Re: recoiling photons evidence?

In message <[EMAIL PROTECTED]>, ralph sansbury 
<[EMAIL PROTECTED]> writes
> RS     The  confusion is in the inadequate concept. The rest mass
> of a photon is zero, its mass in motion due to the relativity
> increase
> is infinity so (1/2)mv^2 =(1/2)mc^4 =infinity times c^4 but also
> hf where f is the frequency is equal to the kinetic energy of the
> moving photon (1/2)mv^2. This says
> that infinity is equal to a finite number. Because of such
> confusion in the concept I am questioning conclusions like you're
> here based on its use.
>      Re a solar sail, this involves much stronger magnetic
> forces than the absorption of radiation by a distant spacecraft
> antenna.
>
> GD  I'm not aware of any magnetic effect on solar sails.
>
> RS    I am aware of the light momentum photon energy argument
> "that when light is emitted from a source there is a recoil
> effect".
> But I am suggesting that there is no evidence for cases like the
> 8Watt transmitter on a distant spacecraft and that solar sails
> involve much greater Wattage and that light pressure on mirrors
> etc involve oscillations in the source and the receiver/reflector
> acting on each other. That is  the mechanism(see Feynman Lectures
> p34-10), Bvq, on oscillating charge moving up and down at
> velocity v in the direction of the propagation of the fields E
> and B causes a driving pressure in the direction of the light
> beam which is called light pressure.
>   Do you know any evidence besides the blanket application of
> the momentum argument showing
> such pressure effects in cases where the emission of photons
> occurs in an isolated source like the spacecraft?
> Ralph

I thought your thesis was that there is no velocity?

As I'm sure you're well aware, the only way to measure the light 
pressure from an 8 watt spacecraft transmitter is to look very 
accurately at its motion, and then disentangle light pressure from the 
other forces on it. That's being done for the "Pioneer anomalous 
acceleration", for instance. What does the available power, or even the 
power density, have to do with it anyway?

But light pressure is routinely being used in laboratories. Look at

MECHANICAL ACTION OF LIGHT ON ATOMS
http://www.wspc.com/books/physics/0585.html

Laser Manipulation of Atoms
http://tycho.usno.navy.mil/clockdev/slowing.htm

for instance.
--
Rabbit arithmetic - 1 plus 1 equals 10
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