Could Quantum Communication with Aliens Solve the Fermi Paradox?

For decades, the search for extraterrestrial intelligence (SETI) has relied on classical science—listening for radio waves, scanning for optical signals, and using telescopes to analyze exoplanets. But could a quantum mechanical approach unlock the answers we've been seeking, or even explain why we haven't yet detected alien civilizations?

Latham Boyle, a researcher at the Higgs Center for Theoretical Physics at the University of Edinburgh, suggests it’s possible. In a recent preprint, Boyle explores the potential for interstellar quantum communication. "Our galaxy and the sea of cosmic background radiation do permit interstellar quantum communication in certain frequency bands," he explains. However, the challenge lies in the physical limitations of current technology. "Interstellar 'quantum' communication requires huge telescopes—much bigger than anything we've built so far," Boyle adds.

Quantum Communication and the Fermi Paradox

The Fermi paradox asks why, given the vastness of the universe, we haven't yet observed signs of extraterrestrial civilizations. Boyle's analysis may offer a solution. He proposes that advanced alien civilizations could be using quantum communication, and the absence of signals may be because Earth lacks the necessary technology to receive such transmissions.

Quantum communication hinges on entangled qubits, particles that remain linked over vast distances. When one qubit's properties are determined, the other's are instantaneously known, even if separated by light-years. This phenomenon, already demonstrated over a thousand kilometers between Earth and space, could allow for faster and more efficient communication than classical methods.

However, the requirements for detecting such quantum signals are daunting. Unlike classical signals, where even a fraction of transmitted photons can be sufficient, quantum communication demands that most of the transmitted photons be detected. To achieve this across interstellar distances, the receiving telescope on Earth would need to be at least 100 kilometers in diameter, far exceeding any current telescope capabilities.

A Potential Explanation for Silence

Boyle speculates that advanced extraterrestrial civilizations might be aware of our technological limitations. If they use quantum communication, they could have determined that Earth lacks the infrastructure to receive their signals, making communication with us pointless—for now.

"If the extraterrestrial sender has a big enough transmitting telescope, they can necessarily also see that we have not yet built a sufficiently large receiving telescope," Boyle notes. This could explain why we haven't heard from them.

While the current focus of SETI remains on classical signals, the concept of quantum communication offers an intriguing new direction. Further research and technological advancements may one day reveal whether interstellar civilizations are using this quantum technique and, in doing so, finally solve the Fermi paradox.

Appell, D. (2024, September 19). Could interstellar quantum communications involve Earth or solve the Fermi paradox? Phys.org; Phys.org. https://phys.org/news/2024-09-interstellar-quantum-communications-involve-earth.html