The Invisible Forces That Shape Us: Dark Matter and the Milky Way
- Tanisha Grover
- Mar 2
- 3 min read
If you are a child of immigrant parents like me, you probably know a thing or two about invisible support systems. My parents are the unseen scaffolding of my life—providing the quiet gravity that keeps me grounded so I can reach for the stars.
I found an unexpected and beautiful parallel to this recently while listening to the latest episode of The Astrophysics Podcast. Host Paul Duffell interviewed Dr. Gurtina Besla, an amazing astronomer who focuses on the invisible universe.
Early in the episode, Dr. Besla talked about growing up in Mississauga, a suburb of Toronto, Canada. She navigated a culturally diverse upbringing before finding her path to astronomy (fun fact: she was originally drawn in by Egyptology and how the pyramids perfectly aligned with the stars!). Hearing her talk about her background resonated with my own family's immigrant story.
But when she transitioned into her actual research, I realized that the cosmos has a literal equivalent to the unseen forces that shape our lives: Dark Matter.
The Invisible Halo
Dr. Besla explained a concept that still blows my mind no matter how many times I hear it: Most of the mass in the universe is completely invisible.
When we look at the Milky Way, we see a beautiful, swirling spiral of bright stars and glowing gas. But that visible stuff is just a tiny fraction of what’s actually there. The galaxy is enveloped in a massive, spherical "halo" of Dark Matter.
We can’t see it. It doesn't emit or reflect light. But we know without a doubt that it is there because of its gravity. Without the immense gravitational pull of this unseen Dark Matter, the Milky Way wouldn't be able to hold itself together. Just like the quiet sacrifices of our families, it’s the invisible gravity that allows the visible "stars" to shine and orbit without spinning out of control.
Chasing "Wakes" in Space
What I loved most about Dr. Besla’s interview is how she actually studies this invisible stuff. You can't put Dark Matter in a jar, so how do you test theories about it?
Dr. Besla develops large-scale computer simulations of our galaxy. As stars and smaller satellite galaxies orbit the Milky Way, they are actively swimming through this sea of dark matter. In the podcast, she talked about a recent, incredibly exciting result: finding observational evidence for "dark matter wakes."
Think of a boat moving through water—it leaves a wake of waves behind it. Dr. Besla and her team predicted that as the Large Magellanic Cloud (a smaller galaxy orbiting ours) plows through the Milky Way's dark matter halo, it should leave a gravitational "wake" behind it. And her team found the evidence! Seeing their theoretical computer models perfectly match real-world observations is a huge win for astrophysics.
Putting Theories to the Test
It is one thing to say "dark matter exists," but it is entirely another to use supercomputers to map its ripples and put our theories to the test right here in our own galactic backyard.
Dr. Besla's journey from a diverse Canadian suburb to mapping the invisible architecture of the cosmos is incredibly inspiring. It’s a great reminder to appreciate the unseen forces in our universe—whether it's the dark matter holding our galaxy together, or the quiet support of our parents holding us together.
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