Looking for technosignatures from other civilisations

In his research Erik Zackrisson scours the skies for signs of technologically advanced life forms. Photo: Mikael Wallerstedt

Hello to Erik Zackrisson, Associate Professor (Docent) at the Department of Physics and Astronomy, whose research project consists in searching for extraterrestrial intelligence. You’re Sweden’s first SETI researcher. What does that involve?

“The backstory is that SETI (the search for extraterrestrial intelligence) started as a scientific field around 1960, when the US and USSR began it, and they’ve been at it ever since. However, it’s gone much more slowly in Europe. The first SETI experiment in Sweden was done in 2013, by me and a colleague at Stockholm University. Since then, we’ve carried on at low intensity. There are currently two SETI projects in Sweden.”

How do you define intelligent life?
“Astronomers define it as living beings that are smart enough to build a radio transmitter. In other words, they have to be technologically advanced.”

What methods do you use?
“For decades, the SETI field was all about a quest for signals from extraterrestrial beings or ‘aliens’. This has been under way for 60 years and nothing has been found. Another approach is to look for ‘technosignatures’ – signs or traces of technology in space, where something has been constructed that doesn’t look natural. We can detect things like that at a much greater distance, and there’s no need for the other civilisation to have any intention of trying to contact us.”

Could you clarify that?
“What we’re looking for are ‘Dyson spheres’. That’s a theoretical concept based on the assumption that a civilisation seeking continuous expansion will eventually have energy problems. A highly advanced civilisation could then create a sphere of satellites around a star to harness its energy, which would make it look different through a telescope.”

Specifically, what do you do?
“For decades, people have scanned every part of the sky, and have masses of data on each object. The most time-efficient way is to look through existing catalogues and not make new observations until you’ve found a good candidate. So what we find are odd stars that behave unexpectedly. We can study how much light a star emits in various wavelengths, and see how the light varies over time. We use machine-learning techniques to sift through the material correctly.”

Why is finding extraterrestrial life important?
“Why we’re looking for life in space is basically out of curiosity. Are we alone, or aren’t we?”

Are there any signs that mean intelligent life might exist?
“We find unusual things in space, and sometimes new astral phenomena. But let’s face it, all the measurements made since the 1960s show that nothing’s there – space is sterile.”

Åsa Malmberg

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