The case of whether extraterrestrial creatures exist has constantly confounded astronomers and the public alike, sparking international debate. However, discovering a particular astronomical megastructure would potentially end this debate and cement the idea that extraterrestrial creatures do exist. These theoretical structures are known as Dyson Spheres.
What are Dyson Spheres?
A Dyson Sphere is a theoretical megastructure proposed by its eponym, the British-American physicist Freeman Dyson. A Dyson Sphere is a construction of a biosphere that encloses the parent star of a solar system. The primary purpose of a Dyson Sphere is to capture the complete energy output of a star to power a home planet. The term ‘Dyson Sphere’ is an umbrella term that also describes numerous variations of the Dyson Sphere, including a Dyson Swarm (unlike the single, monolithic structure of the Dyson Sphere, a Dyson Swarm is comprised of multiple satellites designed to capture the energy output) and a Dyson Bubble (a thin shell with motionless solar sails intended to reflect the light). Hypothetically, if we (humans) were to construct a Dyson Sphere, we would create a base on the closest terrestrial planet to the sun- Mercury. Here, we would have multiple 3D printers and automated devices for the construction of the satellites. Then, these will be propelled and sent to be stationed around the Sun.
What is the significance of finding a Dyson Sphere or its variants?
In 1964, the astronomer Nikolai Kardashev put forward a proposal to measure the advancement of civilisation. The progress of a species would be gauged by how much energy the species would harness; this energy consumption scale will link to where the energy is obtained from. Kardashev initially theorised three ‘Types’ of civilisations:
- Type 1 Civilisation: This is a civilisation capable of completely harnessing the energy of its home planet.
- Type 2 Civilisation: This is a civilisation capable of harnessing the energy output radiated from its star.
- Type 3 Civilisation: This is a civilisation capable of harnessing the energy output of its galaxy.
Whilst there have been numerous extensions into this scale (including Type 4 and Type Omega civilisations), this was the first idea of Kardashev.
Therefore, if Dyson Sphere were found, it could potentially be a sign of intelligent extraterrestrial civilisations that have surpassed the scientific advancements of humanity.
How could we find Dyson Spheres or their variations?
To understand the different methods of finding Dyson Spheres (and their variants), we need to understand the energy budget of Dyson Spheres- this is linked to the ‘AGENT formalism’, which revolves around the following factors:
- α: Total radiation energy that is accumulated by the megastructure
- ∊: Energy that is produced by various other ways
- γ: Thermal waste heat
- ν: Loss of energy through non-thermal and non-photonic means, such as neutrinos
Therefore, the energy budget of a Dyson Sphere can be represented with the following formula:
α + ∊ = γ + ν
As a result, even if a small amount of starlight is collected by a Dyson Sphere, it means that infrared excess will be emitted. There are, however, some factors affecting this, including the potential distance of the Dyson Sphere and the temperature of the shell. The Gaia mission was initiated to map out our galaxy; to do so, the satellite would observe the visible colour and magnitude of the stars (from this, we can obtain data such as the type of star, from white dwarfs to supergiants). Additionally, the satellite also observed and collected data on the near-infrared light. Therefore, this allowed researchers to potentially find correlations between the data collected by Gaia and the hypothetical infrared signatures by Dyson Spheres, using various means, such as Hertzsprung-Russell diagrams.
Continuing the search for Dyson Spheres and their variants
One other hypothetical scenario is that there are numerous installations of Dyson Spheres around stars in different regions of a single galaxy; such a phenomenon would result in the civilizations bordering or being a Type 3 Civilization on the Kardashev Scale. If this were the case, a Fermi Bubble would be created- this is an emptiness in the midst of light in a galaxy (this also results in a significant increase in infrared emissions in the area).
Despite unsuccessful attempts at identifying Dyson Spheres in space, researchers have relentlessly pursued this approach in hopes of potentially discovering intelligent, extraterrestrial civilisations. Perhaps one day, the SETI (search for extraterrestrial life) program will finally result in the discovery of fellow inhabitants of our universe; or, we may simply remain a solitary species in the vast expanse of our universe. However, one definitive fact remains the search and desire to explore the unknown by humans.
Featured Artwork retrieved from:
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