Mysterious radio signals just tore through Antarctic ice. They could be coming from edge of universe

Scientists have detected strange radio signals coming from below the ground in Antarctica. A cosmic detector flying high above Antarctica picked up the strange pulses, which appear to be rising up through the Earth. The discovery was made by an international research group that includes scientists from Penn State. They have published their results in the journal Physical Review Letters.

The Antarctic Impulsive Transient Antenna (ANITA) experiment was flying above the region when it recorded the radio signals. The probe comprises several instruments and radio antennas flown on balloons and aims to learn more about distant cosmic events by studying the signals that reach the Earth. They should ideally bounce off the surface, but in Antarctica, it caught signals that were coming from deep below the ground.

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Radio signals crossed the entire Earth and shot past the surface

They were at steep angles, and likely travelled through kilometres of rock and passed the Earth's crust before tearing through the surface.

“The radio waves that we detected were at really steep angles, like 30 degrees below the surface of the ice,” said Stephanie Wissel, associate professor of Physics, astronomy and astrophysics, who worked on the ANITA team.

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However, if this is the case, then the signals should have been absorbed into the rock and never detected by the instruments on board ANITA. This anomaly has left scientists baffled, who are struggling to determine what could have caused the radio pulses.

“It’s an interesting problem because we still don't actually have an explanation for what those anomalies are, but what we do know is that they're most likely not representing neutrinos,” Wissel said.

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ANITA looks for signals from deep space

ANITA travels through the air to pick up faint signals that come from outer space and interact with ice. The expectation is to record signals from neutrinos, the smallest mass of all subatomic particles, that is abundant in the universe. They are emitted by the sun, gamma-ray bursts and supernovas, and once upon a time, by the Big Bang. Travelling at the speed of light, neutrinos are a treasure trove of information about cosmic events that happen millions of light-years away.

They don't interact much, making them difficult to detect. But the signals noticed in Antarctica didn't behave like neutrinos. Wissel says if it were at all a neutrino that was responsible, it means it travelled a long way without interacting with anything until the end. Based on current models, it should have been absorbed by Earth. She doesn't think it was a neutrino.

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“So, this is the double-edged sword problem. If we detect them, it means they have travelled all this way without interacting with anything else. We could be detecting a neutrino coming from the edge of the observable universe.”

To know more about the signal, the team compared the data gathered by ANITA with information from two other major neutrino detectors, IceCube in Antarctica and the Pierre Auger Observatory in Argentina. Nothing similar was found.

After further simulations and tests, the scientists concluded the signals were "anomalous." They think something new can be at play here - an unknown particle, new interactions and maybe even new Physics.