In 1985, David Deutsch had a radical insight that went beyond both quantum mechanics and computer science. He saw that the laws of physics themselves point to a new kind of computer – one that could simulate any physical system perfectly.
This might sound abstract, but it changed how we think about both computing and reality itself. Let’s break it down.
Alan Turing had shown that regular computers can simulate any other computer. His “universal Turing machine” could theoretically calculate anything that’s calculable. But Deutsch realized this wasn’t enough. Regular computers can’t efficiently simulate quantum systems – they’d need more memory than atoms in the universe just to model a few hundred particles.
Here’s where Deutsch’s breakthrough came in. He proposed that a quantum computer – one that uses quantum mechanics itself – could simulate any physical system perfectly. This became known as the Deutsch-Turing principle: if you can build it in the physical world, a quantum computer can simulate it exactly.
This means the multiverse isn’t just mathematical – it’s computational. Everything that happens, from photosynthesis to human thought, is essentially a quantum computation. And if we can build quantum computers, we can simulate any part of reality with perfect accuracy.
This wasn’t just theory. Deutsch designed the first quantum algorithm, showing how quantum computers could solve certain problems exponentially faster than classical computers. He proved that quantum computers weren’t just regular computers with a quantum twist – they were fundamentally different machines, capable of harnessing the strange properties of quantum mechanics to perform otherwise impossible calculations.
But Deutsch’s insight went deeper. If quantum computers can simulate any physical system, and our brains are physical systems, then consciousness itself must be a kind of computation.
Today’s quantum computers are primitive compared to Deutsch’s vision, but they’re proving him right. They can already simulate quantum systems that classical computers can’t handle. And they’re showing us that computation isn’t just something we invented – it’s woven into the fabric of reality itself.