What Actually Counts as a World Model? Reddit Debates the Definition

neutrino_boy · reddit · 2026-08-29

A Reddit discussion digs into what a world model actually is. Most things currently billed as world models are fancy video generators, but where are the boundaries? Does a physics engine count? Is a simulator a type of world model — and do hardware emulators or digital twins qualify?

Citing a definition that world models should "operate on learned representations, not exclusively hand-crafted physics," the poster asks whether an ML-accelerated fluid simulator counts as a fluid world model, and whether world models are just a rebrand of simulation or fundamentally different — and whether the definition should be limited to models aiming to generally model the whole real world.

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