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Lundi, 15 Novembre 2010 06:00

Navy's Super-Laser to Hunt for 'Dark Energy'

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The Navy has lots of plans for the “Holy Grail” of energy weapons, from burning enemy missiles out of the sky to helping aim a ship’s traditional guns. But the Navy has a more expansive use in mind for

its Free Electron Laser: find the basic power source of the universe.

Oliver K. Baker is a 51 year-old Yale particle physicist. Every few months, he leaves tweedy New Haven for the Jefferson Lab in Newport News, Virginia, where he powers up the Navy’s Free Electron Laser, a laser the size of a schoolbus that uses supercharged electron streams to generate photons in one of a multitude of wavelengths. He fires the resultant beam of light into a tube containing a vacuum  — all in the hope of finding trace elements of so-called “dark energy,” the stuff God uses to heat His celestial home. (Well, maybe, kinda sorta.) Far off as Baker’s research may be from hitting paydirt, the Office of Naval Research, which runs a $163 million project to turn the laser into a death ray, writes the checks that make it possible.

Dark energy is purely theoretical, for the time being: no one’s actually discovered it. But physicists figure that since the universe is accelerating as it expands outward from its Big Bang origins, something must be powering that expansion. Finding the cosmic energy source is a proposition that intrigues the Navy, considering how epochal its discovery and harnessing would be for humanity.

“If proven correctly through quantum mechanics,” explains Quentin Saulter, the Office of Naval Research’s program manager for the Free Electron Laser, dark energy “would comprise the majority of the energy in our universe. The majority of energy in our universe. And we don’t use it.”

Find dark energy, figure out how to make it an applicable power source, and humanity enters a new era. Hydrocarbons become irrelevant against a theoretically unlimited power supply. And that’s just the start: imagine sending emails to the furthest reaches of space. Theoretically, “dark matter particles can go through entire planets with no degradation, so we could communicate through suns, planets and stars,” Baker says. “They have all kinds of applications if we could prove their existence. Energy is just one of them.”

That’s why Saulter dug nearly $300,000 out of his budget just last year alone to fund Baker’s hunt for the mystery particles. It’s an effort that stretches back to 2005, when Baker was a Jeff Lab scientist who asked Saulter if he could borrow the Office of Naval Research’s super-laser from time to time. Saulter was intrigued and provided Baker with access to the Free Electron Laser and seed money to perform related experiments on the Yale campus, using a compact accelerator to generate 34-gigahertz microwave photons. “Right now, the only funding I get to pursue this research is ONR money,” Baker says.

And the money would be irrelevant if ONR didn’t let Baker shoot its laser.  To simplify and summarize his research, Baker’s team of around a dozen scientists uses the Free Electron Laser to look for something called a chameleon particle, predicted in some models of dark energy. A chameleon particle is a unit of dark energy whose mass changes depending on its environment. Inside the vacuum of space, the particle would have mass of zero, the same mass a photon possesses.

Couple a Free Electron Laser with a magnetic field, shooting the laser into a length of empty pipe with transparent flanges sealing the ends, and “I can create chameleon particles, if they exist in this mass and coupling range,” Baker says. “If they tried to penetrate the glass flange, their mass would grow rapidly, so they’d violate energy conservation. They have an energy that’s tuned to the original photon that made them.” The Free Electron Laser generates a higher average power than other lasers, making it ideal for such research.

Then it’s a matter of turning off the laser while the magnetic field remains on. The particles, in theory, should change back into photons. (They’re “chameleons,” after all.) If there are photons still bouncing around the tube — and the Free Electron Laser works with the team’s photon detectors more easily than any regular old laser — Baker will have made a remarkable discovery.

Not that it’s worked so far. “You never know,” Baker says. “We could see something new. Or the theories could be wrong. Or theories could be right but we’re not sensitive enough with our instruments.”

For now, Saulter’s happy to fund the search. After all, the Free Electron Laser’s budget is in the hundreds of millions of dollars. Using a funding arrangement with Jeff Lab, the Office of Naval Research has given Baker about $900,000 over the past five years — a total that amounts to digging through Saulter’s couch cushions for loose change.

“If we can understand [dark energy] and control it and use it to our benefits, we can see things like fossil fuels going away, new types of communications,” Saulter says. “If we can change dark energy… back into regular energy, now you’re talking about Star Trek-like ‘Beam me up, Scotty’-type stuff.”

The Office of Naval Research is still years away from fielding a Free Electron Laser weapon on any ship. It’s safe to say that by the time the weapon comes on board, it won’t be generating its intended 100 kilowatts of power from any dark energy. “FEL will not be powered by dark energy,” concedes Tammy White, a spokeswoman for the office. We’re just looking ahead and into the far future.”

Then again, Baker says, “You just never know. We could be around the corner, we could be years away.”

Image: NASA

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Authors: Spencer Ackerman

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