I did a little work on the speed of light some years ago.  My question was, is 
the speed of a light a dependent or an independent variable.  The analysis I 
did is similar to an exploding body at the center of the teeter toddor.  In 
such a case the teeter toddor will always remain in balance.  It called the 
conservation of the center of mass. It is a consequence of the conservation of 
momentum.   I did such a problem where a body in the center of the teeter 
toddor emitted a photon.  I got some interesting results.  No one has ever 
commented or cared.


http://www.angelfire.com/scifi2/zpt/chapter7.html#Pg12


Frank Znidarsic





-----Original Message-----
From: Jed Rothwell <[email protected]>
To: vortex-l <[email protected]>
Sent: Wed, Aug 24, 2011 6:55 pm
Subject: [Vo]:I meant confidence that light has a speed


I wrote:
 


Scientific instruments and techniques hundreds of years old can measure 
temperature, the speed of an object, the speed of light and many other 
important values with as much confidence as the best technology can today; 
albeit with far less precision.

Note that the speed of light was measured by Roemer in 1676 by observing the 
eclipses of the moons of Jupiter. He measured 2.14 * 10E8 m/s. The modern value 
is 3.00 * 10E8 m/s.


I have confused the issue here. Let me explain what I mean by "confidence" in 
this case. I don't mean the mathematical version, which is what I meant 
elsewhere.


In the 1600s there was a debate over whether light goes instantaneously 
everywhere, or whether it propagates at some speed. Roemer established that the 
latter is correct. He established with 100% confidence that light does move at 
a certain speed. Proof of that cannot be made more certain with the best modern 
methods. The actual number he came up with was remarkably accurate given the 
tools and knowledge of the time, but that's not the "confidence" I had in mind. 
I mean confidence in the conclusion that light moves.


As far as I know, everyone at the time accepted his result.


Here is an interesting footnote to history. I believe the speed of sound was 
not established with this much precision until later. This was done by assuming 
for simplicity that the speed of light is close to infinite over short 
distances, and firing a cannon. The time delay from the flash to the sound of 
the explosion gave the speed of sound. This was done in 1826 at Lake Geneva to 
establish a value to within 1% of the modern figure. I don't know how they 
recorded it. I guess by pressing buttons to start and stop a timer. You would 
think this would mainly record human reaction time but I suppose it depends on 
how far away the cannon was.


- Jed




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