Our world is made of matter. "Everything you see and feel — your laptop, your desk, your chair — they are all ordinary matter," says Aihong Tang, a researcher at Brookhaven National Laboratory.
But matter has a counterpart called antimatter. Each kind of fundamental particle of matter has an antimatter nemesis lurking in the shadows. And true to science-fiction stereotype, if matter and antimatter ever meet, they annihilate in a flash of light.
If you've never run into "antimatter" outside of a Star Trek episode, you're not alone. There's not a lot of antimatter in our universe. And that has physicists confused.
"We actually don't understand why antimatter is as rare as it actually is," says Joel Fajans, a researcher at the University of California, Berkeley. "The Big Bang should have produced just as much matter as anti-matter, but it didn't."
To try and solve the mystery, researchers make small amounts of antimatter in the lab. One recent experiment took place inside a giant particle accelerator called the Relativistic Heavy Ion Collider. The collider smashed together atoms of pure gold. The raw energy of the collisions created particles of antimatter.
The group of scientists that Tang belongs to studied the antimatter counterparts of protons. A proton is the positively charged particle found at the center of atoms; the antimatter version is negatively charged and called (you guessed it) an antiproton.
Tang measured something called the "Strong Nuclear Force" between two antiprotons. In normal matter, the Strong Force is what holds atomic nuclei together. Tang and his group wanted to see if it could hold antiprotons together, as well.
Their result, published in the journal Nature, suggests the Strong Force works the same for antiprotons as it does for protons. "Our experiment confirmed that they indeed behaved just like ordinary matter," Tang says.
Here's why that matters: If antimatter behaves differently than matter, then there may be some asymmetry at work — and that might explain why there are such drastically different amounts in the universe.
Fajans, who was not directly involved with the research, says researchers are going to keep looking for cases where the antimatter acts differently.
"There are four fundamental forces that physicists are aware of, and we're starting to cover all of them," Fajans says. "It's a wonderful time in the antimatter business.
ROBERT SIEGEL, HOST:
Today, researchers announced new results of a study of antimatter.
(SOUNDBITE OF TV SHOW, "STAR TREK")
LEONARD NIMOY: (As Mr. Spock) To parallel universes - one matter, the other, antimatter.
SIEGEL: "Star Trek's" Mr. Spock there, of course. He wasn't involved in today's findings. Here's NPR's Geoff Brumfiel on the scientists who were and what they found.
GEOFF BRUMFIEL, BYLINE: Here's how real-life expert Joel Fajans describes antimatter.
JOEL FAJANS: Antimatter is a mirror universe of particles.
BRUMFIEL: Sounds just like Star Trek - right? - and it is. Regular matter is made of atoms. Your radio, your cell phone, your body - all matter. Antimatter is the sinister backwards version. And what happens when they get together? Take it away, Spock.
(SOUNDBITE OF TV SHOW, "STAR TREK")
NIMOY: (As Mr. Spock) When two identical particles of matter and antimatter meet...
WILLIAM SHATNER: (As Captain Kirk) If they meet...
NIMOY: (As Mr. Spock) Annihilation, Jim - total, complete, absolute annihilation.
BRUMFIEL: Fajans, a respected researcher at the University of California at Berkeley will tell you exactly the same thing.
FAJANS: It blows up - what we call annihilates. It explodes and becomes pure energy.
BRUMFIEL: Antimatter is totally sci-fi, but it's also totally real and really mysterious. Think about it. There's no antimatter radios or antimatter people that we know of. So where is it?
FAJANS: We actually don't understand why antimatter is just as rare as it actually is. Going back to the Big Bang, the Big Bang should have produced just as much matter as antimatter, but it didn't.
BRUMFIEL: To try and solve the mystery, researchers make small amounts of antimatter in the lab. This time, they've done it on Long Island inside a giant particle accelerator called the Relativistic Heavy Ion Collider. Scientists mashed together atoms of pure gold to make particles of antimatter. Aihong Tang led the experiment. He says making antimatter from gold isn't as pricey as it sounds.
AIHONG TANG: The actual amount of gold is actually tiny. It doesn't - worth much.
BRUMFIEL: And the payoff could be huge. In the journal Nature, Tang's group describes forces between the antimatter counterparts of protons. A proton is the positively charged particle found at the center of atoms. The antimatter version is negatively charged and called - you guessed it - an antiproton. See; physics isn't so hard. Anyway, the point is, the force between two antiprotons is just like the force between two regular protons.
TANG: Our experiment confirmed that they indeed behave just like ordinary matter.
BRUMFIEL: And here's why that matters. Discovering a difference between matter and antimatter would probably explain why one is common and the other is rare. This experiment let's scientists rule out one possibility. They'll move on to something else in the name of science and, Joel Fajans says, because it makes them sound cool.
FAJANS: Not so many people get to work on things that "Star Trek" talks about.
BRUMFIEL: Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.