Tim Cook wrote:
> Darren New wrote:
>> Name energy that isn't in the form of mass?
>> Then explain what E=mc^2 means.
> 
> Light isn't in the form of mass.

Yes it is. Photons have mass. Indeed, the reason they go the speed of 
light is (sloppily speaking) that they are *all* energy, so they *have* 
to go the speed of light just to have mass to hold the energy.

> Sound isn't in the form of mass. 

The atoms move to make sound. Sound is kinetic energy, which is mass due 
to relativistic movement.

> Electricity isn't in the form of mass.  

Electrons move, hence kinetic energy, hence mass.

> Magnetism isn't in the form of mass.  

Magnetism consists of photons. Photons have mass.

> E=mc^2 means that the amount of energy stored in a given mass can be 
> determined by multiplying the mass by the speed of light squared. 

Equally, it says that the amount of energy can be determined by 
multiplying the amount of mass by the speed of light squared. That's an 
equal sign there. That's how relativity works.

Where does the kinetic energy in a moving asteroid go if I accelerate my 
spaceship up to the same speed? Does the stationary observer see more 
energy than the observer moving at the same speed? Wouldn't that mean 
that energy can be created and destroyed at will, just by moving the 
observer without changing the experiment? Do you understand why leaving 
a gravity well makes you heavier?

I know what you're trying to say. You're trying to say that there is 
energy that's not the equivalent of mass, and that E=mc^2 only applies 
to mass, not energy. That's incorrect. Intuitive, but incorrect. Really 
and truly.  That's why it took so long to be accepted.

-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

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