Where are we now, and where are we going? These are two questions that humans have been asking themselves for millennia. From philosophers to scientists, great minds throughout history have attempted to answer this question. However, with the advancement of modern science and astronomy, we might be able to answer this in a quite literal manner. The contributions of countless astronomers and astrophysicists helped us to deduce our relative position in an endless universe. And in this quest, the works of Margaret Geller and Vera Cooper Rubin, played a pioneering role.
“The Hitchhiker’s Guide to the Galaxy” is a famous novel series which is about a human who wanders the universe after the earth was blown up. But how would one wander the galaxy without any map? And is it even possible to create a map of the universe?
A Map Must be Made: “Where Are We?”
To us, it might be an impossible feat but to Margaret Geller, in her own words, it is but a modest goal. Receiving her Bachelor’s degree in physics from the UC Berkely, Margaret Geller, continued to study Astrophysics. She obtained her Master’s degree from Princeton University and a Ph. D with a dissertation in astronomy.
In 1970, along with her two colleagues, John P. Huchra and Valerie de Lapparent, she embarked on the quest to map the universe. Limited to only a small telescope, Geller and her team had to spend 25 minutes per galaxy to determine its 3-D position. Although the longitude and the latitude of the galaxy could be determined, its depth was not so easy. But thanks to Geller’s wit and imagination, they managed to measure the “Red Shift” of each galaxy’s light. This means spreading out the light of a galaxy and analyzing its wavelengths. The further a galaxy moves from us, the more shifted the wavelength was towards red.
Geller and Team Peer Into the Universe in Slices
Geller and her two colleagues managed to map out thousands of galaxies, across 700 light-years by taking a slice of the universe. Like a sea filled with continents and land, Geller saw that there were clusters of galaxies spread across an ocean of emptiness. She had discovered the oceans and the continents of the universe and at that moment, they were holding the universe in their hand.
Geller shared the universe with the world in 1985 in her paper “A Slice of the Universe”. She received the “Newcomb Cleveland Prize” along with her colleagues. Her findings and research helped to reshape our understanding of the origin, and the structure and distribution of matter across the universe. But more importantly, her work showed that being imaginative and creative, looking at the grander scale of things, even the impossible becomes yet another modest goal. Margaret Geller, who is now 73, is currently working on a deeper map of the galaxy distribution called “HectoMAP” at the Harvard Center for Astrophysics, contributing to the advancement of science even to this day.
The Physical Anomaly of Galaxy Rotation: “Where Are We Going?”
In an ever-expanding universe, we are in constant motion moving through the cosmos. When we look up at the night sky, the stars that may seem still are actually in constant motion. Much like us, a young Vera Rubin Cooper stared at the night sky in 1938.
“Even then I was more interested in the question than in the answer”
Being driven by curiosity and with the telescope her father made her, Rubin would look to the sky and ask questions that would change the very foundations of astrophysics.
Rubin had finished high school pretty easily and got accepted to Vassar College to study astronomy. Society back then did not accept women in science wholeheartedly. In fact, the last thing her high school physics professor told her was, “You should do OK as long as you stay away from science”. Despite the negative criticism, she pursued her dreams. After she graduated from Vassar College, she obtained her Master’s degree from Cornell University and Ph.D. from Georgetown University. At around this time, despite the lack of facilities for women at the Palomar Observatory, she became the first female astronomer to observe the stars from there. She joined the Carnegie Institution of Washington in 1965 where she met her longtime collaborator, Kent Ford. And the 2 of them set out to work.
Rubin Solves the Problem, and Uncovers the Truth Behind the Darkness
As you might know, the planets that are on the edge of the solar system orbit the sun much slower than the planets closer to the sun. Taking our own solar system as an example, Mercury orbits the sun much quicker than Neptune does. However, when Rubin and Ford observed the rotation rates of galaxies, they were baffled by what they saw. They observed that stars at the edge of galaxies orbited as fast as those close to the center. This simply did not obey the laws of physics as there should not have been enough mass observed in the galaxy to hold it together. Rubin plotted the rotation rates and velocities of a large number of galaxies.
According to this huge amount of data that she published, this galactic behavior was not an anomaly. The data showed clear and irrefutable evidence that this is the typical behavior of all galaxies. This was the first direct evidence for the existence of “Dark Matter”, which are hypothetical particles that do not absorb, emit, or reflect light.
Rubin’s research was followed by other astronomers who started finding more and more evidence of dark matter and astronomers today believe that 85% of the universe is dark matter. Rubin was the second woman astronomer who was elected to the National Academy of Science and there are many physicists who believe that she should have won a Nobel Prize. However, Rubin never sought after awards and accolades. Her goal was the personal satisfaction of the scientific discoveries ignited by her curiosity and imagination. Vera Rubin passed away in 2016 at the age of 88 but is immortalized by her astounding legacy.
Rubin and Geller, Pioneers with Unwavering Determination
Margret Geller and Vera Rubin have not only contributed immensely to the field of astrophysics but also were a guiding light to all women, to rise above any oppression and to follow their dreams. In the modern-day, we see a lot of women astronomers excelling in their fields and walking down the paths laid by Geller, Rubin, and other female astronomers and guiding us on our voyage through the universe. These two female astronomers, with their curious imagination and awe, looked up to the stars, and the universe was never the same again.
References:
01. APS Physics. (2013, April 9). Interview with Dr. Margaret Geller [Video]. YouTube. https://www.youtube.com/watch?v=8c3lM8v68Hw&feature=youtu.be
02. NOVA PBS Official. (2016, January 26). How to Find a Galaxy [Video]. YouTube. https://www.youtube.com/watch?v=gAyZbpSW15U&feature=youtu.be
03. Rubin, V. C. (2011). An Interesting Voyage. The Annual Review of Astronomy and Astrophysics, 49, 1–28. https://doi.org/10.1146/annurev-astro-081710-102545
04. SciShow Space. (2017, July 4). How Vera Rubin Found the First Direct Evidence for Dark Matter | Great Minds [Video]. YouTube. https://www.youtube.com/watch?v=ywppy_2M03I&feature=youtu.be
05. The Lawrence Hall of Science. (2020, August 21). The Story of: Margaret Geller | Stories in STEAM | Storytime! [Video]. YouTube. https://www.youtube.com/watch?v=4fVSaGkkBpw&feature=youtu.be
06. Women in Aviation and Space History – Smithsonian National Air and Space Museum. (n.d.). Smithsonian National Air and Space Museum. Retrieved October 6, 2021, from https://airandspace.si.edu/explore-and-learn/topics/women-in-aviation/rubin.cfm
Image Courtesies:
01. Featured Image: Designed by Dasith Tilakaratna (SEDS UOC). Images resourced from: https://bit.ly/3FoI3nw and https://bit.ly/2YlS18U
02. Image 01: https://bit.ly/3AeEbBN
03. Image 02: https://go.nasa.gov/3oDB18w
04. Image 03: https://s.si.edu/3AbvLvf
05. Image 04: https://bit.ly/3li467K
Article by R. A. D. R. S. Rupasinghe (2nd Year Undergraduate)
