Dyson spheres may indeed exist, but there's a catch.

An illustration of a Dyson sphere surrounded by a star (Image credit: Marc Ward/Stocktrek Images/Getty)

Dyson spheres, theoretical megastructures that advanced alien civilizations could use to envelop a star and extract its energy, have a serious flaw: They are horribly unstable. But now an engineer claims to have found a way to stabilize them—and it only requires two stars.

In the 1960s, physicist and scientist Freeman Dyson introduced the concept of these spheres, which are named after him. He proposed that a sufficiently advanced civilization would have an insatiable thirst for space and energy. If they were diligent enough, they could achieve both by collapsing a planet and turning it into a huge spherical shell. This shell would enclose a star, providing billions of planets across its surface area and capturing vast amounts of solar energy.

Dyson calculated that a shell made from a Jupiter-mass planet could completely envelop the sun in an orbit similar to Earth's. However, the gravity inside the hollow shell balances out, meaning there is nothing holding the shell to the star. They can move in independent directions, meaning that soon the star containing the Dyson sphere would simply collide with the shell, destroying it.