[time-nuts] Measuring speed of light or reproducing a metre

[jmfranke]

The tuning fork was used with a clock. The clock was checked against 
astronomical measurements.

http://www.schoolphysics.co.uk/age16-19/Wave%20properties/Wave%20properties/text/Speed_of%20light/index.html

http://www.nhn.ou.edu/~johnson/Education/Juniorlab/C_Speed/2007-PhysToday-RefFrame-Michelson.pdf

http://www.loc.gov/item/magbellbib002940 synchronizing two forks, letter to 
Bell.

http://www.otherhand.org/home-page/physics/historical-speed-of-light-measurements-in-southern-california/the-mount-wilson-station-1922-1928/

John  WA4WDL

--------------------------------------------------
From: "Jim Lux" <jimlux at earthlink.net>
Sent: Monday, June 24, 2013 4:55 PM
To: <time-nuts at febo.com>
Subject: Re: [time-nuts] Measuring speed of light or reproducing a metre

> On 6/24/13 10:08 AM, Chris Albertson wrote:
>> Using only "moderately" accurate equipment, like mechanical clocks and
>> meter sticks Albert Michelson has able to measure the speed of light and
>> determine it was a constant in all directions.   It was this work the
>> prompted Albert Einstein to think about what t means for C to be 
>> constant.
>>
>> They were working at about the turn of the last century or before 1890 to
>> about 1905 and did not have lasers or HP universal contours.   They used
>> sunlight.
>>
>> One experiment was done here where I live up at the Mt. Wilson 
>> Observatory.
>> They put light from a slit onto to a rotating mirror and then bounced it
>> off a fixed mirror back to the rotating one.  If the speed were infinate
>> the light would go right back up the slit.  But in reality the light 
>> misses
>> because the rotating mirror moves a little while the beam is in flight.
>
> Isn't that the Fizeau technique, which antedates Michelson's?
>
>>
>> The advantage of this is that it is a direct measurement of the speed of
>> light that does not depend on many assumptions and can be done with
>> technology that was available in the late 1800's   One big limitation is
>> the atmosphere.  You need very stable air over the long path length
>
> You need to know the rotation rate of the toothed cog or rotating mirror, 
> don't you?
>
> You could get that by matching against something like a tuning fork, but 
> how do you measure the frequency of the tuning fork.
>
>>
>> This was the experiment that got Einstein thinking.  He said he started 
>> at
>> age 16 to think about how the light from a moving lamp could be the same
>> speed as one from a stationary lamp.  It was total non-sense and 
>> impossible
>> at the time.   We have to remember that those experiments at the time 
>> were
>> are considered to be "Failed Experiments" because "C" could not be 
>> constant.
>>
>>
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