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Friday, Jun. 26, 2009

Scientists harness anti-matter, ordinary matter's 'evil twin'

WASHINGTON — Tom Hanks' new movie, ``Angels and Demons,'' tells of a secret plot to blow up the Vatican and everyone inside it by using ``the most terrible weapon ever made'': anti-matter.

As "Star Trek" fans know, anti-matter is the mirror image of ordinary matter, identical except that its electrical charge is reversed, like the opposite ends of a battery.

Discovered in 1932, anti-matter is sometimes called the ``evil twin'' of the familiar matter that makes up rocks, chairs, earth, air, water and living bodies.

All atoms consist of central nuclei surrounded by one or more electrons. In a normal atom, the nucleus has a positive charge and the electrons are negative. An anti-matter atom is the opposite: Its nucleus is negative and its electrons are positive.

If matter and anti-matter meet, they instantly annihilate each other in an explosive burst of energy. The collision converts matter into energy with 100 percent efficiency, far better than even a hydrogen bomb can do.

Scientists think that anti-matter was created, along with ordinary matter, in the big bang, the theoretical birth of the universe 13.7 billion years ago. Almost all the anti-matter has disappeared — no one knows where — but physicists are re-creating small amounts of it in laboratories in the United States and Europe.

Hanks' movie, which opens May 15, is based on the best-selling novel by Dan Brown, also named ``Angels and Demons,'' but scientists say its plot is physically impossible, at least for now. Brown's device uses a quarter-gram — nine-thousandths of an ounce — of anti-matter, an amount that's billions of times more than today's technology can create.

"It would take millions or billions of years to make this much at the current production rates,'' said Thomas Phillips, a physicist at Duke University in Durham, N.C.

Nevertheless, the Defense Department, the Energy Department, NASA, university physicists and a few private companies are working to produce and manage anti-matter and to develop useful applications for this weird stuff.

Potential applications include propellants for deep space travel, better cancer radiation therapies and detectors for smuggled nuclear materials, according to Gerald Jackson, a physicist and the president of Hbar Technologies in West Chicago, Ill. "Hbar" is physicists' shorthand for anti-hydrogen.

Radiologists already use a simple form of anti-matter in PET — positron emission tomography — scans. A positron is the anti-matter equivalent of an electron.

Jackson is hoping to launch a $30 million, privately funded cancer-therapy program using anti-protons, the heart of an anti-atom's nucleus.

``You may be familiar with proton radiation therapy,'' Phillips wrote in an e-mail. ``Anti-protons are much more effective.''

Since 1995, laboratories have been churning out tiny quantities of anti-hydrogen, an anti-atom composed of an anti-proton and an anti-electron. Their output is measured in nanograms, billionths of a gram.

"Only a few thousand anti-hydrogen atoms have been synthesized to date around the world,'' Jackson said.

He said that anti-matter was being created in the solar system continually as high-energy cosmic rays collided with protons streaming out from the sun, and it could be "harvested" for practical use. His company hopes to test an anti-hydrogen space-propulsion system next year.