Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that (unless somebody has some ingenious solution that I haven't thought of)
I'll show you exactly where the fundamental irreconcilable contradiction is.

Here's the first scenario:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and spaceship (a) accelerates in two seconds to
86% of light speed, travels until it reaches spaceship (b) and then stops
just as fast. When spaceship (a) reaches spaceship (b), what will both
clocks read?

And here's a second scenario:

Two spaceships (one is alien this time) are traveling toward each other at
86% of light speed relative to each other. Nobody knows who has accelerated
and who hasn't this time around. Spaceship (b) has deployed a buoy (in the
direction if the oncoming ship) exactly 100 light hours away from itself so
that it can determine exactly when the alien spaceship has passed the 100
light hour mark.. When the alien spaceship passes the buoy, it start's it's
clock. And at the same time, the buoy sends a signal to spaceship (b). So
the question this time is, when both spaceships meet and decelerate, what
will the clock on the alien spaceship read? And, how much time will have
elapsed since spaceship (b) received it's signal from the buoy (minus 100
hours of course)?

Robert

Robert Calvert wrote:

Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that (unless somebody has some ingenious solution that I haven't thought of)
I'll show you exactly where the fundamental irreconcilable contradiction is.

Here's the first scenario:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and spaceship (a) accelerates in two seconds to
86% of light speed, travels until it reaches spaceship (b) and then stops
just as fast. When spaceship (a) reaches spaceship (b), what will both
clocks read?

To make the math simpler, I'm just going to assume their relative velocity is
sqrt(3)/2, or about 86.6%, which makes gamma equal exactly two. Also, I'll
assume that ship a accelerates from 0 to 0.866c (in ship b's frame) arbitrarily
close to instantaneously instead of in two seconds, so I don't have to worry
about the changing speed of clock ticks over those two seconds.

In this case, it's easy to just calculate everything in ship b's frame--it'll
take 100 hours/0.866 = 115.47 hours for ship a to reach it according to ship
b's own clock, and ship a's clock was ticking at half the rate of ship b's
clock whole time, so when they meet ship a's clock will record that 57.74 hours
have passed.



And here's a second scenario:

Two spaceships (one is alien this time) are traveling toward each other at
86% of light speed relative to each other. Nobody knows who has accelerated
and who hasn't this time around. Spaceship (b) has deployed a buoy (in the
direction if the oncoming ship) exactly 100 light hours away from itself so
that it can determine exactly when the alien spaceship has passed the 100
light hour mark.. When the alien spaceship passes the buoy, it start's it's
clock. And at the same time, the buoy sends a signal to spaceship (b). So
the question this time is, when both spaceships meet and decelerate, what
will the clock on the alien spaceship read? And, how much time will have
elapsed since spaceship (b) received it's signal from the buoy (minus 100
hours of course)?

Again, assuming we use a velocity of about 86.6% light speed so gamma = 2, in
the alien ship's frame the human ship will be only 50 light hours away when the
alien ship passes the buoy, so the alien's clocks will measure the time for
their ships to meet as 50 hours/0.866 = 57.74 hours. Meanwhile, the humans will
see the time between recieving the signal and meeting the alien ship as 15.47
hours, so when they add back the time for the signal to reach them, they'll
find that in their frame the alien ship took 115.47 hours to get from the buoy
to their ship.

--
Jesse Mazer
http://www.jessemazer.com

Robert Calvert wrote:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and spaceship (a) accelerates in two seconds to
86% of light speed, travels until it reaches spaceship (b) and then stops
just as fast. When spaceship (a) reaches spaceship (b), what will both
clocks read?

[...]

Two spaceships (one is alien this time) are traveling toward each other at
86% of light speed relative to each other. Nobody knows who has accelerated
and who hasn't this time around. Spaceship (b) has deployed a buoy (in the
direction if the oncoming ship) exactly 100 light hours away from itself so
that it can determine exactly when the alien spaceship has passed the 100
light hour mark.. When the alien spaceship passes the buoy, it start's it's
clock. And at the same time, the buoy sends a signal to spaceship (b). So
the question this time is, when both spaceships meet and decelerate, what
will the clock on the alien spaceship read? And, how much time will have
elapsed since spaceship (b) received it's signal from the buoy (minus 100
hours of course)?

The problem with both of your scenarios is that both involve non-inertial
frames of reference, so special theory of relativity is not even supposed to
work. And the math involved in general theory of relativity gets very ugly
very fast.

-Timo

--
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"Timo Voipio" wrote in message ...

The problem with both of your scenarios is that both involve non-inertial
frames of reference, so special theory of relativity is not even supposed to
work.

You must be joking.
http://hermes.physics.adelaide.edu.a...eleration.html
http://users.pandora.be/vdmoortel/di...eleration.html

And the math involved in general theory of relativity gets very ugly
very fast.

Not in this case.

Dirk Vdm

"Robert Calvert" wrote in message ...
Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that...

(unless somebody has some ingenious solution that I haven't thought of)

There is your answer.

Martin Hogbin

Hello Robert Calvert , You wrote ,
" spaceship ( a ) accelerates in two seconds to
86% of light speed "

Everyone is reduced to vapor .

Where did they get all that energy ?

If it can't be observed then it's not physics .

Where you trying to be metaphysical in places ?

If so , you should clearly delineate where .

Without general and special relativity ,
you can't understand how the GPS constellation works .

Robert Calvert wrote:

Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that (unless somebody has some ingenious solution that I haven't thought of)
I'll show you exactly where the fundamental irreconcilable contradiction is.

Here's the first scenario:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and
[snip]

Hey stooopid, how do they do that? They cannot. Only local clocks
can be synchronized.

--
Uncle Al
http://www.mazepath.com/uncleal/qz.pdf
http://www.mazepath.com/uncleal/eotvos.htm
(Do something naughty to physics)

Uncle Al wrote:

Robert Calvert wrote:

Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that (unless somebody has some ingenious solution that I haven't thought of)
I'll show you exactly where the fundamental irreconcilable contradiction is.

Here's the first scenario:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and
[snip]

Hey stooopid, how do they do that? They cannot. Only local clocks
can be synchronized.

In his example, both ships start out in the same rest frame, so they should be
able to agree on what it means for their respective clocks to be "synchronized".

--
Jesse Mazer
http://www.jessemazer.com

Jesse Mazer wrote:

Uncle Al wrote:

Robert Calvert wrote:

Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that (unless somebody has some ingenious solution that I haven't thought of)
I'll show you exactly where the fundamental irreconcilable contradiction is.

Here's the first scenario:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and
[snip]

Hey stooopid, how do they do that? They cannot. Only local clocks
can be synchronized.

In his example, both ships start out in the same rest frame, so they should be
able to agree on what it means for their respective clocks to be "synchronized".

Bull****. Twins Paradox. You are making the invalid assumption that
plays through to an invalid conclusion.

http://fourmilab.to/etexts/einstein/specrel/specrel.pdf
http://www.geocities.com/physics_world/sr/ae_1905_error.htm

Which ship moves? How far? Relative to what? According to whom? A
relativistic universe has four distinct distances: luminosity
(inverse square), angular diameter, parallax, and proper motion. No
two of them need agree to maintain consistency.

Reference frames are important,

http://arxiv.org/abs/gr-qc/0205059
Pioneer anomaly
http://arXiv.org/abs/gr-qc/0307042
Rationalized Pioneer anomaly
http://arXiv.org/abs/gr-qc/9810085
Believable rationalized Pioneer anomaly
http://arXiv.org/abs/gr-qc/gr-qc/0310088
Believable Pioneer anomaly updated

--
Uncle Al
http://www.mazepath.com/uncleal/qz.pdf
http://www.mazepath.com/uncleal/eotvos.htm
(Do something naughty to physics)

Uncle Al wrote:

Jesse Mazer wrote:

Uncle Al wrote:

Robert Calvert wrote:

Without going into a long drawn-out discussion about SR, I thought I would
make this one simple for Relativists. Answer all the questions below. After
that (unless somebody has some ingenious solution that I haven't thought of)
I'll show you exactly where the fundamental irreconcilable contradiction is.

Here's the first scenario:

Let's say we have two spaceships that are 100 light hours apart and are
stationary relative to each other. At a prearranged time, both spaceships
start their onboard clocks and
[snip]

Hey stooopid, how do they do that? They cannot. Only local clocks
can be synchronized.

In his example, both ships start out in the same rest frame, so they should be
able to agree on what it means for their respective clocks to be "synchronized".

Bull****. Twins Paradox. You are making the invalid assumption that
plays through to an invalid conclusion.

The twins paradox is a non sequitor here, since the twins are in motion relative to
each other and don't share the same reference frame, while we are talking about two
ships at rest with respect to each other. I agree that once the first ship begins to
move it will no longer share the same definition of simultaneity as the second, but
he specified that they only "synchronized their clocks" at the moment when both are
in the same rest frame. Are you claiming that distant observers at rest with respect
to one another won't agree about simultaneity?


Which ship moves? How far? Relative to what? According to whom? A
relativistic universe has four distinct distances: luminosity
(inverse square), angular diameter, parallax, and proper motion. No
two of them need agree to maintain consistency.

I am just defining distance and motion with respect to rulers at rest in an inertial
reference frame. Are you not familiar with the concept that each reference frame has
its own coordinate system defined by rulers and clocks at rest in this frame, and
thus that each reference frame has its own definition of the distance between two
points or whether or not two distant events happened simultaneously?

Since both ships are initially at rest with respect to one another, they will both
initially agree about the ruler-distance between them, and they will both initially
agree about what it means for their clocks to be synchronized.

--
Jesse Mazer
http://www.jessemazer.com