Dark Energy and Matter

What are dark energy and matter, and do they relate to each other? At the beginning of the 20th century, it was theorized that although the universe was expanding, gravity and the contraction of molecules were progressively slowing the process down. Then, in 1998, scientists observing a distant supernova through the Hubble Space Telescope detected that the universe’s expansion was not slowing down, but rather speeding up. No one knew what the explanation behind this was; scientists considered various possibilities, such as that Einstein’s theory of gravity was not entirely correct, or that the cosmos was filled with an energy fluid that somehow caused this behavior. Nonetheless, astronomers were never certain on what prompted the accelerating expansion, and yet they gave “it” a name: dark energy.

Little is known about dark energy, yet scientists have been able to detect how much of it there is based on its impact on the universe’s expansion. It is understood that it accounts for 68% of the universe; the rest of it is composed of about 5% “normal” matter, and 27% dark matter. Contrary to popular belief, there is a difference between dark matter and dark energy. Nonetheless, they share similarities other than their name.

Dark matter is essentially built up of particles that do not absorb, reflect, or emit light. It is believed that this is what is responsible for exerting physical changes, such as otherwise inexplicable movements seen in galaxies from the stars. Unlike regular matter, it is not made out of baryon particles, and it cannot be considered to be antimatter because it does not exhibit the same properties. Although this is a scientific concept that is largely theoretical, there are recent studies that have made it more possible to understand.

University of Toronto researchers released a study in the Journal of Cosmology and Astroparticle Physics on June 14, 2024. At large, this work addresses and proposes a theory that would justify the invisible nature of dark matter, along with the general structure of the cosmos. The study goes in depth in exploring the phenomenon of matter being evenly distributed across the universe. This behavior, they propose, could suggest that dark matter may be formed of hypothetical particles named axions. Because this type of particle is so hard to track, the implications to understanding and proving their existence could directly lead to a better understanding of the universe.

Axions are often described as fuzzy because of their tendency to behave like waves. This wavelike behavior allows them to travel across galaxies. These properties can tell us more about the nature of dark matter and why by being so evenly spread out, the universe is not as “clumpy” as once predicted when axions are not taken into consideration.

It is said that understanding the nature of dark matter is the secret to comprehending the origins and the currently unsolved mysteries of the universe. This theory suggested by the researchers takes science one step further into uncovering the ambiguous nature of matter and the cosmos.