O'Neill cylinders
Large, rotating, artificial habitats in space for human settlement.
O'Neill cylinders are a concept for massive, self-contained artificial environments built in space. Imagine a huge cylinder, miles long, that spins to create artificial gravity. Inside, you could have cities, farms, and parks, all shielded from space.
The idea is to provide a place for large populations to live and work in space, using resources found there. They are designed to be stable and habitable, offering a solution for long-term human expansion beyond Earth.
O'Neill cylinders are large-scale, rotating space habitats designed to provide artificial gravity through centrifugal force. Proposed by Gerard K. O'Neill in 1974, these structures are envisioned as self-sufficient ecosystems capable of supporting significant populations. The rotation creates a simulated gravity field on the inner surface, with the radius and rotation speed determining the gravity level. Tradeoffs include immense construction challenges, material requirements, and the need for robust environmental control systems.
The mention of O'Neill cylinders in the context of xAI and Ben Horowitz suggests a discussion about ambitious, long-term infrastructure for AI development and potential space-based operations. This aligns with frontier AI labs exploring radical ideas for scaling compute and human presence beyond current terrestrial limitations.
- Ben Horowitz: xAI Executive Exodus, Apple's AI Crisis, The Pace of AI | #232xAI · Moonshots with Peter Diamandis ·
- xAI Grok
- xAI, through discussions with figures like Ben Horowitz, is exploring radical space-based AI infrastructure, which could include concepts like O'Neill cylinders for future operations.
- Bernal spheres
- Smaller, rotating space habitats that are spherical rather than
- Stanford torus
- Another design for a rotating space habitat, shaped like a donut
- Space elevators
- A proposed structure for transporting materials from a planet's
The concept was popularized by physicist Gerard K. O'Neill in his 1977 book 'The High Frontier: Human Colonies in Space'. He proposed them as a way to house large populations in space using resources mined from the Moon and asteroids. Source ↗
While you can't build an O'Neill cylinder today, you can explore simulations of artificial gravity. Search for 'artificial gravity simulator' online and experiment with different rotation speeds and radii to see how they affect the perceived gravity. This can give you a basic feel for the physics involved.
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Questions people ask
- How would O'Neill cylinders create gravity?
- They would spin. The centrifugal force pushing outward on the inhabitants and objects inside would mimic the effect of gravity on a planet's surface.
- Are O'Neill cylinders practical today?
- Currently, the scale of construction and resources required make O'Neill cylinders highly impractical. They remain a theoretical concept for future large-scale space habitation.
First seen on Subvolts Feb 19, 2026. Updated Sep 17, 2026. Written by an AI model from the items above and reviewed against them weekly; report an error.