Forty kilometers above Antarctica, a hot air balloon carries radio antennas that should pick up signals from the sky. Instead, they detect two coming from underground. A seemingly trivial detail, if it weren't for the fact that those radio signals would have had to pass through thousands of kilometers of solid rock without being absorbed. An impossible thing according to the physics we know. And yet there they are, recorded by the detectors, challenging every established theory of subatomic particles.
The scientific community is divided between skepticism and curiosity: are we facing an instrumental error or the discovery of completely new physical phenomena?
When Ice Betrays Expectations
The experiment ANITA (Antarctic Impulsive Transient Antenna) It was supposed to be simple. An array of radio antennas suspended from a hot air balloon, designed to intercept the emissions produced when cosmic neutrinos interact with Antarctic ice. Neutrinos are elusive particles, capable of passing through entire planets without interacting with matter. When they finally do, they produce cascades of secondary particles that emit detectable radio waves.
Ma in 2016 e in 2018, Stephanie Wissel and his team of Penn State University they were faced with something unexpected. The radio signals They did not come from above, as expected, but emerged from the ice at a 30° angle. A detail that involves a journey through thousands of kilometers of Earth's rock.
As I pointed out in this article, distinguishing real cosmic signals from terrestrial interference requires rigorous criteria. In the case of ANITA's radio signals, all the controls they later confirmed the authenticity of the phenomenon.
The Ruthless Mathematics of Radio Signals
The calculations are merciless. For those radio signals to reach the detectors on that trajectory, the particles that generated them They would have had to travel about 6.000 kilometers through solid rock.. An undertaking that should be lethal for any known particle, including high-energy neutrinos.
The researchers simulated every possible scenario. They consulted data from two other large observatories: Ice Cube in Antarctica and thePierre Auger Observatory in Argentina. Neither recorded related events. The study, published in Physical Review Letters, concludes that the signals remain “anomalous,” the scientific term for something that has no explanation in the current theoretical framework.
“We don't have an explanation for these anomalies yet,” he admits. Exchange in interview. “But we know that they most likely do not represent ordinary neutrinos.”
Radio signals and bold hypotheses
Theories proposed to explain these radio signals range from exotic geology to physics beyond the Standard Model. Some researchers hypothesize dark matter particles that interact weakly with ordinary matter. Others suggest “sterile” neutrinos o unknown interactions between known particles.
Ian Shoemaker of Virginia Tech has proposed a more earthly explanation: the signals could be the result of Radio reflections through hidden structures in Antarctic ice, such as subglacial lakes or unusual density stratifications. A possibility that would require detailed radar mapping of the areas involved.
But the glaciological explanation does not convince everyone. The signals show characteristics (vertical polarization, specific duration) typical of interactions between high-energy particles, not of ambient radio reflections. So what?
The technological evolution of radio signal detectors
The mystery may be answered with the next generation of instruments. Wissel's team is developing I CAN (Payload for Ultrahigh Energy Observations), a more sensitive detector that should fly within a few years. “If there are indeed unknown particles out there,” she says, “PUEO should detect more of them.”
The approach is reminiscent of great discoveries of the past: unexplained anomalies that ultimately revealed new physical phenomena. Discoveries of antimatter, quarks, the Higgs boson, often began with data that didn't fit into existing theories.
Questions of perspective
These radio signals from Antarctica raise a larger question about the nature of the universe. If particles can travel across entire planets undetected, what does that mean for our understanding of matter and energy? If these are never-before-seen geological phenomena, how much more do we have to learn about our own planet?
Scientific caution dictates that we should keep the doubt. But the excitement of being faced with something genuinely new is palpable in the words of the researchers. “It’s one of those mysteries that lasts over time,” concludes Wissel. “And I’m excited that when PUEO flies, we will have better sensitivity.”
Until new data arrives, those two radio signals remain there: a silent challenge to our certainties, a reminder that the universe can still surprise us. And perhaps, precisely in these apparently minor anomalies, the keys to understanding phenomena that will change physics forever are hidden.
