Posted on 10/01/2005 8:10:18 PM PDT by GummyIII
Correction Appended
DURING the summer of 1905, while fulfilling his duties in the patent office in Bern, Switzerland, Albert Einstein was fiddling with a tantalizing outcome of the special theory of relativity he'd published in June. His new insight, at once simple and startling, led him to wonder whether "the Lord might be laughing ... and leading me around by the nose."
But by September, confident in the result, Einstein wrote a three-page supplement to the June paper, publishing perhaps the most profound afterthought in the history of science. A hundred years ago this month, the final equation of his short article gave the world E = mc².
In the century since, E = mc² has become the most recognized icon of the modern scientific era. Yet for all its symbolic worth, the equation's intimate presence in everyday life goes largely unnoticed. There is nothing you can do, not a move you can make, not a thought you can have, that doesn't tap directly into E = mc². Einstein's equation is constantly at work, providing an unseen hand that shapes the world into its familiar form. It's an equation that tells of matter, energy and a remarkable bridge between them.
(Excerpt) Read more at nytimes.com ...
Because he never sued anyone else.
David who? ;-)
Ah, I was just being stupid, Gummy. It's past my bedtime. I should never have tried to introduce slapstick into an Einstein thread. (He's the St. Louis Cardinal shortstop.)
Let's try a thought experiment.
Imagine that you have a helium atom whose nucleus consists of two protons and two electrons. These four particles are held together by the strong nuclear force.
Imagine now that one could somehow separate this nucleus into two identical nuclei each containing one proton and one electron. The act of separating these tightly bound particles would require enormous forces operating over a small distance. Once the separation has been accomplished sufficiently to result in two deuterium nuclei, one should then weigh each particle.
What Einstein's theory predicts is that the "binding energy" which is added to the system will be measurable as an increase in mass of the two resulting particles such that the sum of the two particles is greater than the initial mass of the helium atom.
When we run this process in reverse, the binding energy is available to do "work" and we normally see this energy as the fireball and radiation of a fusion bomb.
Now consider what happens when you stretch a metal spring. You are causing forces to act upon a collection of atoms. Acting under the influence of that force, the atoms change position. As they change position, "work" is being done on the atoms as they move through a distance experiencing the force which is holding them together. The energies holding atoms in a solid together are typically much lower than nuclear binding energies because the forces holding atoms together in a spring are electromagnetic forces.
Nevertheless, the atoms in the spring become less tightly bound and the energy stored could theoretically be measured as an increase in mass of the system. The reason we don't measure such mass changes is because it is many, many orders of magnitude smaller than the mass changes caused by nuclear forces.
Similarly to the nuclear case above, if we now release the metal spring it can be made to do "work", that is the energy can leave the system and be observed in objects outside the spring. We could run a clock with the released spring, for example. As the spring relaxes, it exerts a force on the mechanism of the clock, causing motion. The atoms of the spring will move under the action of the electromagnetic force and the atoms will become more tightly bound than in the extended state of the spring. The mass of the entire spring will then be less by the amount predicted by Einstein's equation. But far too little for our instrumentation to measure.
BTTT
That should have said "two protons and two neutrons" and the separation will create two deuterium nuclei each consisting of a proton and a neutron.
I knew that...did you see the ;-)? (wink..)
Hee hee -- I love versatile people, equally at home in the physics lab and the infield!!
I had the same reaction to that paragraph. I don't think any matter is destroyed when a battery releases energy or when gasoline burns. But I'm not a physicist.
I have to remind myself that a news article must pass through the filter of a reporter and an editor. And they typically don't hold doctorates in the subjects they cover. So some inadvertant scrambling of fact is possibly the case.
Did you ever see that classic Bugs Bunny cartoon - a very old one, I believe - based on the Aesop fable of the Tortoise and the Hare ? Bugs is done in by an organized campaign involving a dozen or so turtles. After losing the race, he muses to himself, "You know, I think there's something fishy going on around here", whereupon the dozen or so turtles thrust their heads on screen and intone in unison,
"EHHHHHHHHHHHHHHH, IT'S A POSSIBILTEEEEEEEEEEEEEEEEE !!!!!!!!!!!!!!!"
He studied Physical Zcience.
tagged
Do not worry about your problems with mathematics, I assure you mine are far greater.
Put your hand on a hot stove for a minute, and it seems like an hour.
Sit with a pretty girl for an hour, and it seems like a minute. THAT'S relativity
Albert Einstein
bookmark to read later
"I had the same reaction to that paragraph. I don't think any matter is destroyed when a battery releases energy or when gasoline burns. But I'm not a physicist."
I think you are correct. Batteries operate off oxidation/reduction.
E=mc2 applies to fission and fusion where the products of the reaction are slightly less in mass than the reactants. When heavy compounds such as U235 fissions, the byproducts have less mass than the original U235 they were made from. The resulting energy released (matter becoming energy) is that mass change times the speed of light squared. A little bit of mass change can produce a large energy release. In the case of fusion of some light elements such at Lithium and Deuterium, the fuzed byproducts are less in mass than the original Lithium and Deuterium. That mass results in the same energy production computed by E=mc2.
I don't think that make chemical reactions cause a net change in mass. Fission and Fusion are special cases.
I believe the amount of mass lost is considered negligible for the most part in chemical reactions because it isn't easily measurable.
ping-a-rooney
Perspectives like this drive me crazy.
“What Einstein's theory predicts is that the 'binding energy' which is added to the system will be measurable as an increase in mass of the two resulting particles such that the sum of the two particles is greater than the initial mass of the helium atom.”
Just to be sure I understand—isn’t the sum of the two particles less than the initial mass of the helium atom, due to the loss of the binding energy?
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