As of 2020, the global consumption of energy is 580 million terajoules per year. Of this, 83.1% comes from fossil fuels like coal, oil, and natural gas, 4.3% comes from radioactive sources, and about 12.6% comes from renewable sources like hydro, solar, and wind. We have currently 50 more years of oil reserves left available, given our current consumption of 95 million barrels per day. Hence, even ignoring the environmental impacts of fossil fuel use, it is high time we switch to more renewable sources of energy before we run out. Of all the renewable resources, the Sun is the most powerful. Every second, the sun produces 3.8 terajoules, (the energy of 1 million light bulbs) which is 100 times that of the current energy consumption of a US household per year. While there has been a significant rise in solar energy consumption, humans use about a millionth of all the incident radiation. Even if we maximize our total solar power usage, it will still be a billionth of the total solar energy.
One of the ways to harness the total power of the sun was proposed by the physicist Freeman Dyson in 1960. He imagined a mega-structure that would completely encompass a star and capture a large percentage, if not all, of the solar power output. Such a structure is called a Dyson Sphere. There are many variants of the Dyson Sphere, such as a Dyson swarm, a Dyson bubble, and a Dyson shell, to name a few. However, constructing such structures is currently beyond the capabilities of humans. A 100% reflective satellite deployed around the sun would need an overall density of 0.78 grams per square meter of material. For reference, paper sits at 80 grams per square meter. And while some novel materials like graphene aerogels have a density of 0.16 mg per cubic centimeter, they have not yet been produced on such a large scale. Some other issues include the Dyson Sphere’s vulnerability to gravity, its potential to collapse on the parent star, and vulnerability to being destroyed by incoming interstellar bodies like asteroids and meteors.
Just as a thought experiment, if there existed a civilization that was already building Dyson Spheres, what would alert us of their existence? To understand that, we need to understand the basics of how such a sphere would function. A system of such collectors would absorb solar energy and reradiate it, thereby altering the wavelength of light. This wavelength can be characterized by the emission spectra of the materials it’s made of. Since it has been hypothesized that heavy elements not present in the Sun would go into the construction of the Dyson Spheres, the wavelengths would be atypical to the spectral type of the star in question. A little bit of physics suggests that most known substances would reradiate light in the infrared part of the electromagnetic spectrum. Thus, a Dyson Sphere, constructed around a Sun-like star by intelligent extraterrestrial lifeforms, with materials known to humans, would cause an increase in the infrared radiation in the star system’s emission spectra. This search for technological signatures is the science of technosignatures or technomarkers as opposed to the search for biomarkers. The Search for Extraterrestrial Intelligence (SETI) uses these assumptions and searches for “infrared heavy” spectra from stars similar to our sun. The Fermilab has an ongoing survey to analyze data from their Infrared Astronomical Satellite (IRAS), which yielded 17 potential “ambiguous” candidates, but no confirmation of the existence of the Dyson Spheres of any advanced civilization.
To understand what advanced civilizations mean, we have to go back to 1964, at the Byurakan Conference, where the Russian SETI pioneer Nikolai Kardashev presented a paper titled “Transmission of Information by Extraterrestrial Civilizations”. There, he outlined a scale that could classify civilizations into Type I, Type II, or Type III based on the energy consumption of the respective civilization. He came up with this while looking for alien civilizations and imagining how technological advances would alter the civilizations were they to exist. Broadly speaking, a Type I (planetary) civilization would have mastered the energy consumption from their host planet and used the technology to colonize (terraform) other planets with ease. A Type II (stellar) civilization would come into being when the civilization would have exhausted planetary sources of energy and harnessed the energy of stars, and the exponential progression to a Type III (galactic) would occur when they would harness the energy of entire galaxies. Human civilization is estimated to currently be around 0.73 on the Kardashev scale. Physicist Michio Kaku estimated that within 100-200 years, we would attain a Type I status assuming we continue progressing at a rate of 3% per year. Kardashev himself estimated that if our energy consumption grows at a modest rate of 1% per year, we would be at Type II in 3200 years and Type III in 5800 years. But Type 0 to Type I is the most difficult jump to make. Even though we have made huge breakthroughs in technology and science, we are facing a major crisis of global warming and climate change. Coupling that with internal strife and possible nuclear wars, there is always the danger of our extinction before we even begin to advance to a civilization that harnesses the entire solar system to its benefit.
So, is this really the only path, that we will be wiped away before we advance to the future of science fiction or make contact with other intelligent life in space? It does seem a little saddening, given that we have found no trace of any other intelligent extraterrestrial life, and that the universe is billions of years old. So, we have to wonder, are we really alone in this vast space? This question is known as the Fermi paradox. One of the possible resolutions to this paradox comes in the form of the Great Filter. The Great filter hypothesizes that going from the beginnings of life to the highest stages of civilization on the Kardashev scale must involve crossing a difficult barrier in some step that makes finding advanced extraterrestrial intelligence extremely rare. Either it is rare to reach step 0 (having the necessary conditions for life on another planet) or it’s in the future step that we currently face: either overcoming the necessary challenges to advance to a stage 1 civilization or being wiped out by our hubris before we are able to harness the energy found on this planet. And scientists have argued that since we are unable to find technosignatures of intelligent life, it is most certainly one of these two options.
But a beacon of hope to this grim reckoning comes from the optimistic SETI pioneer Seth Shostak. According to him:
“We don’t see clues to widespread, large-scale engineering, and consequently we must conclude that we’re alone. .…It should also be kept in mind that, as Arthur C. Clarke said, truly advanced engineering would look like magic to us—or be unrecognizable altogether.”
About the Author
Sayani is a PhD student in the Department of Chemistry, University of Georgia. She loves working with chemicals and is studying Metal-Organic Frameworks that might one day be a safe alternative to carrying a wide variety of drugs. Outside of her habitat in the lab, she loves reading crime, learning obsessively about psychology, fiddling with art or dance and any excuse to go on a trip. She can be reached at sr77673@uga.edu.
