Dark Matter: Why study it? What makes it so fascinating?

Universe Today has had some incredible discussions with a wide array of scientists regarding impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics, cosmochemistry, meteorites, radio astronomy, extremophiles, organic chemistry, black holes, cryovolcanism, and planetary protection, and how these intriguing fields contribute to our understanding regarding our place in the cosmos.

Here, Universe Today discusses the mysterious field of dark matter with Dr. Shawn Westerdale, who is an assistant professor in the Department of Physics & Astronomy and head of the Dark Matter and Neutrino Lab at the University of California, Riverside, regarding the importance of studying dark matter, the benefits and challenges, the most exciting aspects about dark matter he’s studied throughout his career, and advice for upcoming students who wish to pursue studying dark matter. So, what is the importance of studying dark matter?

“About 80% of the mass of all matter in the universe is dark matter, despite the fact that our (otherwise extremely successful) model of fundamental particle physics cannot explain what it is,” Dr. Westerdale tells Universe Today. “We can see the gravitational influence of dark matter in our own galaxy and throughout the entire structure of the observable universe. It leaves a clear imprint on all of our cosmological and astrophysical observations through these gravitational interactions, so we know it is there and it does a remarkable job of explaining what we see. But we have no idea what it actually is made of, and this is an essential part of understanding nature.”

The term “dark matter” was first coined in 1906 by French mathematician and theoretical physicist, Dr. Henri Poincaré, to describe work from 1884 by the British mathematical physicist, Dr. William Thomson (Lord Kelvin), regarding velocities of stars and some potentially being dark bodies. Throughout the rest of the 20^th century, dark matter became a focal point in hypothesizing the behavior of galaxies and galaxy clusters with countless studies being published from academia, including the California Institute of Technology, along with research organizations like the SETI Institute. Despite decades of research, including the hypothesis of “cold”, “warm”, and “hot” dark matter, this mysterious substance has yet to be observed. Therefore, what are some of the benefits and challenges of studying dark matter?

Dr. Westerdale tells Universe Today, “We haven’t found it yet, but we have ruled out many models, and in doing so we have helped refine our understanding of nature by ruling out possible modifications to the Standard Model of particle physics. On a sociological level, the study of dark matter has led to many new technologies for detecting radiation. Some of these may lead to new quantum technologies, and others are being developed into new medical imaging devices, just to name a few examples.”

The three methods for attempting to observe dark matter include direct detection, indirect detection, and laboratory experiments using a myriad of laboratories from several countries around the world, including the Large Hadron Collider, which is the world’s largest particle collider. Additionally, several ground- and space-based telescopes have conducted surveys to try and create dark matter maps, including NASA’s Hubble Space Telescope, the Canada-France-Hawaii Telescope, the VLT Survey Telescope, and the Subaru Telescope. But what are the most exciting aspects about dark matter that Dr. Westerdale has studied during his career?

Dr. Westerdale tells Universe Today, “To me the most exciting aspect of dark matter research has been the magnitude of the question. We have such successful models of cosmology and particle physics, and yet for all the success of these models, we still don’t know what most of the universe is even made of or how it got here!”

The study of dark matter comprises some of the most fundamental questions pertaining to cosmology, the nature of the universe, and our place in it. What is the universe made of? How did it form? How did galaxies form? How do galaxies behave the way they do? How has all of this led to us being here and writing articles about dark matter like this one? The answers to these questions continue to elude astrophysicists, cosmologists, and countless other scientists despite decades of research, experiments, models, and hypotheses.

Dr. Westerdale tells Universe Today, “One of the fun challenges of dark matter detection is that we are looking for extremely rare interactions and so we have to go to extraordinary lengths to make our experiments as quiet as possible. We put our detectors in deep underground labs, up to a mile underground, to avoid noise from cosmic rays, and levels of radioactivity that are normally so low they cannot be measured can swamp the signals we’re looking for. It is an exciting challenge to confront these things in our research and figure out how to design detectors that can meet all of our goals.”

Despite the lack of observing dark matter and confirming its existence, this nonetheless signals that the next generation of dark matter enthusiasts, whether they become astrophysicists, cosmologists, or come from other scientific backgrounds, will have their work cut out for them, with some possibly being the ones to confirm dark matter’s existence. Like nearly all scientific research trajectories, the study of dark matter involves constant collaboration between scientists from a myriad of backgrounds and expertise’s. Therefore, what advice can Dr. Westerdale offer to upcoming students who wish to pursue studying dark matter?

Dr. Westerdale tells Universe Today, “Experimental dark matter physics requires a very large breadth of knowledge, and so don’t silo your studies — any physics, math, and engineering skills you learn will at some point be useful. Programming skills are especially important, as are learning statistics, chemistry, and other engineering skills. And when you encounter something new, take the time to learn how it works on a fundamental level — it will be worth it later on once you can see how it fits into the big picture.”

Will we ever observe dark matter and how will it help us better understand our place in the universe in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!