As the essay competition draws to a close, I wanted to add some final remarks about the Change Hypothesis project. It was inspired by Richard Feynman who discovered that most of physics could be explained by just three 'actions': A photon goes from place to place, an electron goes from place to place, and a photon couples with an electron. He showed that these simple 'actions' explained complexity by being repeated billions upon billions of times. It is fascinating that so much can be explained by so little!
So, the aim of the project is to try to describe physics using the least numbers of rules and actions, which becomes rather a fun game. Feynman's 'actions' operate in a framework of amplitudes, so the Change Hypothesis plays the game by supposing that the amplitudes represent the real fundamental things in physics. As an amplitude, represented by Feynman as an arrow, can be described by its position, direction, quantity, and how it's changing, these are then taken as the fundamental things (a guess!). This has the very interesting consequence that everything is made up of the same constituents and every point in space has those constituents, so matter and space are no longer separate.
Most theories expand by having exceptions and additions, which is a big problem as it is then easy to make any theory fit the facts. That's why lots of theories appear so complicated. The Change Hypothesis doesn't allow this. If you want to make changes, you make changes to one of the fundamental rules which in turn will then affect every corner of Nature, so it should soon become apparent if that change is wrong. It also produces a physical picture of Nature that is unique and so should be open to experimental testing.
As you might expect, as it is based on Feynman's theory, the Change Hypothesis can represent photons and electrons and their actions, but even as a framework, for it to work at all, it has to work in a very different way to conventional ideas So, for example, there needs to be constant creation, and movement needs to occur in little jumps. But these ideas aren't added to make things work, they are already in Feynman's theory and just revealed by looking at it differently. These ideas also allow for new, simple and unique explanations of things like gravity. Most interestingly, for me, is that for the theory to work, all change needs to happen at the same speed, and if this is accepted the equations of Relativity can be deduced, which neatly connects Quantum Theory and Relativity together with a very simple idea.
Finally, I would say that the Change Hypothesis is great fun to work on. There are always new ideas coming out of it. Recently I realized that the position, quantity and change are also the basic qualities of consciousness, which gives a good connection between consciousness and physics. Also, as the Change Hypothesis deals with qualities of space, which is also a theme of General Relativity, that seems an area that would be worth exploring further. Perhaps the most interesting area of all would be how (and if) all the fundamental particles could be described by the Change Hypothesis, which would need to be able predict all their qualities and behaviour.
From the point of view of the essay, the amount of unpredictability, undecidability and uncomputability in Nature clearly depends on the view of Nature you take and taking the simple view of the Change Hypothesis seems to reduce all three. But, in the end, the answers to the questions posed by the contest are themselves unanswerable until we have found the ultimate theory of physics. The question then becomes, how do we know when we have actually found it?
Many thanks to the organizers and to everyone who has taken part. I've had great fun, learned new things, and been able to develop and share my own ideas.
David Jewson