Re: Twin paradox revisited ll

On Jul 21, 3:15 pm, "Jeckyl" <no...@xxxxxxxxxxx> wrote:
"bill" <cosmo...@xxxxxxxxxxxxxxx> wrote in message

news:1184981064.527191.20310@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

No I would not. I cannot accept that the traveler *really* believes
that the earth is orbiting the sun at around 1m-s nor do I believe
that this is what would 'really' be happening.

What has the belief of some astronaut got to do with the physics?

My point precisely.

During the acceleration the situation is much more
complicated but the answer is essentially the same.

As regards whether it is 'physically' happening, I cannot
answer this question unless you define exactly what you
mean 'physically'.

By 'physically' I mean the concept that the earth is 'really' orbiting
the sun at 1m-s as distinct from 'apparently' as determined by the
traveller.

In the traveller iFoR it is

In other words 'as far as the traveller is concerned'.

Who was its wrote - 'What has the belief of some astronaut got to do
with the physics?'

It has nothing whatsoever to do with what *we*, as stay at home
observers observers, think but what is claimed the *traveler*
determines is reality.
Yes, for the traveller.
So he *really* believs that the earth is *physically* orbiting the sun
at 1m-s?

It is .. in his iFoR

Who was its wrote - 'What has the belief of some astronaut got to do
with the physics?'

What we can tell is that, when the two twins meet up, the travelling
twin has aged less than the earthbound twin.

One could argue that inertial clocks run as quickly as possible
and that the best way of describing what has happened is
to say that the non-inertial (travelling) twin's clock has been
slowed down.

Other than what one 'could argue' I fully agree with those comments
but I cannot agree, as expressed above, that the stay at home
*physically* ages at the faster rate thus that the traveler could
obliterate all life on earth by taking his foot off the gas pedal.

You need to define 'physically'.

That the traveler destroys all life on the planet.

He destroys nothing .. it just happens over the long period of time that
elapses on the earth

This concept has nothing whatsoever to do with the *total* difference
between the traveler's elapsed time and the twin's elapsed time.

The original posting, to which this lot relates, was that at the very
instant that the astronaut stops accelerating the earth's orbital
velocity of the sun reverts from close to the speed of light to its
more mundane 30K-s - a braking effect that would destroy all life on
the planet - from the traveler's point of view of course but what has
the belief of some astronaut got to do with the physics?

When he returns
home he learns - hopefully - that this has not *physically* taken
place.

But it has

It has *not*. You are mistakenly of the opinion that I am referring to
the *total* difference between the traveler's overall elapsed time and
the twin's overall elapsed time. I'm *not*!

I'm talking about the traveler's view of what's happening back in the
solar system at any given instant.

The fact that the traveler finds on his return that everything is
'normal' back here - that life continues - should indicate to him that
the earth had *not* been orbiting the sun at near light speed, that
what he saw or determined was nothing more than a visual illusion
generated by his rate of travel.

No, it indicates that the passage of time is not universal. Of course,
on his return, the traveller will be aware that, from the earthbound
twin's point of view, nothing unusual has happened.

Having 'believed' that all life on the planet has been obliterated it
would not only be 'from the earthbound twin's point of view, nothing
unusual has happened' but also from the *traveler's* point of view.

It really happens

See above. Continuously repeating the same argument does not give it
validity.

The bit you have not grasped is that the passage of time is not
universal. This is very counterintuitive but it is the inescapable
conclusion of experiment.

Or rather, in the *interpretations* of those experiments. As far as I
am aware there has been no experiment which proved that from the
traveler's point of view it is his twin that ages at the faster rate
than himself.

Time dilation is experimentally proven .. time goes slower for moving
objects.

Time goes slower for moving objects however this does *not* prove that
time goes *faster* for stationary objects.

I am of the opinion that the years are flying by and, as I get older,
this feeling is increasing and the reason for this is that people are
conducting particle acceleration experiments?

My only consolation is that those people are *also* aging at faster
rates than they should every time they conduct those experiments. They
should either wake up to themselves or the claim that an inertial
clock *physically* ticks over at a faster rate because another clock
has been made to move relatively to it should be abandoned. I know
what I would prefer.
Before you start the immolation process - the original posting was
that the traveler (presumably knowledgable in physics and relativity)
*forgets* (or simply *ignores*) his training and, although
experiencing the force of acceleration, is of the opinin that his twin
is physically aging at a faster rate than himself and that his is
*not* the special relativity (or Einstein's 1918 article related)
moving clock.

If he *knows* the details of Einstein's 1918 article - that it is the
clock that experiences the force of acceleration as it moves to the
location of the other clock which is the one that according to
*Einstein* is the one that *physically* incurs time dilation - and,
having personally *experienced* a force of acceleration considers
himself to be at rest he is denying a proper application of knowledge.

Some postings to this discussion insist that acceleration is not
relative however as the traveler hits his accelerator he sees the
light emanating from the earth becoming progressively blue shifted and
the only conclusion at which he can arrive - from his solipsist point
of view - is that the earth is accelerating toward him.

He can therefore *in his own reference frame* obliterate all life on
earth *at the very instant that he take his foot off the gas*. When he
returns to the planet and finds that life has not been extinguished
*at the instant that he took his foot off the gas* but that, although
having aged to a greater extent than himself or that millions of years
have elapsed and that the apes have gained mastery (they should have
been obliterated at that same instant i.e. *all* life), that his
observation (determination, measurement) was, to say the least,
misleading; that it obviously did *not* take place irrespective of
what he determined in his iFoR.

In accordance with the concept that the belief (measurement,
determination, observation) of some astronaut has absolutely nothing
whatsover to do with the physics i.e. with reality he must conclude
that what he saw was *not* reality; that the earth was *not*
physically orbiting the planet at 1m-s or near light speed; that his
twin was *not* physically aging at a faster rate than he was as he
accelerated following turn around.

My argument has always been that the traveler would presumably have
some knowledge of physics and relativity and that he should be allowed
to *apply* that knowledge thus conclude that although being unable to
determine, via any internal dynamic experiment, if he is at rest or is
moving with a uniform velocity his observation that the entire
universe is moving relatively to him is *actually* a result of the
fact that *he* is moving relatively to his location on the launch pad
- *not* that it is the *universe* that has been made to accelerate to
a velocity close to the speed of light relatively to when he was at
rest at the end of his outward bound trip.

.

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