What is dark matter, how do we detect it and what does it mean for our understanding of the universe?

By EMILIA ROSE — science@theaggie.org

How much of the universe do we know about? Everything we can touch, see or even imagine — from the smallest particles to the largest stars —  makes up only around 5% of our universe. Roughly 27% is something that we cannot even see: This substance is aptly named “dark matter.” 

To further explore this mysterious substance, we must first evaluate what it means “to see.” Typically, when we see something, it is due to visible light bouncing off an object’s surface and entering our eyes. Some objects, like our sun, are even able to emit their own light because of the amount of energy they contain. 

Now, what about dark matter? Can light reflect off it, or can it emit light itself? The answer is no. Dark matter is, quite literally, dark. In fact, scientists hypothesize that dark matter doesn’t interact with any form of light at all, making it invisible to the human eye. Given that dark matter is so elusive, and yet makes up so much of our universe, how do we know it’s there and how do we measure its existence in the wider cosmos? For scientists, one of the main forms of detecting dark matter is through gravitational waves. 

Gravitational waves can be thought of as ripples in space-time caused by extreme cosmic events like black holes merging. Similar to when you throw a rock into a lake, these waves extend radially outwards. 

Large observatories like the Laser Interferometer Gravitational-Wave Observatory (LIGO) use machines with extremely long lasers to detect these ripples in space-time. When a gravitational wave passes through, the lasers distort in an incredibly small amount of distance (smaller than a proton), known as a strain. From this distortion, scientists can find the source of the wave and the dynamics of the gravitational event.  

Yet when we look at this event, the gravitational effects we observe don’t match the amount of matter we see. From this, we can infer that there is some unaccounted mass altering the dynamics of the system. This is the implied existence of dark matter.

However, this method has a glaring weakness. Here on Earth, instruments are constantly affected by interference. We have air molecules throughout our atmosphere, minor shifts in the ground with tectonic activity and stray particles coming from outer space. Even with advanced filtering, these disturbances can disrupt readings.

Recently, a research team from the Universities of Birmingham and Sussex designed a new, much smaller detector that counteracts these problems, according to their newly published paper. Giovanni Barontini, a member of this team, commented on the mechanics of their proposed design.

“Due to [the detectors’] compact size, they are marginally sensitive to Newtonian and seismic noise, which are the main sources of noise for km-scale interferometers,” Barontini wrote in the paper.

An interferometer is an instrument that uses light or other waves to make extremely precise distance measurements. In other words, a “km-scale” interferometer would be something like LIGO. This new detector works roughly the same way LIGO does but on a much smaller scale, calibrated to detect gravitational waves at a frequency we have not been able to observe yet.

This is a groundbreaking achievement because it replaces massive, noise-prone machines with a compact device that can see in ranges we haven’t touched, while remaining more resistant to disruptions. 

Centuries ago, humans started out using just their eyes to observe the cosmos. Now, we are working to observe the things our eyes cannot see. But, could there be a limit to how much our detectors can advance?  

Matthew Citron, a high-energy physicist at UC Davis, explained his perspective on the matter.

“I think fundamentally, there are limits to how good a detector can be,” Citron said. “There are certain types of noise that are almost impossible to remove entirely. And, there are certain backgrounds that are impossible to remove as well.”

Jacob Steenis, a UC Davis graduate student in high-energy physics, commented on the idea of a theoretical limit. 

“I do really admire how physicists often find clever ways to sidestep the impossible,” Steenis said. “I have the utmost confidence that — even where limits are found, theoretical or otherwise — physicists will continue to sidestep through indirect methods of measurement. To me, it really is amazing.”

 Imagine two galaxies, both inconceivably massive, orbiting each other at incredible speeds. They circle each other over and over again until they become one. Their collisions are some of the most monumental interactions in our universe; yet when their effects reach us, their influence is almost undetectable. Like ripples fading as they spread across a pond, gravitational waves weaken as they travel vast distances. 

Even with our most precise detectors, parts of our model of the universe still elude us. The existence of dark matter may one day be confidently confirmed, or it may remain something we can only infer through its effects. 

Written by: Emilia Rose — science@theaggie.org

Unidentified objects appear in the sky, like 3I/ATLAS, offer insight into the key signs of life that scientists look for

By EMILIA ROSE — science@theaggie.org

We have insects, birds, fish and even intelligent, bipedal mammals right here on Earth. But what could be beyond Earth? The likelihood of extraterrestrial intelligent life has been subject to the Drake Equation, a formula calculating the probability of intelligent life in the Milky Way. On the other hand, the fact that we haven’t found anything has been subject to Fermi’s famous Paradox, which highlights the dissonance that is found in the absence of extraterrestrial life. However, what if extraterrestrial intelligence has been closer than we thought? 

In July, scientists detected a massive interstellar object, designated 3I/ATLAS, on an orbital path towards the Sun. Harvard Researcher Avi Loeb and his team have published a paper, not yet peer-reviewed, discussing the idea that this object could be an alien probe. Is there any truth to that? 

To determine the answer to this question, we need to look at the methods we use to detect alien lifeforms and their possible spaceships. In an article from Science Daily analyzing Loeb’s findings, the author, Sara Webb, detailed some of the ways we might detect an alien probe.

“Because a natural origin is most likely, we would look for evidence that no aliens were involved. One clue in this direction might be if the object were emitting a ‘tail’ of gas in a way that comets do,” Webb’s article reads. “One very strong piece of evidence would be any kind of radio waves coming from the probe […] Another dead giveaway would be signs of maneuvering or propulsion.” 

In regards to 3I/ATLAS, although he covers many sides of his argument, Loeb notes a few reasons why the object might be of natural origin, rather than an engineered probe.

“The object must be around 20 kilometers in diameter […] and as of writing, the Minor Planet Center does not provide estimates of non-gravitational accelerations for this object,” Loeb said. “It should be noted that for interstellar objects, we have a sample size of only three, therefore rendering an attempt to draw inferences from what is observed is rather problematic.”

Thus, it is unlikely that 3I/ATLAS is an alien spacecraft. It is not only the size of a small moon, but it has shown no signs of artificial propulsion and it is difficult to compare it to other objects that come from beyond our solar system with only a couple of known cases. 

If 3I/ATLAS isn’t a sign of life, what is? How do we look for extraterrestrials in our universe? Dr. David Gold, a professor of geobiology at UC Davis, speaks on the key things we analyze when looking for alien life.

“You need the building blocks of life […] You need things like proteins, you need amino acids. Those things need to be present,” Gold said. “You need water because water drives the chemical reactions that drive life […] And those are common in many places throughout the solar system and throughout the universe.”

Even though many are curious about large spaceships that could be coming in Earth’s direction, the same basic building blocks that scientists assume make up life on Earth are what really guide the search for life elsewhere. Among the things scientists consider are atmospheric composition, temperature and many other indicators. Yet, another question remains: What do we do, and how would we react if we actually detect something? How can we even know if the evidence we find is legitimate? 

One such tool to categorize evidence in terms of the likelihood of alien life, and what the organization Search for Extra Terrestrial Intelligence (SETI) would use to notify the public if alien life were found, is the RIO scale. In simple terms, the RIO scale uses final values from zero (no significance) to 10 (extraordinary) to determine the likelihood of an observed event caused by intelligent extraterrestrial life. When the calculation was performed on 3I/ATLAS, it yielded a one (insignificant) on the RIO scale.

Based on several factors, 3I/ATLAS is unlikely to be anything more than an interstellar asteroid. However, Loeb’s initial reaction to it is enlightening for all of humanity; we continue to form fascinating questions about the objects we observe in our universe. 

Written by: Emilia Rose — science@theaggie.org

Hands on the Land provides free trips that allow students and community members to gain access to the UC Reserves and participate in habitat restoration

By LILA MAGBILANG— science@theaggie.org

Tucked away among the sprawling wilderness of California lies the University of California (UC) Natural Reserve System. With each of the nine UC undergraduate campuses responsible for a handful of these lands, this resource is abundant — yet inconspicuous.

In 2021, a group of graduate students from UC Davis gathered with the common goal of raising awareness about these reserves. With the aim of increasing accessibility for environmental education and habitat restoration, the students saw the reserves as the perfect space to get people out into nature. And thus, Hands on the Land was born. 

Perhaps you have participated in some type of habitat restoration before: maybe you’ve gone out and planted a tree with a group or spent an afternoon weeding. Although any amount of work is beneficial for the well-being of the environment, the founders of Hands on the Land felt something was lacking — there was a disconnect between the people and the land. 

By providing recurring trips to the two reserves closest to UC Davis — McLaughlin and Stebbins Cold Canyon — Hands on the Land invites students and community members to explore the nature surrounding Davis and take part in habitat rehabilitation. With the trips free of charge, the group hopes to incentivize repeated exposure to specific areas for an extended period of time.

Alana Luzzio, a Ph.D. candidate in the Ecology Graduate Group and a founding director of Hands on the Land, described what they’re doing differently. 

“We visit the same two places throughout the year so that participants can see seasonality and phenology,” Luzzio said. “They can see tangible positive impacts of their work from previous trips.”

With trips happening nearly every month for the entire school year, students are encouraged to participate in various seasonal activities Hands on the Land organizes. In October, they can be seen collecting native seeds, and, in February, they might do a controlled burn. 

Repeated and long-term restoration efforts are not only one of the best ways to actually rehabilitate a landscape, but they are also essential aspects of fostering a community of people with the same goals and passions. Though Hands on the Land naturally attracts those already interested in conservation, part of their initiative is making sure that everyone has the opportunity to make a positive impact on the environment. 

Brooke Wainwright, another founding director and Ph.D. candidate in the Ecology Graduate Group, elaborated on their inclusivity efforts.

“If you’ve never been in a natural setting before — if it feels really unfamiliar to you — we want you to come on this trip,” Wainwright said. “You don’t need any experience. You can come from any discipline, and you are welcome at Hands on the Land.”

A typical Hands on the Land trip involves boarding a UC Davis Fleet Service van early in the morning, then making your way through the golden California hills to your destination. Saturday is when the majority of the work is usually done — you’ll spend a good chunk of the day out in nature, surrounded by the gnarled oaks and squawking scrub jays. Then, in the evening, all the volunteers come back to the field station and prepare dinner as one big family. Everyone lends a helping hand. 

On Sunday morning, you’ll find participants engaging in a creative activity — may it be journaling, painting or even just taking a walk — to wrap up their experience. The field station becomes like a little home; somewhere you want to return to. 

Cathy Koehler, the resident director of McLaughlin, explains how difficult it’s been to spread awareness about the UC Reserves. She notes that she is thrilled when someone comes to Hands on the Land and is inspired to come back. 

“We’ve seen that happen where somebody comes out on Hands on the Land and then says, ‘I want to be involved in this more,’” Koehler said. “[The reserves] are places where there are opportunities for students to experience nature in its very many different forms, whether it’s heavily invaded by non-native species, be they animals, be they plants.” 

Vivian Zerkle, a fourth-year environmental science and management major, is one of the Hands on the Land participants who found herself drawn to McLaughlin. After reaching out to Koehler, she was invited to come back to the reserve on her own time, sometimes with a group of friends in tow. Between her individual trips and Hands on the Land, she’s seen the landscape of McLaughlin start to change little-by-little. 

“We pulled so much of this one weed one year,” Zerkle said. “The next year, I returned to that same hillside, and there was so much less of that weed taking over the hill. That was a really cool specific impact — I could see that my group and other volunteers had made a real effort and seen a real result.” 

Restoration takes a long time. To many volunteers, it may seem disheartening to see the vast amount of work that needs to be done to restore just a few acres of land. However, with community mobilization and accessible opportunities for restoration, individuals can make a tangible impact — and part of that is choosing a specific place to dedicate yourself to and fully immerse yourself in.  

As Wainwright noted, everyone is welcome to join a Hands on the Land trip. There will be upcoming trips in November 2025, as well as January, February, April and May 2026. For more information about signing up, follow the Hands on the Land Instagram.

Written by: Lila Magbilang— science@theaggie.org

UC Davis, as part of a multi-institutional team, is working to change how buildings operate with new biosensors and a risk model to maintain energy efficiency

By KATELYN BURNS — science@theaggie.org

A multi-institutional research team, which includes UC Davis, began work on a project to develop a system capable of reducing pathogens in indoor air. The Bioaerosol Risk Assessment interVention Engineering (BRAVE) project features four main areas:

1. Developing new biosensors that allow for the detection of pathogens and other pollutants in real time.
2. Developing a risk model that uses the data from the biosensors to determine the current risk the detected pathogens pose to occupants.
3. Changing how buildings operate, using tools to filter or ventilate the air and making suggestions to occupants: ultimately decreasing pathogens in indoor air.
4. Assessing the project’s outcomes using epidemiological tools, with the goal of determining whether these efforts lead to better outcomes — such as less sickness for occupants and their families. 

Christopher Cappa, a professor in UC Davis’ Department of Civil and Environmental Engineering and UC Davis’ BRAVE project lead, commented on the project and the university’s role in improving building ventilation.

“I’m super excited to see all of this really come together,” Cappa said. “We’ve never had the ability to do this real-time pathogen monitoring in a way that is scalable.”

The COVID-19 pandemic sparked new research and increased interest in indoor air quality. The BRAVE team is leveraging these new developments in technology into an engineering strategy that can improve indoor air quality.

Christine Johnson, a professor of medicine and epidemiology at UC Davis School of Veterinary Medicine and the director of the National Science Foundation (NSF) Center for Pandemic Insights, explained what made the COVID-19 pandemic unique.

“COVID-19 was the first pandemic to emerge with massive, globalized travel and social media playing a big role in how we receive and share information,” Johnson said.

The epidemiological triad, made up of pathogen, host and environmental factors, explains the spread. The changing environment — now with massive, globalized travel and social media — wasn’t the only thing responsible for the pandemic’s spread. As hosts, individuals were immunologically naive to the novel COVID-19 virus. The virus itself contributed to the spread in several ways.  

This virus had such a vast array of responses, from asymptomatic to severe pneumonia. The less sick, or asymptomatic, would continue to travel and spread the virus. Not only did tit result in such a wide array of responses; it mutated fast and was capable of airborne transmission. 

Airborne transmission is not the same as droplet transmission. Droplet transmission involves larger particles, with coughs and sneezes spreading the virus through droplets of saliva and mucus. On the other hand, airborne transmission involves smaller particles travelling further and remaining in the air even after the host has left the area. While 6 feet of social distance may have been enough to prevent droplet transmission and slow the initial spread, once the virus was capable of airborne transmission, 6 feet was no longer enough.

“We’ve got programs for monitoring water and prevention of waterborne pathogens, and it’s about time we do the same to every extent feasible for pathogens that move around through airborne transmission and continue to place a significant burden on society,” Johnson said.

Linsey Marr, a professor of civil and environmental engineering at Virginia Tech and the BRAVE project lead, commented on the project’s goals.

“[Advanced Research Projects Agency for Health (ARPA-H), the government agency funding the project], wants us to be able to detect 25 different things in the air, which is a lot,” Marr said. “Ultimately, they want us to show at least proof of concept that we can detect 100 different things in the air.”

The BRAVE project is still in its early stages. While teams at other institutions are working to further develop the biosensors, UC Davis prepares to eventually demonstrate their biosensors by integrating them into buildings across the country.

Buildings are currently designed to balance thermal comfort and energy efficiency, according to Marr.

“In order to save energy, you want your building to be tight and you want your air that you’re heating or cooling to mostly stay there and recirculate,” Marr said. “That means that things in the air — viruses, bacteria, fungi — can build up in the air over time if you’re not exchanging it with outdoor air to dilute it.”

While recirculating air is more energy-efficient while maintaining a comfortable temperature, recirculating air will eventually need to be filtered or ventilated for health. The biosensor and risk assessment model would be able to determine when intervention becomes necessary, and, otherwise, allow the air to continue to be recirculated and maintain peak energy efficiency. This process involves determining when the health risks make it worth spending that extra energy.

Why demonstrate the systems in buildings across the country? The climate impacts how the building is going to operate, which means testing in different climates are important. In Davis, the hot, dry environment in the summer means buildings have larger heating, ventilation, and air conditioning (HVAC) systems. More moderate climates may have smaller systems, changing the amount of air that can be moved. Alternatively, more humid environments can restrict how often the windows are opened. While BRAVE’s goal is to have general strategies, the final results must be adaptable to specific environments; every building is unique.

“Although the ideas that we have here are very general to any kind of environment, we’re very focused on childcare centers,” Cappa said. “Kids get sick a lot. There can be a lot of transmission through those areas, and so this can be a way to keep those kids healthier, their parents healthier and their families healthier; we think it could have some big impact.”

Currently, the UC Davis team is in discussion with childcare center providers and building managers to find the locations that will eventually be used to demonstrate the project, according to Cappa. The eventual goal is to develop a product that building managers and owners can buy.

“[Having the product] is one thing, and the second thing is that the product works and makes the air healthier and cleaner for building occupants, having less illness as a result,” Marr said.

Individuals have come to expect clean and safe water. The same should be expected of our air, indoors and out. The BRAVE project aims to achieve this with their biosensor, risk assessment model and engineering interventions that ultimately aim to help keep our indoor air clean and decrease the spread of sickness.

Written by: Katelyn Burns — science@theaggie.org