Cracks in the Foundation: How a Cornerstone of Physics is Being Tested with High-Energy Light
For over a century, Lorentz invariance has stood as a bedrock principle of physics, dictating that the laws of nature remain the same for all observers, irrespective of their motion. But in the relentless pursuit of a more complete understanding of the universe, physicists are constantly probing the edges of our knowledge, questioning even the most fundamental assumptions. Now,a team of researchers is shining a light – a very high-energy light – on potential cracks in this foundation.
Lead by Denise Boncioli from Università degli Studi dell’Aquila and Istituto Nazionale di Fisica Nucleare, and Valdir Barbosa bezerra from the Federal University of paraíba, the team is investigating how even subtle violations of Lorentz invariance could affect the journey of ultra-high energy photons, the most energetic particles of light in the cosmos. Their work, which also includes Matteo Giammarco, Iarley Pereira Lobo, Pedro Morais, and Francesco Salamida, explores the consequences of these violations both across the vast expanse of intergalactic space and within Earth’s own atmosphere and crust.
“Imagine a photon traveling billions of light-years to reach us,” explains Boncioli. “If Lorentz invariance isn’t perfectly upheld, its behavior – how it interacts with other particles, how much energy it loses – could be subtly altered along the way.”
The team’s research focuses on how these violations might manifest in two key areas: the spectra of ultra-high energy photons and the characteristics of extensive air showers. When these photons collide with the Earth’s atmosphere, they create a cascade of secondary particles known as an air shower. By modeling how Lorentz invariance violation could alter the probability of photon interactions and the energy required for these interactions, the researchers can predict how these showers might deviate from what’s expected under standard physics.
one particularly intriguing aspect of the study involves the potential for detecting upward-going showers originating from photon interactions within the Earth’s crust. “If lorentz invariance is violated, it could enhance the production of these upward-going showers,” notes Bezerra, “offering a unique signature that we could potentially observe.”
The team is using data from cutting-edge experiments like the Pierre Auger Observatory and IceCube to search for these telltale signs. By comparing their theoretical predictions with observational data, they aim to place constraints on the parameters of Lorentz invariance violation.
“It’s like searching for a tiny wobble in a perfectly spinning top,” says Giammarco. “We’re looking for subtle deviations from the expected behavior of these photons that could indicate a deeper,more complex reality.”
While the research is still ongoing,the implications are profound. If Lorentz invariance is indeed violated, even slightly, it woudl necessitate a revision
