Predictions for the final unified theory of physics

Over the new year I enjoyed reading Lee Smolin's book "Three Roads To Quantum Gravity". In the epilogue he gives ten predictions about how the present revolution in physics will end. Lee Smolin is one of the leading lights in this venture, so his predictions are to be taken seriously. But I also like to think that they are offered in a light spirit, and that this is a game we can all join in. So with the start of the millennium as a good excuse I offer my own predictions here. Some of them agree with those of Smolin, but others sharply disagree, and since I have no career in physics to risk I have no worries about being as speculative as I please.

I may add to these predictions or modify them during the year 2001 but after that I will leave them to the vagaries of time. Many of them already appear in my 1998 book Event-Symmetric Space-Time which is available for free on the internet.

I am not the originator of all of these ideas and am just making predictions about which will prove to be valid. However, I think there are many individual ideas here that very few other physicists support at present, and as a whole they present a vision of physics which is unique to myself.

The mathematical nature of the final theory

• The present revolution in physics will end with the discovery of an intricate and unique mathematical structure with the power to explain all the laws of physics including a consistent theory of quantum gravity and a unified theory of all fields and particles.
• This will be discovered and recognised for what it is by the year 2050, but its full consequences will take much longer to work out.
• Its implications for mathematics will be as significant as its implications for physics. Indeed, it is just as likely to be discovered by a pure mathematician with no particular interest in physics, as by a physicist seeking a theory of quantum gravity.
• Once found it will be seen that there are many disparate but equivalent ways to construct the structure using different branches of mathematics. Many will be elegant but none will be noticeably more simple than the rest to single it out as the most fundamental.
• Many of the mathematical structures which have been hypothesised as important in physics will be recognised in these formulations including: supersymmetry, knot theory, quantum groups, non-commutative geometry, n-category theory, topos theory, exceptional groups and much more.
• In at least some formulations, the structure will be a finite algebraic structure in the same sense that the monster group is finite. However, it will be very much larger.
• The existence of this structure will be explained in part by a principle of universality which generalise chaos theory, self-organisation and thermodynamics.
• The structure will also lead to practical innovations in other subjects such as engineering, artificial intelligence and economics.

Implications for the nature of physics

• The finite size of the structure will imply that there is a finite limit to the amount of information which can be contained within any region of space-time, and this limit will not grow with its size.
• In some constructions certain entities will be fundamental and others will be derived, while in other constructions these roles will be reversed. This will explain many known dualities of physics and predict new ones.
• The fact that there are no real numbers in some constructions will tell us that real numbers are not fundamental to physics and that quantum mechanics can be reformulated without complex numbers.
• Information theory and the mathematical theory of universal computers will be important in understanding how the structure relates to our universe.
• Causality will have to be discarded as a fundamental principle of science. This will apply to bother temporal and ontological causality.

Predictions about particle physics.

• The theory will have a unique low energy vacuum corresponding to 3+1 dimensional space-time with a low energy spectrum of particles in agreement with what we observe. All the physical constants in this limit will be uniquely determined, but they may be difficult to calculate.
• The theory will have other vacuum states with varying numbers of space and time dimensions, and various constants. Some of these will be exactly the string theories we know but only the vacuum describing physics as we know it will be stable.
• These vacua will contain a menagerie of topological objects of various dimensions which have a unified description. The strings and membranes of superstring theory as well as the loops and knots of loop quantum gravity will be examples of such objects.
• Quantum mechanics as we know it will be seen as a special case of a more general theory with non-linear evolution of states, but it will still conserve a total probability and have a non-linear superposition principle similar to that known for solitons.
• The first and second quantisations known to physicists will both be seen as parts of a multiple quantisation process which is an echo of one way of constructing the mathematical structure. This will involve a finite number of quantisation steps after which further quantisation returns the same structure. The process will also be tied to a ladder of higher dimensional entities in physics, and will explain the democratic principle of string theory as well as classical/quantum dualities.

Implications for the small-scale structure of space-time

• The theory will include a model of space-time which is discrete at the Planck scale in the sense that there is a minimum measurable distance and time and a finite limit to the amount of information to a finite volume of space.
• As well as the total bound to the amount of information in the universe, there will be a version of the holographic principle which states that the amount of information in a volume of space has a limit proportional to the area of any surface which can surround it.
• Space-time will be a relational concept between events and transition processes which generalises the diffeomorphism symmetry of general relativity to a permutation symmetry of discrete events. This symmetry will be hidden at low energies.
• At very high temperatures and/or densities the structure of space-time will break down so that the event-symmetry is no longer hidden and all approximations to causality and locality will be invalidated. This will replace the concept of the singularity in general relativity.
• The theory of loop quantum gravity will be vindicated as a description of quantised space-time in 3+1 dimensions.

Implications for the large-scale structure of space-time

• The arrow of time will not have a unique direction over the entire universe. CPT symmetry will be perfect so there will be no distinction between forward in time and backward in time on very-large scales in the universe. There will be localised areas of space-time which have a thermodynamic arrow of time, such as the observable part of the universe which we inhabit.
• Black holes and white holes are the same thing. The distinction between them is a consequence only of the direction of times arrow in the space which surrounds it. A black hole which survives through an epoch where the arrow of time reverses will transform into a white hole.
• When the consequences of the final theory are examined in detail it will be realised that the big bang is not the origin in time of the whole universe. It is just a localised feature which looks like a white hole on the large scale, with our universe inside it.
• The entire universe is much larger than what we can observe, but because of the finite limit to information, the question as to whether it is actually finite or infinite will cease to have meaning.

The philosophical implications

• The theory will give no particular explanation for consciousness. Instead the nature of our experiences will come to be seen as a problem for psychology and philosophy rather than physics.
• It has been remarked that there are many ways in which the parameters of physics appear to be fine tuned specifically to make the universe a place where intelligent life can evolve. Since the theory will give unique values for these parameters. It will rule out any kind of anthropic principle and any explanation based on tuning or evolution of the constants. Instead the fact that the theory is related to principles of universality may be seen as the only possible explanation for both the complexity and simplicity in nature.

This page was last updated on 6th January 2001