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<\/div>\n<\/figure>\nNeuroscience seems an unlikely place to find fundamental truths that could apply to everything in the universe. Brains<\/a> are specific objects that do things that few, if any, other objects in the universe seem capable of. They perceive. They act. They read magazine articles. They are usually the exception, not the rule.<\/p>\n That is perhaps why the free-energy principle (FEP) has garnered so much attention. What began in the early 2000s as a tool to explain cognitive processes like perception and action began to be presented as a \u201cunified brain theory\u201d<\/a>. Then the FEP outgrew the brain, being put forward as a definition of life and, inevitably, as the basis for a new kind of artificial intelligence that can reason. Today, some proponents argue that the FEP even encapsulates what it means for something in the universe to exist at all. \u201cYou can read the free-energy principle as a physics of self-organisation,\u201d says its originator, Karl Friston<\/a> at University College London. \u201cIt is a description of things that persist.\u201d<\/p>\n Yet some researchers are sceptical that the FEP can live up to many of its loftiest promises, having grown frustrated with its shifting scope. \u201cIt has been a moving target,\u201d says Matteo Colombo<\/a>, philosopher and cognitive scientist at Tilburg University, the Netherlands.<\/p>\n All of which has made the FEP a source of both fascination and frustration. Its dizzying breadth is key to its enduring appeal, even while it remains famously difficult to get your head around. So, given the claims that it can be used to explain\u2026<\/p>\n<\/p><\/div>\n