The Grand Design
Stephen Hawking and Leonard Mlodinow
Ch. 1 The Mystery of Being
p 5 Raises philosophical questions like "Where did this all come from? Did the universe need a creator?" Then responds with "Traditionally these are questions for philosophy, but philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics." I think these are really stupid statements, so my immediate impression was that I hope Hawking gets a great burst of sales from pre-publicity, because if this kind of statement characterizes the approach, the public is going to get wind of it. Another thing that came to mind was G. K. Chesterton's statement "Philosophy is thought that is well thought-out" None of this seems well thought-out.
p6 gives Feynmann a ride, and points to idea that universe has no single history.
p7 basically argues against common sense, in that it is tied to common experience. Also introduces a kind of post-modern view of truth. "If two such physical theories or models accurately predict the same events, one cannot be said to be more real than the other; rather, we are free to use whichever model is most convenient." This appears to be saying there is no ultimate truth or reality.
p8 Points to M-theory as the model for an ultimate "theory of everything".
p10 Ends with profoundly philosophical questions "Why is there something rather than nothing?, Why do we exist?, Why this particular set of laws and not some other?" but has trivialized philosophy and rambled in a post-modern way, even after declaring that philosophy is dead.
Ch. 2 The Rule of Law
p15-28 A rather lame historical essay about the development of physical law.
p 29 Again raises philosophical questions "What is the origin of the laws? Are there any exceptions to the laws, i.e., miracles? Is there only one set of possible laws?" Does raise the view of Galileo, Descartes and Newton that the laws are the work of God, but then flippantly dismisses it as "a definition of God as the embodiment of the laws of nature." That's the kind of thing Steven Weinberg says, so it gives you some idea of the thought that has influenced these authors.
p 30 Drags out LaPlace's reply to Napoleon about where God fits "Sire, I have not needed that hypothesis."
p 30-31 Raises and ridicules the idea of free will.
p 31 "Though we feel that we can choose what we do, our understanding of the molecular basis of biology shows that biological processes are governed by the laws of physics and chemistry and are therefore as determined as the orbits of the planets."
p 32 pg 1 "it seems that we are no more than biological machines and that free will is just an illusion." Sounds like Daniel Dennett. This whole thing does not sound like Hawking to me - just a rambling of all the common punch lines of the new atheists.
p 33 Continues with the general rambling about the complexity of human consciousness, and it is not apparent why either author would pretend to have any particular expertise on that subject.
p 34 "This book is rooted in the concept of scientific determinism, which implies that the answer to question two is that there are no miracles, or exceptions to the laws of nature."
p 34 Later in the same paragraph, "do we really have reason to believe that an objective reality exists?" This seems like a swing from total philosophical materialism to some kind of weird non-materialism, all in one paragraph!
Ch. 3 What Is Reality?
p 42 "There is no picture- or theory-independent concept of reality."
p 48 Has spent several pages defending the idea of "model-dependent realism".
p 51 Qualities of a good model.
Ch. 4 Alternative Histories
p63 Uses buckyball interference to make the case that quantum phenomena are sometimes counterintuitive - behave like waves when you expect point particle behavior.
p74 probabilities as fundamental randomness in QM
p75 Idea of all possible paths in interpreting Young experiment
p77 Feynman view of quantum reality
p79 "It turns out that for large objects, paths very similar to the path predicted by Newton's will have similar phases and add up to give by far the largest contribution to the sum, and so the only destination that has a probability effectively greater than zero is the destination predicted by Newtonian theory, and that destination has a probability that is very nearly one." This is like my baseball wavelength example, and appears to totally undermine their claim that the double-slit type wave behavior can be applied to the whole universe, except in the very early stages where the universe is of quantum scale.
p80 Sum over histories formulation of quantum mechanics
p82 "observations you make on a system affect its past." This refers to the ideas of Wheeler, interesting since Wheeler thought we made the past.
p82 "Quantum physics tells us that no mattter how thorough our observation of the present, the (unobserved) past, like the future, is indefinite and exists only as a spectrum of possibilities. The universe, according to quantum physics, has no single past, or history. "
p83 "We will see that, like a particle, the universe doesn't have just a single history, but every possible history, each with its own probability; and our observations of its current state affect its past and determine the different histories of the universe, just as the observations of the particles in the double-slit experiment affect the particles' past."
Ch. 5 The Theory of Everything
p88 Good statement about comparison of electricity/magnetism and gravity.
p90-100 Good buildup of basic ideas fo E&M and Relativity
p100 The rationale for general relativity
p101-102 Good qualitative description of general relativity
p102 Says there would be a 10km/day error in the GPS system if general relativit were not taken into account.
p103 Overview of the four forces.
p104 QED and other quantum field theories
p106 Feynman diagrams
p108 Lamb shift
p115 Touches on string theory
p117 Calls "M theory" the common theory that unites the 5 or so string theories. Says that it implies 10 spatial dimensions plus one time dimension.
p118 pg2 "The laws of M-theory therefore allow for different universes with different apparent laws, depending on how the internal space is curled. M-theory has solutions that allow for many different internal spaces, perhaps as many as 10500 ..."
p119 Pretty well morphs M-theory into multiverse.
This chapter is a great overview of a lot of modern physics information and offers some redemption for the bad start in chapter 1. Maybe not as eloquent as Greene's Elegant Universe, but a good job of packing a lot of ideas into a short chapter in accessible language.
Ch. 6 Choosing Our Universe
p124 After spinning over creation myths, goes to evidence for a beginning.
p125 Eddingtons balloon in picturing expanding universe
p126 Friedmann equation
p127 More on Friedmann equation, Lemaitre's contribution.
p127 Cosmic Microwave Background Radiation
p128 H-He abundance
p129 Discusses fact that all rules break down near the singularity
p129 Discussion of inflation, with assertion that space can expand faster than the speed of light.
p130 Fluctuations in CMBR measured by COBE and WMAP.
p130 Discussion of the uniformity of CMBR as an argument for inflation because there is not enough time for thermal equilibrium of the CMBR otherwise - "there would have been enough time for equalization to happen in the extremely tiny preinflationary early universe."
p130 "The problem is, for our theoretical models of inflation to work, the initial state of the universe had to be set up in a very special and highly improbable way. Thus traditional inflation theory resolves one set of issues but creates another - the need for a very special initial state."
p134 A new idea to me "In the early universe - when the universe was small enough to be governed by both general relativity and quantum theory - there were effectively four dimensions of space and none of time. That means that when we speak of the 'beginning' of the universe, we are skirting the subtle issue that as we look backward toward the very early universe, time as we know it does not exist!"
p135 "This idea that histories should be closed surfaces without boundary is called the no-boundary condition."
p135 "The realization that time behaves like space presents a new alternative. It removes the age-old objection to the universe having a beginning, but also means that the beginning of the universe was governed by the laws of science and doesn't need to be set in motion by some god." Interesting that on p29 they flippantly dismiss the idea that the laws of nature are creations of God as "a definition of God as the embodiment of the laws of nature." Now they have come to the point where they say "the laws of science are God".
p 136 "The universe appeared spontaneously, starting off in every possible way." This by way of summary after asserting that the beginning of the universe can be described by a Feynman sum over histories.
p136 Visualization of creation as like the formation of bubbles of steam in boiling water - the different bubbles represent different histories.
p138 The necessary non-uniformities in inflation as revealed by COBE and WMAP.
p138 picture from WMAP at 13.7 Gy with variations in temperature in thousandths of a degree.
p139 "So look carefully at the map of the microwave sky. It is the blueprint for all the structure in the universe. We are the product of quantum fluctuations in the very early universe. If one were religious, one would say that God really does play dice."
p139 "top down" rather than "bottom up" they say because the universe is a Feynman sum over histories. This line of reasoning is followed to pg 140 where it concludes "We create history by our observation, rather than history creating us." Sounds very "Wheeler-ish".
p142 An interesting comment, also appearing earlier: "The no-boundary condition implies that the probability amplitude is highest for histories in which the universe starts out completely smooth. The amplitude is reduced for universes that are more irregular." According to WMAP, our universe was slightly irregular, with temperature variations of milli-degrees Kelvin.
p143 Parrots the principle of mediocraty.
p144 "There seems to be a vast landscape of possible universes. However, as we'll see in the next chapter, universes in which life like us can exist are rare. We live in one in which life is possible, but if the universe were only slightly different, beings like us could not exist. What are we to make of this fine-tuning? Is it evidence that the universe, after all, was designed by a benevolent creator? Or does science offer another explanation?"
Ch. 7 The Apparent Miracle
p149 "Our solar system has other 'lucky' properties without which sophisticated life- forms might never have evolved."
p152 Nice "Goldilocks zone" illustration of Earth in habitable zone.
p153 Goes through some of the "rare Earth" scenarios, and on p153 comments on Newton's belief that it was God's creation. They comment "It is easy to understand why one might think that. The many improbable occurrences that conspired to enable our existence, and our world's human-friendly design, would indeed by puzzling if ours were the only solar system in the universe." Then goes off on a discussion worthy of Sagan.
p154 Does actually name the "weak anthropic principle" that he has been using.
p154 Then goes off on some "selection" scenarios that are similar to those Hugh Ross uses in "Why the Universe is the Way It Is".
p155 Moves to a stronger form of the anthropic principle, which surprised me a bit. "The strong anthropic principle suggests that the fact that we exist imposes constraints not just on our environment but on the possible form and content of the laws of nature themselves. The idea arose because it is not only the peculiar characteristics of our solar system that seem oddly conducive to the development of human life but also the characteristics of our entire universe, and that is much more difficult to explain."
p156 Part of the tale I tell in "Windows of Creation", so keep these few pages in mind to review that treatment.
p159 A discussion of the carbon resonance necessary for the triple-alpha process to proceed. A good Hoyle quote, but no source for it - need to find it. "I do not believe than any scientist who examined the evidence would fail to draw the inference that the laws of nuclear physics have been deliberately designed with regard to the consequences they produce inside the stars." Source is Hoyle, F., in Stockwood, M., ed., "Religion and the Scientists: Addresses Delivered in the University Church, Cambridge," Lent Term, 1957, SCM Press: London, 1959, p.64
p159 "Such calculations show that a change of as little as 0.5% in the strength of the strong nuclear force, or 4 percent in the electric force, would destroy either nearly all carbon or all oxygen in every star, and hence the possibility of life as we know it. "
p160 More anthropic details - actually quite a good summary. Includes requirement of three space dimensions for stable orbits.
p161 "The emergence of the complex structures capable of supporting intelligent observers seems to be very fragile. The laws of nature form a system hat is extremely fine-tuned, and very litle in physical law can be altered without destroying the possibility of the development of life as we know it. Were it not for a series of startling coincidences in the precise details of physical law, it seems, humans and similar life-forms would never have come into being."
p162 Discussion of dark energy and the 120 orders of magnitude reduction
p162 "Our universe and its laws appear to have a design that both is tailor-made to support us and, if we are to exist, leaves little room for alteration. That is not easily explained, and raises the natural question of why it is that way."
p164 "The multiverse idea is not a notion invented to account for the miracle of fine-tuning. It is a consequence of the no-boundary condition as well as many other theories of modern cosmology."
p165 "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."
Ch. 8 The Grand Design
p 171 Interesting that pp171-180 are devoted to describing Conway's "Game of Life".
p180 "If the total energy of the universe must always remain zero, and it costs energy to create a body, how can a whole universe be created from nothing? That is why there must be a law like gravity. Because gravity is attractive, gravitational energy is negative." "Bodies such as stars or black holes cannot just appear out of nothing. But a whole universe can."
p180 "Because there is a law like gravity, the universe can and will create itself from nothing in the manner described in Chapter 6. Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the universe going."
The full sentence was 'Light blue touch-paper - stand well back' later replaced by 'Light blue touch-paper and retire.' The expression 'Light blue touch-paper!' therefore became a way of suggesting someone had done something dangerous or foolhardy and needed to beware of the consequences, especially, for example, when having said something that was likely to cause someone else to respond explosively.
p180-181 Further defense of supersymmetry, and M-theory as the only general candidate for a "complete theory of the universe. If it is finite - and this has yet to be proved it will be a model of a universe that creates itself."
p181 "If the theory is confirmed by observation, it will be the successful conclusion of a search going back more than 3,000 years. We will have found the Grand Design."