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
- 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
- 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
- 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
- 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
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