Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

Imagine a vast, self-sustaining habitat floating in the depths of space,

where entire communities could live, work, and flourish,

in a garden park world tailored to their needs and desires.

The Bonor Sphere is one of the earliest and most iconic visions of a space habitat, conceptualized

by John Desmond Bernal in 1929.

This bold idea presented a self-sustaining, rotating, rotating spherical structure 10 miles

wide, designed to house thousands of people in space, the sphere's rotation

would create artificial gravity on its inner surface, enabling residents to live and work

in an earth-like environment. With provisions for agricultural zones, living quarters, and energy

systems that harness solar power, the Bernersphere offered a comprehensive

approach to human settlement beyond Earth, addressing fundamental needs such as food production,

atmosphere control, and radiation protection.

Berners' concept inspired future space architects and science fiction creators by presenting the vision of a

permanent, habitable outpost in space. It laid the groundwork for later, more complex designs

like Girard Keon-Hill space habitats and influenced the broader discussion on space colonization.

The Bernal sphere embodies the ambition of expanding human civilization to the

stars, envisioning not just survival, but the possibility of thriving in the cosmos. Today, we'll

be exploring the design, its pros and cons, and when or if we should build one. But we should

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