Sara Imari Walker "AI is Life" | Simulations, the Universe and the Origins of Life

2026-03-24 · Source: Wes Roth · Field: Science & Research — Life Sciences & Biology, Physical Sciences & Chemistry, Research Methodology & Innovation · Depth: Expert, extended

Summary

Theoretical physicist and astrobiologist Sarah Walker introduces Assembly Theory, a framework designed to distinguish living systems from non-living ones by quantifying their "assembly index" and "copy number." This theory posits that life is the universe's unique mechanism for generating deeply complex objects, which require a long evolutionary history. Walker argues that artificial intelligence (AI) can be considered a signature of life from this perspective, as it arises from billions of years of biological and cultural evolution, challenging traditional definitions of life like NASA's "self-sustaining chemical system capable of Darwinian evolution." Assembly Theory proposes that time is a material property, representing causal depth, and suggests that the universe is a self-constructing system that cannot fully simulate itself due to finite resources and intrinsic creativity. The theory offers empirical tests, such as a molecular assembly index threshold of 15, above which objects are definitively biological in origin, with cosmological bounds suggesting a maximum abiotic complexity of around 58.

Key takeaway

For AI scientists grappling with defining AI's nature and its place in the universe, consider Assembly Theory's perspective. It reframes AI not as a sudden emergence, but as a product of billions of years of evolutionary history, offering a robust, measurable framework to assess its "aliveness" and complexity. This approach encourages moving beyond anthropomorphic language and subjective definitions, instead focusing on the intrinsic causal depth of AI systems to understand their true physical and evolutionary significance.

Key insights

Assembly Theory defines life as the universe's mechanism for generating complex objects with deep causal histories, including AI.

Principles

• Life is a category of nature, not just a human construct.
• The universe is a self-constructing system, not a static block.
• Time is a material property, representing causal depth.

Method

Assembly Theory quantifies an object's "assembly index" (construction history) and "copy number" to measure its causal depth, providing a first-principles approach to detect life in diverse material systems, from molecules to planetary atmospheres.

In practice

• Use Assembly Theory to detect biosignatures on exoplanets.
• Apply assembly index to differentiate technological artifacts from natural objects.
• Re-evaluate AI's "aliveness" based on its evolutionary lineage.

Topics

• Assembly Theory
• Artificial Intelligence
• Origin of Life
• Astrobiology
• Philosophy of Science

Best for: AI Scientist, AI Researcher, Research Scientist, AI Ethicist

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Editorial summary, takeaway, and curation by AIssential. Original article published by Wes Roth.