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Natural Science Forum / Physics / Relativity / January 2007



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Has the University of New South Wales,  lost it.

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THE_ONE - 28 Jan 2007 13:52 GMT
See

http://www.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm

Click on Time dilation.

The animation shows Jasper's and Zoe's observation of a single light
clock in action.

Now there is only one clock in the animated experiment, but according
to UNSW, the number of ticks of the clock is different when viewed
from different reference frames. ???

According to UNSW, over the given time period of the experiment,
Jasper counts 6 clock ticks, and Zoe counts 10 ticks ???

Granted, it does say that the rate of these ticks differ from the
different reference frames, but that simply means that if one had an
atomic clock in each frame, and one measured the rate of the clock
ticks, then the rate of the clock ticks when measured would be
different in each frame, but the number of ticks would still be the
same, since there is only ONE BLOODY CLOCK !
Dumbledore_ - 28 Jan 2007 17:44 GMT
> See
>
[quoted text clipped - 18 lines]
> different in each frame, but the number of ticks would still be the
> same, since there is only ONE BLOODY CLOCK !

So relativists can't count... <shrug>
What's new?
Dirk Van de moortel - 28 Jan 2007 18:15 GMT
> See
>
[quoted text clipped - 18 lines]
> different in each frame, but the number of ticks would still be the
> same, since there is only ONE BLOODY CLOCK !

Yes, you are right.
The time dilation animation does not try to make you understand
why there is time dilation and why you get 10/6.
The text does that in a reasonably adequate way.
The creator of the animation assumes that you have read the text
and understand it, and so he tries to illaustrate the effect. It does
so however in a very poor way.
Very silly.

Dirk Vdm
Dumbledore_ - 28 Jan 2007 19:10 GMT
"Dork Van de merde" aka
"Dork Van de psychopath",
"Dork Van de psychotic fumble mumbler",
"Dork Van de fuckhead",
[anip]

 http://users.telenet.be/vdmoortel/dirk/Physics/TwinsEvents.html
"We use 3 inertial reference frames" [because Dorks can't get the result
they want in two].
"In neither of these frames any form of acceleration is felt" [neither one of
all three].
"In order for the travelling twin to make HIS trip, SHE must be in frame S'
while going away".
"if T = 5 years and v = 0.8c, then the stay at home twin will have aged
10 years".

Belgium is where the farts blow.

"Your conclusion is dead wrong.
Start over, but skip the first part and the conclusion." -- Dork Van de
fuckhead.

"You made a mistake" -- Dork Van de psychotic fumble mumbler.

ASSistant professor Paul B. Andersen, tusseladd:

"That is, we can reverse the directions of the frames
which is the same as interchanging the frames,
which - as I have told you a LOT of times,
OBVIOUSLY will lead to the transform:
 t = (tau-xi*v/c^2)/sqrt(1-v^2/c^2)
 x = (xi - v*tau)/sqrt(1-v^2/c^2)
or:
 tau = (t+xv/c^2)/sqrt(1-v^2/c^2)
 xi = (x + vt)/sqrt(1-v^2/c^2)"
THE_ONE - 29 Jan 2007 12:19 GMT
On Jan 28, 1:15 pm, "Dirk Van de moortel" <dirkvandemoor...@ThankS-NO-
SperM.hotmail.com> wrote:

> > See
>
[quoted text clipped - 27 lines]
>
> Dirk Vdm- Hide quoted text -- Show quoted text -

Thanks for seeing the light !

It is just that it annoys me that Universities can make such errors.

It reminds me of university grads such as Doctors and specifically
Dentists. I used to run into numerous problems after each time
additional amalgam implants were  added to my teeth.  It caused nasty
myofacial pains that lasted for months and never completely faded
away, and eventually led to myofacial muscle spasms that occurred on
average of every second day. On top of that, body temperature dropped,
the tip of my nose was always blue, and my hands were always ice cold.

But I assumed, while still at a young age, that university grads with
qualifications such as now being a Doctor, in combination to the fact
that the medical association also supported the actions that which my
dentist was practicing, was also constructed out of university grads
with impressive degrees, that they all new exactly what they were
doing, and therefore that what they were doing was completely safe.  
The impression that was quit strong during that time, was that Doctors
were Gods.

And so the problems that I was having, just did not make sense at
all.  This was especially the case when my immune system also
collapsed which led to numbers of other health problems.  But by
chance, I stumbled into someone else who had also experienced these
same problems.  He connected me with Dentist in particular who did
basically nothing but remove amalgam fillings. His office walls were
covered with letters from his patients, thanking him for saving their
lives.  Not one square inch of any of the four walls was left
uncovered.  Letters were even overlapping due to having run out of
room.   I read some of them, and felt much better when I saw that they
said things such as, " My blood circulation has returned to normal.
" , " I can shake hands again without people saying that my hands are
ice cold every damn time. " , " I am no longer being controlled by
massive Candida yeast infections, internally and externally, now that
my immune system has recovered ", , etc., etc.  Their were hundreds
and hundreds of letters saying THANK YOU THANK YOU THANK YOU......

I too recovered after having all those amalgam filling removed which
by the way contain 50% Mercury.

It turns out that the Mercury, a heavy metal, messes with the immune
system, and much more, as it proceeds to replace light metals within
the body, with this heavy metal. Most people however, are not effected
because it is known to have a knee effect, meaning that the health can
be reduced a bit over time, but eventually you hit the knee point
where all hell breaks loose, but for most people, they would not reach
that knee point until they were well over a hundred years old.  But
some are not so lucky, and they can be hit while still just in their
twenties.  Both the Canadian, and American Dental Associations had
refused to release any test results that had proven that the amalgam
filling were safe for all.  That is because they did not have any test
results of this nature, but in fact of the opposite.  So instead they
quietly gradually reduced the use of the metal amalgam fillings.

And so, when I see universities F_CK up, I become concerned about what
the outcome of such mistakes will be in the long run.
Dirk Van de moortel - 29 Jan 2007 12:42 GMT
> On Jan 28, 1:15 pm, "Dirk Van de moortel" <dirkvandemoor...@ThankS-NO-
> SperM.hotmail.com> wrote:
[quoted text clipped - 34 lines]
>
> It is just that it annoys me that Universities can make such errors.

Well, it's not the university that made the error. It's the grad
student they asked to create the animation and the prof who
failed to scrutinize the result
But afaiac it's not a big deal though. I hate these animations
anyway, so I never even look at them. Perhaps that's what
the prof didn't as well ;-)

> It reminds me of university grads such as Doctors and specifically
> Dentists. I used to run into numerous problems after each time
[quoted text clipped - 49 lines]
> And so, when I see universities F_CK up, I become concerned about what
> the outcome of such mistakes will be in the long run.

Quite a story there. Thanks for sharing.

Cheers and take care,
Dirk Vdm
THE_ONE - 29 Jan 2007 13:02 GMT
On Jan 29, 8:13 am, "Dirk Van de moortel" <dirkvandemoor...@ThankS-NO-
SperM.hotmail.com> wrote:

> > On Jan 28, 1:15 pm, "Dirk Van de moortel" <dirkvandemoor...@ThankS-NO-
> > SperM.hotmail.com> wrote:
[quoted text clipped - 96 lines]
> Cheers and take care,
> Dirk Vdm- Hide quoted text -- Show quoted text -- Hide quoted text -- Show quoted text -

Thanks again.

By the way, the Amalgam fillings, even at that time, were illegal in
many European countries.  In other countries, it was at least illegal
to add or remove amalgam fillings in women if they were pregnant. The
spill of mercury, which occurs in either of these practices, goes into
the skin of the mouth and also the stomach if you happen to swallow
any of the fluid that was in the mouth.  This then exposed the fetus
to high levels of mercury, and so it was considered to not be a safe
practice.

Having had the nasty experiences that I have been exposed to, I have
even made a quick exit from a room once. A large fluorescent tube was
dropped and it shattered.  The fact that these light tubes contain
mercury, forced me to respond without even thinking.
sal - 29 Jan 2007 16:26 GMT
> By the way, the Amalgam fillings, even at that time, were illegal in many
> European countries.  In other countries, it was at least illegal to add or
> remove amalgam fillings in women if they were pregnant. The spill of
> mercury, which occurs in either of these practices, goes into the skin of
> the mouth and also the stomach if you happen to swallow any of the fluid
> that was in the mouth.

And any vapor which is released may also be inhaled.

Anyone considering having amalgam fillings removed should be aware that it
may be important to undergo a course of chelation therapy at the same
time, to soak up the mercury which will inevitably be freed up by the
process, some of which will find its way into your bloodstream.  Absent
the chelation, filling removal can supposedly make the problems worse.

Signature

Nospam becomes physicsinsights to fix the email

Trevor Morris - 29 Jan 2007 12:01 GMT
> See
>
[quoted text clipped - 18 lines]
> different in each frame, but the number of ticks would still be the
> same, since there is only ONE BLOODY CLOCK !

Ironic that UNSW should get this wrong - Geoffrey Builder & Simon Prokhovnik
must be spinning in their graves...
Dirk Van de moortel - 29 Jan 2007 12:13 GMT
>> See
>>
[quoted text clipped - 21 lines]
> Ironic that UNSW should get this wrong - Geoffrey Builder & Simon Prokhovnik
> must be spinning in their graves...

I just wrote them an email asking them to correct this, together
with another mistake.
The other is in the length contraction part. See if you can find it.

Dirk Vdm
Trevor Morris - 29 Jan 2007 15:52 GMT
>>> See
>>>
[quoted text clipped - 27 lines]
>
> Dirk Vdm

On closer examination, I think all the animations are OK as far as they go.
I am not so sure about some of the text, because for example Jasper should
be judging the rate of Zoe's clock only in terms of his own clock, not in
terms of her perception of her clock.  This is what may have thrown the OP -
the ratio 10:6 is that between the rate of Jasper's clock (which is not
mentioned directly) and Zoe's.

The squirting of the purple paint spray or a particular passage of a light
pulse through a semi-silvered mirror (red flash in the first animation) are
each unique physical events.  So there can obviously be only one number of
ticks between such events, using a single clock.  And that is just what we
get in the animations: two transits of the light pulse across the car
between sprays or red flashes.

But because the timed events involve two separate locations in Jasper's
frame and only one in Zoe's, there is a lack of simultaneity between the
given events at the two ends of the verandah as judged in the two frames, as
is explained with a third animation.

I can't see anything actually incorrect in the UNSW article as a
conventional exposition of SR, but of course I would prefer a different
approach altogether...

TM
Sue... - 29 Jan 2007 16:44 GMT
>  I can't see anything actually incorrect in the UNSW article as a
> conventional exposition of SR, but of course I would prefer a different
> approach altogether...

The absurdity of resolving the apparent confllict with Maxwell's
equations  and the principle of relativity by reference to biological
process has been discredited since P. Langevin's time.

http://www.iisc.ernet.in/currsci/dec252005/2009.pdf

See equation 511 for the resolution taught in a *real* physics
program.
http://farside.ph.utexas.edu/teaching/em/lectures/node50.html

Sue...

Time-independent Maxwell equations
Time-dependent Maxwell's equations
http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html

Maxwell's equations in classic electrodynamics
(classic field theory)_
a) Maxwell equations (no movement),
b) Maxwell equations (with moved bodies)
http://www.wolfram-stanek.de/
maxwell_equations.htm#maxwell_classic_extended

> TM- Hide quoted text -- Show quoted text -
Trevor Morris - 29 Jan 2007 21:43 GMT
>>  I can't see anything actually incorrect in the UNSW article as a
>> conventional exposition of SR, but of course I would prefer a different
[quoted text clipped - 5 lines]
>
> http://www.iisc.ernet.in/currsci/dec252005/2009.pdf

Thanks for the reference. I entirely agree with the author that it is not
necessary to bring in GR to resolve the Twins Paradox, but his conclusion
has been reached by many authors before. And I am not sure what biological
processes have to do with it.

> See equation 511 for the resolution taught in a *real* physics
> program.
> http://farside.ph.utexas.edu/teaching/em/lectures/node50.html
>
> Sue...

Thanks for this one and the others below too: nice to see someone at last
getting around to retarded potentials in this context(apart from Heaviside,
Lorentz and Feynman, that is).

TM

> Time-independent Maxwell equations
> Time-dependent Maxwell's equations
[quoted text clipped - 8 lines]
>
>> TM- Hide quoted text -- Show quoted text -
Sue... - 29 Jan 2007 23:01 GMT
> >>  I can't see anything actually incorrect in the UNSW article as a
> >> conventional exposition of SR, but of course I would prefer a different
[quoted text clipped - 8 lines]
> has been reached by many authors before. And I am not sure what biological
> processes have to do with it.

The website of the OP makes unfounded statements about biological
clocks.

> > See equation 511 for the resolution taught in a *real* physics
> > program.
[quoted text clipped - 3 lines]
> getting around to retarded potentials in this context(apart from Heaviside,
> Lorentz and Feynman, that is).

Indeed, Heaviside's work with reactive components should have
made SR unecessary but it was little understood at the time.

Sue...

> TM
>
[quoted text clipped - 10 lines]
>
> >> TM- Hide quoted text -- Show quoted text -- Hide quoted text -- Show quoted text -
Dirk Van de moortel - 29 Jan 2007 17:55 GMT
>>>> See
>>>>
[quoted text clipped - 39 lines]
> each unique physical events.  So there can obviously be only one number of
> ticks between such events, using a single clock.

Yes, it's the same remark as for the time dilation. Both clocks should
be shown for both observers in both views. The painting of the spots
should be marked by a clock in Jasper's verandah, showing 2*10/6
ticks.

> And that is just what we
> get in the animations: two transits of the light pulse across the car
[quoted text clipped - 8 lines]
> conventional exposition of SR, but of course I would prefer a different
> approach altogether...

Apart from the poor and misleading animations, there's a double
error in the paragraph immediately following the lenght contraction
animation.
The phrases
   " ... so the length that Zoe measures is 2cT' "
and
   " The length that Jasper measures for the verandah is 2cT = 2cT'g "
should, since the relative speed between Jasper and the Paint can is
not c, but v, be replaced with
   " ... so the length that Zoe measures is 2vT' "
and
   " The length that Jasper measures for the verandah is 2vT = 2vT'g "

By the way, I haven't checked the remainder of the page.
I briefly looked at 3 aspects and found 3 mistakes.

I'm curious about their response.
Haven't heard anything yet.

Dirk Vdm
Trevor Morris - 29 Jan 2007 21:49 GMT
>>>>> See
>>>>>
[quoted text clipped - 44 lines]
> should be marked by a clock in Jasper's verandah, showing 2*10/6
> ticks.

Agreed, as above.

>> And that is just what we get in the animations: two transits of the light
>> pulse across the car between sprays or red flashes.
[quoted text clipped - 20 lines]
> and
>    " The length that Jasper measures for the verandah is 2vT = 2vT'g "

Agreed again: c should be v in those equations.

TM

> By the way, I haven't checked the remainder of the page.
> I briefly looked at 3 aspects and found 3 mistakes.
[quoted text clipped - 3 lines]
>
> Dirk Vdm
Dirk Van de moortel - 29 Jan 2007 23:39 GMT
> See
>
[quoted text clipped - 18 lines]
> different in each frame, but the number of ticks would still be the
> same, since there is only ONE BLOODY CLOCK !

Just received a message to notify me that they are aware of
the problem with the clocks, and that it is not easy to fix it.
I sort of insisted that it can be rather easily done by merely
duplicating Zoe's clock from Zoe's view into Jasper's verandah,
and thus having the two counts next to each other (perhaps in
different colours), resulting in 6 for the count of the clock ticks
of Joe's car and 10 for the count of the ticks in the veranda itself.
We'll have to wait and see. I'm sure they have other priorities.

The error with the speed in the paragraph following the length
contraction animation has been corrected.

Dirk Vdm
THE_ONE - 30 Jan 2007 05:21 GMT
A SITE  REVIEW.

Time dilation

In the animations below, Zoe is travelling at speed v as she drives
past Jasper's verandah. She has various clocks on board: clocks that
work using the laws of mechanics and/or electromagnetism. According to
Einstein's principle of special relativity, these laws by which these
clocks operate are the same for her and for Jasper, so it doesn't
matter what sort of clock we choose. So let's choose a very simple
electromagnetic clock. It uses electromagnetic waves and mirrors: it
has a pulse of light going from side to side across her car (whose
width is w). Zoe has timing apparatus to measure the time between
reflections in the windows. So does Jasper, and for this purpose, the
mirrors are only partially reflecting so that some of the light gets
out.

> This is true, Zoe and Jasper could also be wearing wrist watches which will also be affected by velocity of motion, if in motion across Space.

Prior to the experiment, Zoe parks her car  next to Jasper's verandah
so we can observe her clock, shown in the diagram at right.
Coincidentally, the car and the verandah are the same length.

> Blah blah blah.

The animation below shows Jasper's and Zoe's observations of the
events. In Jasper's frame, Zoe is travelling left to right at v =
0.8*c, and the pulse of light traces the lines shown, each of which is
the hypotenuse of a right angled triangle. In Zoe's frame, Jasper and
his verandah are travelling right to left at speed v = 0.8*c, and the
light pulse of the clock just goes sideways, to and fro across the
car. The red counters record each time that the light pulse strikes
one of the windows: each window reflection is a tick of the clock.
(You can use the 'step' function to check that this happens.) You can
also check the constancy of the speed of light for the two observers
by checking that the light pulse travels the same distance per frame.

>> Yes,  " The animation below shows Jasper's and Zoe's observations of the events."  , it is to be strongly noted that these are OBSERVATIONS and therefore can not dictate facts. <<

>>Therefore, " In Zoe's ( observational )  frame, Jasper and his verandah are travelling right to left at speed v = 0.8*c, and the light pulse of the clock ( apparently ) just goes sideways, to and fro across the car. ". <<

>> Let's raise the height of the mirrors on Zoe's vehicle, such they are above Zoe's head.  Now let us position a laser, that is stationary relative to the ground, in such a position that Zoe will drive under it at one point while in motion across that same ground.  The mirrors are at  the same height as the laser. The laser is pointed just at the appropriate angle, and emits a pulse of light just at the right time, such that  the pulse of light will hit one of the mirrors on the vehicle just as it passes by, and will now reflect off of this mirror just at the appropriate angle such that it will strike the second mirror on the opposite side of the vehicle even though the vehicle has moved further away at its constant velocity. Thanks to the angle of the laser, and the timing of the release of the pulse being correctly set in time with the movement and position of the vehicle, these reflections will then continue onward as the vehicle continues onward. <<

>> So, even thought we have emitted a pulse of light at just the right time and angle such that the light continues to reflect off of the mirrors as the vehicle continues to be on the move, from Zoe's OBSERVATIONAL point of view,  it APPEARS as thought the light is ONLY moving  " sideways, to and fro across the car.", even thought this is not the case.  Hence OBSERVATIONAL findings, do not support the complete description of the actual event. <<

Now the speed of light c in each of the animations is the same -
that's what the principle of relativity is all about. But the
distances are different: for Jasper, each tick of Zoe's clock is the
time T taken for light to trace the hypotenuse of the right angled
triangle. For Zoe, the light pulse covers only w, the width of the
car, in each tick. So the constant speed of light means that the light
beam clock ticks at different rates for Jasper and for Zoe! Jasper
observes Zoe's clock running more slowly than Zoe does. (The red
counters give the number of ticks of the clock as measured by each of
the observers.) Let's call T' the time that Zoe measures for one tick
of the clock, so

>>Wrong.     It says that  " the speed of light c in each of the animations is the same ", but in actual fact it is only OBSERVED and MEASURED to be the same cspeed of light. This does not mean that the independent speed of that light itself when related to a moving body or moving frame, will create a relative speed equal to c as a total, but may only be OBSERVED and MEASURED to be so.<<

>>Wrong.     It says that " For Zoe, the light pulse covers only w, the width of the car ", but in fact, as I pointed out previously, it is only observed to be such a case. This does not mean that this is the ACTUAL situation.  <<

>>Wrong.     It says that " So the constant speed of light means that the light beam clock ticks at different rates for Jasper and for Zoe! ", but this is incomplete.  Each clock tick is an EVENT.  If say 10 events occur on Zoe's vehicle, over a given time period, and then Zoe stops the clock by blocking the path, then ten events have occurred, and that is all.   Now if Zoe was wearing a wrist watch, and Zoe had been moving at a velocity of 260,000 km per sec. , in combination with the distance between each mirror being a huge 75,000 km, then  Zoe would see that the 10 events would have occurred in 2.5 seconds, and this is partially due to the fact that Zoe's watch is running at half speed while at this specific 260,000 km per sec. velocity.

75,000 km * 10 = 750,000 km
750,000 km / 2.5 = 300,000 km per sec.

Jasper, on the other hand, has a wrist watch that is running twice as
fast as Zoe's is.  To Jasper, it appeared as thought 5 seconds had
passed for these 10 events to occur.  To Jasper, each hypotenuse path
of the light is measured to be 150,000 km in length.

150,000 km * 10 = 1500,000 km
1500,000 km / 5 = 300,000 km per sec.

So yes, both Zoe and Jasper measure the speed of light to be the
300,000 km per sec., and yes " the constant speed of light means that
the light beam clock ticks at different rates for Jasper and for Zoe!
", but the number of EVENTS or TICKS is still 10 and only 10 when
viewed from either frame, regardless of the fact that they tick at
different rates as Zoe's and Jasper's wrist watches indicate. <<

w = cT'.

>> Yes.   w = cT'.
c = 300,000 km per sec.
10 clock ticks = 2.5 sec.  ,  therefore   1 tick = 0.25 sec. ,  and
so  T' = 0.25 sec.
w =  c * 0.25sec  = 75,000 km <<

Pythagoras meets Einstein

How to relate, T, the time of a tick on Zoe's clock as Jasper observes
it, to T', the time of a tick on the same clock, as Zoe sees it? Look
at the triangle at the right of the animation above. Light travels at
c, so the hypotenuse has length cT. One side of the triangle is the
width w of the car. The other side is vT, where v is the speed of the
car relative to Jasper. Pythagoras' theorem says that the square of
the hyptenuse is the sum of the squares on the other two sides. Here,
this gives

(cT)^2 = w^2 + (vT)^2.

>>Yes.   (cT)^2 = w^2 + (vT)^2.      In my example of the velocity being 260,000 km per second,

w^2 = 75,000 * 75,000

(vT)^2. =  ( 260,000 km * 0.5 sec  ) * ( 260,000 km * 0.5 sec  )

(cT)^2 = w^2 + (vT)^2 = 150,000 km  per 0.5 sec.

Yep, that all checks out.  <<

Combining the two equations above:

(cT)2 = (cT')^2 + (vT)^2,        then dividing by c and rearranging
gives

T'2 = T2 - (v/c)^2T^2            whence

T' = T(1 - (v/c)^2)1/2 = T/y, where y = 1/(1 - (v/c)^2)^1/2.

>> OK <<

So Jasper observes Zoe's clock to tick more slowly by a factor y,
which is always greater than or equal to one. This factor y occurs
regularly in special relativity, so we have plotted it at right. (The
dashed line plots 1/y.) We notice that, unless v is a substantial
fraction of c, y is approximately 1. This of course is why we don't
notice time dilation at ordinary speeds. For an airplane travelling
near the speed of sound, y = 1.0000000000005. Note that 1/y(v/c) is
the equation of a circle, although we
have stretched the horizontal axis so that the dashed line looks like
an elipse. So y (the solid line) is conveniently remembered as the
reciprocal of a circle.

>>Wrong.   Jasper has no idea how fast Zoe's wrist watch is ticking.   Jasper, as does Zoe, is only watching the 10 light clock ticks.  The rate of which these ticks occur can only be determined by monitoring their wrist watches and comparing the watch readings with the time periods of the 10 Events of the 10 light clock ticks.<<

In the animations, Zoe's car travels at 0.8c, so ? = 1.67, so Jasper
measures Zoe's clock to have ticks that are 60% of the time that Zoe
measures.

>>Wrong.   Zoe's clock and Jaspers clock are one in the same, since each tick is simply an event that is revealed to both.   However, if Jasper was able to know of Zoe's measuring of the tick rate, in the case of Zoe's car traveling at 0.8c, Jasper would see the clock to have ticks that are 167% of the time that Zoe measures.

In my example where  Zoe's car traveling at 0.8666c, or 260,000 km per
second, Jasper would see the clock to have ticks that are 200% of the
time that Zoe measures, for the rate on the ticks seen by Zoe is seen
as a shorter time period since Zoe's clock is ticking half the speed
in comparison with Jasper's.<<
THE_ONE - 30 Jan 2007 05:33 GMT
A SITE  REVIEW.

Time dilation

In the animations below, Zoe is travelling at speed v as she drives
past Jasper's verandah. She has various clocks on board: clocks that
work using the laws of mechanics and/or electromagnetism. According to
Einstein's principle of special relativity, these laws by which these
clocks operate are the same for her and
for Jasper, so it doesn't matter what sort of clock we choose. So
let's choose a very simple electromagnetic clock. It uses
electromagnetic waves and mirrors: it has a pulse of light going from
side to side across her car (whose width is w). Zoe has timing
apparatus to measure the time between reflections in the windows. So
does Jasper, and for this purpose, the mirrors are only partially
reflecting so that some of the light gets out.

<< This is true, Zoe and Jasper could also be wearing wrist watches
which will also be affected by velocity of motion, if in motion across
Space.<<

Prior to the experiment, Zoe parks her car  next to Jasper's verandah
so we can observe her clock, shown in the diagram at right.
Coincidentally, the car and the verandah are the same length.

<< Blah blah blah.<<

The animation below shows Jasper's and Zoe's observations of the
events. In Jasper's frame, Zoe is travelling left to right at v =
0.8*c, and the pulse of light traces the lines shown, each of which is
the hypotenuse of a right angled triangle. In Zoe's frame, Jasper and
his verandah are travelling right to left at speed v = 0.8*c, and the
light pulse of the clock just goes sideways, to and fro across the
car. The red counters record each time that the light pulse strikes
one of the windows: each window reflection is a tick of the clock.
(You can use the 'step' function to check that this happens.) You can
also check the constancy of the speed of light for the two observers
by checking that the light pulse travels the same distance per frame.

<< Yes,  " The animation below shows Jasper's and Zoe's observations
of the events."  , it is to be strongly noted that these are
OBSERVATIONS and therefore can not dictate facts. <<

<< Therefore, " In Zoe's ( observational )  frame, Jasper and his
verandah are travelling right to left at speed v = 0.8*c, and the
light pulse of the clock ( apparently ) just goes sideways, to and fro
across the car. ". <<

<< Let's raise the height of the mirrors on Zoe's vehicle, such they
are above Zoe's head.  Now let us position a laser, that is stationary
relative to the ground, in such a position that Zoe will drive under
it at one point while in motion across that same ground.  The mirrors
are at  the same height as the laser. The laser is
pointed just at the appropriate angle, and emits a pulse of light just
at the right time, such that  the pulse of light will hit one of the
mirrors on the vehicle just as it passes by, and will now reflect off
of this mirror just at the appropriate angle such that it will strike
the second mirror on the opposite side of the vehicle even
though the vehicle has moved further away at its constant velocity.
Thanks to the angle of the laser, and the timing of the release of the
pulse being correctly set in time with the movement and position of
the vehicle, these reflections will then continue onward as the
vehicle continues onward. <<

<< So, even thought we have emitted a pulse of light at just the right
time and angle such that the light continues to reflect off of the
mirrors as the vehicle continues to be on the move, from Zoe's
OBSERVATIONAL point of view,  it APPEARS as thought the light is ONLY
moving  " sideways, to and fro across the car.", even thought this is
not the case.  Hence OBSERVATIONAL findings, do not support the
complete description of the actual event. <<

Now the speed of light c in each of the animations is the same -
that's what the principle of relativity is all about. But the
distances are different: for Jasper, each tick of Zoe's clock is the
time T taken for light to trace the hypotenuse of the right angled
triangle. For Zoe, the light pulse covers only w, the width of the
car, in each tick. So the constant speed of light means that the light
beam clock ticks at different rates for Jasper and for Zoe! Jasper
observes Zoe's clock running more slowly than Zoe does. (The red
counters give the number of ticks of the clock as measured by each of
the observers.) Let's call T' the time that Zoe measures for one tick
of the clock, so w = cT'..

<< Wrong.     It says that  " the speed of light c in each of the
animations is the same ", but in actual fact it is only OBSERVED and
MEASURED to be the same cspeed of light. This does not mean that the
Independent speed of that light itself when related to a moving body
or moving frame, will create a relative
speed equal to c as a total, but may only be OBSERVED and MEASURED to
be so. <<

<< Wrong.     It says that " For Zoe, the light pulse covers only w,
the width of the car ", but in fact, as I pointed out previously, it
is only observed to be such a case. This does not mean that this is
the ACTUAL situation.  <<

<< Wrong.     It says that " So the constant speed of light means that
the light beam clock ticks at different rates for Jasper and for Zoe!
", but this is incomplete.  Each clock tick is an EVENT.  If say 10
events occur on Zoe's vehicle, over a given time period, and then Zoe
stops the clock by blocking the path, then ten events have occurred,
and that is all.   Now if Zoe was wearing a wrist watch, and Zoe had
been moving at a velocity of 260,000 km per sec. , in combination with
the distance between each mirror being a huge 75,000 km, then  Zoe
would see that the 10 events would have occurred in 2.5 seconds, and
this is partially due to the fact that Zoe's watch is running at half
speed while at this specific 260,000 km per sec. velocity.

75,000 km * 10 = 750,000 km
750,000 km / 2.5 = 300,000 km per sec.

Jasper, on the other hand, has a wrist watch that is running twice as
fast as Zoe's is.  To Jasper, it appeared as thought 5 seconds had
passed for these 10 events to occur.  To Jasper, each hypotenuse path
of the light is measured to be 150,000 km in length.

150,000 km * 10 = 1500,000 km
1500,000 km / 5 = 300,000 km per sec.

So yes, both Zoe and Jasper measure the speed of light to be the
300,000 km per sec., and yes " the constant speed of light means that
the light beam clock ticks at different rates for Jasper and for Zoe!
", but the number of EVENTS or TICKS is still 10 and only 10 when
viewed from either frame, regardless of the
fact that they tick at different rates as Zoe's and Jasper's wrist
watches indicate. <<

w = cT'.

<< Yes.   w = cT'.
c = 300,000 km per sec.
10 clock ticks = 2.5 sec.  ,  therefore   1 tick = 0.25 sec. ,  and
so  T' = 0.25 sec.
w =  c * 0.25sec  = 75,000 km <<

Pythagoras meets Einstein

How to relate, T, the time of a tick on Zoe's clock as Jasper observes
it, to T', the time of a tick on the same clock, as Zoe sees it? Look
at the triangle at the right of the animation above. Light travels at
c, so the hypotenuse has length cT. One side of the triangle is the
width w of the car. The other side is vT, where v is the speed of the
car relative to Jasper. Pythagoras' theorem says that the square of
the hyptenuse is the sum of the squares on the other two sides. Here,
this gives

(cT)^2 = w^2 + (vT)^2.

<< Yes.   (cT)^2 = w^2 + (vT)^2.      In my example of the velocity
being 260,000 km per second,

w^2 = 75,000 * 75,000

(vT)^2. =  ( 260,000 km * 0.5 sec  ) * ( 260,000 km * 0.5 sec  )

(cT)^2 = w^2 + (vT)^2 = 150,000 km  per 0.5 sec.

Yep, that all checks out.  <<

Combining the two equations above:

(cT)2 = (cT')^2 + (vT)^2,        then dividing by c and rearranging
gives

T'2 = T2 - (v/c)^2T^2            whence

T' = T(1 - (v/c)^2)1/2 = T/y, where y = 1/(1 - (v/c)^2)^1/2.

<< OK <<

So Jasper observes Zoe's clock to tick more slowly by a factor y,
which is always greater than or equal to one. This factor y occurs
regularly in special relativity, so we have plotted it at right. (The
dashed line plots 1/y.) We notice that, unless v is a substantial
fraction of c, y is approximately 1. This of course is why we don't
notice time dilation at ordinary speeds. For an airplane travelling
near the speed of sound, y = 1.0000000000005. Note that 1/y(v/c) is
the equation of a circle, although we
have stretched the horizontal axis so that the dashed line looks like
an elipse. So y (the solid line) is conveniently remembered as the
reciprocal of a circle.

<< Wrong.   Jasper has no idea how fast Zoe's wrist watch is
ticking.   Jasper, as does Zoe, is only watching the 10 light clock
ticks.  The rate of which these ticks occur can only be determined by
monitoring their wrist watches and comparing the watch readings with
the time periods of the 10 Events of the 10 light clock ticks.<<

In the animations, Zoe's car travels at 0.8c, so ? = 1.67, so Jasper
measures Zoe's clock to have ticks that are 60% of the time that Zoe
measures.

<< Wrong.   Zoe's clock and Jaspers clock are one in the same, since
each tick is simply an event that is revealed to both.   However, if
Jasper was able to know of Zoe's measuring of the tick rate, in the
case of Zoe's car traveling at 0.8c, Jasper would see the clock to
have ticks that are 167% of the time that Zoe measures.

In my example where  Zoe's car traveling at 0.8666c, or 260,000 km per
second, Jasper would see the clock to have ticks that are 200% of the
time that Zoe measures, for the rate on the ticks seen by Zoe is seen
as a shorter time period since Zoe's clock is ticking half the speed
in comparison with Jasper's.<<
THE_ONE - 30 Jan 2007 05:55 GMT
A SITE  REVIEW.

Time dilation

In the animations below, Zoe is travelling at speed v as she drives
past Jasper's verandah. She has various clocks on board: clocks that
work using the laws of mechanics and/or electromagnetism. According to
Einstein's principle of special relativity, these laws by which these
clocks operate are the same for her and for jasper, so it doesn't
matter what sort of clock we choose. So let's choose a very simple
electromagnetic clock. It uses electromagnetic waves and mirrors: it
has a pulse of light going from side to side across her car (whose
width is w). Zoe has timing apparatus to measure the time between
reflections in the windows. So does Jasper, and for this purpose, the
mirrors are only partially reflecting so that some of the light gets
out.

<< This is true, Zoe and Jasper could also be wearing wrist watches
which will also be affected by velocity of motion, if in motion across
Space. <<

Prior to the experiment, Zoe parks her car  next to Jasper's verandah
so we can observe her clock, shown in the diagram at right.
Coincidentally, the car and the verandah are the same length.

<< Blah blah blah.<<

The animation below shows Jasper's and Zoe's observations of the
events. In Jasper's frame, Zoe is travelling left to right at v =
0.8*c, and the pulse of light traces the lines shown, each of which is
the hypotenuse of a right angled triangle. In Zoe's frame, Jasper and
his verandah are travelling right to left at speed v = 0.8*c, and the
light pulse of the clock just goes sideways, to and fro across the
car. The red counters record each time that the light pulse strikes
one of the windows: each window reflection is a tick of the clock.
(You can use the 'step' function to check that this happens.) You can
also check the constancy of the speed of light for the two Observers
by checking that the light pulse travels the same distance per frame.

<< Yes,  " The animation below shows Jasper's and Zoe's observations
of the events."  , it is to be strongly noted that these are
OBSERVATIONS and therefore can not dictate facts. <<

<< Therefore, " In Zoe's ( observational )  frame, Jasper and his
verandah are travelling right to left at speed v = 0.8*c, and the
light pulse of the clock ( apparently ) just goes sideways, to and fro
across the car. ". <<

<< Let's raise the height of the mirrors on Zoe's vehicle, such they
are above Zoe's head.  Now let us position a laser, that is stationary
relative to the ground, in such a position that Zoe will drive under
it at one point while in motion across that same ground.  The mirrors
are at  the same height as the laser. The laser is pointed just at the
appropriate angle, and emits a pulse of light just at the right time,
such that  the pulse of light will hit one of the mirrors on the
vehicle just as it passes by, and will now reflect off of this mirror
just at the appropriate angle such that it will strike the second
mirror on the opposite side of the vehicle even though the vehicle has
moved further away at its constant velocity. Thanks to the angle of
the laser, and the timing of the release of the pulse being correctly
set in time with the movement and position of the vehicle, these
reflections will then continue onward as the vehicle continues onward.
<<

<< So, even thought we have emitted a pulse of light at just the right
time and angle such that the light continues to reflect off of the
mirrors as the vehicle continues to be on the move, from Zoe's
OBSERVATIONAL point of view,  it APPEARS as thought the light is ONLY
moving  " sideways, to and fro across the car.", even thought this is
not the case.  Hence OBSERVATIONAL findings, do not support the
complete description of the actual event. <<

Now the speed of light c in each of the animations is the same -
that's what the principle of relativity is all about. But the
distances are different: for Jasper, each tick of Zoe's clock is the
time T taken for light to trace the hypotenuse of the right angled
triangle. For Zoe, the light pulse covers only w, the width of the
car, in each tick. So the constant speed of light means that the light
beam clock ticks at different rates for Jasper and for Zoe! Jasper
observes Zoe's clock running more slowly than Zoe does. (The red
counters give the number of ticks of the clock as measured by each of
the observers.) Let's call T' the time that Zoe measures for one tick
of the clock, so w = cT'.

<< 1 Wrong.     It says that  " the speed of light c in each of the
animations is the same ", but in actual fact it is only OBSERVED and
MEASURED to be the same cspeed of light. This does not mean that the
independent speed of that light itself when related to a moving body
or moving frame, will create a relative speed equal to c as a total,
but may only be OBSERVED and MEASURED to be so.<<

<< 2 Wrong.     It says that " For Zoe, the light pulse covers only w,
the width of the car ", but in fact, as I pointed out previously, it
is only observed to be such a case. This does not mean that this is
the ACTUAL situation.  <<

<< 3 Wrong.     It says that " So the constant speed of light means
that the light beam clock ticks at different rates for Jasper and for
Zoe! ", but this is incomplete.  Each clock tick is an EVENT.  If say
10 events occur on Zoe's vehicle, over a given time period, and then
Zoe stops the clock by blocking the path, then ten events have
occurred, and that is all.   Now if Zoe was wearing a wrist watch, and
Zoe had been moving at a velocity of 260,000 km per sec. , in
combination with the distance between each mirror being a huge 75,000
km, then  Zoe would see that the 10 events would have occurred in 2.5
seconds, and this is partially due to the fact that Zoe's watch is
running at half speed while at this specific 260,000 km per sec.
velocity.

75,000 km * 10 = 750,000 km
750,000 km / 2.5 = 300,000 km per sec.

Jasper, on the other hand, has a wrist watch that is running twice as
fast as Zoe's is.  To Jasper, it appeared as thought 5 seconds had
passed for these 10 events to occur.  To Jasper, each hypotenuse path
of the light is measured to be 150,000 km in length.

150,000 km * 10 = 1500,000 km
1500,000 km / 5 = 300,000 km per sec.

So yes, both Zoe and Jasper measure the speed of light to be the
300,000 km per sec., and yes " the constant speed of light means that
the light beam clock ticks at different rates for Jasper and for Zoe!
", but the number of EVENTS or TICKS is still 10 and only 10 when
viewed from either frame, regardless of the fact that they tick at
different rates as Zoe's and Jasper's wrist watches indicate. <<

w = cT'.

<< Yes.   w = cT'.
c = 300,000 km per sec.
10 clock ticks = 2.5 sec.  ,  therefore   1 tick = 0.25 sec. ,  and
so  T' = 0.25 sec.
w =  c * 0.25sec  = 75,000 km <<

Pythagoras meets Einstein

How to relate, T, the time of a tick on Zoe's clock as Jasper observes
it, to T', the time of a tick on the same clock, as Zoe sees it? Look
at the triangle at the right of the animation above. Light travels at
c, so the hypotenuse has length cT. One sideof the triangle is the
width w of the car. The other side is vT, where v is the speed of the
car relative to Jasper. Pythagoras' theorem says that the square of
the hyptenuse is the sum of the squares on the other two sides. Here,
this gives

(cT)^2 = w^2 + (vT)^2.

>>Yes.   (cT)^2 = w^2 + (vT)^2.      In my example of the velocity being 260,000 km per second,

w^2 = 75,000 * 75,000

(vT)^2. =  ( 260,000 km * 0.5 sec  ) * ( 260,000 km * 0.5 sec  )

(cT)^2 = w^2 + (vT)^2 = 150,000 km  per 0.5 sec.

Yep, that all checks out.  <<

Combining the two equations above:

(cT)2 = (cT')^2 + (vT)^2,    then dividing by c and rearranging gives

T'2 = T2 - (v/c)^2T^2        whence

T' = T(1 - (v/c)^2)1/2 = T/y, where y = 1/(1 - (v/c)^2)^1/2.

<< OK <<

So Jasper observes Zoe's clock to tick more slowly by a factor y,
which is always greater than or equal to one. This factor y occurs
regularly in special relativity, so we have plotted it at right. (The
dashed line plots 1/y.) We notice that, unless v is a substantial
fraction of c, y is approximately 1. This of course is why we don't
notice time dilation at ordinary speeds. For an airplane travelling
near the speed of sound, y = 1.0000000000005. Note that 1/y(v/c) is
the equation of a circle, although we have stretched the horizontal
axis so that the dashed line looks like an elipse. So y (the solid
line) is conveniently remembered as the reciprocal of a circle.

<< Wrong.   Jasper has no idea how fast Zoe's wrist watch is
ticking.   Jasper, as does Zoe, is only watching the 10 light clock
ticks.  The rate of which these ticks occur can only be determined by
monitoring their wrist watches and comparing the watch readings with
the time periods of the 10 Events of the 10 light clock ticks.<<

In the animations, Zoe's car travels at 0.8c, so ? = 1.67, so Jasper
measures Zoe's clock to have ticks that are 60% of the time that Zoe
measures.

<< Wrong.   Zoe's clock and Jaspers clock are one in the same, since
each tick is simply an event that is revealed to both.   However, if
Jasper was able to know of Zoe's measuring of the tick rate, in the
case of Zoe's car traveling at 0.8c, Jasper would see the clock to
have ticks that are 167% of the time that Zoe measures.

In my example where  Zoe's car traveling at 0.8666c, or 260,000 km per
second, Jasper would see the clock to have ticks that are 200% of the
time that Zoe measures, for the rate on the ticks seen by Zoe is seen
as a shorter time period since Zoe's WRIST WATCH is ticking half the
speed in comparison with Jasper's.<<
Dirk Van de moortel - 30 Jan 2007 11:07 GMT
>A SITE  REVIEW.

[snip]

> The animation below shows Jasper's and Zoe's observations of the
> events. In Jasper's frame, Zoe is travelling left to right at v =
[quoted text clipped - 11 lines]
> of the events."  , it is to be strongly noted that these are
> OBSERVATIONS and therefore can not dictate facts. <<

In physics observations are defined as facts.

[snip remainder of rant]

Dirk Vdm
Dumbledore_ - 30 Jan 2007 11:06 GMT
"Dork Van de merde" aka
"Dork Van de psychopath",
"Dork Van de psychotic fumble mumbler",
"Dork Van de fuckhead",
[anip]

 http://users.telenet.be/vdmoortel/dirk/Physics/TwinsEvents.html
"We use 3 inertial reference frames" [because Dorks can't get the result
they want in two].
"In neither of these frames any form of acceleration is felt" [neither one of
all three].
"In order for the travelling twin to make HIS trip, SHE must be in frame S'
while going away".
"if T = 5 years and v = 0.8c, then the stay at home twin will have aged
10 years".

Belgium is where the farts blow.

"Your conclusion is dead wrong.
Start over, but skip the first part and the conclusion." -- Dork Van de
fuckhead.

"You made a mistake" -- Dork Van de psychotic fumble mumbler.

ASSistant professor Paul B. Andersen, tusseladd:

"That is, we can reverse the directions of the frames
which is the same as interchanging the frames,
which - as I have told you a LOT of times,
OBVIOUSLY will lead to the transform:
 t = (tau-xi*v/c^2)/sqrt(1-v^2/c^2)
 x = (xi - v*tau)/sqrt(1-v^2/c^2)
or:
 tau = (t+xv/c^2)/sqrt(1-v^2/c^2)
 xi = (x + vt)/sqrt(1-v^2/c^2)"
harry - 30 Jan 2007 09:01 GMT
> See
>
> http://www.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm

UNSW - brings up dear old memories :-)

> Click on Time dilation.

OK

> The animation shows Jasper's and Zoe's observation of a single light
> clock in action.
>
> Now there is only one clock in the animated experiment, but according
> to UNSW, the number of ticks of the clock is different when viewed
> from different reference frames. ???

No, didn't you notice the "timing apparatus"? ;-)
Of course, each reference frame has - by definition - its own reference
clocks.

Harald

> According to UNSW, over the given time period of the experiment,
> Jasper counts 6 clock ticks, and Zoe counts 10 ticks ???
<
> Granted, it does say that the rate of these ticks differ from the
> different reference frames, but that simply means that if one had an
> atomic clock in each frame, and one measured the rate of the clock
> ticks, then the rate of the clock ticks when measured would be
> different in each frame, but the number of ticks would still be the
> same, since there is only ONE BLOODY CLOCK !
THE_ONE - 30 Jan 2007 10:12 GMT
On Jan 30, 4:01 am, "harry" <harald.vanlintelButNotT...@epfl.ch>
wrote:

> > See
>
[quoted text clipped - 22 lines]
> > different in each frame, but the number of ticks would still be the
> > same, since there is only ONE BLOODY CLOCK !- Hide quoted text -- Show quoted text -

True, but it is basically nothing but an equivalent of the wrist watch
that I have mentioned, which was also used to measure the time between
the reflection from one mirror to the other mirror.

Still, the number of counts, or ticks of the LIGHT CLOCK, would still
be the same for both observers.

The difference noted, is that each timing apparatus in each frame,
will measure different time periods between each LIGHT CLOCK tick.

THE_ONE
harry - 30 Jan 2007 10:58 GMT
> On Jan 30, 4:01 am, "harry" <harald.vanlintelButNotT...@epfl.ch>
> wrote:
[quoted text clipped - 5 lines]
>>
>> > Click on Time dilation.

>> OK
>>
[quoted text clipped - 4 lines]
>> > to UNSW, the number of ticks of the clock is different when viewed
>> > from different reference frames. ???

>> No, didn't you notice the "timing apparatus"? ;-)
>> Of course, each reference frame has - by definition - its own reference
[quoted text clipped - 19 lines]
> Still, the number of counts, or ticks of the LIGHT CLOCK, would still
> be the same for both observers.

Sure the same events are seen to happen, independent of one's perspective.

> The difference noted, is that each timing apparatus in each frame,
> will measure different time periods between each LIGHT CLOCK tick.

Yes, that's what they tried to illustrate. It would be clearer if they had
shown a light clock in each frame.

Cheers,
Harald

> THE_ONE
THE_ONE - 30 Jan 2007 11:33 GMT
On Jan 30, 5:58 am, "harry" <harald.vanlintelButNotT...@epfl.ch>
wrote:

> > On Jan 30, 4:01 am, "harry" <harald.vanlintelButNotT...@epfl.ch>
> > wrote:
[quoted text clipped - 45 lines]
>
> > THE_ONE- Hide quoted text -- Show quoted text -- Hide quoted text -- Show quoted text -

Yep, I thought it looked sloppy.

Well, I better get back to work and see if I can get those damn cells
to bond with the I.R. solar cell beads, such
that the damaged retina electro-bypass circuit can finally be up and
running while being powered by the
body heat ( I.R. ) alone.

Just kidding !

THE_ONE
harry - 30 Jan 2007 13:06 GMT
> On Jan 30, 5:58 am, "harry" <harald.vanlintelButNotT...@epfl.ch>
> wrote:
[quoted text clipped - 64 lines]
>
> Just kidding !

One of the PhD students here may want to discuss that with you - not
kidding!

Harald
THE_ONE - 30 Jan 2007 10:15 GMT
On Jan 30, 4:01 am, "harry" <harald.vanlintelButNotT...@epfl.ch>
wrote:

> > See
>
[quoted text clipped - 22 lines]
> > different in each frame, but the number of ticks would still be the
> > same, since there is only ONE BLOODY CLOCK !- Hide quoted text -- Show quoted text -

True, but it is basically nothing but an equivalent of the two wrist
watches that I have mentioned, which were also used to measure the
time between the reflection from one mirror to the other mirror.

Still, the number of counts, or ticks of the LIGHT CLOCK, would still
be the same for both observers.

The difference noted, is that each timing apparatus in each frame,
will measure different time periods between each LIGHT CLOCK tick.

THE_ONE
 
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