About a week ago, the new Wolfram Physics Project was annouced. Its goal is no less than to answer one of the three questions, and it’s intriguing on so many levels.
It’s not quantizing gravity, and it’s not a gravitational particle with its own quantum field: it’s all of physics emerging from something more fundamental: a computationally irreversible directed graph. This is way more exciting than those other ideas.
 Space emerges, from the structure of the graph.
 Time emerges as the graph calculations progress, but this emergent time is fundamentally different than emergent space.
 There are multiple paths through the graph that reach the same state; this causal invariance leads to the emergence of special relativity.
 Energy and momentum are graphedge flux through, respectively, space and timelike slices in the graph.
 There’s a speed of light, which remains an immutable speed limit, and it’s related to energy by E = m c².
 This massenergy can warp the shape of the graph as Einstein predicted in general relativity.
 It allows for black holes, as event horizons in the graph.
 There are hints at how particles manifest, as locally stable and selfpropagating graph structures.
 Some of these particles would be so small and have such weak interactions with our everyday life that they’d look at awful lot like dark matter.
 Applying the same notion of causal invariance along another dimension enables things that look a lot like waveparticle duality, the uncertainty principle, and quantum entanglement.^{1}
 And now for something completely different, it even seems to explain why P ≠ NP.
You look at the laws of quantum mechanics and you say, what does an interaction between quantum systems look like? From the outside it looks like entanglement, and from the inside it looks like wave function collapse.
But perhaps the most interesting observation was at the very end, about rule space. All the observations above were derived without actually knowing the rules for our univserse. Space, time, momentum, energy, etc., they are emergent properties of this entire class of graph. Our rules (presuming of course that any of this is on the right path; it obviously might not be), are what we’d need to make more detailed testable predictions, say about the mass, spin, and charge of fundamental particles. Presuming we find such rules, it raises obvious questions: Why are these the rules that generate our universe? What makes them special?
The simpliest explanation is that they’re special only because they’re the rules that create the universe, which is both a perfectly reasonable argument and a completely unsatisfying tautology. Luckily there is also casual invariance in rule space, which means our rules are neither universal, nor special; our rules are just one of many rulesets, each of which represents a different expression of the universe. In other words, there’s a rule set that describes the universe we see, which makes it special to us, but there are many valid rulesets as well—just like my inertia reference frame is no more special than yours.
It’s all very satisfying, and still a little vague, but exciting.

This reminds me of a quote I really love. ↩