A question about SR and speed

How can the speed of light c be independent of the movement of the observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time? If the distance factor changes then so
must the speed product, by definition. How can it be otherwise and the use
of the word "speed" make any real sense?

Thanks for all answers.

"David Johnson" wrote in message
. com...
How can the speed of light c be independent of the movement of the
observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time? If the distance factor changes then
so
must the speed product, by definition. How can it be otherwise and the use
of the word "speed" make any real sense?

Thanks for all answers.

Because time is also relative. Time slows down as speed increases. This has
been proven by flying atomic clocks in opposite directions and then
comparing the time differential.

Paul Murphy

David Johnson wrote:
How can the speed of light c be independent of the movement of the observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time?


Why not?--that's the way nature works and is verified by millions of
observations and experiments. The Global Positioning System offers
a continuous empirical verification of both special and general
relativity.

Velocity Definition
http://scienceworld.wolfram.com/physics/Velocity.html

Distance is now define in terms of light propagation
http://scienceworld.wolfram.com/physics/Meter.html

Special Relativity
http://scienceworld.wolfram.com/phys...elativity.html

There has NEVER been a prediction of Special Relativity that was
contradicted by an observation. NEVER! So far, SR has survived
almost one hundred years without being falsified.

David Johnson wrote:
How can the speed of light c be independent of the movement of the observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time? If the distance factor changes then so
must the speed product, by definition. How can it be otherwise and the use
of the word "speed" make any real sense?

Michaelson and Morley found that puzzling as well when they tried to
measure the speed of light in different directions and establish an
absolute reference frame (the wind of the "aether").

It took Einstein to figure out that if the distance factor changes,
then so does the time factor -- so c remains constant regardless of the
observer's relative motion.

Mojo
--
Morris Jones *
Monrovia, CA
http://www.whiteoaks.com
Old Town Astronomers: http://www.otastro.org

On Thu, 16 Dec 2004 14:06:20 GMT, "David Johnson"
wrote:

How can the speed of light c be independent of the movement of the observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time? If the distance factor changes then so
must the speed product, by definition. How can it be otherwise and the use
of the word "speed" make any real sense?

You have the explanation in your post, but you just can't see it. You
said:

... definition of speed is distance/time

so obviously if the distance factor changes but c is constant, then
time must change.

Nick

--
Nick Theodorakis

contact form:
http://theodorakis.net/contact.html

Indeed it is. I wasn't claiming originality; this is how the equations
of SR are derived in most textbooks.

I was'nt accusing you of anything. I did want to point out that MM is the
experimental basis for the constant velocity of light. More importantly, the
sucess in SR describibg (quantitatively) other physical observations is further
justification.
Another point is that if you can't understand the concept, then accept it
as an artical of faith that is justified by its sucess.
If you can't accept the concept then design an experiment to disprove it.

This is a response to all who responded to my question.
What clock is supposed to keep track of the time? I've read that every kind
of clock, atomic, pendulum, thermodynamic, balance wheel etc., reacts to
different conditions differently and, in particular, that the atomic clock
will slow down when subject to acceleration.



"Morris Jones" wrote in message
...
David Johnson wrote:
How can the speed of light c be independent of the movement of the
observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time? If the distance factor changes then
so
must the speed product, by definition. How can it be otherwise and the
use
of the word "speed" make any real sense?

Michaelson and Morley found that puzzling as well when they tried to
measure the speed of light in different directions and establish an
absolute reference frame (the wind of the "aether").

It took Einstein to figure out that if the distance factor changes,
then so does the time factor -- so c remains constant regardless of the
observer's relative motion.

Mojo
--
Morris Jones *
Monrovia, CA
http://www.whiteoaks.com
Old Town Astronomers: http://www.otastro.org

David Johnson wrote:

This is a response to all who responded to my question.
What clock is supposed to keep track of the time?

For the purposes of the derivations of SR perfect idealised ones that
have been synchronised and moved into position very slowly to avoid any
unwanted relativistic effects.

I've read that every kind
of clock, atomic, pendulum, thermodynamic, balance wheel etc., reacts to
different conditions differently and, in particular, that the atomic clock
will slow down when subject to acceleration.

Real clocks suffer all sorts of effects. GR shows that gravity alters
their frequency too. And all these effects have to be compensated for in
the GPS system. Amusingly though because electronic engineers have the
same sorts of problems in accepting relativity that you do they provided
a means to switch off the relativistic corrections "just in case".
However, SR + GR predictions were found to be exactly right. This was
not a surprise to the physicists and astronomers.

You can derive the formulae for special relativity rather elegantly by
requiring only that the laws of physics should be the same in all
inertial frames and observing very carefully the passage of two metre
rules past each other at constant speed v and the distinct events that
occur as seen from the ends of the rods. Taking c = constant on the
basis of Maxwell's equations. One of the classic SR books has this
derivation in it. It only requires basic high school linear algebra.

event 1 -----*_____ first contact rhs

event 2 =====* last contact rhs

event 3 *===== first contact lhs

event 4 _____*----- last contact lhs

NB events 2 + 3 would be at identical times if the moving rod was the
same length and classical galilean physics applied and this is not ruled
out. The answer should not depend on which rod you consider the moving
one. Taken together this is sufficient to derive the formulae for SR.

Regards,
Martin Brown

This is a response to all who responded to a question I asked recently. I
was unable to respond immediately so I'm using a new post in order to make
the response possible to find. Below are a couple of the responses to my
quesiton and they reflect the essential point that most respondents made.

What kind of clock is supposed to keep track of the time? I've read that
every kind
of clock, atomic, pendulum, thermodynamic, balance wheel etc., reacts to
different conditions differently and, in particular, that the atomic clock
will slow down when subject to acceleration.




David Johnson wrote:
How can the speed of light c be independent of the movement of the
observer
as the Special Relativity Theory claims it is when the concept and
definition of speed is distance/time? If the distance factor changes then
so
must the speed product, by definition. How can it be otherwise and the
use
of the word "speed" make any real sense?


Because time is also relative. Time slows down as speed increases. This
has
been proven by flying atomic clocks in opposite directions and then
comparing the time differential.

Paul Murphy

-----

Michaelson and Morley found that puzzling as well when they tried to
measure the speed of light in different directions and establish an
absolute reference frame (the wind of the "aether").

It took Einstein to figure out that if the distance factor changes,
then so does the time factor -- so c remains constant regardless of the
observer's relative motion.

Mojo
--
Morris Jones *
Monrovia, CA
http://www.whiteoaks.com
Old Town Astronomers: http://www.otastro.org

Martin Brown wrote:

Real clocks suffer all sorts of effects. GR shows that gravity alters

their frequency too. And all these effects have to be compensated for
in
the GPS system. Amusingly though because electronic engineers have
the
same sorts of problems in accepting relativity that you do they
provided
a means to switch off the relativistic corrections "just in case".
However, SR + GR predictions were found to be exactly right. This was

not a surprise to the physicists and astronomers.

The on-board clocks do not need to be corrected for GPS to function
properly. All one needs to know is how to compute GPS time from what
is being broadcast by the satellite -- and to that extent, if the
on-orbit clocks were wildly inaccurate, but in a known way, GPS would
still work fine. It is merely for (great!) bureaucratic convenience
that the apparent rate of the on-orbit clocks matches those on the
ground.

The only "real" relativitistic corrections in GPS pertain to the
eccentricity of the orbits. I recall this is a receiver-applied fix
from data broadcast by the satellite -- check the GPS signal
specification for the nitty gritty. The corrections amount to some
number of metres if I remember right. Not huge, but trivially
observed.

You can derive the formulae for special relativity rather elegantly
by
requiring only that the laws of physics should be the same in all
inertial frames and observing very carefully the passage of two metre

rules past each other at constant speed v and the distinct events
that
occur as seen from the ends of the rods. Taking c = constant on the
basis of Maxwell's equations. One of the classic SR books has this
derivation in it. It only requires basic high school linear algebra.

You can do much better. From some some simple topological and spatial
assumptions -- NOT including the constancy of 'c' in all reference
frames -- one can derive the general form of the transformation. From
this derivation a reference-frame independent "universal speed limit"
pops out, and it is our observations of reality that connect this speed
to the speed of light.

See:

http://groups.google.ca/groups?q=spe...t.com&r num=4