MADRID – On Halloween’s eve, the world celebrates its first “Dark Matter Day,” which is not a scary story but the commemoration of a decades-long hunt to cast light on an astrophysical enigma called dark matter.
Under the suitable slogan of “Don’t be Afraid of the Dark” the event has the backing of scientific institutions such as CERN – the European Organization for Nuclear Reasearch – and the United Kingdom’s Royal Astronomical Society, to mention just two.
It is difficult to imagine, gazing at the untold millions of stars, planets, asteroids, and comets dotting the sky at night, that we can only see 4.9 percent of our Universe.
Tuesday’s festive astrophysical initiative launched by the Interactions Collaboration Group seeks to raise public awareness on this great cosmic mystery by stating that “dark matter is the glue that holds galaxies together, but we don’t know what it is.”
Scientists believe that dark matter, currently only detectable by its gravity-based effects in space, accounts for over a quarter (26.8 percent) of the Universe’s total mass and energy.
Astrophysicists have another mysterious component to deal with called dark energy, possibly the driving force behind the universe’s accelerating expansion, which could account for another 68.3 percent of the cosmos.
It is important not to confuse these two “Dark” concepts.
We know that dark matter exists because of the way it interacts with the Cosmos and has been known since the 1930s, thanks to astrophysicist Fritz Zwicky, who concluded that in order for galaxy clusters to behave the way they do, they needed a lot more mass than what was actually visible, therefore an unseen “dark” matter made a lot of sense.
Zwicki’s work was rescued in the 1970s thanks to the research and findings made by United States astronomer Vera Rubin.
Spanish physicist Sonia Fernandez Vidal spoke with EFE to explain that Dark Matter could also be visible common matter, only shaped in an unknown or undetectable way.
It could be an exotic, non-conventional type of matter that neither emits nor absorbs light, she said.
While galaxies tend to concentrate most of their visible mass in their centers, many of them have a black hole inside.
Stars rotate around the Galactic center as if on a roundabout and are able to remain in place and not spin-off into space thanks to the force of gravity tethering them in an amazing dance of celestial mechanics.
However, the combined gravitational weight of the stars in a Galaxy is not enough to keep from spinning away into space, so another force must be slowing them down and keeping them locked in place.
Fernandez described the role of dark matter’s gravitational force as a “spider web made up of an invisible filament” adding that, “dark matter is what enables galaxies to exist.”
Furthermore, these same long strands of filaments apparently connect Galaxies to each other.
They are known as baryons that connect particles together giving them the appearance of a cosmic-sized web.
Most dark matter hunters are deployed in underground detection facilities on Earth, buried deep to avoid external influences, and tasked with detecting Neutrinos, cosmic particles that interact with the weak subatomic force and gravity.
One such location is the IceCube Neutrino Observatory in Antarctica, although there are other facilities buried under large mountains, like Gran Sasso (Italy) or Canfranc (Spain).
According to Fernandez, dark matter is one of the “biggest challenges of particle physics” and understanding its true nature could help explain the origins, evolution, and overall structure of our universe.
Events to celebrate Dark Matter Day are due to be held in countries such as Canada, United States, Mexico, Peru, Colombia, Chile, Brazil, Spain, France, Italy, United Kingdom, Austria, Germany and Sweden.