The Science of Discworld Revised Edition

physicists have constructed ever-larger and more energetic particle accelerators in the search for this elusive particle, such as the new Large Hadron Collider, due to start up in 2007.
    Late in 2001, scientists analysing data from its predecessor, the Large Electron Positron Collider (LEP), announced that the Higgs boson probably doesn’t exist. If it does, then it has to be even more massive than everyone expected, and the LEP scientists are sceptical. No good substitute for Higgs’s theory exists, not even the fashionable concept of ‘supersymmetry’ which pairs every known particle with a more massive partner. Supersymmetry predicts
several
Higgs particles, with masses well inside the range where the LEP data prove that no such thing exists. Some physicists still hope that the Higgs boson will show up when the new accelerator comes on line— but if it doesn’t, particle physics will have to rethink the entire basis of their subject.
    Whatever happens to the Higgs boson, they’re already starting to wonder whether there are more layers of reality further down, particles more ‘ultimate’ still.
    Turtles all the way down?
    Does physics go all the way down, or does it stop at some level? If it stops, is that the Ultimate Secret, or just a point beyond which the physicists’ way of thinking fails?
    The conceptual problem here is difficult because the universe is a becoming – a process – and we want to think of it as a thing. We don’t only find it puzzling that the universe was so different back then, that particles behaved differently, that the universe then became the universe now, and will perhaps eventually cease expanding and collapse back to a point in a Big Crunch. We are familiar with babies becoming children becoming adults, but these processes always surprise us – we like
things
to keep the same character, so ‘becoming’ is difficult for our minds to handle.
    There is another element of the first moments of our universe that is even more difficult to think about. Where did the Laws come from? Why
are
there such things as protons and electrons, quarks and gluons? We usually separate processes into two conceptually distinct causal chunks: the initial conditions, and the rules by which they are transformed as time passes. For the solar system, for instance, the initial conditions are the positions and speeds of the planets at some chosen instant of time; the rules are the laws of gravitation and motion, which tell us how those positions and speeds will change thereafter. But for the beginning of the universe, the initial conditions seem not to be there at all. Even
there
isn’t there! So it seems that it’s
all
done by rules. Where did the rules come from? Did they have to be invented? Or were they just sitting in some unimaginable timeless pseudo-existence, waiting to be called up? Or did they uncurl in the early moments of the universe, as Something appeared – so that the universe invented its own rules along with space and time?
    Two recent books by top-ranking scientists explore how rules could be ‘invented’. The most recent is Stuart Kauffman’s 2000
Investigations
. This is mainly aimed at biology and economics, but it begins with rules of physics. In a new answer to the old question ‘what is life?’, Kauffman defines a lifeform to be an ‘autonomous agent’—any entity or system that can redirect energy and reproduce. ‘Autonomous’ here
means
that such a system makes up its own rules, determines its own behaviour. Such lifeforms need not be at all conventional. For example, the quantum-mechanical vacuum is a seething mass of particles and antiparticles, being created and annihilated in amazingly complicated ways. A vacuum has more than enough complexity to organise itself into an autonomous agent. If it did, then quantum mechanics would be able to make up its own rules.
    The other noteworthy book on this topic is Lee Smolin’s 1997
The Life of the Cosmos
, which asks: can universes evolve? A remarkable feature of our universe is the presence of Black Holes. These are regions of space-time that contain so much mass that light (and matter) cannot get out; they are formed by the collapse of massive stars. It used to be thought that Black Holes are rare, but now they seem to be showing up all over the place, in particular at the cores of most galaxies. Theoretical work shows that the constants of our universe are unusually good for making Black Holes.
    Why? Smolin