Scientists using NASA's WISE orbiting observatory attempted to find "obvious" signatures of advanced civilizations by looking at 100,000 galaxies. They came up empty.
Jason T. Wright, a professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University who came up with the plan to look for aliens, says, "The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization's technologies would be detectible in mid-infrared wavelengths - exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes."
"Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy's stars to power computers, space flight, communication or something we can't yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelength. This same basic physic causes your computer to radiate heat while it is turned on," he adds.
While the study ruled out this kind of alien civilization having conquered an entire galaxy, it by no means was conclusive in saying there is no alien life in those 100,000 galaxies. There is still the possibility that many advanced alien life forms exist in those galaxies, just not to the point that they have managed to harness the entire galaxy as an energy source.
In 1964, astronomer Nikolai Kardashev came up with the Kardashev scale, a way to categorize civilizations in terms of how advanced their technology is based on how much energy they use. It ranges from Type 0 to (depending on who you ask) Type III, Type IV, or Type V. Humans have not reached a Type I civilization yet, meaning we have learned how to harness all of the energy of the Sun that has reached Earth. A Type II civilization would have learned how to harness all the energy radiated by their parent star. A Type III, which is what the researchers believed they would be able to detect, would extend to all stars in a galaxy. A Type IV civilization, which Kardashev believed was outside the realm of possibility for any species, would be able to harness all of the energy in the universe via currently unknown physics. A Type V civilization would extend beyond even that by being able to manipulate the entire universe or multiverse at their will.
As our current understanding of the possibilities of life outside of Earth continues to evolve and our abilities to detect and study alien worlds improves every year, perhaps we will find other civilizations in the universe, just not as advanced as a Kardashev Type III.
Photo: NASA Goddard Flight Center/Wikimedia Commons