In the ten years since its publication in , Stephen Hawking s classic work has become a landmark volume in scientific writing, with than nine million copies in forty languages sold worldwide That edition was on the cutting edge of what was then known about the origins and nature of the universe But the intervening years have seen extraordinary advances in the technology of observing both the micro and the macrocosmic worlds These observations have confirmed many of Professor Hawking s theoretical predictions in the first edition of his book, including the recent discoveries of the Cosmic Background Explorer satellite COBE , which probed back in time to within , years of the universe s beginning and revealed wrinkles in the fabric of space time that he had projected Eager to bring to his original text the new knowledge revealed by these observations, as well as his own recent research, Professor Hawking has prepared a new introduction to the book, written an entirely new chapter on wormholes and time travel, and updated the chapters throughout The main idea to take away from this book is that time has a clear direction Entropy is the idea that the universe moves from highly ordered states to less ordered states If you take the lid off a bottle of perfume, and leave it off for a few days the perfume will go from being highly ordered all in the bottle to highly disordered all over the room Hawking uses this idea to explain why travelling back in time is impossible It requires very little energy to knock a glass over and smash it The main idea to take away from this book is that time has a clear direction Entropy is the idea that the universe moves from highly ordered states to less ordered states If you take the lid off a bottle of perfume, and leave it off for a few days the perfume will go from being highly ordered all in the bottle to highly disordered all over the room Hawking uses this idea to explain why travelling back in time is impossible It requires very little energy to knock a glass over and smash it but think of how much energy it would take to make the glass jump back into place all of the bits perfectly back where they were prior to the glass breaking It would be impossible and that impossibility is what gives time its clear direction.Philosophically, I tend to feel that the book makes far too much of the Uncertainty Principle But that is another story.This isn t the easiest book to read in the world and is probably the most bought science book of all time while also being the one most likely gave up on after a chapter or two but it is a fascinating read all the same This book puts me in mind of the story about how a Harvard number theorist, through some malfunction of the scheduling computer, got assigned to teach an introductory course in pre calculus Being one of those individuals to whom math came so easily that they couldn t grasp how difficult others found it, the professor had no idea what to cover in such a course So, he went to the chair of the department, who told him You ll want to start with the real number line and then progress to inequalit This book puts me in mind of the story about how a Harvard number theorist, through some malfunction of the scheduling computer, got assigned to teach an introductory course in pre calculus Being one of those individuals to whom math came so easily that they couldn t grasp how difficult others found it, the professor had no idea what to cover in such a course So, he went to the chair of the department, who told him You ll want to start with the real number line and then progress to inequalities from there, move on to quadratic equations, then trigonometry and the wrapping function, Cartesian and polar coordinate systems, and, if time permits, conic sections The professor thanked the chairperson and went off to meet with his first class Next week, he was back What should I teach them now he said A Brief History of Time is like that Professor Hawking doesn t seem to notice when his treatment progresses from the obvious to the arcane, ending with his concept of imaginary time very nearly incomprehensible in this overly brief presentation.Fun nonetheless It is not clear to me who is in the target audience for this book At times it tries to explain basic concepts of modern physics in simple language, and at other times it assumes a familiarity with the same subject For the first time I think I understand why absolute time is not consistent with relativity theory or that space time curvature supplants the notion of gravity, and for that I thank the author There are a few other things I believe I have a glimpse of having finally slogged thro It is not clear to me who is in the target audience for this book At times it tries to explain basic concepts of modern physics in simple language, and at other times it assumes a familiarity with the same subject For the first time I think I understand why absolute time is not consistent with relativity theory or that space time curvature supplants the notion of gravity, and for that I thank the author There are a few other things I believe I have a glimpse of having finally slogged through the book.On the other hand, there are many places where he writes as if it were clear what he is talking about even though it would require a good deal of background knowledge To give but one example, he starts talking about summing up over possible world histories I cannot locate the quotation without explaining what that would mean Trained in statistics, I have some idea that he is talking about mathematical expectation in the context of quantum mechanics, but I don t know how another reader might make any sense of it and I certainly don t havethan a vague notion There are irritating writing practices that could have used some editing, e.g., the use of the naked pronominal adjective this when in the middle of a dense explanation of an abstruse concept e.g., This had serious implications for the ultimate fate of massive stars My biggest complaints, however, are about his philosophical opinions Obviously he is entitled to think as he wishes about the ultimate questions, but his assertion that his hypothesis of a finite world without beginning or end would leave no place for God seems beside the point The classic divide has not changed some folks look around and say stuff just is, and other folks say there s a power behind the stuff that has at least as much going for it as we do That argument hasn t changed with his theories At one point in the book he claims that the late John Paul II told gathered scientists that they mustn t inquire into the Big Bang because that was God s territory I would wager with anyone reading this comment that such an assertion is just plain false JPII was a flawed mortal, to be sure, but he was no dope it certainly sounds to me like someone hearing what he thinks the pope would say And the Galileo jokes are pretty dumb does anyone think that JPII, who apologized for the embarrassing Galileo fiasco, would go after this guy It must be all that influence the Vatican has had in Britain over the last 400 years that has him scared Other philosophical complaints involve his use of entropy he defines it first within closed systems and then uses it to explain why the thermodynamic arrow of time and the personal arrow of time must run in the same direction leaping from a box of molecules to the entire universe , his droning on about what black holes are like when he doesn t know for sure they exist, his statements about random and being 95% certain a theory is true does that mean about 95 out of 100 theories like that are true His opinions may be very rich, deep, though provoking, but how would I or most general readers know You can t really evaluate a judgment unless you know something in the field And so that is why I ultimately cannot recommend this book if you know physics inside and out, you might find his opinions interesting If you don t, you can only walk around parroting what he says about black holes as if you had a clue what you were talking about What we all really need is a remedial course in physics Isn t it amazing that a person can read a book like A Brief History of Time by Stephen Hawking and come away feeling both smarter and dumber than before he started What a universe we live in It s quite short and generally a quick read Not every page is filled with mind blowing numbing theories and brain busting equations Some of it is just history, say on Newton and such However, there were a few pages worth of passages where my wee brain felt like it was getting sucked into a black holem Isn t it amazing that a person can read a book like A Brief History of Time by Stephen Hawking and come away feeling both smarter and dumber than before he started What a universe we live in It s quite short and generally a quick read Not every page is filled with mind blowing numbing theories and brain busting equations Some of it is just history, say on Newton and such However, there were a few pages worth of passages where my wee brain felt like it was getting sucked into a black holemainly during the black hole segment.I ve forgotten so much since I left school, and since school was such a long time ago, some of what was taught back then is now outdated, it was nice to read this refresher cleanser I came away with a better understanding of the Big Bang theory and why it s plausible Not the tv show Its existence is not plausible I m trying to sort out the time space quantifiability thing That s going to require a rereadand probably further study elsewhere.Surprisingly, I also came away with the idea that God and science can coexist I didn t expect that I figured someone like Hawking would be like, God Pssh, whatever But that s not his take at all, or at least that not the impression this book left me with A Brief History of Time was written with accessibility in mind, knowing full well idiots like me wouldn t buy it, read it or recommend it if it were impossibly dense Hawking s sense of humor even comes through on occasion, which is always appreciated in these sciencey texty thingies So, I ll probably move on to his Briefer History next and I d be quite willing to read others as well