So far, anti-matter has only found widespread use in science fiction, like the upcoming film “Angels and Demons.” Many scientists, though think the fabled substance could revolutionize our understanding of energy – and are getting closer to doing so.

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.

“NASA has identified anti-matter as the ultimate energy source for exploration of the outer reaches, and outside, of the solar system,” Jackson said. “This work is all theory to date, but we are moving quickly to the experimental stage.”

Because it’s so unstable, anti-matter has to be stored in a vacuum and kept away from a container’s walls by powerful magnets.

NASA has designed such a container – called HiPAT, for High Performance Antiproton Trap, which is capable of storing a trillion anti-protons for at least 18 days – at the Marshall Space Flight Center in Huntsville, Ala.

Most anti-matter is created in the AntiProton Source Department of the Fermi National Accelerator Laboratory in Batavia, Ill. Small portions have been produced at the Brookhaven National Laboratory in Upton, N.Y., and at CERN, a European nuclear collider in Geneva.

Brown’s fictional quarter-gram of anti-matter supposedly was stolen from CERN.

The new Large Hadron Collider in Geneva will be able to generate much larger quantities than these others when it begins operating next fall – but nowhere near enough to blow up the Vatican.

Scientists hope that their anti-matter experiments will help answer a number of major questions about the nature of the universe.

Phillips has presented a proposal to the Fermi lab for an “anti-matter gravity experiment” to test how gravity affects anti-matter. For example, would an anti-apple fall up or down?

“Our understanding of gravity might be incomplete,” Phillips said.

Scientists at the Massachusetts Institute of Technology, led by Nobel laureate Samuel Ting, have proposed an anti-matter experiment to be flown on the International Space Station.

NASA is considering the plan.

Another experiment would test the effect of magnetism on anti-helium, another form of anti-matter, said Benjamin Monreal, a physicist at the University of California, Santa Barbara.

A baffling question is why the universe consists almost entirely of matter and not anti-matter. Scientists think that both substances were created in equal measure at the big bang.

“Where is all the anti-matter in the universe?” Monreal asked. He speculated that it may be hiding in anti-matter galaxies, even in unseen anti-matter universes.

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