From a light bulb solar system to the cosmological constant: a journey to becoming a cosmologist

Taken from the June 2021 issue of Physics World where it first appeared under the headline “Reaching out to the stars”. Members of the Institute of Physics can enjoy the full issue via the Physics World app.

Luz Ángela García, a cosmology postdoc in Bogotá, Colombia, talks to Rob Lea about her journey into physics and astronomy as a woman from South America

Luz Ángela García is an astrophysicist who dreams of cracking the ultimate cosmological conundrum : why the universe is expanding at an accelerating rate. Currently a postdoctoral researcher at Universidad ECCI in Bogotá, Colombia, García has overcome many barriers to succeed in her field. Her motivation is her lifelong drive to understand the universe, which began in childhood with a quirky choice of bedroom decoration.

García grew up in Colombia’s capital city, Bogotá, more than 2500 m above sea level in the Andes. Bogotá’s connection to the stars is cruelly severed by air pollution, but as a young girl, García found another way to introduce the wonders of space to her daily life. “I built a little solar system on the wall of the bedroom I shared with my brothers when I was about eight years old with the light bulb as the Sun,” she recalls.

This interest in space was noticed by García’s family, who bought her a basic telescope, which she used to study objects like the Moon and Jupiter. Even then  –  before she had heard of dark energy or supernovae  –  curiosity about the vastness of the cosmos was brewing in the budding astronomer’s mind.

The vastness of space

Perhaps it is not surprising that her current research is so integrally concerned with the size of the universe; the idea of the unimaginable scale of space manifested early in García’s life, as did the concept of how tremendous cosmic distances affect what we see and how we see it. “My reproduction on the wall was not exactly to scale,” she laughs. “But still, I was puzzled by concepts like distances between the astronomical objects –  mostly in our solar system  –  and even though I knew the Sun was a star, I wanted to know why it looks so different from other stars.

“Remarkably, this led to part of my current research but at cosmological scales. I’m now actually using those distances to prove how dark energy is changing or shaping the way we see the universe.”

It wasn’t long before García’s teachers noticed their pupil’s burgeoning interest in the universe. When she was around 12 years old her biology teacher, Diana Pava, introduced the budding scientist to the work of Carl Sagan  –  through his magnum opus, the TV series Cosmos. By the age of 14, encouraged by her physics teacher Ernesto Campos, García was helping her fellow students understand scientific concepts such as thermodynamics and optics. “It was very cool indeed. Every time I tried to explain something, I was getting some additional insight,” García says. “I think that was very important in both my career as a lecturer and as someone doing science outreach. I was getting an insightful message for my future.”

From this point onwards García had set her mind on a career in the sciences, even if she wasn’t exactly sure which science it would be. Yet, the stars were not the only thing that was obscured from García’s view in these early years in Bogotá.

Discovering inequality

The positive attitudes of her family and educators had hidden from García the fact that women face additional obstacles to entering scientific fields. García had been no stranger to resistance, of course. She had frequently been encouraged to consider a more mundane career that didn’t require as much effort. But this new challenge was different, more than a mere irritation. When beginning her bachelor’s degree in physics at the Universidad Nacional de Colombia, the male-dominated lecture halls made her question the pursuit of a career in science entirely.

“During my degree, there were not many women studying with me  –  only about 20% of the people in my cohort  –  and just three female physics lecturers. That was the first indication to me that science was a male-dominated field.” García points out that these numbers dropped off still further as she progressed through academia. “That realization made me question if I was going to succeed in physics or astronomy.”

The discovery of the prevalent stereotype of a “scientist” after she had already decided on a career in the field has given García a unique insight into the harm it could potentially do to young women considering futures in science, technology, engineering and maths (STEM) subjects. “There is this common misconception that if you study science, you should be somehow a genius or socially awkward, or someone like Einstein. Old, with messy grey hair, and male,” she says. “We have to fix ideas about how a scientist should look. It’s definitely something that will not help a new generation to build careers in science.”

There is this common misconception that if you study science, you should be a genius or socially awkward; or old, grey and male

Fortunately, García had the determination to succeed, contrary to these stereotypes. Later, while earning her PhD at Colombia’s Observatorio Astronómico Nacional, her determination was bolstered by invaluable support from her supervisor Emma Ryan-Weber, now an associate professor at Swinburne University of Technology in Australia and the leader of the intergalactic medium research group at the Centre for Astrophysics and Supercomputing.

Challenging the status quo

In her current postdoc research García has taken a more radical approach to the cosmological constant, once described by Einstein as “his greatest blunder”. Cosmologists believe that the cosmological constant could explain the accelerating expansion of the universe, possibly caused by dark energy. García suggests that dark energy could have started to play a role in the expansion of the universe shortly after the Big Bang – much earlier than current models suggest. Theories such as this are collectively known as Early Dark Energy (EDE) models.

“Our current understanding of cosmological proxies like type Ia supernovae allows us to infer that the universe is speeding up its expansion,” she says. “The ultimate effect of such a so-far-invisible component is that it causes negative pressure that beats the gravitational pull among galaxies.”

By suggesting a paradigm shift away from a long-standing aspect of cosmology – the idea that dark energy only plays a role in later epochs of the universe’s history – García’s work could be considered revolutionary. As a woman from Colombia, her career in science is a testament to another long-overdue paradigm shift  –  the imbalance of gender and ethnicity in science.

“The prospects for young South American women in STEM and academia have improved significantly due to the realization that there are so many female scientists from the region who are making important contributions in their disciplines,” García says. “However, inequality, sexism, lack of opportunities and discrimination continue to be the main obstacles for young women to pursue their dreams in STEM.”

She believes that institutions have a critical role in nurturing young women to continue in academia. “There are four main strategies that can be followed,” García explains. “Giving visibility to women’s work and achievements; promoting parity in jobs and salaries; advocating for a safe, diverse and healthy work environment; and finally, not tolerating any form of abuse, harassment or discrimination towards minorities.”

For young girls in South American cities dreaming of the stars and a career in science, García is clear: the stars may be beyond our reach, but a scientific career certainly isn’t. “My advice is to pursue their dreams and be passionate about their careers and fearless of beating the obstacles along the way,” she concludes. “There are plenty of opportunities waiting for them, and nature needs young creative minds to unveil its secrets.”

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