The Dark Matter

Stupefied astronomers on Wednesday unveiled the first and only known galaxy without dark matter, the invisible and poorly-understood substance thought to make up a quarter of the Universe. The discovery could revise or even upend theories of how galaxies are formed. 

According to Roberto Abraham, an astronomer at the University of Toronto "This is really bizarre. For a galaxy this size, it should have 30 times as much dark matter as regular matter. 

There are 200 billion observable galaxies, perhaps more, astronomers estimate. Dark matter is defined on Google as non-luminous material which is postulated to exist in space and which could take either of two forms: weakly interacting particles (cold dark matter) or high-energy randomly moving particles created soon after the Big Bang (hot dark matter). 

The Big Bang theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution. 

According to science.com, roughly 80 percent of the mass of the universe is made up of material that scientists cannot directly observe. Known as dark matter, this bizarre ingredient does not emit light or energy. So why do scientists think it dominates?

Studies of other galaxies in the 1950s first indicated that the universe contained more matter than seen by the naked eye. Support for dark matter has grown, and although no solid direct evidence of dark matter has been detected, there have been strong possibilities in recent years. The familiar material of the universe, known as baryonic matter, is composed of protons, neutrons and electrons. 

Dark matter may be made of baryonic or non-baryonic matter. To hold the elements of the universe together, dark matter must make up approximately 80 percent of its matter. The missing matter could simply be more challenging to detect, made up of regular, baryonic matter. 

Potential candidates include dim brown dwarfs, white dwarfs and neutrino stars. Super-massive black holes could also be part of the difference. But these hard-to-spot objects would have to play a more dominant role than scientists have observed to make up the missing mass, while other elements suggest that dark matter is more exotic.