George Dishman wrote:
wrote in message
oups.com...

N:dlzc D:aol T:com (dlzc) wrote:

Maxwell provides the conundrum I describe, since light travels at
c for
all
observers, yet light leaves "forward" from an object travelling at
c. He
seems to be running towards Fizeau next...

Then wasn't Maxwell saying c'=c+v

David said "light travels at c for all observers"
hence c'=c.

If c'=c for ALL observers, does not l'=l for those SAME observers?

http://www.fnal.gov/pub/inquiring/mo...ght_page9.html

, and thus in direct conflict with AE?

See section 6 of Einstein's original paper:

http://www.fnal.gov/pub/inquiring/mo...ght_page9.html

How is the increasing length per time (velocity) of these jets
measured?

Length isn't too meaningful as the jets are a
continuous flow so there is no clear end to the
jet. Measuring the speed depends on non-uniformity
in the flow by following the progress of 'knots'
of matter. For example:

The view is of a train coming out of a tunnel; select a carriage (=
knot)
and measure to engine. Length is carriage - engine velocity is
carriage
- tunnel mouth / time

http://www.stsci.edu/ftp/science/m87/m87.html

and in particular this set of frames:

http://www.stsci.edu/ftp/science/m87/bw3.gif

Or look at the attached radio map he

http://www.phy.duke.edu/~kolena/superluminalmotion.html

You might also practice your maths by trying
to answer the questions on that page ;-)

SR believers might claim that the only legitimate measurement would
be
that of a traveller on the jet!

SR provides a set of rules for converting
measurements in one frame into another frame.
Both measurements are "legitimate" in their
respective frames.

If we applied SR to the observed velocity length which we are seeing,
then the jet would vanish! (Travelling at c it reduces to nil)

We can see the speed of the jet by way of the increasing angle between
the source and the "top", if we have a fair idea of the distance from
here.
The passenger on the jet has NO angle to observe, and so he continues
to be mistaken in his belief that he is closer to the top than he
measures. :-)

Otherwise, SR is decapitated right
here, with the obvious and trivial observation that velocity has
NOT
shrunken the moving body!

It has. Someone riding on the jet would measure
a greater distance between the same knots than
an observer at rest wrt the source and viewing
the jet perpendicular to its motion.

similar to above

Cheers
Jim G
c'=c+v