Here’s the first of two crucial excerpts from my conversation with Jonathan Gorard.

The core idea of Wolfram Physics is that we can model the universe as a hypergraph. If we want this idea to be taken seriously, we’re going to have to derive physics from the hypergraph.

The twin pillars of physics, as we know it, are quantum mechanics and general relativity.

In this episode, Jonathan explains how quantum mechanics can be derived from the Wolfram model, indeed, how quantum mechanics unexpectedly fell out of the model.

It’s a fascinating story.

We start with the role of the observer. According to Jonathan, it turns out not to be necessary to narrow our focus to only causally invariant rules.

Why not? Because macroscopic observers like ourselves impose causal invariance through our coarse-graining of the hypergraph. In other words, by squinting at the universe, seeing only its large-scale features and glossing over the finer details, we reduce multiple paths through the multiway graph to a single timeline, and, in the process, impose causal invariance.

Jonathan goes on to explain that this coarse-graining can be modelled with completion rules. These are fake rules, similar to the true rules of Wolfram Physics, but posited solely to model the coarse-graining of the hypergraph by the observer.

And here’s the thing. According to Jonathan, these completion rules are formally equivalent to the collapse of the wavefunction in quantum mechanics. In other words, we finally have an explanation for how the observer causes the collapse of the wavefunction, reducing Schrödinger’s half live, half dead cat to one that’s either dead or alive.

If Jonathan’s right, then this is a true breakthrough, not just in quantum mechanics, but in the philosophy of physics.

In the next episode, we’ll move on to the other pillar of physics: Jonathan will explain how to derive general relativity from the hypergraph.

There’s much more to explain about each of these derivations, but we’re finally getting to the crux of Wolfram Physics, the question of whether it can, after all, model our universe.

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Jonathan’s seminal paper on how to derive quantum mechanics

• Some Quantum Mechanical Properties of the Wolfram Model

Jonathan Gorard

• Jonathan Gorard at The Wolfram Physics Project
• Jonathan Gorard at Cardiff University
• Jonathan Gorard on Twitter

• The Centre for Applied Compositionality
• The Wolfram Physics Project

Concepts mentioned by Jonathan

• Causal invariance
• Computational irreducibility
• Celestial mechanics
• Molecular dynamics
• Space-like separation
• Heisenberg’s uncertainty principle
• Heisenberg’s microscope experiment
• Quantum entanglement
• Bell’s inequalities
• Multiway system
• Coarse-graining
• Schrödinger equation
• Unitary operator
• Hermitian operator
• Conjugate transpose operation
• Time reversal
• Wavefunction collapse
• Quantum interference
• Quantum tunnelling

Stephen Wolfram’s books

• A New Kind of Science
• A project to find the Fundamental Theory of Physics

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The Last Theory is hosted by Mark Jeffery, founder of Open Web Mind