"Alain" <ele### [at] netscapenet> wrote in message 
news:47274dcc@news.povray.org...
> ... Gamma radiation is light. The kynetic energy mass gets transformed 
> into light. And remember: light can push objects. It's just that this push 
> is normaly to small for you to notice, but it can easily be demonstrated 
> with a very simple experiment.
> Take an empty globe of glass, place a needle holding a light rotor made 
> from a glass axis and holding 3 or 4 blades, white on one side, black on 
> the other. Place the rotor on the needle. Remove all air from the globe. 
> Have ANY light shining on that rotor, even a candle light, and the rotor 
> will spinn. That experiment is over 100 years old!

I saw that experiment in a high-school physics lab three decades ago.  I was 
mightily impressed -- in fact it was one of my first "WOW" moments in 
science.  It completely turned my mind to suddenly realise that:

a.  Light actually has a mass that exerts force on "solid" matter.

b.  Even at typical levels, light's force on macro-scale objects is strong 
enough that I could stand in an average lab in an average country-town 
high-school and watch a finely-balanced vane turn in a vacuum, impelled by 
nothing but light.

Until then, I'd thought that the effects of things down at quantum 
dimensions could not be observed so simply at our size.

-- 
Brian

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