[ad_1]
Stephen Wolfram is a cult figure in programming and mathematics. He is the mastermind behind Wolfram Alpha, a website that tries to answer questions by using algorithms to examine a massive database of information. He is also responsible for Mathematica, a computer system used by scientists around the world.
Last week, Wolfram launched a new company: Wolfram Physics Project, an ambitious attempt to develop new physics for our Universe.
The new physics, he declares, is computational. The guiding idea is that it can all be reduced to applying simple rules to fundamental building blocks.
What is the point of the ‘new physics’?
Why do we need such a theory? After all, we already have two extraordinarily successful physical theories.
These are general relativity, a theory of gravity and the large-scale structure of the Universe, and quantum mechanics, a theory of the basic components of matter, subatomic particles, and their interactions. Haven’t we licked up the physics?
Not quite. While we have an excellent theory of how gravity works for large objects like stars and planets and even people, we don’t understand gravity at extremely high energies or for extremely small things.
General relativity “breaks” when we try to extend it to the miniature realm where quantum mechanics rules. This has led to a search for the holy grail of physics: a theory of quantum gravity, which would combine what we know of general relativity with what we know of quantum mechanics to produce an entirely new physical theory.
The best current approach we have for quantum gravity is string theory. This theory has been a work in progress for 50 or so years, and while it has achieved some success, there is growing dissatisfaction with it as an approach.
How is Wolfram’s approach different?
Wolfram is trying to provide an alternative to string theory. It does this through a branch of mathematics called graph theory, which studies groups of points or nodes connected by lines or edges.
Think of a social media platform. Start with one person: Betty. Then add a simple rule: each person adds three friends. Apply the rule to Betty: Now she has three friends. Apply the rule again to each person (including the person you started with, namely: Betty). Keep applying the rule and very soon the friends network will form a complex graph.
A simple rule several times creates a complex network of points and connections. (Author provided)
Wolfram’s proposal is that the universe can be modeled in the same way. The goal of physics, he suggests, is to develop the rules that the universal graph obeys.
The key to his suggestion is that a properly complicated graph looks like geometry. For example, imagine a cube and a graph that looks like it.
(Author provided)
Over: In the same way that a collection of points and lines can approximate a solid cube, Wolfram argues that space itself can be a mesh that joins a series of nodes.
Wolfram argues that extremely complex graphics resemble surfaces and volumes: add enough nodes and connect them with enough lines and form a kind of mesh. He argues that space itself can be considered as a mesh that joins a series of nodes in this way.
What does this have to do with physics?
How can complicated node meshes help with the project of reconciling general relativity and quantum mechanics? Well, quantum theory deals with discrete objects with discrete properties. General relativity, on the other hand, treats the universe as a continuum and gravity as a continuous force.
If we can build a theory that can do what general relativity does but starts from discrete structures like graphs, then the prospects for reconciling general relativity and quantum mechanics begin to look more promising.
If we can build a geometry that looks like the one that general relativity gives us using a discrete structure, then the prospects look even better.
Space can be a complex mesh of points connected by a simple rule that is repeated many times. (Wolfram Physics Project)
So is it time to get excited?
While Wolfram’s project is promising, it contains more than a hint of arrogance. Wolfram takes on the Einsteins and Hawkings of the world, and he does so without spending a life publishing in physics magazines.
(He published several physics articles as a teenage prodigy, but that was 40 years ago, as well as a book A new kind of science, which is the spiritual predecessor of the Wolfram Physics Project.)
Also, his approach is not entirely original. It is similar to two existing approaches to quantum gravity: causal set theory and loop quantum gravity, neither of which gets much mention in Wolfram’s great designs.
However, the project is notable for three reasons.
First, Wolfram has a wide audience and will do a lot to popularize the approach he advocates. Advocates of loop quantum gravity in particular lament the dominance of string theory within the physical community. Wolfram can help underwrite a paradigm shift in physics.
Second, Wolfram provides a very careful overview of the project, from the basic principles of graph theory to general relativity. This will make it easier for people to catch up on the general approach and potentially be able to make their own contributions.
Third, the project is “open source”, inviting contributions from citizen scientists.
At least this gives us all something to do right now, between baking sourdough and playing Animal crossing, that is to say. 
Sam Baron, Associate Professor, Australian Catholic University.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
