Dyson spheres , the hypothetical mega-structures that advanced alien civilizations could use to enclose a star and harness its energy, suffer from a fatal flaw: They're catastrophically unstable. But now an engineer claims to have found a way to stabilize a Dyson sphere, and all it takes is two stars.
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In the 1960s, physicist Freeman Dyson toyed with the idea of these eponymous spheres. He envisioned that a sufficiently advanced society would have an insatiable need for living space and energy. And if they were industrious enough, they could solve both challenges by dismantling a planet and turning it into a giant spherical shell. This sphere would enclose a star, providing the surface area of billions of planets and capturing vast amounts of solar energy.
Dyson calculated that a shell made of a planet the mass of Jupiter could completely enclose the sun at about the orbit of Earth. But gravity inside a hollow shell cancels out, meaning there is nothing to tie the shell to the star. It is free to move in independent directions, meaning that soon enough the star hosting a Dyson sphere will simply fall into the shell, destroying it.
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In a paper published Jan. 29 in the journal Monthly Notices of the Royal Astronomical Society, Colin McInnes, an engineer at the University of Glasgow, has found a way to theoretically stabilize a Dyson sphere. The trick is that it requires a system with at least two stars.
McInnes found a stable – and useful – configuration. This only happens in binary systems in which one star is much smaller than the other. In this case, the Dyson sphere can enclose the smaller of the two stars. The motion of this smaller star acts as a gravitational anchor, keeping the Dyson sphere moving in the same orbit around the larger star, preventing a catastrophic collision.
There are several reservations about this. The smaller star must not be larger than about one tenth of the mass of its larger companion, otherwise the gravitational stable point disappears. And the sphere must be extremely light and thin compared to the two stars, otherwise its own gravitational influence mixes into the dynamics of the system and destroys stability.
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And of course, this analysis ignores any practical mechanical estimates, such as the pressures and stresses that the sphere may experience or the way a such sphere is constructed. Although it is unlikely that people will build a Dyson sphere in the distant future – or ever – this research helps inform the search for extraterrestrial civilizations.
Source: livescience
