Brian Greene: That Famous Equation and You

[David Farber <dave () farber net>]

Begin forwarded message:

From: Brett Glass <brett () lariat org>
Date: September 30, 2005 1:44:03 PM EDT
To: dave () farber net, Ip Ip <ip () v2 listbox com>
Subject: Re: [IP] Brian Greene: That Famous Equation and You


At 10:50 AM 9/30/2005, Brian Greene wrote:


> The standard illustrations of Einstein's equation - bombs and power
> stations - have perpetuated a belief that E = mc has a special
> association with nuclear reactions and is thus removed from
> ordinary activity.
>
> This isn't true. When you drive your car, E = mc is at work. As the
> engine burns gasoline to produce energy in the form of motion, it
> does so by converting some of the gasoline's mass into energy, in
> accord with Einstein's formula. When you use your MP3 player, E =
> mc2 is at work. As the player drains the battery to produce energy
> in the form of sound waves, it does so by converting some of the
> battery's mass into energy, as dictated by Einstein's formula.

Dave:

Alas, the above are common misconceptions that bear correcting. When
one burns gasoline, one doesn't convert any of its mass into energy.
One is merely allowing the chemical bonds in the gasoline (and the
air used to burn it) to rearrange themselves so that the resulting atoms
and molecules have less chemical potential energy. It's the equivalent
of allowing an anvil to descend from the top of a building to the  
bottom,
and using a rope attached to the anvil to turn a shaft or do other work
as it falls. The anvil has precisely the same mass at the bottom as it
did at the top; it merely has less gravitational potential energy  
because
it is closer to the center of the Earth. A similar process occurs on a
molecular level when a battery is discharged or gasoline is burned.

Right now, the only known processes in which matter is actually
converted to energy are ones that involve the transmutation of elements
into other elements or isotopes. Such processes aren't uncommon in the
universe -- stars, such as our sun, are constantly carrying them out  
-- but
they do not occur when one burns gasoline or discharges a battery.  
Which is
sort of a shame. If it were really so clean and easy to convert  
matter to
energy, all of the geopolitical,economic, and environmental problems
surrounding fossil fuels and similar energy sources would be instantly
solved.

--Brett Glass




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