While we haven't found any evidence of alien life yet, that doesn't mean it's not out there, beyond our reach. Now, a team of researchers has put together a mathematical model showing aliens could potentially be communicating across space – via quantum physics.
Efforts are well underway to make quantum communications a reality here on Earth. The idea is that quantum mechanics provide certain properties that would make information transfer inherently faster and more secure than regular systems… if we can get it to work.
One of the major hurdles to overcome before quantum networks can be established is that they're very fragile and susceptible to interference. According to this latest study, such networks could fly across space without breaking up.
"Quantum states you generally think of as very delicate, and if there's any kind of external interaction, you kind of destroy that state," lead author of the research, theoretical physicist Arjun Berera from the University of Edinburgh in the UK, told Science News.
Berera and his colleague Jaime Calderón-Figueroa, a fellow theoretical physicist at the University of Edinburgh, ran calculations on the movement of X-rays across the emptiness of space to check for potential decoherence (the breaking up of the quantum state).
If photons – particles of light – were used as the quantum particles, the researchers determined, they could be beamed across hundreds of thousands of light-years at least, a greater stretch of distance than the entire Milky Way galaxy.
That's partly because the average density of matter in space is much less than it is on Earth, and this 'cleaner' environment means less chance of interference. Even gravitational pulls wouldn't be enough to knock a quantum communication network off course.
"It is plausible that quantum communication mediated by photons could be established across interstellar distances, in particular for photons in the X-ray region below the electron mass," write the researchers in their published paper.
That alien life forms might be using quantum networks to speak to each other or to try and get in touch with us is, of course, pure speculation – but at the same time it gives astronomers another potential sign of life they can monitor for.
The "considerable information transfer" possible with a quantum signal would make it attractive to any extraterrestrial intelligence out there in the cosmos, the researchers say, though it may require a fully functioning quantum computer in order to decode it.
And even quantum communication isn't magic: Information still can't travel faster than the speed of light, so transmissions may take several years to reach their destinations.
Based on these findings, we can now add quantum communication as well as classical communication to the possible ways aliens might be chatting with each other – or perhaps might be trying to make themselves known to us.
"In principle, it should be possible to detect a quantum signal coming from an astrophysical body or even an intelligent signal from an extraterrestrial civilization," write the researchers.
The research has been published in Physical Review D.