The delicate and difficult dynamics between matter and antimatter
We’re all comfortable with the notion that opposites attract, particularly when you’re talking about charged particles like protons and electrons. The key mechanic that holds much of our universe together is the attraction between positively-charged protons looking to be balanced by negatively-charged electrons. Antimatter throws some of this for a loop though. While antimatter atoms are still based around positive and negative particles attracting each other, introducing them to their opposite form of matter doesn’t lead to attraction as much as… explosions. In our matter-based world, this incompatibility, shall we say, has made studying antimatter quite difficult, but researchers have started making progress on figuring out just how opposed matter and antimatter really are.
A “normal” atom is made of neutral neutrons, positive protons and negative electrons, and the opposite is true for antimatter. Antineutrons are still neutral, but antiprotons are negatively charged and positrons carry a positive charge. This was first theorized back in 1928, and antimatter has been found to exist naturally in a few pockets of the world, sometimes as a product of radioactive decay of certain isotopes like potassium 40, but also thanks to gamma ray flashes in thunderstorms. Researchers have been working on ways to artificially create antimatter in particle accelerators, leaving only the issue of storing it long enough to work with.
Containment without contact
Since even fleeting contact between matter and antimatter leads to the instantaneous destruction of both in a flash of energy, most traditional storage concepts can’t be used. Thankfully, the reverse side of opposites attracting can be put to use, meaning antimatter can be held in place with a strong electric and magnetic fields. Like matched polarity magnets repulsing each other, metal cans with magnetic and electric fields have been created that can suspend small collections of antimatter particles. Even if suspending some antiprotons is successful, there’s still a risk that they’ll find some positrons and become neutral anti-hydrogen atoms, which would then be harder for the magnetic and electric fields to hold in place…
This isn’t insurmountable though. Scientists working at the CERN particle accelerator recently managed to trap enough anti-hydrogen atoms to shoot a few lasers at them. Aside from the sci-fi headlines this produced, it also allowed them to discover that antimatter isn’t so different from the matter we’re used to. The inverted charges of each particle didn’t seem to make a difference in how light was absorbed or emitted from the antimatter atoms, which gets us closer to understanding and possibly harness antimatter. It’s actually already put to use in positron emission tomography (PET) scans in hospitals, but could someday be used as very concentrated sources of energy. If we could reliably control the flow of particles, a feed of matter and antimatter particles destroying each other could even be used to power rockets, at a much better power-to-weight ratio than conventional fuels we use now. We just need to figure out how to safely bring everything together first.
Source: Antimatter Is Starting to Yield Its Secrets by Phil Plait, Bad Astronomy
