Danny C Price, Curtin University
“Extraordinary claims require extraordinary evidence.”
– Carl Sagan (Cosmos, 1980)
This phrase is the Standard which astronomers will apply to a curious signal captured with the Chinese “Sky Eye” telescope which strength be a transmission of extraterrestrial technology.
An article reporting the signal was published on the website of China’s state-backed Science and Technology Daily newspaper, but was later removed. So, have astronomers finally found evidence of intelligent life beyond Earth? And is it muffled?
We should be intrigued, but not too excited (yet). A signal of interest must go through many tests to verify whether it really bears the signature of extraterrestrial technology or is simply the result of an unexpected source of terrestrial interference.
And regarding deletion: press releases are normally scheduled for simultaneous publication with peer-reviewed results – which are not yet available – so it was probably published a little earlier by mistake.
An eye on the sky
Sky Eye, which is officially known as Five Hundred Meter Aperture Spherical Telescope (FAST), is the largest and most sensitive single-dish radio telescope in the world. A marvel of engineering, its gargantuan structure is built inside a natural pool in the mountains of Guizhou, China.
The telescope is so huge that it cannot be physically tilted, but it can be pointed in one direction by thousands of actuators that distort the reflective surface of the telescope. By distorting the surface, the location of the telescope’s focal point changes and the telescope can look at a different part of the sky.
FAST detects radiation at radio wavelengths (up to 10cm) and is used for astronomical research in a wide range of fields. One area is the search for extraterrestrial intelligence, or SETI.
SETI observations are mostly made in “piggy-back” mode, which means they are taken while the telescope is also running its main science programs. In this way, large swaths of the sky can be scanned for signs of extraterrestrial technology – or “technosignatures” – without interfering with other scientific operations. For special targets like nearby exoplanets, dedicated SETI observations are always made.
The hunt for alien technology
Searches for technosignatures have continued since the 1960s, when the American astronomer Frank Drake pointed the 26 meter Tatel telescope to two nearby Sun-like stars and scanned them for signs of technology.
Over the years, searches for technosignatures have become much more rigorous and sensitive. The systems in place at FAST are also capable of processing billions of times more radio spectrum than Drake’s experiment.
Read also: The search for extraterrestrial life
Despite this progress, we have yet to find any evidence of life beyond Earth.
FAST sifts through huge amounts of data. The telescope feeds 38 billion samples per second into a high-performance computer array, which then produces extremely detailed maps of incoming radio signals. These charts are then searched for signals that look like technosignatures.
With such a large collection area, FAST can pick up incredibly weak signals. It is about 20 times more sensitive than Australia’s Murriyang Telescope at Parkes Radio Observatory. FAST could easily detect a transmitter on a nearby exoplanet with an output power similar to the radar systems we have here on Earth.
The problem of sensitivity
The problem with being so sensitive is that you may discover radio interference that would otherwise be too weak to detect. We SETI researchers have had this problem before.
Last year, using Murriyang, we detected an extremely interesting signal which we called BLC1.
However, it turned out to be very strange interference (not aliens). To discover its true nature, we had to develop a new verification framework.
With BLC1, it took about a year from when it was initially reported to when the peer-reviewed analysis was published. Likewise, we may have to wait for some time for the FAST signal to be analyzed in depth.
Professor Zhang Tongjie, chief scientist of the China Extraterrestrial Civilization Research Group, acknowledged this in the Science & Technology Daily report:
Also read: What will extraterrestrial life look like?
The possibility that the suspicious signal is some kind of radio interference is also very high and should be further confirmed and ruled out. It can be a long process.
And we may have to get used to a gap between finding candidate signals and verifying them. FAST and other telescopes are likely to find many more signals of interest.
Most of them will turn out to be interference, but some may be new astrophysical phenomena, and some may be authentic technosignatures.
Stay intrigued
Will FAST’s extraordinary signals meet the extraordinary burden of proof? Until their work is reviewed and published, it’s still too early to tell, but it’s encouraging that their SETI search algorithms are finding curious signals.
Between FAST, the Revolutionary Listening initiative, and the SETI Institute COSMIC program, the SETI domain is seeing a lot of interest and activity. And it’s not just radio waves: research is also underway using optical and infrared light.
For now: stay intrigued, but don’t get too excited.
Danny C PricePrincipal Investigator, Curtin University
This article is republished from The conversation under Creative Commons license. Read it original article.
Comments are closed.