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Brian Greene: That Famous Equation and You
From: David Farber <dave () farber net>
Date: Fri, 30 Sep 2005 13:54:11 -0400
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 equivalentof 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 itdid 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 theuniverse -- 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 ------------------------------------- You are subscribed as lists-ip () insecure org To manage your subscription, go to http://v2.listbox.com/member/?listname=ip Archives at: http://www.interesting-people.org/archives/interesting-people/
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- Brian Greene: That Famous Equation and You David Farber (Sep 30)
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