In 1960, British theoretical physicist Freeman Dyson published a one-page paper in the journal Science that offered perhaps the most hopeful vision ever conceived of humanity’s technological future.

In the realm of science fiction, Dyson spheres and ringworlds have been staples for decades. But it is well known that the simplest designs are unstable against gravitational forces and would thus be ...

Dyson spheres, the hypothetical mega-structures that advanced alien civilizations might use to enclose a star and harness its energy, suffer from a fatal flaw: They are catastrophically unstable. But ...