Continuing on the theme of Dyson spheres I raised earlier today by linking to Centauri Dreams' post
, The Atlantic
's Ross Andersen takes a look
at an ongoing effort by some astronomers to find some of those megascale constructions.
Last month a trio of astronomers led by Penn State's Jason Wright began a two-year search for Dyson Spheres, a search that will span the Milky Way, along with millions of other galaxies. Their project was just awarded a sizable grant from the Templeton Foundation, a philanthropic organization that funds research on the "big questions" that face humanity, questions relating to "human purpose and ultimate reality."
So how do Wright and his team aim to find a Dyson Sphere? Though the word "sphere" summons to mind a solid structure, Wright says his team won't be looking for solid shells. "Even though there is enough mass in our solar system to construct a solid sphere, such a structure would not be mechanically feasible," Wright told me. "It would probably have to be more like a swarm of collectors."
[. . .]
Compared with SETI, a search that focuses on Dyson Spheres assumes a lot less about the goals of futuristic alien civilizations. Compared with SETI, a search for Dyson Spheres assumes a lot less about the goals of futuristic alien civilizations. In fact, most of its assumptions proceed directly from simple biology. As Wright, the project leader, explained to me, "life, by definition, uses energy, which it must reradiate as waste heat." The larger the civilization, the more energy it uses and the more heat it reradiates. Life also (by definition) reproduces, which introduces the possibility of exponentially increasing energy demands. If left unchecked, those increases will eventually outstrip the available energy on a planet. That would leave a growing civilization no choice but to mine energy from other planets and, eventually, their stars.
Let's use the Earth as a test case. As Oliver Morton has pointed out with a lovely metaphor, the sun beams a total of 120,000 terawatts per day onto our planet. That's 10,000 times the amount that flows through our industrial civilization. That's a lot of energy, but remember that our industrial civilization is young, and growing fast. In just the past 30 years, we've doubled our global energy supply. At that doubling rate, in 400 years we will be collecting or generating enough energy to match the total sunlight that comes to our planet. At that point, it may be time to draw up plans for a Dyson Sphere.
It's conceivable that an advanced alien civilization could be exponentially more energy-intensive than ours, especially when you consider that its industrial revolutions and energy doublings may have begun billions of years ago. Dyson Spheres could be an ancient and prolific phenomenon in our universe.
Dyson Spheres also fit squarely within with another theoretical model of civilizational advancement: the Kardashev Scale. In 1964, Soviet astronomer Nikolai Kardashev tried to plot out a theory of technological advancement based on a civilization's mastery of larger and larger energy sources over time. Under the Kardashev Scale, a Type I civilization uses all of the energy available on its home planet, a Type II civilization uses all of the energy from its local star, and a Type III civilization makes use of all the energy in its galaxy. The search for Dyson Spheres is, in essence, a search for Type II civilizations. And because it is premised on a civilization's energy usage, it has another advantage over efforts like SETI's: It allows us to find aliens that aren't necessarily interested in talking to us.