In 1801 an English physicist conducted what was to become the famous Double-Slit experiment. In the experiment, electrons shot through two screens showed up as bars spaced with empty lines, called inference patterns, on a board behind them. This demonstrated that light, when unobserved, consisted of waves affected by gravity, and showed how the particles of light interfere with one another when passed through small spaces.

In with the old and in with the new

Now physicists have taken this age old method and replicated it with antimatter, a curious fundamental particle which occupies another half of the energy in the universe.


Every member of the grand library of fundamental particles shares most of their characteristics with an antimatter replica, the ladder possesing an opposite charge and some other quantum tweaks. So rather than shooting electrons at the two slits, researchers from Switzerland and Italy used positrons, the animater doppelganger of electrons.

Obeying the laws

Several experiments have suggested that antimatter should obey the laws of gravity exactly the same way as normal matter. But if there is even a slight difference between the two, it could act as a catalyst for understanding the bizarre interactions between matter and antimatter.


For instance, if each particle observed has an antimatter twin, and that when the two collide they disappear in a phenomenon called annihilation, why isn’t everything exploding? Is there just far more matter than antimatter?

A positive antimatter result

After 200 hours of firing positrons from some decaying radioactive material at a similar setup to the famous double-slit, the Italian and Swiss researchers found that individual positrons acted as waves when no one was looking, in exactly the same way that electrons do.


The study is yet to be subjected to peer-review, and seems more proof of concept rather than confirmation, but it could lead to more sensitive testing – the kind that can detect even the smallest inference pattern changes. That’s the kind of delicate science which we’ll need to really begin to understand antimatter.