Have scientists discovered a dark matter particle?

Deep beneath the Black Hills of South Dakota, US, in an old gold mine, a tank of liquid xenon has been used to produce an unusual particle reaction that may be a link to “dark matter”.

Scientists conducting an experiment there say they have found a single “unexplained particle interaction” that resembles a dark matter particle, though researchers have not called this a confirmed detection.

“Dark matter” and “dark energy” are substances whose presence humans have detected, but have yet to actually observe. This is the closest scientists have come to possibly uncovering the universe’s most elusive form of matter.

Dark matter is an invisible substance that is believed to make up roughly 27 percent of all matter in the universe. Similarly, dark energy, thought to make up 68 percent of everything in the universe, is an invisible force that pushes galaxies apart and speeds up the expansion of the universe.

Ordinary matter, which is everything we can see and touch, accounts for only 5 percent of everything that exists.

Scientists found proof that this unseen matter exists in the universe by observing its gravitational pull, which affects how galaxies spin and how light bends around large clusters of it.

What it is made of, and what it looks like, has remained a mystery to scientists since its discovery nearly a century ago, as it cannot be detected directly because it does not reflect light or electromagnetic radiation.

The first clue to the existence of dark matter was discovered in the 1930s, when Swiss astronomer Fritz Zwicky noticed that the galaxies in the Coma Cluster were moving too fast for the cluster’s visible mass to hold them in place, suggesting something else had to be applying gravity. Similar observations were made over the following decades – all signs pointing to the presence of invisible matter, scientists say.