Hi list !
Searching for "newton jupiter moons speed of light" I found this very
nice page:
http://galileoandeinstein.physics.virginia.edu/lectures/spedlite.html
A lot of the early measurements of c are described, with the accuracies
reached.
But most of the older methods are rather difficult to demonstrate to
kids, as they need long series of observations...
Best regards,
Jean-Louis
On 24/06/2013 21:26, Chris Albertson wrote:
On Mon, Jun 24, 2013 at 1:55 PM, Jim Lux <[email protected]> wrote:
On 6/24/13 10:08 AM, Chris Albertson wrote:
Isn't that the Fizeau technique, which antedates Michelson's?
Michelson got the precision good enough that it finally put the question
to rest. We used a miles-long baseline of very clear and still air.
You need to know the rotation rate of the toothed cog or rotating mirror,
don't you?
I think you have to count the number of rotations over a larger time
interval. And at the same time make sure the spin rate is constant. They
used a large hexagon with mirrors on all the faces and spun it up using
some kind of clock work.
You can see if the wheel is speeding up or slowing down because the slit of
returned light should have constant offset. So the experiment has a
built-in check on the rate remaining constant. And then you count the
turns over some long interval using gears or what not. They built a shed
to house this thing on the side or Mt. Wilson. All that is left no is the
concrete foundation and concrete pier for the instrument. This was a not
small scale lab experiment. It must have been well funded to be able to
pour tons of concrete at a remote location like that.
I think the harder part is knowing what the long baseline is. How to
measure 5 miles distance with the required accuracy in 1900? Yes they have
survey equipment back them put how good was it? I I don't think they
needed to know the exact length, just that it was a long constant length.
They were only trying to show the "C" was not constant. But of course the
experiment "failed"
--
Jean-Louis Oneto
OCA GeoAzur - 2130 Route de l'Observatoire
Caussols 06460 Saint-Vallier de Thiey - France
email: [email protected]
phone: (+33)[0]4.93.40.54.25
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