The Alpha Magnetic Spectrometer riding on the I.S.S. might just have found the first clues about Dark Matter. This $1.6 billion particle detector has been counting incoming particles emanating from space for two years now and scientists are excited by the data which they have been analyzing. It appears that there are far more energetic positrons, the anti-matter version of electrons, zipping around in space than previously thought. It is difficult to explain why these particles are as abundant as they are with current methods, with the only possibility being that they are a temporary phenomenon caused by a pulsar throwing large amounts of electromagnetic radiation in our direction. Yet it is theorized by scientists trying to find Dark Matter that these positrons could be formed by weakly interacting massive particles of Dark Matter colliding and annihilating each other. Not enough data has been collected to definitively prove anything yet but the data is high quality and this experiment will continue for another 18 years.
There is not likely to be another experiment of this scope for many decades. The Alpha Magnetic Spectrometer took 16 years to develop and is large enough that it needed to be launched by the 2nd to last space shuttle mission. It has already cataloged 25 billion high energy particles in the last 2 years, including 6.8 billion electrons and positrons. This amount of positrons far exceeds the amount expected by other sources, so even if Dark Matter isn’t causing these particles we may be able to use this data to further science in other ways. The key to linking this data to Dark Matter lay in the distribution of energy of positrons. If the data shows that the ratio of positrons vs. electrons rises as the energies of the particles rise then that would indicate Dark Matter. Should the ratio of positrons vs. electrons fall slowly as the energies of the particles rise, then that would indicate that the positrons are being supplied by a pulsar. More data is needed to make this determination and now that scientists know exactly what they are looking for it is thought that this determination should be made in the next few years. The data released only includes low energy particles and a few examples of higher energy particles. It may take more time to get enough data on the higher energy particles needed to make a determination.
Dark Matter accounts for 26.8% of the universe according to the latest results from the Planck mission but there is still much that we don’t know about it. For the last few decades, scientists have pondered what are the properties of this unknown substance. Many theories have been put forward including MACHOs, axions, supersymmetrical particles, Hot Dark Matter, Warm Dark Matter, and Cold Dark Matter also known as WIMPs. The results of the Alpha Magnetic Spectrometer seems to be pointing toward the weakly interacting massive particles (WIMPs) as the correct theory of Dark Matter. Knowing which theory to pursue will allow for funding to be put into the right place and more experiments to be designed based on the properties of WIMPs, allowing for a greater understanding of Dark Matter in the shortest possible time frame. When can we expect to hear more about advances in these areas? “We will publish things when we are absolutely sure” was the response from the very serious spokesperson for the project.