This is scientific American 60 second science. I'm Christopher in Tagata.

The Earth is studded with telescopes, listening for electromagnetic radiation from the great beyond.

And a decade ago, astronomers stumbled upon a mysterious signal,

a powerful pulse of radio waves just a few thousandths of a second long.

Mysterious because...

What is the nature of the sources?

Avilob, a theoretical astrophysicist at Harvard.

Whatever the sources are, he says.

They seem to be brighter by tens of billions of times more than the brightest radio sources we know about.

The radio pulses are known as fast radio bursts, and Lobe says you'd need something tens of billions of

times brighter than a pulsar to produce him so he and his colleague Menasviliulingham

investigated another possibility. We know of one simple way to generate very powerful radio waves and that's using radio antenna.

A radio antenna built and controlled by extraterrestrials to be more precise.

Logan Lingham did the math on how big that stellar-powered radio antenna would have to be

to transmit signals like fast radio bursts, and whether it would even hold up from an engineering

standpoint, like would it melt under its own heat.

Using those energy and engineering constraints, they found that the radio beam

emitter would have to be twice the diameter of Earth.

Pretty big for us, but at least theoretically possible, he says, for more advanced

civilizations. The study is in the Astrophysical Journal letters. To be clear, this is definitely not proof that intelligent aliens exist.

It's just proof of concept that someone smarter than us could in theory build such a thing.

And why you might build it?

...