Now: The Physics of Time Illustrated Edition

I enjoyed reading Muller’s book, maybe as much for its loose ends as its clear discussions along the way. He combines a reconstruction of some basics of relativity and quantum physics with an over-riding question — time’s arrow and our experience of a “now” in time — and a general, philosophical position on the limits of scientific knowledge. And, despite the subject matter, it’s written in an almost breezy manner, although you’ll certainly find yourself going back to read passages a second or third time to understand subtle points.The bulk of the book really is Muller’s laying out of his own understanding of the current landscape of physics and cosmology.It deserves being called a “reconstruction” because he seeks to overturn some popular scientific misconceptions along the way. The expansion of the universe, for example, does not mean that galaxies are moving away from one another, but that the space between them is expanding. That may seem like a difference between two ways of describing the same thing, but the difference will become important later when Muller addresses the question of time, “now”, and time’s arrow. Just as space is continually created by cosmological expansion, he will claim that time is also expanding.He also corrects the popular construction of space-time as three axes of space and a fourth time axis, similar to the spatial axes. That popular picture gives us the impression of a linear expanse of time — past, present, and future — on which we just happen to sit at a point we call the present, as if future and past also existed as accessible points, at least in principle. Again, correcting this picture will play an important part in his own conception of time later in the book.Muller devotes extensive discussions to indeterminacy and entropy. He recounts Einstein’s opposition to indeterminacy as an objective characteristic of reality. This is part of his general argument that physics is “incomplete”. Despite Einstein’s protests, indeterminacy actually does turn out to be a feature of objective reality. The common sense determinism of scientific thought, that the past determines the future, turns out to be false. Physics, in turn, is incomplete, in that it cannot compute the future even given complete knowledge of the past and present. The idealized “complete” knowledge of the past and present — the position and velocity of all particles — is unobtainable, because there simply are no such determinate, objective positions and velocities.His discussion of entropy takes up the perhaps dominant explanation of time’s arrow, by Arthur Eddington — that the arrow of time is the arrow of increasing entropy. Muller considers Eddington’s account in some interesting discussions of the relation between local entropy and cosmological entropy. Certainly we, through intentional activity, can decrease local entropy. Our experience of time’s arrow is not one of ever-increasing entropy. Muller wants us to see that, in an important sense, the idea that time as entropy cannot go backwards is illusory — local entropy certainly does go backwards. The familiar illustration of entropy’s direction — reversing the film sequence of a cup breaking, now showing the pieces of the cup bizarrely flying together — is misleading. Cups do actually come together, reversing entropy, when we make them.I’m unsure exactly how to understand the relation between the problem of time’s arrow in physics and the importance that Muller gives to the human experience of time (and local entropy). But he certainly does mean to claim that physics turns out to be incomplete in another sense beyond that implied by objective indeterminacy. That other sense of incompleteness has to do with conscious experience, such as our conscious experience of time.Muller is a scientist who does not think the reach of scientific knowledge is complete — there are phenomena beyond the reach of scientific knowledge. In particular, science cannot grant us knowledge of conscious phenomena, e.g., what it is like to see blue. We can certainly have scientific accounts of what happens when we are conscious (e.g., that certain areas of the brain are active), but that is not a description of the conscious experience itself (see Thomas Nagel’s classic paper, “What Is It Like to be a Bat?” for a fuller treatment of the problem, although Muller doesn’t cite Nagel).All of these themes come together toward the end of the book in Muller’s speculations about “now”. The direction of time, and our position at “now”, are not adequately explained by our current physics. Our experience of “now” is likewise unaccounted for in physics (actually our conscious experience of anything is unaccounted for by physics).We do however, from quantum physics, have a way of distinguishing the past from the present and the future. What separates the past from “now” is the determination of the past — quantum uncertainty has been resolved in the past (through “measurement” — a still mysterious natural process that collapses the wave function of quantum physics). In the present, and in the future, no such determination has occurred. In fact, Muller thinks that time is continuously created, just as space is, in the cosmological expansion of the universe.The claim is speculative, and probably requires a lot more physics (especially concerning measurement). But Muller offers some thoughts on experiments we might make to go forward.Muller’s claims on indeterminacy, local entropy, and the unattainability of scientific accounts of conscious experience also lead him to some conclusions about free will. Certainly indeterminacy is not the same thing as free will — indeterminacy has nothing to do with intentional behavior. But indeterminacy at least may remove one obstacle to accepting free will, that our future actions are not strictly determined by the past or present. His account of free will is, like his account of the continuous creation of “now”, speculative, but interesting. He would like to say that, since “now” and the future are undetermined, in the physical sense, they are open to willful determination — explained by him as generation of local decreases in entropy. Those local decreases are the province of life and its productions (order, structure, intentional action . . . civilization).In my own understanding, from reading Muller, the marriage of all of these themes isn’t really consummated. The flow of time, free will, and what blue looks like are all phenomena that appear not to be well understood, certainly by science, and possibly will never be understood by scientists. I’m just not sure how all are related to one another, or if “now” does not turn out to be inextricable from the conscious experience that Muller thinks cannot be adequately described in scientific terms.But Muller is refreshingly provocative. And I think it is especially refreshing, in not only a scientific but a scientistic age, to find a physicist who does not think that physics can encompass everything.One minor quibble. Well maybe not minor. Muller delves deeply into some important philosophical problems — the status of conscious experience, free will, the limits of objective knowledge. And he does discuss some philosophical treatments of those issues. But, given that he teaches at a university with one of the world’s leading philosophy departments, there’s no evidence (that I could find in the book) that he’d actually walked over to the philosophy department to find out what they thought. Doing so may have substantially enriched and applied additional rigor to his treatments of those issues.

Do humans have souls? Do they transcend our physical bodies? Why does Richard A. Muller spend a significant fraction of the text of this new popular level book about the physics of time discussing this?The answer seems to simply be that the question of whether he has a soul is one that is dear to the author’s heart. I’ve tried to figure out if there is any link between this subject and the main purpose of the book but I failed.The primary purpose of the book is to introduce a new and still speculative theory of Muller’s that our sense of ‘now’ and of our involuntary ‘motion’ along the arrow of time is a result of new time being created moment to moment. We ‘travel’ to this new time and occupy it as it is created, and the old time becomes the past. The future really does not exist, as it is not yet created.I like the idea. It feels right to me, and Muller proposes a few thoughts about how his theory might be falsified. But it is early days—way too soon to tell whether this or alternate hypotheses might be the path to better understanding the mystical and perplexing nature of time in our reality.Muller is an experimentalist, and he repeatedly insists that theoretical physics—manipulating equations using advanced math—is a waste of time unless the resulting theory is rooted in the physical world in such a way that it can be tested. Indeed he gets rather curmudgeonly about it in places. His belittling of 1933 Nobel Prize winner Paul Dirac is rather unbecoming and speaks more about Muller than Dirac.Setting that aside as an anomaly, or as hasty writing and editing, I found most of Muller’s book a fascinating read. It carefully develops and clearly explains the physics relevant to our understanding of time. Einstein’s relativity is explained and the subsequent development of quantum physics and its various interpretations are explained well.Then in Part IV of the book he goes on this strange walk-about into ‘not-physics’. I call it that because that is really his point. Things that are ‘not-physics’—not science—are real and are important.Despite the disconnect with the rest of the book, it’s a point worth making, and I’m glad he made it, and I guess I understand why it’s in this book. If Muller had written a book devoted entirely to his untestable beliefs and perceptions (his favorite example is “what does ‘blue’ look like?”) nobody would take it seriously, and probably no publisher would even consider it. At least this way he gets his message in print.And yes, it feels like he’s preaching here in Part IV. His main point is succinctly summarized by this quote from page 266:<i>“Physics itself is not a religion. It is a rigorous discipline, with strict rules about what is considered proven and unproven. But when this discipline is presumed to represent all of reality, it takes on aspects of religion. … The dogma that physics encompasses </i>all<i> reality has no more justification than the dogma that the Bible encompasses all truth.”</i>I agree. Muller argues that there is a huge body of knowledge that is not testable, but which nevertheless guides us successfully through our daily lives. (‘My boss hates chocolate’ is an example of such knowledge.) The target audience of his argument is the not inconsiderable group of physicists who ascribe to Physicalism/Reductionism—the idea that there is nothing real beyond what can be observed and characterized using science.I guess if there is a connection between his beliefs and Physics it comes from the fact that science has proven that some things cannot be observed and characterized, even in principle. He runs with the idea that reality is not amenable to logic or experiment (for example, the delicious paradox that there is no such thing as simultaneity of an event to different observers and yet quantum fields collapse instantaneously everywhere in the observed universe, to use an example relevant to the rest of this book) and uses it to justify injecting unprovable belief systems into that void.Such as believing that he has a soul. By ‘soul’ Muller specifically means the “I” that processes and acts upon physical inputs to the body—the ‘location’ of the mind.Muller has a peculiar fear of Star Trek style-beaming, or cloning. He asks “would the re-assembled physical body be ‘me’”? I find this odd, given that, as he points out, our current body consists of almost no atoms that we were originally made of. I think where he went wrong is thinking that the “I” is somehow sacrosanct. I believe that I would be a different “me” if I drove to Cleveland vs. if I didn’t.That brings up another point that Muller insists on. He is convinced that humans have ‘free will’. Personally, I think exercising my free will by choosing to drive to Cleveland tells all that needs to be told. No, seriously. Free will is not an absolute. We have choices, but we are denied most that we might imagine and many more that God might have.Regardless, I have no true objection to Muller’s beliefs, or to his inclusion of them in this book. From my perspective, that void of logic stands at the very core of reality and defines it. The universe, via its Big Bang, has emerged from it as an island of simple objective rule-following processes, but they are not fundamental, and physicists are now finally beginning to realize that. Life emerged as an island of self-replicating, self-preserving information (DNA), but it is no more fundamental than the universe it happens to find itself in. Its massive complexity does seem amenable to effectively tapping into the ‘free will’ fountain flowing from the quantum field. The emergence of useful information out of incoherent, indifferent uncertainty is what life does best. And that achievement is worth celebrating—worth formulating any number of religious beliefs around. But outside of our safe, limited realm, in the incomprehensible chaos of the vacuum, it is Paradox that rules supreme.

This is a really tough subject and I’ve read multiple books on it. I think this one is the best. Better than Stephen Hawking’s. It intersperses some historical debates and discoveries with the authors explanations. The hardest thing for me was understanding thins just based on a narrative. The equations at the end of the book help a bit. Most books don’t have this. I still can’t wrap my arms around a lot of it, but this book is really really helpful. I’ll bet taking a course on this subject would be fun. I recommend the book highly

It waz my 6th physics book, and it was great. It gives you a complete perspective of physics and time

Minha filha de 13 anos está adorando o livro....

昨年出版された、新しい本で、その意味で、現代物理学の考え方の一部を表現していると思う。この分野の専門家ではないので、その理論の適格性については不明である。科学の限界性を論じていることには好感が持てるが、それを超えた、主観的意見の背景については十分な記述がない。また東洋的思想への配慮はあまり感じられない。

Muito bom mesmo, com tipologia textual muito tranquila de ser compreendido para quem já tem um certo domínio da língua inglesa

Plantea posiblidades interesantes, pero asume que el lector tiene un conocimiento medio de la física cuántica, citando principios, propiedades o experimentos sin explicarlos.Buen libro, pero requiere conocimiento previo y no es para cualquiera.