Knowing which method to use when trying to communicate with aliens is one of the most difficult decisions. Advanced alien civilizations could be making use of a variety of methods.
Examples are visible light, ultraviolet light, X-rays or even the use of a different wavelength along the electromagnetic spectrum.
After researching a total of 700 stars, a Breakthrough Listen project found eleven potential alien signals. Unfortunately, all those signals ended up being false positives. The researchers looked at each star for about fifteen minutes, using a radio telescope.
“In order for us to discover a distant transmitter, they’d have to ping us in just the right time window,” says Rene Heller, astrophysicist at the Max Planck Institute for Solar System Research. They’d also have to be using the same frequency we are listening in.
“This Breakthrough Listen project tried to find if we have neighbors shouting to the rest of the Galaxy, using comparable radio technology to our own,” says Jaymie Matthews, Professor of Astrophysics at University of British Columbia. So what should be done?
Listen to more stars, at greater distances, and tune in to more frequencies.
Making use of the right spectrum
In a paper, published on the arXiv server, researcher Michael Hippke discovered that if we were to use photons to communicate across galaxies, we should aim to send them at wavelengths of around one nanometer. Then, they would place the waves in the X-ray part of the electromagnetic spectrum.
Their higher energy means they are able to travel more efficiently over long distances. In comparison, radio waves have a wavelength of between 1mm and 10km.
Since the 1950s, the preferred method of communication has been through photons. However, there are other viable options. They range from a neutrino to a megastructure, each with its own advantages and disadvantages.
Mega structures
One of the most extreme ways to communicate with aliens could involve building an artificial object and launching it into space.
In a 2005 paper, Luc Arnold proposed a way to detect artificial objects in a similar way that we use to detect exoplanets, known as the transit method. The method examines the light dim as something moves in front of the star.
Although this may sound like something out of science-fiction, there is already one star with a strange behavior. The existence of some kind of megastructure built around it could explain its abnormality.
Because of its unpredictable brightness, KIC 8462852 has spawned theories ranging from clouds of comets to an exploding planet.
Recently, it drew attention when it dipped in brightness, according to Tabetha Boyajian from Louisiana State University, who discovered the star.
Researchers are still studying the star, in the hopes of working out what is causing the dips.
For the time being, we should start working on our own megastructure, in case there is any advanced extraterrestrial civilization waiting to hear from us.
