Well this has been pretty much all over the Internet for the last week, but I wanted to wait and see how it was received before writing about it. A team of Italian scientists have recently released a paper on their experiment to detect dark matter directly, and I must say they present some very promising results. Before presenting the results, let me just explain the idea behind the experiment…

One (and the most widely accepted) theory of what dark matter may be, is the WIMP theory. That is, dark matter consisting of Weakly Interacting Massive Particles and we “just” have to figure out which particle that might be. Another quite certain thing we know about dark matter is that it encloses the Galaxy in a halo that extends far longer than the galaxy itself. The galaxy is like the meat ball in the bowl of dark matter soup. The important part of the WIMP acronym is the weakly interacting part. Even though it is extremely rare that a dark matter particle interacts with another (bright? Ok, you can hit me) matter particle, releasing detectable light, it CAN happen. The problem is that it would be almost impossible to detect these events because they would easily drown in the sea of other unrelated interaction events, so we need a clever, and as it turns out, quite simple idea to overcome it.

As the Sun and the rest of the Solar System moves around the center of the Galaxy, we are dragged through the soup of dark matter particles. So when the Earth revolves around the Sun, we will in half the time be traveling in the direction of the galactic rotation, and in the other half in the opposite direction, which essentially just means that we move just a little faster and slower around the Galaxy every 6 months. If we then assume that the dark matter particles are not moving with the galaxy (which there would be no reason to think they are), we should be hitting more dark matter particles in some 6 months than in the other. Just like you feel less wind when you’re riding your bike slowly. Now if we are able to detect events that vary with this annual cycle, dark matter WIMPs would be very likely to be the reason for it. We simply know of nothing else that would cause this effect.

As you’ve of course guessed by now, this is exactly what the Italian scientists have measured, and to a very high precision as well. There simply is no doubt that there is something changing with our velocity around the Galaxy, and thus the seasons of the year, but it’s very important to note that it is by no means certain that it is actually dark matter. But lets just say the results are interesting in all cases. If it’s not dark matter, it must be something else we don’t know about, which is interesting by definition. If it turns out to be dark matter particles though, we’ve just come one step closer at solving one of the greatest mysteries of modern science.