Currently, we’re slowly transitioning to renewables and fusion energy may become available in the future. If we don’t destroy ourselves or the environment, as humanity progresses further, we will likely gain complete control of the Earth’s resources. At that stage, we’ll probably begin to look outwards for new places to expand into. But, if we want to expand into outer space someday, our planet’s resources are not enough (see the Kardashev scale below). We’d need incredible amounts of energy, even to expand into our solar system. Luckily, we know where to find it: the Sun. To harvest energy from the Sun, we can build a megastructure called the “Dyson Sphere” around it and capture a large percentage of its power output.

What is a Dyson Sphere?

First proposed by theoretical physicist Freeman Dyson in 1960, a Dyson sphere is a hypothetical megastructure that completely encompasses a star and captures a large percentage of its power output.

He proposed a system of orbiting structures designed to intercept and collect all energy produced by the Sun. He initially described it as a shell, but that would be impractical. A solid shell enveloping the Sun (or any other star) would be vulnerable to impacts. By crashing into it, the asteroids and comets would shatter it and the entire structure would crash straight into the Sun.

A more viable design for a Dyson sphere might be a Dyson swarm, an enormous set of orbiting panels that collect the Sun’s power and beam it elsewhere.

Dyson Sphere cutaway
Dyson Sphere cutaway. Image: Wikimedia

Dyson’s proposal did not detail how such a system would be constructed, but focused only on issues of energy collection, on the basis that such a structure could be distinguished by its unusual emission spectrum in comparison to a star. His 1960 paper “Search for Artificial Stellar Sources of Infra-Red Radiation”, published in the journal Science, is credited with being the first to formalize the concept of the Dyson sphere.

But how to build a Dyson sphere or a Dyson swarm? “Kurzgesagt – In a Nutshell” channel published a very informative video about that, which you can watch it below:

If humans want to expand into space, it will take us incredible amounts of energy. How do we do that? We could build a Dyson Sphere around the Sun and use its energy. It would be the most ambitious construction project in history.

Kardashev scale

Without mentioning the Kardashev scale, the concept of the Dyson sphere would be not fully understood. The Kardashev scale is a method of measuring a civilization’s level of technological advancement based on the amount of energy a civilization is able to use. In 1964, Soviet astronomer Nikolai Kardashev (born April 25, 1932) defined three levels of civilizations, based on the order of magnitude of power available to them:

Type I

A Type I civilization, also called a planetary civilization can use and store all of the energy available on its planet. For the Earth-Sun system, this value is close to 7×1017 watts.

Type II

Also called a stellar civilization – a civilization capable of harnessing the energy radiated by its own star. Our Type I brains can hardly imagine how someone would do this, but we’ve tried our best, imagining things like a Dyson Sphere. Successful construction of a Dyson sphere would make a civilization’s status Type II, with energy consumption at ≈4×1033 erg/sec.

Type III

A civilization in possession of energy on the scale of its own galaxy, with energy consumption at ≈4×1044 erg/sec for our galaxy, the Milky Way.

A Type III civilization – also called a galactic civilization- can control energy on the scale of its entire host galaxy.

In 2015, a study of galactic mid-infrared emissions came to the conclusion that “Kardashev Type-III civilizations are either very rare or do not exist in the local Universe”.

Where are we now?

Humans have not yet reached the level of even a Type 1 civilization. Physicist and futurist Michio Kaku suggested that humans may attain Type I status in 100–200 years, Type II status in a few thousand years, and Type III level in 100,000 to a million years.

Carl Sagan suggested defining intermediate values (not considered in Kardashev’s original scale) by interpolating and extrapolating the values given above for types I (1016 W), II (1026 W) and III (1036 W), which would produce the formula

K = (log10P – 6) / 10

where value K is a civilization’s Kardashev rating and P is the power it uses, in watts. Using this extrapolation, a “Type 0” civilization, not defined by Kardashev, would control about 1 MW of power.

In 2012, total world energy consumption was 553 exajoules (553×1018 J=153,611 TWh), equivalent to an average power consumption of 17.54 TW (or 0.7244 on Sagan’s Kardashev scale).

In recent years, astronomers explored that possibility with a bizarre star, known to astronomers as KIC 8462852 – more popularly called Tabby’s Star or Boyajiyan Star for Tabetha Boyajian, the lead researcher who discovered the irregular light fluctuation. This star’s strange light was originally thought to indicate a possible Dyson sphere. That idea has been discarded. In fact, even she was very skeptical.

In her TED talk, Boyajian reminded everyone that skepticism is the best policy whenever delving into alien territory. Her exact quote is as follows:

“Extraordinary claims require extraordinary evidence, and it is my job, my responsibility, as an astronomer to remind people that alien hypotheses should always be a last resort.”

But scientists still looking for the signs of Dyson Spheres around the distant stars. Using the Gaia mission data might help.

Freeman Dyson

Freeman Dyson - Dyson Sphere first conceptualized by him.
Freeman Dyson at the Long Now Seminar in San Francisco, California in 2005. Image: Wikipedia

Freeman John Dyson FRS (December 15, 1923 – February 28, 2020) is an English-born American theoretical physicist and mathematician. He is known for his work in quantum electrodynamics, solid-state physics, astronomy, and nuclear engineering. He theorized several concepts that bear his name such as Dyson’s transform, Dyson tree, Dyson series, and Dyson sphere.

He is professor emeritus in the Institute for Advanced Study in Princeton, a Visitor of Ralston College, and a member of the Board of Sponsors of the Bulletin of the Atomic Scientists.


M. Özgür Nevres

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