M-theory and god

Anthony Rose reviews Stephen Hawking & Leonard Mlodinow's 'The Grand Design' Bantam Press 2010, pp208, £18.99 hbk

For all the attention it has received, Stephen Hawking and Leonard Mlodinow’s new book The Grand Design is relatively uncontroversial with regard to the science. This is despite what you may have been led to believe from several newspaper reviews, with the story even making the front page of The Times. Perhaps the attention it has received is a reflection not of any ‘shocking’ conclusions that Hawking draws with regard to the absence of a god or gods, but of the state of the average level of general scientific education.

The book covers what you would expect from a modern ‘popular science’ cosmology and particle physics book: primarily the theories of special and general relativity, which are presented very clearly, and quantum mechanics, which, apart from the ubiquitous discussion of the double-slit experiment and other quantum ‘weirdness’, is primarily focused on the idea of the multiverse. This forms a core element of Hawking’s concluding arguments in regard to the creation of the universe. Perhaps a few words are required to introduce this idea briefly.

Quantum mechanics is the theory required for an understanding of the behaviour of the building blocks of the universe, the particles and forces on which all macroscopic structure depends. This theory has been developed and refined since the early 20th century, when it was gradually realised that ‘classical’ physics could not provide an accurate description of new scientific discoveries.

Quantum mechanics, and the quantum field theories which were built upon it, now provide us with a fantastically accurate description of sub-atomic processes, although anyone who has studied quantum mechanics will know that everyday experience cannot be applied in this realm. One of the non-intuitive aspects of quantum mechanics is that instead of a single version of history having happened, the sum of all possible histories must be taken into account. What this means is that, if you consider a particle passing between two points, it is not enough to assume that the particle took a straight line path between these two points. Due to the probabilistic nature of quantum mechanics, all of the possible paths must be considered, including paths that involved the particle travelling around the galaxy before reaching a point close to the starting point.

Extrapolating the idea of the sum of all histories to the universe is what leads us to the multiverse. The theory of the multiverse states that the birth of our universe was a quantum event, when the size of the universe was what is known as a singularity, a point of infinite density and curvature, and our laws of physics do not apply. It can be argued that this quantum event not only spawned the universe that we find ourselves in now, but an astronomical number of different universes (a number of 10500 is stated by Hawking: 10 with 500 zeros after it, although I am not sure how he arrives at this figure). It is impossible to explain this idea coherently in such a short review as this, but Hawking does a very good job of providing a pedagogical introduction to it, particularly the connection between the sum of all histories concept and the multiverse.

Hawking goes on to explain that the idea of the multiverse can arise naturally within M-theory, which is a vague umbrella term for a collection of theories that are still being fleshed out and meshed together, and based on work primarily in the areas of string theory and quantum gravity.

Hawking applies some of the ideas of the multiverse to address one question, which is why our universe is hospitable for life, when this seems statistically very unlikely. There are a number of parameters that define the universe that we live in, such as the strength of the different forces, or the number of spatial dimensions we live in, to name but two. Physicists have been searching for a theory that will provide these values as an output, a Grand Unified Theory of which these are a natural consequence.

One of the cosmological arguments offered by those in favour of intelligent design is that these parameters are so finely tuned in order to allow us to exist that shifting any of them by a few percent will generally lead to a universe in which nothing is capable of existence.

What Hawking argues is that the theory of the multiverse can provide us with a Goldilocks style analysis: the reason that these numbers appear so finely tuned is that we exist in this universe and are here to observe them, and there could be a countless number of universes in which these numbers ended up at some other values and subsequently life did not develop. In the same way that it is argued that conditions on Earth have been tailored by some mysterious designing god to be hospitable for life, this argument can also be applied to the state of our universe. The theory of the multiverse offers a possible scientific explanation of this, although there is currently no evidence for this theory.

This lack of evidence leads us to another counter argument against the idea of the multiverse, and against M-theory, and that is that these are questions that are still beyond the realm of modern science. Can we really say with any certainty that the existence of a multiverse could ever be proved? In my opinion it seems far too early to make claims of that nature in either direction.

However, as scientists and not theologians, we are able to separate our lack of evidence for a theory from their lack of evidence for a belief. We can make progress in the direction of being able to prove, or disprove, any prospective Grand Unifying Theory in a way that religion is simply incapable of doing. The Large Hadron Collider at CERN in Geneva is now colliding beams of protons at energies of 7 TeV (tera-electron volts), allowing us to probe new physics that may lie in the previously unexplored TeV scale, where the Standard Model (the name given to our current theory of particle physics) begins to look shaky.

Among the various pieces of supporting evidence that could materialise from this work is the discovery of ‘supersymmetry’, a proposed new symmetry between the two groups of particles in the Standard Model (fermions and bosons), which both the ATLAS and CMS detectors are well equipped to discover. The existence of supersymmetry is a requirement for M-theory, and if it is realised in nature then there will be a number of observable particles, as each currently understood partner has a proposed ‘superpartner’, likely to be in the mass range accessible at this experiment.

So, Hawking explains, M-theory is a candidate for a Grand Unifying Theory, and may well have something to say, at some time in the future, about the beginnings of the universe. This theory is still very much in its infancy, and even after the details are fleshed out over the coming years (decades!) it may well not stand up to experimental verification. The only thing we know with any certainty is that there is a great deal of physics that remains unknown, and the effective theory that is the Standard Model is about to face its greatest challenge yet, in the shape of the Large Hadron Collider (as well as a huge number of other experiments that are pushing at the boundaries of what we know about fundamental physics - such as investigating the nature of neutrinos, dark matter and a huge number of other phenomena). A quote from Engels in Anti-Dühring springs to mind when considering this question: “... how young the whole of human history still is, and how ridiculous it would be to attempt to ascribe any absolute validity to our present views ...”. There are inevitably a huge number of surprises to come over the next few years.

Science is inherently revolutionary due to the constant testing and development by members of the scientific community. It is vital for the progress of humanity that society is educated against the irrationality and lack of understanding so prevalent today. A strong scientific education and the skills that come along with it, such as the ability to think critically, are the key to this social progression. Simply speaking, members of society that do not have a basic understanding of science and the scientific method are simply not in a position to develop informed opinions on the challenges that face our world. Science alone will not provide a means of social change, but it is in the interests of the working class to develop scientific literacy and education.

I’ll leave you with a nice summary from the authors themselves: “Many people through the ages have attributed to god the beauty and complexity of nature that in their time seemed to have no scientific explanation. But just as Darwin and Wallace explained how the apparently miraculous design of living forms could appear without intervention by a supreme being, the multiverse concept can explain the fine-tuning of physical law without the need for a benevolent creator who made the universe for our benefit”.