A recent experiment conducted over Antarctica to detect cosmic radio waves has uncovered strange signals emanating from deep within the ice, challenging the current understanding of particle physics, according to scientists.

The Antarctic Impulsive Transient Antenna (ANITA) experiment involves radio antennas flown on NASA balloons over Antarctica at altitudes ranging from 19 to 24 miles. Recently, the detector picked up radio pulses that appeared to be rising up through the Earth at steep angles, up to 30 degrees below the surface of the ice. This indicates that the radio signals traveled through thousands of miles of solid rock to reach the detector, a phenomenon that contradicts existing models of particle physics.

Researchers are puzzled by these anomalies as the current understanding of particle physics suggests that these radio pulses should have been absorbed by the rock, making detection impossible. The team published their findings in the journal Physical Review Letters in March.

The primary goal of ANITA is to collect data on deep space events by analyzing signals reaching Earth. The experiment is crucial in the search for neutrinos, which are elusive particles with no charge and the smallest mass among subatomic particles.

Neutrinos are widespread in the universe, constantly passing through everything, and typically originate from high-energy sources like the Sun or supernovae. However, detecting their signals is extremely challenging. ANITA aims to overcome this challenge by detecting the radio emissions produced when neutrinos interact with Antarctic ice.

As the detector flies over ice, it looks for 'ice showers,' which are cascades of particles triggered by neutrinos hitting the ice. These showers produce radio signals that ANITA can detect. Researchers can differentiate between ice and air showers to identify the particle that created the signal and trace it back to its source.

Despite analyzing data from multiple flights and comparing it to mathematical models and simulations, the researchers have been unable to explain the anomalous signals detected by ANITA. The signals do not match any known particle-based signals, ruling out the possibility of them being ice-interacting neutrinos or tau leptons.

The team also compared ANITA's data with findings from other neutrino detectors but did not find any similar anomalies. The nature of these strange signals remains a mystery, with researchers hoping that future detectors like the Payload for Ultrahigh Energy Observation (PUEO) mission will provide more insights.

Wissel's team at Penn State is currently working on the PUEO mission, which is expected to have better sensitivity in detecting neutrino signals. The researchers are optimistic that this new detector will shed light on the mysterious signals and potentially uncover the true nature of these anomalies.