The Guardian reports:

The close encounter will have to wait. Astronomers have come up empty-handed after scanning the heavens for signs of intelligent life in the most extensive search ever performed.

Researchers used ground-based telescopes to eavesdrop on 1,327 stars within 160 light years of Earth. During three years of observations they found no evidence of signals that could plausibly come from an alien civilisation.

The only signals picked up by the Green Bank telescope in West Virginia and the Parkes telescope in Australia had more Earthly origins, the scientists found, with mobile phones and other terrestrial technology providing plenty of noise, and more transient signals coming from overflying satellites.

“It’s quiet out there,” said Danny Price, an astronomer at the University of California, Berkeley, and a member of the Breakthrough Listen project, which aims to scan a million nearby stars, the entire plane of the Milky Way, and 100 neighbouring galaxies for radio and optical signals.

“We haven’t found anything in the data, but I’m certainly not giving up hope. There are still so many more stars to look at and more search approaches to consider.”

The scientists hope to spot “technosignatures”, which could reveal the presence an alien civilisation. These powerful electromagnetic signals are distinct from the various bursts of natural radiation that pour constantly through the galaxy. [Continue reading…]

Come the day that technosignatures emanating from outer space are actually detected, we shouldn’t be too quick to declare that these represent the discovery of intelligent life.

Human beings have yet to demonstrate that the creation of advanced technology is compatible with the continued existence of the biosphere on which we depend.

The development of systems that result in this organism destroying its own habitat have resulted in the creation of our own cosmically detectable technosignatures. But these signs arguably reveal more about our destructive capacities than they say about our intelligence.

Conversely, it seems eminently reasonable to suppose that the most intelligent life forms elsewhere in this galaxy might have no technosignature. They might speak so softly that from afar there is nothing to hear.

Thus, the Earth-based search for intelligent life, constrained by the instruments we use, is less a search for life than it is a search for technology.

If or when such technology is discovered, it may well be coming from a planet where the machines are still running but their creators long ago expired.

As humans, our collective tendency to equate technology with advanced life forms most often results from mistaking scale with complexity — thus fools easily become enamored with towers.

The most complex structures on this planet, however, design humans instead of being designed by humans. Thus far, nothing we have created matches the exquisite molecular complexity of the building blocks of life itself — proteins.

As a measure of the gulf that remains between life and technology, the fact that the most advanced computer systems in existence are required in an ongoing effort to model protein folding surely tells why we should remain more in awe of life itself than we are in the lifeless tools we have created to study it.