As Yoda tells us “the dark side of the force is strong in this one.”
Add up all the mass in the stars, planets, asteroids, dust – anything that we can call an object. Then compare that total to the amount of mass expected from other sources of data (specifically look at how things move and then figure how how much stuff must be around to make it move). It turns out that there is a lot of missing mass in the universe – 95% is unaccounted for. One postulated source of this missing mass is a form of stuff that we cannot see, matter that does not interact with light in the usual way. Dark Matter
Now a new discovery from the international space station may shed some light on this dark subject. As reported on earthsky.org
“One of the great discoveries of the coming century will be the direct detection of dark matter. This mysterious substance, thought to compose some 23% of the mass of our universe, is currently one of the most-sought substances in existence, the source of thousands of scientific papers and endless hours of speculation over the last half of the last century, despite the fact that it has not yet been directly detected. Now an analysis of 41 billion cosmic rays striking a state-of-the-art instrument called the Alpha Magnetic Spectrometer (AMS) particle detector aboard the International Space Station (ISS) may have come close to detecting dark matter. It shows:
… an unexpected excess of cosmic-ray antielectrons (positrons) relative to electrons.
One possible explanation is that:
…the positrons are being created in annihilations of dark matter particles.
MIT physicist Sam Ting, who leads the experiment, said in a news release from Europe’s CERN particle physics center:”
In other words, this this excess of one type of particle may be the signature of the illusion dark matter.