, but here I am using
'real' in a specific way to mean 'as measured'. I would not
use the word in this context without explaining what I meant
by it.

If we 'measured' or 'determined' the shape of a steel rod placed in a
tank of water we would *assume* that it has bent at the surface of the
water however we *then * apply our knowledge (as Confucius suggested
we should) and come to the conclusion that *in reality* the rod has
*not* been deformed but that this is only a visual illusion in the
same way that the *apparent* slowing down of a *stationary* clock is
the result of a visual illusion created by *our* motion relative to
*it*.

Correct. When we make a measurement of a relatively moving
clock we do exactly the same. We make allowance for all known
effects. _After we have done that_ we find the moving clock to be
ticking more slowly than our own.

Granted. What I'm saying is that if a person who is accompanying that
clock finds that our clock is ticking more slowly than his own we have
a paradox which, apparently, Einstein sought to overcome with his 1918
article.

We can also use analogies to explain what we mean or
talk only in mathematical language. As Daryl has suggested
the more ways you have of looking at the subject the better
your understanding will be.

In 1989 I read an article in a local newspaper supposedly quoting
David Mermin from Cornwell University as stating that the moon
physically ceases to exist if nobody looks at it. The author continued
that it is the actual act of looking at the moon that creates its
reality and that this is the belief held by some of the world's best
physicists.

Such points may be relevant to a discussion about quantum
mechanics but they are not relevant to SR.

The 'observation creates reality' concept that the moon ceases to
exist if nobody looks at it or - conversely - that it is the act of
observation that creates reality, *is* relevant to the idea that if
the traveler observes the other clock to be ticking over at a slower
rate than his own clock this is, in his opinion, 'reality' in the same
way that Hafele or Keating (hypothetically) observing the laboratory
clocks apparently ticking over at faster rate than their own clocks
could have assumed that the laboratory clocks *were* ticking over at
the faster rate than their own clocks thus, consequently, that the
earth was spinning at a faster rate than it was before they took off.

A former Head of the School of Mathematics at the University of New
South Wales, Australia, Professor Simon Prokhovnik in his article 'The
twin Paradoxes of Special Relativity: Their Resolutions and
Implications' (having provided an equation in support of his theory)
wrote "There are plenty of self-consistent mathematical systems which
have scant relevance to physical phenomena or observations."

I agree, but SR is not one of them.

Einstein stated "As far as the propositions of mathematics refer to
reality, they are not certain; and as far as they are certain, they do
not refer to reality." He, of course, referred to *all* other
propositions of mathematics *except* SR did he?

It must be very difficult to provide logical analogies for
mathematical systems that have no application to reality.

In his opinion, all life is extinguished yet you classify this as
being 'no change'?

Incorrect. as explained below, he does not believe that.

If I was in his position I would head for the
nearest star.

I agree that all experimental results require interpretation but
the interpretations used in SR are no different from those used
in Newtonian physics. If you use light to measure some distant
event you must make allowance for its transit time, for example.
This is perfectly normal, indeed not to do so would be an
obvious error.

In their book 'The Matter Myth' Professors Paul Davies and John
Gribbin depict the explosion of a star that is two light years away
from the earth at the instant that the light from another exploded
star located another two light years further out reaches that star's
location and point out that, from our point of view, those stars
exploded simultaneously *and* at the very instant that we saw those
explosions based on the concept of 'zero four-dimensional spacetime
continuum' whereby we do *not* 'make allowance for [lights] transit
time'.

In his book 'Fiction Stranger Than Truth' Nikolai Rudakov quoted
Mendelssohn as stating

"It is not much sense for an astronomer, who sees a flare appear on
the sun, to say that the flare occurred eight minutes earlier because
the light takes eight minutes to travel this distance.
Since no faster means exist to inform the observer sooner of this
event, the latter only acquires physical reality for him at the moment
when he sees it."

This refusal to accept reality, i.e. not allowing for the transit time
of light, *is* 'an obvious error' or, in my opinion, mushroom
treatment.

Yes, of course it is. If you believe that relativity does that
you are suffering under a serious delusion.

What gave you that impression?

.

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