The final hunt for Axions is on
February, 2018: Scientists predict that roughly 80 percent of the mass of the
universe is made up of material known as dark matter. Scientists could not
observe the dark matter directly, since dark matter, by definition, is black
and does not emit light or energy. Without presence of dark matter, many
movements of heavenly bodies, especially those in our galaxy, the Milky Way,
may not be completely justified.
Marian Kowalski, the Polish astronomer and the pioneer of statistical research on star movements, noticed that the movements of stars close to us could not be explained solely by the movement of the Sun already in 1859. Kowalski predicted the rotation of the Milky Way and is known as the man who "shook the foundations" of the galaxy. Later on, in 1933, the Swiss Fritz Zwicky analyzed the movements of structures in the Coma galaxy cluster and concluded that they moved as if there were a much larger amount of matter in their surroundings than that seen by astronomers. That mysterious material, which acts as nodal points of extreme gravitation, was named the dark matter.
Some scientists have also suggested particles that may be responsible for the existence of dark matter. Among the candidates are axions, extremely light particles, which would interact with ordinary matter almost exclusively by gravity. Some others postulate a “lighting through a wall” phenomena, in which a photon could change into axions, which after some time will transform back into a photon. Some recent theoretical works also envisage the possibility of axions interacting with gluons and nucleons.
However, the axions remain elusive till the date. There was no trace of the existence of axions with potentials between 10-24 and 10-17 electronvolts (eV) were found. Currently, scientists want to tighten the constraints imposed by theory on the interaction of axions with nucleons by 40 times, in an attempt to finally track axions. This is equivalent to drastically reduce the hiding places for axions, that they may eventually expose themselves.