Dark Matter — Still Dark
Dark matter continues to live up to its name. The most recent results from the European Space Agency’s Planck spacecraft appear to cast serious doubt on previous claims of potential detections of the elusive dark matter particles.
For decades, astronomers have found what appears to be compelling evidence for the existence of matter that does not emit any light, but whose gravitational pull is responsible for holding cosmic structures together. In fact, dark matter far outweighs ordinary matter — the stuff of which galaxies, stars, planets, and humans are made of — in its contribution to the universe’s energy budget. Yet, all attempts to actually detect the particles that constitute dark matter have so far failed (see a concise recent review).
There have been, however, a few promising signs in the form of an unexpected positron anomaly–an excess in the number of the positively charged anti-particles of the electrons. The excess was detected by the Alpha Magnetic Spectrometer (AMS)–an experiment on board the International Space Station. Last year, this experiment reported that in analyzing cosmic rays, contrary to expectations, the ratio of positrons to electrons increased with increasing energy of the particles. This finding was —> Read More Here