Lecture explores ever-expanding understanding of the universe

On 8 October, Professor Amanda Weltman delivered her inaugural lecture at the University of Cape Town (UCT). The event took place in the Maths Block’s M304 lecture theatre, an apt location given that this was where Professor Weltman used to lecture first-year students.

Professor Weltman, a leading figure in theoretical physics at UCT’s Department of Mathematics and Applied Mathematics, currently heads UCT’s High Energy Physics, Cosmology & Astrophysics Theory Group (HEPCAT). Her contributions to the field have earned her global recognition, with over 10 000 citations and numerous accolades to her name. In 2020, she was promoted to full professor.

UCT Vice-Chancellor Professor Mosa Moshabela opened the evening with words of appreciation for Weltman and her academic journey. “Inaugural lectures capture in one moment the long, arduous journey that [the scholar] has travelled to get to where they are. For the new generation and next generation of scholars, they also get to see what it takes to get to this point,” Professor Moshabela said. He added that these occasions allow the university community to celebrate both the scholar’s work and its far-reaching impact.

A tribute to the journey and the people who shaped it

In her lecture, titled “From the Laboratory to the Sky: New Windows on the Universe”, Weltman paid tribute to her early influences, particularly her two “very mathematical parents”. Their guidance and passion for numbers had a profound effect on her career. She explained how her work is built on three pillars: mathematics, physical intuition, and creativity. These elements, she noted, form the foundation of how she approaches the big questions in her field; questions that seek to explain the very nature of the universe itself.

“We only really understand less than 5% of the total energy of the universe.”

She invited the audience to embark on a journey that spans from the tiniest, vibrating strings of matter to the vast expanse of the universe, highlighting the importance of building and testing theories across various scales. Her lecture provided an overview of the current understanding of the universe, while she also commented on the unresolved crises cosmologists face today.

“You will learn about chameleon gravity, a novel theory of gravity I developed as a PhD student,” she said, referring to her ground-breaking work, “and the many efforts over the years to discover its effects in laboratory and astrophysical observations.” She added: “We only really understand less than 5% of the total energy of the universe. Ninety-five percent of it is dark ... We call it dark matter and dark energy simply because it doesn’t interact with light.”

She spoke about fast radio bursts, the focus of her work for the past few years, and emphasised the potential of using the radio sky as a tool for fundamental physics discoveries; a method that could revolutionise our understanding of the universe.

The role of curiosity and creativity in scientific discovery

Weltman’s career has been marked by her ability to think creatively, ask the right questions, and find innovative ways to answer them. Her work in theoretical physics, particularly her research on chameleon gravity, has made her a leading figure in her field. Chameleon gravity is a theory she authored during her PhD at Columbia University, where she studied under the physicist Professor Brian Greene.

“Being able to ask the right questions at precisely the right time.”

After completing her PhD in 2007, she spent time as a postdoctoral research associate at the University of Cambridge’s Centre for Theoretical Cosmology, where her research continued to flourish. In 2007, she returned to South Africa to join UCT as a lecturer, and soon after, she founded the HEPCAT group, which has since become a hub for ground-breaking research, fostering the next generation of cosmologists and theoretical physicists.

Over the years, Weltman has received numerous awards, including the Meiring Naude Medal from the Royal Society of South Africa and the Elsevier Young Scientist Award. In 2021, she was awarded the prestigious South African Research Chair in Physical Cosmology, further solidifying her position as a leader in her field.

Throughout her career, Weltman has maintained a balance between her rigorous research and her commitment to teaching and mentorship. She has inspired many young scientists to further their careers, and she continues to serve as a role model for women in science.

In his vote of thanks, Professor Jeff Murugan, UCT’s acting deputy vice-chancellor for Research and Internationalisation, praised her not only for her academic contributions but for her exceptional ability to balance the many facets of her life. “She is also a role model in how she balances the different aspects of her life; never letting one responsibility overshadow another but instead showing us all how to weave together family, mentorship and scientific pursuit in a way that enriches them all,” he said.

“Only a select few of us will ever have the privilege of being able to ask the right questions at precisely the right time. Amanda is one such rare scientist.”