The Symmetric Twin Paradox [Physics]

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From: colp on 17 Jun 2010 05:36

On Jun 17, 5:56 pm, "Peter Webb"
<webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > When
> > this is tested by actual experiment, the travelling twin is younger.
>
> In the symmetric paradox that I spoke of in my previous post, both
> twins travel and they are the same age, despite the predictions of SR.
> I'm not going to argue about the classic paradox because the paradox
> is much easier to show in the symmetric case.
>
> ________________________________
> If the situation is that both twins travel, and this is symmetric, then SR
> predicts that they will have aged the same amount when re-united into the
> same inertial frame.

Wrong. SR predicts that one twin will observe time dilation of the
other both on the outgoing and incoming legs. In no case does SR
predict that that a twin will observe any kind of time compression of
the other twin that would be necessary to compensate for the
theoretically observed time dilation. Without such compensation for
the observed time dilation, SR predicts that a twin will be older than
the twin he observes, which contradicts with logical result of the
twins being the same age.

> If you do believe SR predicts anything different, then
> you are wrong about the predictions of SR.

If I am wrong and you understand SR then why are you unable to
identify any error in my reasoning?

>
> Can you produce a single experiment which shows that SR is wrong?

Yes, I have described the thought experiment that shows that SR is
wrong, and you have been unable to show any flaws in my argument. The
experiment is described in full at the following page:

http://adsabs.harvard.edu/abs/2008arXiv0804.2008N

From: Androcles on 17 Jun 2010 05:43

"Paul Cardinale" <pcardinale(a)volcanomail.com> wrote in message
news:34dbe709-3cc8-408b-9648-83e1e0e33d5e(a)d8g2000yqf.googlegroups.com...
|A person of normal intelligence

That leaves you out.

From: Tom Roberts on 17 Jun 2010 09:13

Peter Webb wrote:
> GPS will function without any GR effect applied if indeed exists. You
> can google the previous few posts by yours truly to understand how GPS
> works.

This is just plain not true. The relativistic effects in the GPS are well known
and are MEASURED to agree with the predictions of GR to excellent accuracy. The
GPS could not possibly work without applying the relativistic effects.

Note that the GPS is an ENGINEERED system, and consists of clocks
both in satellites and on the ground.

It is true that a similar system without ground clocks could IN PRINCIPLE be
designed to work without relativistic corrections; IN PRACTICE the engineering
of such a system would be impossible (e.g. any satellite that missed its orbit
by a small amount would be useless); the required perfection does not occur in
the real world. Fortunately, the designers of the GPS knew this and designed a
system that actually works; it requires BOTH relativistic corrections and daily
parameter updates (the largest corrections are to satellite orbits). Note that
the manufactured modification to the satellite clocks (due to relativistic
effects) completely dwarfs the daily updates.

Tom Roberts

From: kado on 17 Jun 2010 09:17

On Jun 16, 7:10 pm, colp <c...(a)solder.ath.cx> wrote:
>
snip
>
> Some solutions proposed by the relativists are:
>
> 1. Only consider one frame of reference, since SR fails when moving
> between inertial frames.
> 2. Ignore the paradox. Draw some timelines and say that everything is
> O.K.
> 3. Claim that the time dilation will be compensated for by
> acceleration, even though there is no experimental support for time
> compression arising from acceleration.
> 4. Feet stamping and name calling.

I am in general agreement with your assessment, but there are
several things that must be addressed to enhance your position,
and before this debate can be elevated to a logical and
intellectual level.

This paradox arises from the tenets of Einstein's Special Theory
of Relativity of 1905.

Einstein's Special Relativity addresses only uniform motion.
Uniform motion implies (actually demands by definition) velocity,
i.e., uniform (constant) speed in a straight line. So the resolution
of the subject paradox cannot employ any notion acceleration,
that by definition is a time rate change of velocity.
Furthermore, the idea of acceleration was not introduced into
Einstein's arsenal until he formulated the General Theory of
Relativity, a decade after this paradox arose. In other words;
any notion of acceleration cannot be applied to resolve this
paradox.
Moreover, the concept of uniform motion excludes any turning
around. This in it's self creates another paradox, for it prevents
the twins from ever coming together again.

Einstein employed the idea that time contracts (not compresses,
yes I realize this is nit picking, but such nit picking is
important),
always contracts. and only contracts when moving near the
velocity (not speed) of light. The idea of time dilation was
formulated in the mid 1960, about a decade after the death of
Einstein, so the idea of time dilation also did not exist in
Einstein's Special Relativity.

Nevertheless, Special Relativity predicts that the traveling twin
will age slower than the stay-on-Earth twin, while at the same
time the stay-on-Earth twin will age slower than the traveling
twin, because of the 'slower ticking clocks' with the frame of
reference of each twin and Nature is time symmetrical.

So even if the twins cannot ever come together, each will still
be younger than the other at any instant (point in time) by the
tenets of SR.

Now don't bring up Einstein's Principle of the Relativity of
Simultaneity, because Einstein really goofed on this by
basing this foolish idea on when the phenomenon/event/
thing of interest is observed by the human observer, not
when it occurred. The finite speed of light prevents the
observation/detection of any 'thing' from being simultaneous
with the occurrence, even if it occurred only a few meters
away from the observer. It does not take a postulate to make
the detection of a particular phenomenon from following the
occurrence, and not being simultaneous with the occurrence,
just common sense and a knowledge of physics. The
concept of simultaneity is valid, and the idea of 'any point in
time' is valid, especially if measured by like slow ticking
clocks.

So the twin paradox has not been resolved, even if all the
silly relativists who think they understand SR come with all
the BS posted on this thread.

D.Y. Kadoshima

From: Tom Roberts on 17 Jun 2010 09:21

colp wrote:
> On Jun 17, 1:25 pm, "Peter Webb"
> <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
>> Have you got a single experiment where SR predicts time dilation but it does
>> not occur?
>
> The symmetric twin thought experiment (as described in the OP) is such
> an experiment.

No. It is a GEDANKEN, not an experiment. There are no actual measurements of
this situation.

> In the experiment SR predicts that the twins will both be younger than
> each other when they return to Earth, which is of course impossible.

This is just plain not true. You and that paper did not actually use SR. The
comic book used does not describe the actual theory accurately enough to be useful.

> Some solutions proposed by the relativists are:
> [...]

Those are not the real solution. The REAL solution is to actually use SR in the
analysis of this gedanken.

Tom Roberts