Author: Kayla Otoo
Editors: Flynn Ma, Roberto Bailey
Artist: Alvina Zheng
Our universe comprises 68% dark energy, 27% dark matter, and 5% normal matter. We can only see 5% of the things in the universe. Many don’t realize the significant role dark matter and energy plays in our universe, like how crucial it is in the formation of galaxies, or its role in driving the never-ending expansion of our universe.
Firstly, dark matter isn’t just dark. It’s invisible. It also does not interact with the electromagnetic field. In fact, it was originally called missing matter because astronomers couldn’t even find it in any electromagnetic spectrum. Furthermore, it doesn’t emit, reflect, or refract light — light just passes straight through it. We only know dark matter exists because of its gravitational effects on the objects we can observe.
Secondly, dark matter comprises particles called baryons, a composite subatomic particle made up of three quarks. The most common types of baryons are protons and neutrons. This is an accurate conclusion because baryonic clouds are detectable by the radiation they absorb when passing through. Axions and Weakly Interacting Massive Particles also make up dark matter. Finally, keep in mind that dark matter and antimatter are not the same. Gamma rays are not produced when antimatter and matter are destroyed, whereas the destruction of dark matter will produce strong gamma rays.
In 2007, NASA’s Hubble Space Telescope carried out surveys, such as the “COSMOS survey,” to develop new theories of dark matter. They could see the large scale of dark matter distributed in our universe through a three-dimensional map. Consequently, many theories of dark matter formation were confirmed. Also, scientists finally understood how galaxies grew and clustered over billions of years. Two years later, in 2009, Hubble revealed new evidence. Galaxies are embedded in the halos of dark matter. For example, the Perseus galaxy cluster. This cluster of small galaxies remained intact even when the larger galaxies surrounding them were being ripped apart by the gravitational pull from other galaxies. Therefore, the galaxies were cushioned by a halo of dark matter. Another well-known galaxy cluster is the bullet cluster. The bullet cluster is currently some of the best evidence we have of dark matter’s existence in our universe. It was formed by two smaller clusters colliding, producing a shock wave from the interacting hot gasses. Through gravitational lensing, one can see that most of the mass of the combined cluster is around the galaxies and not in its center. As a result, the amount of dark matter in galaxy clusters is now known.
In conclusion, the existence of dark matter, which is an integral component of our universe that accounts for a substantial portion of its mass, has become more evident through advanced astronomical observations and theories. From the Hubble Space Telescope's revelations to the insights gained from the Bullet Cluster, our understanding of dark matter's role in galaxy formation and cosmic structure continues to evolve, highlighting its fundamental significance in the vast cosmos.
NASA. 2023. “Dark Energy, Dark Matter | Science Mission Directorate.” Science.nasa.gov.
“StarChild: Dark Matter.” n.d. Starchild.gsfc.nasa.gov.
“What Is a Baryon?” 2017. ChemistryViews. August 1, 2017.