Search finds no signs of advanced aliens in 100,000 galaxies
Thursday, April 23, 2015, 9:28 - In a universe as expansive and ancient as ours is, you'd think that at least one galaxy-spanning alien civilization would have developed, but astronomers have found no signs of one. What does this mean?
Scanning through 100,000 galaxies, imaged by NASA's space-based Widefield Infrared Survey Explorer (WISE) telescope, a team led by Penn State researcher Roger Griffith searched for obvious signs of alien life. However this wasn't a search for radio signals, or biological signs, or even evidence of massive construction projects - although that last one is close.
"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 detectable in mid-infrared wavelengths - exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes," Jason T. Wright, from the Center for Exoplanets and Habitable Worlds at Penn State University, told Penn State News.
"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 wavelengths," Wright added. "This same basic physics causes your computer to radiate heat while it is turned on."
How advanced is 'advanced'?
When speaking of a civilization that can harness the energy of an entire galaxy for its power needs, this is one of the most advanced we can currently conceive of - a Type III civilization on the hypothetical Kardashev scale. For reference, humanity has yet to achieve the level of a Type I civilization, which is one capable of collecting and using 100 percent of the energy Earth receives from the Sun (around 350 quadrillion Watts or roughly 100,000 times what we are capable of producing currently).
A Type III civilization could harness star light using something called a Dyson sphere - an enormous spherical shell completely surrounding a star, which, if it was positioned in the star's habitable zone, would provide living space equal to 100s of millions of Earths. They could even tap into the supermassive black hole at the centre of their galaxy for energy.
Very likely, they would be so advanced that they could manipulate matter in ways we cannot even contemplate right now, and given current thoughts on the future of humanity, these civilizations could even be post-biological - existing entirely as machines and virtual intelligences.
Anything good to report?
Of the 100,000 galaxies the team pulled from the WISE database, the study authors wrote that none showed signs of an advanced galaxy-spanning alien civilization - one that would be converting at least 85 per cent of its galaxy's starlight into infrared radiation.
So, no Type III civilizations detected, although, as Wright pointed out, it could meant that they just don't use enough energy to be noticed by the method the team used.
There were a few interesting finds, though. A small number of the galaxies examined showed enough 'extra heat' that it could represent a civilization converting over half of their galaxy's starlight to infrared. This extra heat could have a natural explanation, but Jessica Maldonado, a student at California State Polytechnic University in Pomona, found six objects among them that had not been classified before.
"When you're looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it's not what you were looking for," said study co-investigator Steinn Sigurdsson. "Sure enough, Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what's going on."
What does this mean for us?
To the best of their ability, scientists estimate billions of potentially habitable worlds in our own galaxy, and our own existence proves that it's possible for intelligent life to develop. So, simply looking at it statistically, alien life must exist out there, both in our own galaxy and in the billions of other galaxies in the visible universe.
No obvious signs of a Type III civilization could mean a number of things:
- No Type III civilizations exist yet, or
- With the enormous distances between galaxies, the light that carries the evidence for these civilizations may not have arrived here yet, or
- We still lack the technology to detect the evidence of these civilizations, or
- Type III civilizations may not leave behind the evidence we think, meaning that we're simply not looking for the right thing, or
- It may be impossible to achieve a Type III civilization.
One possibility that has implications for us here on Earth is that it could be very difficult to reach the technological level to even be considered a Type I civilization. Many species could end up destroying themselves, either through war, environmental degradation or extreme climate disruption. They could be wiped out by a disease or other natural calamity, or through an astronomical source, such as an asteroid collision, gamma ray burst or nearby supernova. Surviving to become a Type II or Type III civilization would very likely be even more difficult, given the time and development needed.
None of this means that we shouldn't continue the search for civilizations beyond our solar system, though. Discovering an alien civilization would have a profound effect on us and our view of the universe, and although opinions differ on whether we should contact any aliens we discover, the potential rewards for doing so may far outweigh the dangers.Twitter