Knocking on Heaven's Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World

This book appears to have multiple objectives. One, listed in the conclusion, is to show how high-energy physicists and cosmologists determine their course. In other words, how does science work, at least for this subset of scientists? A further objective is to show the relevance of scientific thought to today's complex challenges. The writing is very clear and the reader should follow what the author has written without any significant effort. The description of how the Large Hadron Collider works is the best I have seen, although its relevance to the objectives is more questionable, and it could have been better edited.How science works is given by example, mainly involving fundamental particle physics, which appears to be the author's own area of work. The Higgs mechanism is explained from a theoretical viewpoint, then follow the problems arising from no direct observational evidence, and thus having to design indirect experiments. Such examples are given to show how science works for the modern particle physicist, and not simply to explain modern physics, although the reader will get this as well, at least up to a point.Nevertheless, there is an obvious problem: where to draw the line regarding what to include and what to leave out. If everything is included, the account gets bogged down in subsidiary side-explanations, but if too little is included, the reader is left with too many questions and may understand less than when he/she started. (Actually, this is how science really works. Very often as the scientist begins to unravel a problem, more problems simply grow up from nowhere; it is only when a genuine advance is made that answers to this morass of problems suddenly self-assemble into a coherent whole. This gives the researcher quite a remarkable feeling, and if the author was trying to encourage more young people to take up science, an example of something like this would have been highly desirable. Possible suggestion for the next edition?)As an example of what I found troubling, the explanation for why a photon has no mass was that a hypercharge gauge boson interacted with one of the weak gauge bosons and the combination no longer interacts with the weak charge of the vacuum (i.e., the Higgs field). The hypercharge gauge boson is not mentioned anywhere else, there are three weak gauge bosons with different charge (+1, 0, -1. If weak charge is conserved, how many hypercharge bosons are there? What happens if the collision results in net weak charge? A two-charged particle? Together with one or two postulated Higgs fields that have an internal broken symmetry, this is quite a set of postulates to explain one fact. Observational support for the mechanism is claimed from the following: in a Bose condensate the electrons pair and such pairs impede the photon's progress, which conveys mass to the photon. Two objections come to mind: how do we know the photon has mass there, and why does this not happen as photons go through a crystal of, say, sodium chloride, where the photon hits a number of electron pairs.This example is not unique, but that raises the question, is this what the author intended to happen? There are no examples of looking back, just in case there has been a wrong turning, and as the example above ought to show, there could be some doubt as to whether that is right. On the other hand, if the objective is to encourage critical scientific thought, this book is actually a gold-mine. If you wish to understand how high-energy physicists think, this book appears to be very good. If you wish to know how science ought to work, then this is perhaps more debatable. In terms of Kuhn's concept of how science works in practice, the young scientist should read this book, not so much for how science should work, but rather for how to go about advancing their own careers. Finally, the author often lapses into first person asides, and accordingly you get an insight into Lisa Randall, the person. This is most unusual in a scientific book, and well worth reading.

I just finished Randall's book Warped Passages and enjoyed it very much. So it was with anticipation that approached reading this book. Randall notes the intended audience for this book saying that it "is intended for an interested lay reader who would like to have a greater understanding of current theoretical and experimental physics and who wants a better appreciation of the nature of modern science - as well as the principles of sound scientific thought." The title is explained in the book: "Scientists knock on heaven's door in an attempt to cross the threshold separating the known from the unknown."She begins by discussing the many misconceptions people have about science today and introduces us to the concept of effective theories, which is a technique scientists use to study "particles and forces that have effects at the distances in question." A whole chapter is then spent on the contribution of Galileo in establishing the foundations of science thought. Some time is spent discussing the different aims for science and religion. She notes that the goals of science and religion are intrinsically different. Science addresses physical reality, whereas religion tends to be concerned with psychological or social human desires. Early modern scientists actually viewed the "Book of Nature" and the "Book of God" as similar paths to edification and revelation.We are next taken on a journey from the sub-atomic scales all the way down to something known as the Planck length (10-33 cm). We learn of the discoveries of electrons and quarks, fixed-target verses particles colliders, the Higgs mechanism, and more.Section III of the book delves into the machinery and measurements behind the science, notably the Large Hadron Collider (LHC) at CERN. A chapter is spent discussing the conception, construction, first tests, and problems encountered with the LHC. Some feared the LHC would be capable of producing black holes, and maybe even destroy the earth. Randall puts our fears at bay by explaining all we need to know about this. She continues by discussing calculating and dealing with risk citing common examples such as climate change and the financial crisis and explains how risk can be mitigated. The next topic deals with measurement and uncertainty where we learn the meaning of the terms accuracy, precision, and systemic uncertainty. A chapter is devoted to the CMS and ATLAS experiments. These are the two general purpose detectors of the LHC. They are incredibly large and extremely complex wonders of engineering. Perhaps Randall's own theories will be verified here. Space is devoted to explaining in more detail the detection system. Here we have the trackers (innermost part of the detector), the electromagnetic calorimeter, the hadron calorimeter, and on the outermost part of the detectors we have the muon detector. There are many images provided to show us all that is described in the text.Section IV of the book deals with the topics of modeling and prediction of results. The concept of beauty and its relationship to science is explored, and we are given some insight into the process of model building. This segues into the nature of the Higgs boson, the Higgs field, symmetry breaking, and how the Higgs imparts mass to particles via something called the Higgs mechanism. We also learn about how the particles produced in the LHC can be used to identify the "fingerprints" of the latest theories. One theory of the author, called the Randall-Sundrum theory, proposes a warped geometry involving two types of branes in close proximity. Randall expresses the anxiety provoking nature of waiting for the LHC results. She notes that "They could change our view of the underlying nature of reality [...] When the results are in, whole new worlds could emerge. Within our lifetimes, we just might see the universe very differently." The text would not be complete with a discussion of inflation, dark matter and dark energy. We are informed of the various dark matter detection methods, and the various experiments worldwide that are being conducted in a attempt to detect it.Randal has given us here a glimpse into the world of high-energy physicists and cosmologists, their hopes, and the experiments that could answer the fundamental questions about the universe we live in.

I am sure Randall is a brilliant, and possibly an original scientist, however I find her thoughts on the philosophy of science, on creativity, and on human nature generally mundane. This would not matter so much if it were not for the fact they take up so much of her book. This inadvertent banality somehow extends into the scientific passages, in the form of repetitions - she sometimes repeats the same point three times in the same paragraph - as if she does not trust her audience will be able to accept some of the more surprising ideas she is presenting.On the positive side, the author did come across as a genuine and likeable person, if not a great stylist. Perhaps she just needs a bit more faith in her readers.

There were sections of this that I enjoyed and found useful, but there was a lot of material that I felt she'd written up for other occasions (public lectures, student course material, etc) and had pressed into service to fill out the book. Its relevance to the topic at hand seemed somewhat tenuous e.g. the chapter 'Risky Business'. On the other hand the diagrams on pp. 73 and 254/5 were useful. Just one more small point: when drawing nucleons in the context of their constituent parts do we have to show an encasing sphere? Is this meant to be a physical reality? I somehow doubt it - it's not labelled as a 'sheath' or 'wrapper'. If it has no physical counterpart, why add it?

The best description of CERN I have come across. How did Europe manage to organise it when everything else it to touch seems to turn to dust!Very comprehensible (well mostly) great book.MM

Lisa is an excellent communicator. She does a good job of giving you a feel of what is going on in a difficult subject without patronizing the reader. It would be too much to ask for her to provide a solid understanding of quantum chromodynamics and the Higgs mechanism without the use of sophisticated mathematics. Her views on the history and philosophy of science are also of interest.

I have a scientific background but this is not the most riveting read. It starts very slowly and by then I had lost interest