Ultima Thule

In ancient times the northernmost region of the habitable world - hence, any distant, unknown or mysterious land.

Wednesday, August 30, 2006

Atomic force weaker than thought

By Aussiegirl

I find it hard to imagine the delicacy of technique that can isolate a single electron in some sort of bottle, and then measure its motion. Probably this new, more accurate value of the "fine structure constant" -- I love the poetry of this name! -- will in turn be found to be slightly inaccurate. So goes the slow progress of science towards a better and better understanding of our natural world -- but of course never getting any closer to the ultimate mystery of existence.
Here's another article on this subject: Refining the fine-structure constant. And another: Atoms looser than expected.
And if that isn't enough to satisfy those of my readers who can't get enough of this constant, here's a long, 4-screen article from April 2003 exhaustively delving into this topic, asking just what are laws of nature, using other methods of investigating this constant, and explaining what's at stake if a fundamental constant is found to have changed: Are the laws of nature changing with time?

Atomic force weaker than thought - LiveScience - MSNBC.com

By Sara Goudarzi
Staff Writer

A fundamental force that holds electrons inside atoms and governs how charged particles and light interact is a little weaker than previously thought, scientists reported today.

The strength of electromagnetic force, one of the four fundamental forces of nature, is specified through a value known as the fine structure constant. Through studying an individual electron in isolation, scientists were able to calculate a new value for this number that is six times more precise than previous estimates.

"Little did we know that the binding energies of all the atoms in the universe were smaller by a millionth of a percent — a lot of energy given the huge number of atoms in the universe," said Gerald Gabrielse, a researcher at Harvard University.

Gabrielse and his colleagues developed a giant atom by isolating an electron in a bottle devoid of almost all particles and chilled to temperatures colder than the surface of Pluto.

Similar to a real atom, they kept the lone electron in circular motion through electric and magnetic forces. The electron also wobbled down in the direction of the magnetic field, a setup similar to a merry-go-round, with an electromagnetic trap as the carousel and the electron as the lone horse.

The setup was sensitive enough to sense when the electron is moving upwards and when the motion is restricted, allowing the electron's energy to be precisely measured. This helped refine measurements of the fine structure constant.

The more precise value could help improve the design of electric devices and aid scientists in the details of the workings of the universe, the researchers say.

These results appear in two papers in the July 21 issue of the journal Physical Review Letters.


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