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Quantum mechanics is a proper mind-bending prospect. From first, second, and even third glance it seems to make no sense, appears illogical and also feels a lot like science fiction. From my past investigations into the mysterious subatomic world all I got out of it was something about a cat being both dead and alive at the same time and became horribly bogged down with curious terminology like quantum entanglement, quantum superposition and the uncertainty principle. Trying to get my head around even the most basic of these ideas has often lead to weeks incapacitated in bed from crippling headaches and panic attacks but I was determined to get a better understanding one way or another and found a new, less scary looking resource to hopefully help me on my way in the form of the book "Quantum: A Guide for the Perplexed (2003)" by Jim Al-Khalili. I figured if a book devoted entirely to making the complexities of the quantum world understandable to people like me with little understanding couldn't help then I would simply have to admit defeat.
So, a little more on Professor Al-Khalili's credentials if we will to make sure we're not being diddled by a science hawking charlatan on this widely debated topic: so he's an Iraqi-born British theoretical physicist who became a leading expert on mathematical models of exotic atomic nuclei...oookay; he seems to be widely published and has picked up many fellowships and awards including the "Royal Society Michael Faraday Prize for science communication" and the "Institute of Physics' Public Awareness of Physics Award" and was given an OBE in 2008 (well he has the Queen's stamp of approval); and most importantly he is currently the Professor of Theoretical Physics at the University of Surrey (my old university, yay) not to mention he's a bit like Brian Cox trying to make science more accessible to the layperson with many TV documentaries and appearances on TV shows under his belt like Horizon, Bang Goes The Theory, Tomorrow's World to name but a few. I think it's safe to say we can trust him...
So on to the book which I have to say is written with a very nice, conversational and personal style with a few drops of humour and the odd flair for drama here and there to keep what could be a very dry and heavily technical subject quite engaging throughout. There are plenty of diagrams, quotes, real world examples and even a poem thrown in (apparently quantum mechanics is beautiful). Professor Al-Khalili sets his mission statement for the book out very clearly in his introduction where he captivates straight away by hamming up the mystery of the quantum domain due to its counterintuitive nature despite the fact it has an undeniable mathematical accuracy allowing for precise predictions in all kinds of situations and finally lays out clearly that, despite having his own clear views on the subject, he wishes to maintain a neutrality that will allow all different perspectives to be challenged to hopefully allow for a better overall understanding. The first chapter starts with the very well-known double slit experiment and is the perfect way to ease us in to quantum mechanics whilst revealing what is so devilishly enigmatic about it.
So for those that don't know the experiment begins by shining a light (a wave) on to a screen that has two thin slits in it leading to a second screen that can display the interference pattern of the light which will look like light and dark bands depending on how the light emerges from the slits by merging, overlapping and spreading out. So where the peaks (or troughs) of two waves merge together they will create a more intense light hence a light band will appear on the second screen, and where the peak of one wave meets the trough of another they cancel each other out and produce a dark band. Taking a similar experiment with sand falling through two slits we end up with a different result with two piles forming under each slit as the sand had to fall through one or the other slits with no interference to spread them out since sand behaves as a particle. So far, so good? Now, if we repeat this experiment with atoms being fired into slits and appearing on a second screen we'd assume that it'd behave as a particle since they are just tiny entities. Taking one slit first, we end up with a pattern more or less opposite the slit so the atoms have behaved as a particle. Phew. But fire atoms at two slits...well it all goes to hell in a hand basket. The atoms no longer behave like a particle, but end up displaying the hallmarks of wave interference and spread out in the same banding fashion as light waves indicating that the atom must have gone through both slits at the same time. Impossible! However, if you add in a detector to observe each atom, it appears to only pass through one or the other slit and produces results just like sand with two bands opposite each slit and thus acts entirely like a particle almost like it is aware it is being spied on. Screw you atoms!
So now the book has left us in a state where we are forced to dismiss all preconceptions about the world as we know it and try to have an open mind about what is to come which is unfortunately horrendously counterintuitive at times. The book proceeds along on a fairly logical journey in exploring this bizarre topic firstly by taking a step back and looking in to the history of how quantum mechanics, or physics, came to be by looking at the origins and the contributions of the key players starting with Max Planck (considered one of the founding forefathers) and his constant, Einstein (if it makes you feel any better he couldn't really get his head around much of this stuff either), Niels Bohr and Louise de Broglie. This second chapter was most informative and helped in really appreciating just how far quantum mechanics has come from old world views, but it really doesn't help in general levels of understanding. From here on out you have to simply accept that nothing the book covers is going to be simple and that frustration is inevitable, even though a real effort has been made to make things as comprehensible as possible.
Next we are lead through the complex ideas of "probability and chance" and are introduced to the idea of "determinism" i.e. if we know the precise position and state of motion of every particle in a system then, based upon Newton's laws, we can predict how these particles will move and interact and get a view of the future. Thankfully this is not possible but for the simplest of systems so if you're worried that fate is out of your own hands and everything is predestined don't be. This then leads on to the idea of "chaos theory" and the "butterfly effect" but then we see how it's all so different in the subatomic world with "quantum unpredictability" where the best that we can do is assign probabilities to where e.g. an electron will be by introducing the concept of the wavefunction i.e. detailing the quantum state and behaviour of a particle (when we're not looking at it). Next up is "Heisenberg's uncertainty principle" which states we cannot know both the precise position AND momentum of a quantum particle at the same time so we can never possess complete information. I'll be honest, at this point things were already getting a bit tricky to get one's head around and we've only just begun to scratch the surface...
Next up is the idea of "superposition" which is basically the interference caused when two waves hit each other resulting in a third wavefunction meaning that the atom can be in both multiple states and multiple positions at the same time. Ah man - now I'm officially foxed! This is supposedly enough to understand the double-slit experiment - it is not an atom going through a slit (although it is) but in theory the wavefunction which can go through both slits at the same time causing a superposition between the two new wavefunctions that exit the slits hence the interference and changed probability distributions (light and dark banding). Yes, it all makes sense now...but not really. It all pretty much just becomes a technical nightmare from here onwards spanning such topics as quantum entanglement and non-locality, quantum chaology, Schrodinger's cat example, decoherence, quantum spin, the atomic nucleus, antimatter, quantum tunnelling, quarks, quantum theory of light, string theory, black holes - OVERLOAD ALERT. The book finishes up with practical uses gained from the understanding of quantum mechanics such as the ability to make CDs and DVDs, the microchip, laser fibre-optics, tools in medicine such as Nuclear Magnetic Resonance and Positron Emission Tomography, and the future for atomic engineering and nanotechnology (it's all gone a bit Star Trek) as well as all the modern day experiments further advancing the field, especially to do with quantum computers, although this book was written over 10 years ago and so there may well have been many advancements since then and so some of this book may eventually become a little outdated.
So this is not a book for light reading, you a) have to be interested in science-y, geeky stuff and 2) have to be in a receptive state of mind during your perusal or it will be a fruitless exercise. This is also a book that requires many, many breaks to take in what you've just read so I found myself just reading it a chapter at a time and hoping for successful assimilation (with mixed results leaving me often feeling frustrated). I like the way the book is structured throughout as if you have something in particular you want to learn about you should be able to find it with very few difficulties, though that's probably where the lack of difficulty ends. The best thing about this book is the fact it is so very clearly aimed at the layperson (though assuming a certain level of intelligence) and the harder concepts are broken down into accessible diagrams and real world examples like imagining police searching for a burglar based upon the likelihood of his location due to his pattern of crimes, or a jewel thief defeating a very sophisticated security system (something I'm sure we've all dabbled with at some point in our lives) and there is very little hint of the scary mathematics that can be derived from this field so this book offers up as much chance as any of getting to grips with this subject. Even better still, the mostly unbiased nature of this book explores all the viewpoints from different schools of thought from the traditional Copenhagen to the Broglie-Bohm interpretations and it's nice to see that even the experts in this field are still grappling with vast areas of this confuzzling topic so at least I'm not the only one.
As a resource, I found this book quite enlightening and now feel slightly more at ease with some of the more basic concepts which was my main aim, but this is an amazingly comprehensive book spanning across practically all areas of the subject from the history of the field and the raging ongoing debates from different schools of thought, to trying to understand the fundamental building blocks, to practical uses and on to the future and whilst I was reading the book I felt at the very least a vague understanding of most things I read, but if anyone asked me to explain what I'd read just 5 minutes ago my answers would be very limited as the subject matter is just too complicated and most of what I read simply evaporated into the ether without being successfully absorbed into the old grey cells. I feel that there is certainly an information overload and perhaps from one perspective in trying to help us poor, suffering novices battle against such intense brain mashing bafflement there was just too much information to have to sift through, but on the other hand you can dip in and out of this book focusing on just one topic at a time and the straightforward nature of the book in trying to strip out overly technical elements certainly helps. I'd recommend this book for giving you an overall understanding (or at least awareness) of basic concepts and a sense of the field as a whole, but it won't make you into an expert overnight as much of what you read will probably, though I can't speak for everyone, just go over your head.