A groundbreaking study by a University of Cincinnati physicist and an international team proposes a theoretical method to produce axions within fusion reactors. This scientific breakthrough tackles a challenge that even eluded fictional physicists on the popular television show “The Big Bang Theory.”
In the CBS sitcom, characters Sheldon Cooper and Leonard Hofstadter grappled with the concept of axion production over three episodes in Season 5, ultimately leaving the problem unsolved. However, UC physics professor Jure Zupan, alongside collaborators from the Fermi National Laboratory, MIT, and the Technion-Israel Institute of Technology, has published a potential solution in the Journal of High Energy Physics.
Why Axions Matter to Dark Matter Research
Axions are theoretical subatomic particles that could hold the key to understanding dark matter, a component believed to play a significant role in shaping the universe since the Big Bang nearly 14 billion years ago. Despite never being directly detected, dark matter is thought to constitute the majority of the universe’s matter, with ordinary matter—such as stars, planets, and humans—making up only a small fraction. Dark matter is named for its inability to absorb or reflect light, with its presence inferred through gravitational effects.
The unusual movements of galaxies and their stars suggest that large amounts of unseen matter are exerting gravitational forces. One leading hypothesis is that dark matter consists of extremely light particles, such as axions.
Fusion Reactors as a Source of New Particles
In their study, Zupan and his colleagues explored a fusion reactor design utilizing deuterium and tritium fuel within a lithium-lined vessel. This type of reactor is under development through an international collaboration in southern France. Such reactors generate vast numbers of neutrons alongside energy, which the researchers suggest could lead to the creation of particles linked to the dark sector.
“Neutrons interact with material in the walls. The resulting nuclear reactions can then create new particles,” Zupan explained. Another potential production avenue involves neutrons colliding with other particles and slowing down, releasing energy in a process known as bremsstrahlung, or “braking radiation.”
Through these mechanisms, the reactor could theoretically produce axions or axion-like particles. Zupan noted that this is where the fictional physicists on television fell short.
The Big Bang Theory Easter Egg Explained
“The Big Bang Theory,” which aired from 2007 to 2019, won seven Emmys and remains a favorite on streaming platforms, according to Nielsen. “The general idea from our paper was discussed in ‘The Big Bang Theory’ years ago, but Sheldon and Leonard couldn’t make it work,” Zupan said.
In one episode, a whiteboard displays an equation and diagram representing how axions are produced in the sun. In a later episode, a different equation appears, with a sad face drawn underneath—an indication of failure. Zupan explained that the equation compares the chances of detecting axions from a fusion reactor with those from the sun, and the comparison is not favorable.
“The sun is a huge object producing a lot of power. The chance of having new particles produced from the sun that would stream to Earth is larger than having them produced in fusion reactors using the same processes as in the Sun. However, one can still produce them in reactors using a different set of processes,” he said.
The show never explicitly mentions axions or explains the whiteboards, serving instead as inside jokes for scientists. The series is known for weaving scientific concepts like Schrödinger’s cat and the Doppler effect into its plots, along with appearances by Nobel Prize winners and “Star Trek” alumni.
“That’s why it’s fantastic to watch as a scientist,” Zupan remarked. “There are many layers to the jokes.”
Implications and Future Directions
This innovative approach to axion production in fusion reactors could open new avenues for dark matter research. If successful, it would mark a significant advancement in our understanding of the universe’s fundamental components. The potential to produce axions in a controlled environment could provide experimental evidence for their existence, offering insights into the elusive nature of dark matter.
The research team emphasizes the importance of continued exploration and experimentation in this field. As fusion technology advances, the possibility of detecting axions becomes more tangible, potentially revolutionizing our comprehension of the cosmos.
As the scientific community continues to unravel the mysteries of dark matter, the work of Zupan and his colleagues represents a promising step forward. The fusion of theoretical physics and cutting-edge technology may one day illuminate the dark corners of our universe, offering answers to questions that have puzzled scientists for decades.
