Ohio University’s Science Cafe hosts Hee-Jong Seo to explain the science and research behind the ever-expanding universe. 

The universe is expanding. The most accepted theory is that the universe will accelerate through its continuous expansion until gravity can no longer hold it together, and the entire universe will tear apart in a “big rip.” 

Don’t panic; there are trillions of years between now and the collapse of the universe. Physicists and astronomers have been researching the mysteries of the universe for hundreds of years, and each year they understand a little more than they did the previous year. 

On Nov. 15, The Front Room Coffeehouse hosted Hee-Jong Seo for the semester’s third science café. Students, staff, and community members crowded the coffeeshop to listen and learn from Seo, an associate professor in the department of physics and astronomy, who has a doctorate in astronomy. 

Her presentation, titled “The Hitchhiker’s Guide to the Expanding Universe,” is a play on the title of the popular science fiction book: “The Hitchhiker’s Guide to the Galaxy.” Seo explained the science behind the expansion of the universe and the research that fuels scientists’ conclusions. 

Cosmology is the study of the universe, but what does that include? In the early 1900s, scientists still questioned if the Milky Way was the entire universe. In 1924, Edwin Hubble, the namesake for the Hubble Space Telescope, announced that the Milky Way is only one of many galaxies in the vast universe. A few years prior, astronomer Henrietta Leavitt discovered that it is possible to measure the distance of stars and galaxies by using a function known as Cepheid Variables. This discovery was crucial for Hubble to prove that our galaxy is not the entire universe. 

In 1929, Hubble put forth the first theory that the universe was not infinite and steady, but it was expanding. He discovered that the more distant a galaxy is, the faster it appears to be moving away from us, a phenomenon now known as Hubble flow.  

Today, one of the biggest projects in the field of astronomy is the Dark Energy Spectroscopic Instrument, or DESI. DESI measures and collects data for millions of galaxies, constructing a 3D map of nearby universes. Seo is the co-chair of the Galaxy Quasar Clustering Science Working Group for DESI. According to Seo, the goal is to collect nearly 35 million galaxies, and they are about halfway there. 

But, endless information about the universe still remains undiscovered: only 4.9% of the universe is known, what astronomers call ordinary matter, and the other 95.1% is dark energy and dark matter, termed “dark” simply because they don’t know what it is. Seo’s academic field is dedicated to unraveling the mysteries of dark energy. 

One of the most notorious phenomena fueled by dark energy is the Big Bang: the theory that a cosmic eruption triggered the creation of all that is known. Contrary to popular belief, the Big Bang was not an explosion that went off like a bomb in previously empty space, the Big Bang is space itself expanding. There is no point of origin; it is continuous and ongoing. As Seo said, “There is no center. We are all the same. The universe is homogenous and isotropic.” 

Recently, Seo’s academic work focuses on early DESI data. This year alone, she contributed to nearly 20 scholarly articles in various cosmology journals, all focused on DESI and its findings. As DESI continues to gather data on the millions of galaxies within its reach, Seo will continue to analyze and interpret the data, each bit moving astronomers closer to unraveling the secrets of the universe.