Matter and Antimatter



he science headlines around the world at the moment are reporting how a Canadian-led group of researchers have managed to trap antimatter for more than a quarter of an hour. They used instruments at CERN, near Geneva to make this elusive material, and a novel idea to trap it. This is amazing news. In the past we could only look at our data and see that for a minute fraction of a second, we had a particle or two of antimatter. In movies, “losing antimatter containment” is usually the last phrase uttered before the explosion occurs.

Antimatter has been described as the mirror image of what we call “ordinary matter”. We are made of “ordinary matter”, made of atoms, which in turn are collections of protons, neutrons and electrons. Antimatter is made of antiprotons, antineutrons and antielectrons (which we call positrons). If we bring a particle and its corresponding antiparticle together, they annihilate each other, releasing energy.

Imagine you have no money, so you find a kindly and better-off friend and ask him to loan you a dollar. So you now have a dollar, but you are also in debt for a dollar, so you really still have no money. You could say that you have a dollar and an antidollar. If you bring the dollar and antidollar together, they annihilate one another. The banking industry makes a huge amount of profit in trading real and antidollars.  To a large degree the recent financial explosion happened because some major banks lost containment of their antidollars.

Our universe started as colossal burst of energy. When the temperature had fallen enough, the energy started to turn into matter. We would expect that this process would be exactly the reverse of what happens when a particle and its corresponding antiparticle meet. In this case, a chunk of energy would convert into a particle and antiparticle. Probably some would promptly annihilate each other again, releasing the energy again, but a lot of them must have avoided this fate, because there is a lot of matter around today.  We would therefore expect that for every proton, neutron and electron making us, the Earth, the Solar System and so on, there are corresponding antiprotons, antineutrons and positrons out there somewhere, just as for every dollar you borrowed to buy your home or new car, there is an antidollar circulating in the banking system.

If our universe was once filled with equal amounts of matter and antimatter, we could imagine that where they were mixed equally, they would eventually wipe each other out. In other places, where there was an excess of one form over the other, we would be left with a remnant of whatever form of matter was in excess.  We would get neighbourhoods composed of 100 per cent of one form of matter, quarantined from other neighbourhoods by large chunks of empty space. If we were to bring all those clouds together, all the matter would cancel out. However, so far our observations suggest our universe is dominated by ordinary matter. Hopefully, having some real antimatter to study, rather than having to work with theoretical concepts will help us find out what is really going on.

Jupiter, Mars and Venus form a procession out of the sunrise glow. Saturn is high in the southern sky. The Moon will be full on the 15th. The Summer Solstice, the northernmost point in the Sunís yearly travels, will be at 10:16 PDT on the 21st.

Ken Tapping is an astronomer with the National Research Council’s Herzberg Institute of Astrophysics, and is based at the Dominion Radio Astrophysical Observatory, Penticton.