Monday, January 26, 2015

Book review: "Cracking the Particle Code of the Universe" by John Moffat

Cracking the Particle Code of the Universe: the Hunt for the Higgs Boson
By John W Moffat
Oxford University Press (2014)

John Moffat’s new book covers the history of the Standard Model of particle physics from its beginnings to the recent discovery of the Higgs boson – or, as Moffat cautiously calls it, the new particle most physicists believe is the Standard Model Higgs. But Cracking the Particle Code of the Universe isn’t just any book about the Standard Model: it’s about the model as seen through the eyes of an insider, one who has witnessed many fads and statistical fluctuations come and go. As an emeritus professor at the University of Toronto, Canada and a senior researcher at the nearby Perimeter Institute, Moffat has the credentials to do more than just explain the theory and the experiments that back it up: he also offers his own opinion on the interpretation of the data, the status of the theories and the community’s reaction to the discovery of the Higgs.

The first half of the book is mainly dedicated to introducing the reader to the ingredients of the Standard Model, the particles and their properties, the relevance of gauge symmetries, symmetry breaking, and the workings of particle accelerators. Moffat also explains some proposed extensions and alternatives to the Standard Model, such as technicolor, supersymmetry, preons, additional dimensions and composite Higgs models as well as models based on his own work. In each case he lays out the experimental situation and the technical aspects that speak for and against these models.

In the second half of the book, Moffat recalls how the discovery unfolded at the LHC and comments on the data that the collisions yielded. He reports from several conferences he attended, or papers and lectures that appeared online, and summarizes how the experimental analysis proceeded and how it was interpreted. In this, he includes his own judgment and relates discussions with theorists and experimentalists. We meet many prominent people in particle physics, including Guido Altarelli, Jim Hartle and Stephen Hawking, to mention just a few. Moffat repeatedly calls for a cautious approach to claims that the Standard Model Higgs has indeed been discovered, and points out that not all necessary characteristics have been found. He finds that the experimentalists are careful with their claims, but that the theoreticians jump to conclusions.

The book covers the situation up to March 2013, so of course it is already somewhat outdated; the ATLAS collaboration’s evidence for the spin-0 nature of the Higgs boson was only published in June 2013, for example. But this does not matter all that much because the book will give the dedicated reader the necessary background to follow and understand the relevance of new data.

Moffat’s writing sometimes gets quite technical, albeit without recourse to equations, and I doubt that readers will fully understand his elaborations without at least some knowledge of quantum field theory. He introduces the main concepts he needs for his explanations, but he does so very briefly; for example, his book features the briefest explanation of gauge invariance I have ever come across, and many important concepts, such as cross-sections or the relation between the masses of force-carriers and the range of the force, are only explained in footnotes. The glossary can be used for orientation, but even so, the book will seem very demanding for readers who encounter the technical terms for the first time. However, even if they are not able to follow each argument in detail, they should still understand the main issues and the conclusions that Moffat draws.

Towards the end of the book, Moffat discusses several shortcomings of the Standard Model, including the Higgs mass hierarchy problem, the gauge hierarchy problem, and the unexplained values of particle masses. He also briefly mentions the cosmological constant problem, as it is related to questions about the nature of the vacuum in quantum field theory, but on the whole he stands clear from discussing cosmology. He does, however, comment on the anthropic principle and the multiverse and does not hesitate to express his dismay about the idea.

While Moffat gives some space to discussing his own contributions to the field, he does not promote his point of view as the only reasonable one. Rather, he makes a point of emphasizing the necessity of investigating alternative models. The measured mass of the particle-that-may-be-the-Higgs is, he notes, larger than expected, and this makes it even more pressing to find models better equipped to address the problems with “naturalness” in the Standard Model.

I have met Moffat on various occasions and I have found him to be not only a great physicist and an insightful thinker, but also one who is typically more up-to-date than many of his younger colleagues. As the book also reflects, he closely follows the online presentations and discussions of particle physics and particle physicists, and is conscious of the social problems and cognitive biases that media hype can produce. In his book, Moffat especially criticizes bloggers for spreading premature conclusions.

Moffat’s recollections also document that science is a community enterprise and that we sometimes forget to pay proper attention to the human element in our data interpretation. We all like to be confirmed in our beliefs, but as my physics teacher liked to say “belief belongs into the church.” I find it astonishing that many theoretical physicists these days publicly express their conviction that a popular theory “must be” right even when still unconfirmed by data – and that this has become accepted behavior for scientists. A theoretician who works on alternative models today is seen too easily as an outsider (a non-believer), and it takes much courage, persistence, and stable funding sources to persevere outside mainstream, like Moffat has done for decade and still does. This is an unfortunate trend that many in the community do not seem to be aware of, or do not see why it is of concern, and it is good that Moffat in his book touches on this point.

In summary, Moffat’s new book is a well-done and well-written survey of the history, achievements, and shortcomings of the Standard Model of particle physics. It will equip the reader with all the necessary knowledge to put into context the coming headlines about new discoveries at the LHC and future colliders.

This review first appeared in Physics World on Dec 4th under the title "A strong model, with flaws".

14 comments:

Phillip Helbig said...

Sounds interesting.

"He does, however, comment on the anthropic principle and the multiverse and does not hesitate to express his dismay about the idea. "

Landau purportedly said that cosmologists were often wrong but never in doubt. I notice that many who don't like the multiverses are often critical but don't offer any disproof. Whether or not you accept all of his ideas, Tegmark makes the point that multiverses are not a theory, but rather consequences of other theories, which we believe for other reasons, and that coming up with a new theory which is just as good but gets by without a multiverse is not always possible; certainly most of those in dismay don't offer such an alternative theory.

Phillip Helbig said...

“belief belongs into the church.”

Should be "belief belongs in the church". (German "in" with accusative is often "into" in English, but not here.)

Sabine Hossenfelder said...

I have a lot of sympathy for Tegmark's argument. I think he kinda misses the point of doing science, but at least his argument is logically coherent.

Re church: Some editor at Physics World is very unhappy now (this is the corrected version) ;)

L. Edgar Otto said...

Many writers and theoreticians have placed emphasis on a sort of cosmic code (Heinz Pagels) or nature's code (Peter Rowlands) or a DNA like code analog in some sort of inorganic analog.
The particle code is not a separate concept to space codes as to where one is more the primary foundation of a unifying model as a standard one.
The same general methods that treat the coefficients and variables one or the other primary is a matter of taste of the same primitive ideas of physical dimensions and motion.
I had something to say earlier but it has been awhile that either did not post in the fb book sharing or was lost somewhere in that sharing- but a lot has changed including many new speculative papers now offered once the general questions becomes widely known.

Uncle Al said...

"unexplained values of particle masses." The pendulum equation: "masses"? Quantum mechanics is discrete, algebraic, and entangled. Empirically predictive gravitation is continuous, geometric, and separable. Physical theory is drylabbed. Targeted falsifying observation is nekulturny. Minor falsifying observations abound, thus unending parameterizations. Opposite shoes non-identically fit into geometric reality. Look.

http://backreaction.blogspot.com/2013/12/the-finetuned-cube.html
Are 120 [123 vs. quantum gravitation] orders of magnitude wrong really so bad? Yes.

Uncle Al said...

arXiv:1501.01919 "Paradoxes Of Cosmological Physics In The Beginning Of The 21-St Century"

(arXiv added another digit for monthly submissions. How can we have so much "knowledge" and so little advance? Management!)

coraifeartaigh said...

Just a minor point - much as I admire Hawking's great work, I think few particle physicists would describe him as "prominent in particle physics". Certainly, Lochlainn's gang didn't see him this way

joel rice said...

Bee - a nice exposition of Gauge Theory would be just the thing, since I have been wrestling with t'Hooft '50 years of yang mills' - Does he get into the subject of Anomalies ?
It would be interesting to think that spinors depend on what kind of interaction might cause a particle to arrive in a different state than it started out with - depending on whether it interacts with a photon or a W boson - it might arrive as a neutrino.
I used to see Moffat's articles in JMP back when.

joel rice said...

Bee - regarding Tegmark. I wonder if he would consider an opposite view that when it comes to what exists, there is only one algebra that determines what exists - as far as particles are concerned, and everything else is fantasy land.
sorta like nominalism vs platonism, but more specific.
also wondered if funding institutions have ideas about the cost of being stuck, or the benefits of becoming unstuck.
and estimation of the cost of increased hassle of devising ingenious ways to make things work that are not totally suited to the task.

L. Edgar Otto said...

joel,

There is an algebra that "determines what exists". This is the Dirac Algebra. But it is not enough to answer if its very consistent relation to cosmological effects are observable.

The problem is rather subtle. It should not be considered a final answer in any case because in the debate of objective reductionist verses sensation such as the entire funding and pursuit of neurobiology concerns it is not clear by observation we capture all sensations we experience, such as visual sampling of our dreams or drug effects.

I just saw a paper that suggests the entanglement adds weight to particles. As Uncle AI points out presented on arXiv it is quite intelligent as so many in this explosion of speculations by scientist if not competent scientific journalist or popularization's who may not depend on some graph of trends in what subjects are most published in trends.

The article suggests a lot including better possible QM and GR unification but states for a quantum gravity theory effects can be measurable and observable by this really common way to explore at least the concepts.

The weight problem in string theory has been with us a long time. So it is possible that given two models that we may measure one means we can measure the other - or in this level of foundations some things remain not observable as a mathematical (geometric or combinatoric) model.

The idea of different distances of something two places at once can reduce to weights or measures of perturbation or even compacting. A code length of decoherence where in representation of the spaces possible we have different times and lengths or some other physically interpreted dimensions.

In general we square things including two dimensional spaces such as the complex plane as if at one intersecting point. Content and boundary. Then what cannot be seen so is hidden in one representation is considered an illusion (of which the questionable half truth of renormalization or holographic principles is a given way to balance things.

What this amounts to is the restriction of degrees of freedom int he translating from one representation to another for those weight distances at least as the underlying arithmetic where the variables and coefficients of an algebraic equation are the same sort of functions or coordinate representations. The simplest form of this is not just that lines in one system become circles in the other but that on such a plane, brane, or what have you the knight moves as in a chess game become the queen moves in the reduction, open or reentry over the board. So to distinguish weights we need see these visualizations as different measurable differences too where they can be observed effects part of the time and over quasifinite continuities.

joel rice said...

L Edgar
On the contrary - Dirac algebra does NOT determine what exists ! Try getting quarks and color out of Dirac algebra.
I emphasize that Bee is right that Pure Thought is insufficient. Here is why: Octonions make Color explicit - but we can not detect free quarks and gluons. As if that is bad enough, we CAN detect mass and charge, but the algebra HIDES them ! That is why isospin is not at all obvious from inspection ! It took Heisenberg to see isospin and he got it considering physics.

conclusion: Einstein was totally wrong. Not only is the Lord subtle, he is a mean, nasty and cruel sonofabitch !

There is a ping-pong between math and physics. If Hamilton does not like complex quaternions because it does not seem 'economical' - you lose - and Maxwell wins !

Not only is it true that Physics needs Math - it is just as true that you need Physics to make sense of Algebra ! In algebra, the generations make sense, but in physics they just tack on two more copies of the first generation. Back and forth it goes.

Sabine Hossenfelder said...

coraifeartaigh,

That's a phrase the editor added. Sorry about that, I couldn't find my original file. I think I had just written "prominent people". Best,

B.

Sabine Hossenfelder said...

Joel:

What I actually wrote was that if you want to learn something about the math underlying the SM, then Moffat's book is not a good starting point. It's too brief on that account. He only explains that what he later uses, and that as briefly as possible. No, he doesn't discuss anomalies. Best,

B.

Sabine Hossenfelder said...

Joel:

Regarding Tegmark. I don't really see the point in speculating about what he might be speculating about. Best,

B.