Plot Device of Mass Destruction: Antimatter's True Story

The scoop: Angels & Demons, a movie adaptation of Dan Brown's best-selling novel, includes an antimatter bomb at the heart of its plot.

What is so alluring -- and downright alarming -- about antimatter, and is there any real science behind it? A Brookhaven National Laboratory physicist gives his take.

With the movie Angels & Demons about to drop, we can be certain another wave of worry about science-run-amok will drop with it. In this case, the hype will surround everyone's favorite example of Star Trek science: antimatter.

The word "antimatter" might sound terrifying, but the real thing is just about as frightening as ordinary matter. To understand why, it's helpful to think about what antimatter is, how it's created and the scientific mysteries hiding behind it.

Antimatter was a truly impressive theoretical prediction during the infant years of quantum mechanics and particle physics. In the 1920s, a fellow named Paul Dirac was fiddling with the idea of particles traveling near the speed of light, and stumbled upon a formula with two solutions -- one with a positive energy (+), and one with a negative energy (-).

At first it seemed to be "unphysical," at least until Dirac imagined an "anti electron" (or positron) having a positive energy and a positive charge -- exactly opposite of an electron. Carl Anderson discovered positrons in 1931, yet in spite of Dirac's clear prediction, Anderson did everything he could to disprove positrons existed because it was "quite radical" at the time. Clearly nature disagrees.

Now when an electron meets its mirror twin the positron, they annihilate into energy (usually into two photons, or pieces of light). I suppose these two seemingly strange facts about antimatter -- that it's a "mirror" of normal matter and able to annihilate it into energy -- is what gives it an air of mystery and danger, exploited for powerful dramatic effect by author Dan Brown and others.

And yet, at least to a particle physicist, antimatter is just another member in a veritable zoo of particles.

Every particle has an anti-particle, one with an opposite charge and opposite "magnetic moment." And creating them isn't that big of a problem. For example: if you ramp up the Large Hadron Collider at CERN and smash together two protons, hundreds of particles fly out. You can be sure that half of them will be matter particles, and the other half will be antimatter particles. Yet if you could add up the atomic debris, you'd always get two protons -- i.e. matter and energy are conserved, and you get out only what you put in.
 
That said, I should point out that anti-particles aren't exactly the same as antimatter.

The anti electron was discovered in 1931 and the antiproton by 1955, but it wasn't until 1995 that scientists made anti-hydrogen (anti electron + antiproton) in an experiment at CERN. My textbook-addled graduate student brain wasn't impressed at the time, since I knew about Dirac and all of the anti-particle partners to the zillions of particles we saw in heavy ion collisions at CERN. I failed to appreciate both how difficult it was to coax antiprotons and positrons to play nice with each other amid a relatively high-energy collision. I also failed to appreciate just how interesting it would be if anti-hydrogen was even slightly different than normal hydrogen.

Why? We only see ordinary matter around us. Heck, why should we see any matter at all if it is always produced alongside antimatter, and the two so easily annihilate!

Thanks to very precise experiments, we now know that some particles aren't the same as their anti-particles, and the conundrum gives rise to what is called "CP violation". The measurement of CP violation has been the focus of major particle physics labs across the globe, but so far the data don't yet tell us how matter outpaced antimatter in the early universe.

But we haven't given up. It is now the goal of several space-borne experiments, such as PAMELA or AMS-02 (provided it can find a shuttle in which to be sent to the space station), to find more non-trivial anti-atoms such as anti-helium, which might suggest the existence of anti-stars... and even anti-galaxies. The prospect is possible if such a region of antimatter spun off into isolation right after the big bang.

So when you get down to it, there's no need to lose sleep over antimatter. It's a venerable subject in particle physics whose mystery should far outshine any fears about its destructive power.

Peter Steinberg is a physicist at Brookhaven National Laboratory who works on experiments at the RHIC (Brookhaven) and LHC (CERN) colliders. He also writes for his blog Entropy Bound as well as the US-LHC blogs. The views expressed are the author's alone and do not represent the official position of the Discovery Channel.

Article posted April 28, 2009.

Got something to say? Email your questions, comments or concerns to discoveryspace@discovery.com.

MORE OPINIONS