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Natural Science Forum / Physics / Relativity / December 2006



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Relativity - Affine Geometry ?

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Chris - 17 Dec 2006 18:46 GMT
Relativity - Affine Geometry ?
Abstract:

Einstein addressed the twin paradox in special relativity in a relatively
unknown, unusual and rarely cited paper written in 1918, in the form of a
dialogue between a critic and a relativist. Contrary to most textbook
versions of the resolution, Einstein admitted that the special relativistic
time dilation was symmetric for the twins, and he had to invoke,
asymmetrically, the general relativistic gravitational time dilation during
the brief periods of acceleration to justify the asymmetrical aging.
Notably, Einstein did not use any argument related to simultaneity or
Doppler shift in his analysis. I discuss Einstein's resolution and several
conceptual issues that arise. It is concluded that Einstein's resolution
using gravitational time dilation suffers from logical and physical flaws,
and gives incorrect answers in a general setting. The counter examples imply
the need to reconsider many issues related to the comparison of transported
clocks. The failure of the accepted views and resolutions is traced to the
fact that the special relativity principle formulated originally for physics
in empty space is not valid in the matter-filled universe.
Einstein's special theory of relativity is about measurements between frames
of reference in a state of non acceleration. It is an observation that the
velocity of light is independent of the relative velocity between observer
and the source. From this Lorenz postulated a length contraction to allow
for this. Einstein derived the same equation from the observations.
If you look at this equation there is no special frame so any frame may be
taken as the reference frame.
Let us consider the passage of mesons from the origin in the upper
atmosphere to their arrival at a counter on the earth's surface. The
observer "sees" the origin from his frame and since he is "looking" at the
meson then this point is only a few feet above the laboratory roof because
of the Lorenz contraction. Thus accounting for the short passage time. The
"meson" "sees" the path it travels from the upper atmosphere to the surface
as the same few feet as it is "looking" at the observer's reference frame.
It seems to me that there is no real contraction, only an effect similar to
perspective as a result of the way light travels and is only an appearance.
Relativity is 4-space perspective.
This would mean that a journey in a very fast space craft to a nearby solar
system (say 10 light years) would take a time given after the length
contraction and time contraction had been allowed for. (This is called the
4-velocity) I suggest that the 4-velocity is the "real" velocity and what we
see is the result of 4-space perspective.
V=v/sqr(1-(v/c)^2) V is the 4-velocity and the velocity in all frames.
It would therefore be possible for deep space journeys with a fast
spacecraft in normal time spans. (By fast I mean velocities close to that of
light - say closer than 99%c).
It also strikes me that since all frames are equivalent the "Twin Paradox"
does not occur, the two brothers will agree both about the time and distance
travelled.
Since perspective is the projection of 3-space to 2-space then relativity is
the projection of 4-space to 3-space.
Hello,

So even the man himself admitted his idea had been misinterpreted by his
followers.  The general theory relativity that deals with acceleration does
not map well into special relativity because the forces on the objects do
not influence signal exchanges in any way.

If you think of the star ship journey in terms of a two dimensional space
time diagram (other massive objects are too far away to be of any influence)
then you have a hill.  Now in normal hills the distance over the hill is
longer than the distance along the flat, but in the relativity case the
distance over the hill is shorter than the flat because it is a negative
hill.

That is because one of the dimensions is jct and the other is x now using
Pythagoras the hypotenuse for this negative hill, which is really just a
wobbly 'v' is 2*( x^2-(ct)^2)^0.5 and that is less than 2x.  This is because
we are in hyperspace. x is the "rest" distance and "t" is the time
calculated at the x/v where v is the velocity. So the distance travelled is
2*(x^2-(c(x/v))^2)^0.5.  and that takes (that distance)/v in real time.

The precise shape of the curve only means we need to do an integration along
the curve VIS differential geometry, I get it now, with my brand new brain,
fitted after they took out my old one a couple of months ago.

Get it! So space travel is really very easy you just have to fast enough.

"The faster you go, the quicker you get there" just like running a race!

I didn't win!

My understanding of special relativity is limited. However my opinion is
that the contraction effects are a 4-perspective effect due to the constancy
of the velocity of light, there is no physical contraction at all.

My mind forms a concept of a ^ shaped hill of the space-time trajectory of a
return particle path where the path over the hill is shorter that the path
taken at rest or very slowly, so the higher the velocity the shorter the
path over the hill. It is a metric space.

The other related point is the relativistic momentum now since the path
depends on the velocity then there is the notion of a real or true velocity
v/gamma. In the momentum of a particle the momentum as measured by collision
is m v/gamma so as the velocity increases the mass remains the same.

In the derivation of the kinetic energy the formula:
   mv/sqr(1-(v/c)^2)

may be separated into to partial fractions
   m x v/Sqr(1-(v/c)^2)
When you integrate with respect to v from 0 to a number less than c to find
the kinetic energy.

This gives the solution mc2 for the rest mass energy as with the older
Einstein version. He chose his method because of theological augment to make
the maths easier, he said "God would not choose such a complicated
mathematics". God is not stupid either.

This method gives the idea of a true or real velocity of v/sqr(1-(v/c)^2).

I am aware that this in not original but unfortunately theologians kill
people who come up with this (several times a month) along with the doubters
of Gauss.

Such is the evil of man (I disagree with you so your brain has gone wrong, I
will remove it) - Doctor your head has gone wrong it needs amputating!

However the time taken for a round trip works out different from the usual
relativity theory, as in a Metric space.

The general theory is a metric space where the distance shortest between
adjacent points is given by a metric resulting from the sum mass + energy
nearby. It could be represented by a matrix which could include the special
theory as terms in the matrix to work out the distance between adjacent
points.

Again there is no real contraction it caused by 4-perpective due the metric
caused by the constancy of the velocity of light.

Relativity - la Géométrie de Affine? Résumé:

Einstein a adressé le jumeau paradoxe dans spécial relativity dans un
relativement , insolite et rarement papier écrit dans 1918, sous form d'un
dialogue entre un critique et un relativist. La plupart des versions
exemplaires contraires de la résolution, Einstein a admis que la dilatation
de temps de relativistic spéciale était symétrique pour les jumeaux, et il
devait invoquer, asymétriquement, le relativistic général la dilatation de
temps gravitationnelle pendant les périodes brèves d'accélération pour
justifier le vieillir asymétrique. Notamment, Einstein n'a pas utilisé
d'argument relaté au changement de simultaneity ou Doppler dans son analyse.
Je discute Einstein et conceptuel qui . Il est conclu que Einstein en
utilisant gravitationnel temps dilatation de logique et physique défauts, et
donne inexact réponses dans un général reglage. Les exemples opposés
suggèrent que le besoin reconsidère beaucoup de questions relatées à la
comparaison d'horloges transportées. L'échec de l'accepté vues et
résolutions est tracé au fait qui le spécial relativity a formulé au début
pour physique dans vide espace n'est pas dans le question-rempli univers.
Einstein la théorie spéciale de relativity est des mesures entre les cadres
de référence dans un état de non-accélération. C'est une observation qui la
vélocité de lumière est indépendant du relatif entre observateur et la
source. De ce Lorenz a postulé une contraction de longueur pour tenir le
compte de ceci. Einstein a dérivé l'équation pareile des observations. Si
vous regardez cette équation il n'y a pas de cadre spéciale si n'importe
quel cadre peut être pris comme le cadre de référence. Considérons le
passage de mesons de l'origine dans l'atmosphère supérieure à leur arrivée à
un compteur sur la surface de la terre. L'observateur "voit" l'origine de
son cadre et puisque il "regarde" au meson alors ce point est seulement
quelques pieds au-dessus du toit de laboratoire à cause de la contraction de
Lorenz. Ainsi expliquant le temps de passage court. Le "meson" "voit" le
sentier il voyage de l'atmosphère supérieure à la surface comme pareil peu
de pieds comme il "regarde" au cadre de référence de l'observateur. Il m'a
l'air de qu'il n'y a pas de vraie contraction, seulement un effet similaire
à la perspective par suite des voyages de lumière de façon et est seulement
une apparence. Relativity est 4-la perspective spatial. Ceci signifierait
qu'un voyage dans un très spatial métier à un proche solaire système (dit 10
léger années) prendrait un temps donné après la longueur contraction et
avait été tenu compte de. (Ceci est appelé le de 4 vélocités) je suggère que
le de 4 vélocités est la "vraie" vélocité et que nous voyons sommes le
résultat de 4-la perspective spatial. V=v/sqr(1-(v/c)^2) V est le 4-et la
dans tout . Il donc serait possible pour profond spatial voyages avec un
rapide vaisseau spatial dans normal temps . (Par le jeûne je vélocités
moyennes ferment à que de lumière - dit plus près que 99%c). Il aussi frappe
me que puisque tous cadres sont équivalent le "Jumeau Paradoxe" n'arrive
pas, le deux frères consentira du temps et distance voyagé. Puisque la
perspective est la projection de de 3 espaces à de 2 espaces alors
relativity est la projection de de 4 espaces à de 3 espaces. Bonjour,

Si même l'homme s'a admis son idée avait été mal interprétée par ses
disciples. Le relativity de théorie général qui traite l'accélération ne
fait pas la carte bien dans relativity spécial parce que les forces sur les
objets n'influencent pas les échanges de signal dans la façon.

Si vous pense de l'étoile bateau sur le plan d'un à deux dimensions spatial
temps (autre massif objets trop loin seront obligé à être de n'importe
quelle influence) alors vous a une colline. Maintenant dans les collines
normales la distance par-dessus la colline est plus longue que la distance
le long du plat, mais dans le cas de relativity la distance par-dessus la
colline est plus courte que le plat parce que c'est une colline négative.

Cela est parce qu'une des dimensions sont jct et l'autre est x Pythagoras
qui utilisant maintenant l'hypoténuse pour cette colline négative, qui est
vraiment seulement un tremble 'v' est 2* (x^2-(ct)^2)^0.5 et cela est moins
de 2x. Ceci est parce que nous sommes dans hyperspace. x est la distance de
"repos" et "t" est le temps calculé au x/v où v est la vélocité. Si la
distance voyagée est 2*(x^2-(c(x/v))^2)^0.5. Et cela prend (cette distance)
/v en temps réel.

La forme précise de la courbe signifie seulement nous avons besoin de faire
une intégration le long du VIS de courbe géométrie différentielle, je le
reçois maintenant, avec mon cerveau tout neuf, ajusté après ils ont sorti
mon vieux un mois quelques il y a.

Le recevoir! Donc le voyage d'espace est vraiment très facile que vous venez
de jeûner assez.

"Le plus rapide vous allez, le plus rapide vous recevez là-bas" tout comme
courir une race!

Je n'ai pas gagné!

Mon est la compréhension de relativity spécial est limitée. Cependant mon
opinion est que les effets de contraction sont un effet de 4 perspectives
grâce à la constance de la vélocité de lumière, il n'y a pas de contraction
physique du tout.

Mon esprit forme un concept d'un ^ la colline formée de la trajectoire de
spatial-temps d'un sentier de particule de retour où le sentier par-dessus
la colline est plus court que le sentier pris en repos ou très lentement,
donc le plus haut la vélocité le plus court le sentier par-dessus la
colline. C'est un espace métrique.

L'autre relaté point est le relativistic maintenant puisque le sentier
dépendt de la vélocité alors est la notion d'un vrai ou vrai vélocité . Dans
l'élan d'une particule l'élan comme mesuré par la collision est le v/gamma
de m si comme la vélocité augmente la masse reste pareil.

Dans la dérivation de l'énergie cinétique la formule: mv/sqr(1-(v/c)^2)

Peut être séparé dans à m de fractions partiel x v/Sqr(1-(v/c)^2) Quand vous
intégrez par rapport à v de 0 à un numéro moins de c pour trouver l'énergie
cinétique.

Ceci donne mc2 pour l'énergie de masse de repos à la solution comme avec la
plus vieille version de Einstein. Il a choisi sa méthode à cause de
théologique accroît faire les maths facile, il a dit "Dieu ne choisirait pas
un tel compliqué mathématiques". Dieu n'est pas stupide ou.

Cette méthode donne l'idée d'un vrai ou vrai vélocité de v/sqr(1-(v/c)^2).

Je suis conscient que ceci dans pas original mais malheureusement les
théologiens tuent des gens qui propose ceci (à plusieurs reprises un mois)
avec les sceptiques de Gauss.

Tel est le diabolique d'homme (je suis en désaccord avec vous si votre
cerveau a fait une erreur, je l'enlèverai) - le Médecin que votre tête a
fait une erreur il a besoin d'amputer!

Cependant le temps pris pour un voyage circulaire travaille hors différent
de la théorie de relativity normale, comme dans un espace Métrique.

La théorie générale est un espace métrique où la distance la plus courte
entre les points adjacents est donnée par un résulter métrique de la masse
de somme + l'énergie proche. Il pourrait être représenté par une matrice qui
pourrait inclure la théorie spéciale comme les termes dans la matrice pour
travailler hors la distance entre les points adjacents.

Encore est aucun vrai contraction il a causé par 4-dû le métrique causé par
la constance de la vélocité de lumière.
Tom Roberts - 19 Dec 2006 05:47 GMT
> Einstein addressed the twin paradox in special relativity in a relatively
> unknown, unusual and rarely cited paper written in 1918, [...]

Hmmm. In that paper Einstein claimed GR is necessary to resolve the
paradox. But he is considering a DIFFERENT issue than the simple
question of how they can have different elapsed proper times between
meetings. Einstein is considering: how we can tell which twin is
inertial? SR has no mechanism to do that except by fiat -- one must
stipulate that this particular twin is inertial, and the rest follows.
But in GR no such stipulation is required, one can simply integrate
their proper times over their trajectories, whatever they are, inertial
or not.

    Today most authors take a geometrical approach to SR, and this
    difficulty disappears -- even in SR the spacetime manifold is
    taken as given, and that includes the determination of which
    frames are inertial, which resolves the problem.

It's not clear to me whether or not you understand this distinction.

BTW relativity is NOT affine geometry, it is Riemannian geometry -- the
concept of metric is essential.

> It seems to me that there is no real contraction, only an effect similar to
> perspective as a result of the way light travels and is only an appearance.
> Relativity is 4-space perspective.

That is correct. "Length contraction" and "time dilation" are simply
geometric projections (aka perspective).

> It also strikes me that since all frames are equivalent the "Twin Paradox"
> does not occur, the two brothers will agree both about the time and distance
> travelled.

See above. In SR two inertial twins can meet at most once, so the twin
paradox cannot involve two inertial twins. The analyst must select one
to be inertial, and that breaks the "symmetry".

> [... rest unread]

Tom Roberts
Sue... - 19 Dec 2006 07:14 GMT
> > Einstein addressed the twin paradox in special relativity in a relatively
> > unknown, unusual and rarely cited paper written in 1918, [...]
[quoted text clipped - 3 lines]
> question of how they can have different elapsed proper times between
> meetings.

Does he ever use the term "elapsed proper times"
http://www.nrao.edu/~smyers/courses/astro12/speedoflight.html
http://farside.ph.utexas.edu/teaching/jk1/lectures/node14.html

> Einstein is considering: how we can tell which twin is
> inertial?

In the 1920 paper the the term "inertial' appears only with
regard to Newton and in the chapter on "relativistic mass".

> SR has no mechanism to do that except by fiat -- one must
> stipulate that this particular twin is inertial, and the rest follows.

No... SR has no mechanism... Period.
<<A Lorentz transformation or any other coordinate
transformation will convert electric or magnetic
fields into mixtures of electric and magnetic fields,
but no transformation mixes them with the
gravitational field. >>
http://www.aip.org/pt/vol-58/iss-11/p31.html

The [] Incompatibility of the Law of Propagation of
Light with the Principle of Relativity  [is only] Apparent.
http://www.bartleby.com/173/7.html

You are doing  roll-your-own-relatvity,  not Einstein's
relativity if you are going to stipulate things he
didn't.

Einstein makes the mass/energy connection with the
"relativistic mass" heurism. Not by stipulating which
body is inertial.
http://www.bartleby.com/173/14.html
http://www.bartleby.com/173/15.html

> But in GR no such stipulation is required, one can simply integrate
> their proper times over their trajectories, whatever they are, inertial
> or not.

Yes... the stipulation is improper in SR and also improper in GR.

>     Today most authors take a geometrical approach to SR, and this
>     difficulty disappears -- even in SR the spacetime manifold is
[quoted text clipped - 20 lines]
> paradox cannot involve two inertial twins. The analyst must select one
> to be inertial, and that breaks the "symmetry".

No... there never was a symmetry.
Light has no mass to be inertial therefore:
<<A Lorentz transformation or any other coordinate
transformation will convert electric or magnetic
fields into mixtures of electric and magnetic fields,
but no transformation mixes them with the
gravitational field. >>
http://www.aip.org/pt/vol-58/iss-11/p31.html

Sue...

>  > [... rest unread]
>
> Tom Roberts
Sorcerer - 19 Dec 2006 09:56 GMT
[...]
I've never seen an aether, have you?
Chris - 19 Dec 2006 14:04 GMT
I do not understand it. There is no connection with any inertal frame,
acceleration is not mentioned in special relativity.

It is a clear case of a metric space and reinmann manifold is another name
for a metric space.

any how do you know anyone what has visited tau ceti, and met any of the
"tube worms" who live there. Nah but Maia has and it only took two hour
there and two hour back and she only lives down the road like m freind
hillary and the bar girl I know.

It is the church theologians who mucked up eistiens beautiful theory.

Ba! Rubbish! they said as they cut out her brain. Me ex gp said that, and I
have to visit the surgery tomorrow.

Now they want to inject me with flue. (that is to see if I survive - trial
by ordeal)

Chris.

>> > Einstein addressed the twin paradox in special relativity in a
>> > relatively
[quoted text clipped - 89 lines]
>>
>> Tom Roberts
Sue... - 28 Dec 2006 14:11 GMT
> I do not understand it. There is no connection with any inertal frame,
> acceleration is not mentioned in special relativity.

The connection is made by mass/energy equivalence.
http://www.bartleby.com/173/15.html

> It is a clear case of a metric space and reinmann manifold is another name
> for a metric space.
[quoted text clipped - 11 lines]
> Now they want to inject me with flue. (that is to see if I survive - trial
> by ordeal)

LOL

<<A Lorentz transformation or any other coordinate
transformation will convert electric or magnetic
fields into mixtures of electric and magnetic fields,
but no transformation mixes them with the
gravitational field. >>
http://www.aip.org/pt/vol-58/iss-11/p31.html
http://nobelprize.org/nobel_prizes/physics/laureates/1921/einstein-lecture.html

Sue...

> Chris.
>
[quoted text clipped - 91 lines]
> >>
> >> Tom Roberts
Sorcerer - 28 Dec 2006 16:06 GMT
[...]

I've never seen an aether, Dennis. Have you?

http://tinyurl.com/yndvwx

http://www.quackwatch.org/01QuackeryRelatedTopics/pseudo.html

http://www.youtube.com/watch?v=Pf3z935R37E
John Kennaugh - 28 Dec 2006 12:20 GMT
>> It seems to me that there is no real contraction, only an effect
>>similar to  perspective as a result of the way light travels and is
[quoted text clipped - 3 lines]
>That is correct. "Length contraction" and "time dilation" are simply
>geometric projections (aka perspective).

OK I look at 2 rods 1m in front of me both 1m long and they are the same
length.
I now move one rod. I perceive it to be shorter because it is further
away or it may appear shorter because I am viewing it at an angle. Its
true length has not changed and if at some future date I return it to
its original position it will appear the same length as it did
originally and the same length as its twin. That is "geometric
projections (aka perspective)". The change in length is an *apparent*
change in length not an *actual* change in length.

While I can appreciate that length contraction may be "geometric
projections (aka perspective)" I cannot see how you can claim the same
for time dilation if you accept the accepted result of the twin paradox.
If it were simply "geometric projections (aka perspective)" then there
would be no *actual* time dilation only *apparent* time dilation so that
when the twins watches are brought back together they should show the
same time/date.

Perhaps you can demonstrate how this is possible by showing how
"geometric projections (aka perspective)" in respect of Length
Contraction could result in a permanent difference in length.

Signature

John Kennaugh
to email convert the number from hex to decimal

Tom Roberts - 29 Dec 2006 05:17 GMT
>> "Length contraction" and "time dilation" are simply
>> geometric projections (aka perspective).
>
> While I can appreciate that length contraction may be "geometric
> projections (aka perspective)" I cannot see how you can claim the same
> for time dilation if you accept the accepted result of the twin paradox.

The twin paradox does not directly involve "time dilation". It is rather
a demonstration that the integrated proper time between a given pair of
points is path dependent.

"Time dilation" is just the observation that when one observes a moving
clock, the interval between its ticks is longer than the interval one
observes when it is at rest. Crucial to this observation is the fact
that it requires two synchronized clocks to measure the interval between
two ticks of a moving clock.

"time dilation" and "length contraction" are both simply projections of
one invariant length onto another coordinate system -- just like a
building appears to be wider when viewed from its front than from its
corner. The twin paradox, on the other hand, is analogous to the fact
that the sum of two sides of a triangle are longer than the third side.

> Perhaps you can demonstrate how this is possible by showing how
> "geometric projections (aka perspective)" in respect of Length
> Contraction could result in a permanent difference in length.

But it doesn't -- when you take that erstwhile moving clock and bring it
to rest in your inertial frame, then its tick rate will be the same as
your identical clock's tick rate -- just as the moving ruler, when
brought to rest in your inertial frame, has a length the same as your
identical rulers.

The length of a ruler is a differential distance, as is the time
interval between ticks. Integrated proper time over a path, as in the
twin paradox, is like the path length of sides of a triangle (integrated
distance over the path consisting of 1 or two sides).

Tom Roberts
Sue... - 29 Dec 2006 06:21 GMT
> >> "Length contraction" and "time dilation" are simply
> >> geometric projections (aka perspective).
> >
> > While I can appreciate that length contraction may be "geometric
> > projections (aka perspective)" I cannot see how you can claim the same
> > for time dilation if you accept the accepted result of the twin paradox.

Tom,
Did you omit some specifics?

The twin paradox does not directly involve "time dilation".
[because time dilation may sometimes desribe retarded
time, the Sagnac effect, the Doppler effect or nuclear
resonance]

[Yes... Time-dilation  belongs in scare-quotes]

<<
It is rather
a demonstration that the integrated proper [space-time]
between a given pair of points is path dependent.

"Time dilation" is just the observation that when one observes
[calculates?] a moving  clock, the interval between its ticks is
longer than the interval one  observes [calculates?] when it is at
rest. Crucial  to this [calculation] observation is the fact
that it requires two [Einstein synchronized? ] synchronized
clocks to measure the interval between
two ticks of a moving clock.

"time dilation" and "length contraction" are both simply [sometimes?]
projections of  one invariant length onto another coordinate
system -- just like a  building appears to be wider when viewed
from its front than from its  corner. The twin paradox, on the
other hand, is analogous to the fact
that the sum of two sides of a triangle are longer than the third side.

[ No... the twin paradox results from improperly mixing imaginaries
and reals]
http://www.nrao.edu/~smyers/courses/astro12/speedoflight.html

> > Perhaps you can demonstrate how this is possible by showing how
> > "geometric projections (aka perspective)" in respect of Length
> > Contraction could result in a permanent difference in length.

<<
But it doesn't -- when you take that erstwhile moving clock
and bring it  to rest in your inertial frame, then its tick rate
will be the same as  your identical clock's tick rate -- just
as the moving ruler, when  brought to rest in your inertial
frame, has a length the same as your  identical rulers.

The length of a ruler is a differential distance, as is the time
interval between ticks. Integrated proper time over a path, as in the
twin paradox, is like the path length of sides of a triangle
(integrated
distance over the path consisting of 1 or two sides).

S: No... that is mixing dielectric and inertial effects impropely.

<<A Lorentz transformation or any other coordinate
transformation will convert electric or magnetic
fields into mixtures of electric and magnetic fields,
but no transformation mixes them with the
gravitational field. >>
--S. Weinberg
http://www.aip.org/pt/vol-58/iss-11/p31.html see also:
--C. S. Unnikrishnan
http://www.iisc.ernet.in/currsci/dec252005/2009.pdf

Sue...

> Tom Roberts
Koobee Wublee - 29 Dec 2006 08:03 GMT
> The twin paradox does not directly involve "time dilation". It is rather
> a demonstration that the integrated proper time between a given pair of
> points is path dependent.

This is truly amazing.  Another name for the twin paradox is the time
paradox.  It addresses the very core belief of SR that is the symmetric
time dilation itself.

> "Time dilation" is just the observation that when one observes a moving
> clock, the interval between its ticks is longer than the interval one
> observes when it is at rest. Crucial to this observation is the fact
> that it requires two synchronized clocks to measure the interval between
> two ticks of a moving clock.

How about when the twins actually meet with no relative speed between
them?

> "time dilation" and "length contraction" are both simply projections of
> one invariant length onto another coordinate system -- just like a
> building appears to be wider when viewed from its front than from its
> corner. The twin paradox, on the other hand, is analogous to the fact
> that the sum of two sides of a triangle are longer than the third side.

Were you a preacher once?
bergeron - 31 Dec 2006 21:15 GMT
> > The twin paradox does not directly involve "time dilation". It is rather
> > a demonstration that the integrated proper time between a given pair of
> > points is path dependent.
>
> This is truly amazing.  Another name for the twin paradox is the time
> paradox.

 Another, more accurate name would be ``The Eternal Wulblee Stumper."

> It addresses the very core belief of SR that is the symmetric
> time dilation itself.

 Unfortunately, you fail to realize what has been addressed.
It is very easy to see that the twins are _not_ a symmetric
system. Simply include the means by which the acceleration
is accomplished and you might possibly be able to figure out
which twin undergoes the greatest acceleration from the ratio
of their masses and therefore which undergoes the largest boost
relative to the original common inertial frame.

 Normally, most students figure out that the problem assumes
the earth is much more massive than the rocket ship and then,
employing a lengthy tradition going back at least to Galileo,
ignores details like fuel consumption, method of propulsion,
number of passengers, luggage and other details which are
completely irrelevant to the point of the exercise. For the
most part, students manage to recognize the point.

> > "Time dilation" is just the observation that when one observes a moving
> > clock, the interval between its ticks is longer than the interval one
[quoted text clipped - 4 lines]
> How about when the twins actually meet with no relative speed between
> them?

 What about it? You can build in all of the accelerations, turns,
barrel rolls, and loop-the-loops you want to make the question as
difficult as you feel necessary. Since you can't seem to get the
idea that the elapsed time is the line integral over a world
line, you are only making it more difficult to miss the point
entirely.
Koobee Wublee - 31 Dec 2006 21:47 GMT
> > This is truly amazing.  Another name for the twin paradox is the time
> > paradox.
>
>  Another, more accurate name would be ``The Eternal Wulblee Stumper."

Good idea.  Will you stick to it?

> > It addresses the very core belief of SR that is the symmetric
> > time dilation itself.
>
> Unfortunately, you fail to realize what has been addressed.

Sadly, you have failed to realize all these resolutions are absolute
BS.

> It is very easy to see that the twins are _not_ a symmetric
> system.

Then, you are denying the principle of relativity.  You cannot embrace
the Lorentz transform and discard the principle of relativity.

> Simply include the means by which the acceleration
> is accomplished and you might possibly be able to figure out
> which twin undergoes the greatest acceleration from the ratio
> of their masses and therefore which undergoes the largest boost
> relative to the original common inertial frame.

Show me the math.

> Normally, most students figure out that the problem assumes
> the earth is much more massive than the rocket ship and then,
[quoted text clipped - 3 lines]
> completely irrelevant to the point of the exercise. For the
> most part, students manage to recognize the point.

Through more BS.

> > How about when the twins actually meet with no relative speed between
> > them?

> What about it? You can build in all of the accelerations, turns,
> barrel rolls, and loop-the-loops you want to make the question as
> difficult as you feel necessary. Since you can't seem to get the
> idea that the elapsed time is the line integral over a world
> line, you are only making it more difficult to miss the point
> entirely.

You can easily design an experiment to allow both twins to travel and
experiencing the same acceleration.  In doing so, you will see your
hand-waving is fruitless.  <shrug>
 
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