A Brief History of Time

Bill

Rating: really liked it
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.

* * *
August 30, 2022 addendum --

Time to jump in here, I fear:

Having garnered over 650 "Likes," this far-from-serious scribble is by far my most popular review ever — and, truth be told, undeservedly so.

For a more thoughtful consideration of a somewhat related book, try my take on Jim Holt's Why Does the World Exist? here: https://www.goodreads.com/book/show/8...

Daniel

Rating: really liked it
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 have more than 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!

Ahmad Sharabiani

Rating: really liked it
A Brief History of Time: From the Big Bang to Black Holes, Stephen Hawking

What is it that our eyes do that could possibly affect things?

A Brief History of Time: From the Big Bang to Black Holes is a popular-science book on cosmology (the study of the universe) by British physicist Stephen Hawking. It was first published in 1988. Hawking wrote the book for nonspecialist readers with no prior knowledge of scientific theories.

In A Brief History of Time, Stephen Hawking attempts to explain a range of subjects in cosmology, including the Big Bang, black holes and light cones, to the non-specialist reader.

His main goal is to give an overview of the subject, but he also attempts to explain some complex mathematics.

In the 1996 edition of the book and subsequent editions, Hawking discusses the possibility of time travel and wormholes and explores the possibility of having a Universe without a quantum singularity at the beginning of time.

تاریخ نخستین خوانش: روز چهارم ماه مارس سال 1996میلادی

عنوان: تاریخچه زمان: از انفجار بزرگ تا سیاهچالها؛ نوشته: استیون هاوکینگ؛ مترجم: محمدرضا محجوب؛ نشر: تهران، انتشار، چاپ نخست 1369، مشخصات ظاهری 231ص، مصور، نمودار، چاپ سوم: زمستان 1369؛ ‏چاپ پنجم: 1375؛ چاپ ششم: 1378؛ چاپ هفتم: 1380؛ ‌شابک ایکس-964573519؛ موضوع نوشتارهای نویسندگان بریتانیا - سده 20م

این کتاب به عنوان پرخوانشگرترین کتاب «کیهان‌ شناسی» شهرت یافته، و به بیش از سی و سه زبان دنیا تا سال1993 میلادی، ترجمه و چاپ شده‌ است «هاوکینگ» در این کتاب با زبانی ساده به بازگویی داستان جهان پرداخته است

در مورد مفاهیم اساسی مانند «فضا» و «زمان»، بلوک‌های اساسی ساختاری، که جهان را تشکیل می‌دهد (مانند کوارک‌ها)، و نیروهای اساسی حاکم بر آن (همانند گرانش) گفتگو می‌کند؛ ایشان در مورد پدیده‌ های کیهان‌شناختی مانند «بیگ بنگ» و «سیاه ‌چاله‌ها» نیز می‌نویسند؛ «هاوکینگ» این کتاب را برای خوانشگرانی که هیچ دانش پیشین درباره ی گیتی ندارند، برای آنهایی که تنها علاقمند به یادگیری چیزهای تازه در اینباره هستند، نوشتند؛

مینویسند: (روزی یک دانشمند مشهور -گویا برتراند راسل- درباره ی نجوم یک سخنرانی عمومی کرد، در آن سخنرانی او شرح داد که چگونه زمین به دور خورشید می‌چرخد، و خورشید نیز به نوبه خود به دور مرکز مجموعه عظیمی از ستاره‌ها به نام کهکشان ما می‌چرخد؛ در پایان سخنرانی، پیرزن نحیفی در انتهای سالن به پا خاست و گفت: «آنچه که به ما گفتی مزخرف است؛ جهان صفحه‌ای صاف است که بر پشت یک لاک‌پشت غول‌پیکر قرار دارد.»؛ دانشمند قبل از پاسخ دادن لبخند متکبرانه‌ای زد و سپس گفت: «خوب آن لاک‌پشت بر روی چه ایستاده است؟»؛ پیرزن گفت: «مرد جوان، تو خیلی زیرکی، ولی لاک‌پشت‌های بیشماری تا آن پایین روی هم قرار دارند!»؛ اکثر مردم تصویری از جهان را به عنوان برج بلندی که از تعداد نامحدودی لاک‌پشت روی هم قرار گرفته و تشکیل شده است مضحک و مسخره می‌پندارند، اما چرا ما فکر می‌کنیم چیز بهتری می‌دانیم؟ ما درباره جهان چه می‌دانیم و چگونه این دانش را کسب کرده‌ایم؟ جهان از کجا پدید آمده است و به کجا می‌رود؟ آیا جهان آغازی دارد و اگر چنین است، قبل از آن چه اتفاقی روی داده است؟ ماهیت زمان چیست؟ آیا روزی به پایان خواهد رسید؟ آیا ما می‌توانیم در زمان به عقب برگردیم؟ پیشرفت‌های اخیر در فیزیک، که تا حدودی فن‌آوریهای جدید شگفت‌انگیز هستند، به این پرسش‌های دیرینه پاسخ‌هایی ارائه می‌دهند؛ ممکن است روزی این پاسخ‌ها به اندازه گردش زمین به دور خورشید برای ما بدیهی به نظر برسند، یا شاید به اندازه برجی از لاک‌پشت‌ها مسخره جلوه کنند. فقط گذشت زمان -هر چه که باشد- می‌تواند حقیقت را روشن کند.)؛

تاریخ بهنگام رسانی 18/07/1399هجری خورشیدی؛ 11/06/1400هجری خورشیدی؛ ا. شربیانی

Jason Koivu

Rating: really liked it
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 hole...mainly 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 reread...and 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!

Sean Barrs

Rating: really liked it
Stephen Hawking writes in a very simple and approachable way. On the surface the book has been written for the common man, for he who has little knowledge of theoretical physics.

Hawking uses basic terminology and he tries not to overload his writing with explanations and information dumps, but at times it is very clear that the reader needs a certain level of knowledge to understand what he's talking about. As such, Hawking makes certain assumptions as he shifts from concept to concept which left me a little confused. Things that don't appear related are related and it made me question who the intended readership really was.

I do believe this is a book every reader should try because it is an important one, full of discussions and ideas that could really open up your mind. But I would warn you to be prepared, although this seems like light reading, much of it may go over your head.

Approach with caution.

David Sarkies

Rating: really liked it
Things I learnt from Stephen Hawking
11 October 2014

Ever since I took up physics in year 11 I have had a love affair with the subject, which is odd since I went on to study an arts/law degree (but that probably had something to do with the fact that I would not have had the staying power to pour all of my energy into helping human knowledge advance towards establishing a unified theory). I still wonder where I ended up getting this book, and it had been sitting on my shelf for quite a while (probably because I was too busy listening to people tell me why I shouldn't read this book), but it wasn't until John Lennox said that it was the most unfinished book (that is people start reading it but do not have the staying power to get to the end) ever written (I'm sure there are other books that beat this book though). There are quite a few things that I have discovered while reading this book, and it is these discoveries that I wish to share with you:

1) This is not an anti-God book
One of the impressions that I got from certain people was that this was a book that an atheist wrote to try to argue that God does not exist, in much the same way that Richard Dawkins does in his books. However, that statement could not be further from the truth. In fact, throughout the book the question of the existence of God perpetually hangs in the background. Granted, Hawkings does suggest that if the concept of a infinite bounded universe (don't ask) turns out to be true then it would undermine God's existence, however he does not actually say that this may be the case. In fact his final sentence in this book is that the reason we study physics and try to find a unified theory is because we, as a race, seek to understand the mind of God.

2) Stephen Hawkings is actually a really good writer
This probably goes without saying, especially since the cover of my book says that it is a 'record breaking best seller'. While he is involved in some very serious and complicated research he is able to write in a way that many of us who have probably studied physics up to a year twelve level (that is the end of High school) can understand. Okay, I probably have an advantage over most other people since my Dad is a theoretical physicist that we have regular conversations about some of these high level concepts (such as by having any more than three dimensions would cause the orbits of the planets to collapse), but I still found that he was very easy to follow and he explained many of these high level concepts in a way that many of us could understand.

3) Scientists have a strange way of viewing the universe
Many of us would be familiar with this guy:



but as it turns out, after reading this book, I have come to the conclusion that a lot of theoretical physicists seem to live in the same world that he does. Okay, they probably don't spend their time at the comic book store, or arguing whether Babylon Five is better than Star Trek (actually, one of my primary school friends is a theoretical physicist, and we did have such an argument), but they do seem to see the world in a way that we ordinary people would consider strange.

For instance, we see space as flat, meaning that if we look at a star, as far as we are concerned the star is in that direction. However physicists see space as being curved and that a straight line is not necessarily straight. We would see a brick wall as being a solid object and that the idea of walking through one would result in a sore nose. However physicists see it as being made up of mostly space, and the only reason we can't walk through it is because the nuclear forces (forces that exist inside an atom, not the force that can level an entire city) prevent us for doing so. Then there is the concept of dimensions: to us there are only three dimensions, however some scientists (and Hawking is not one of them) see that there are in fact ten, or even more, dimensions.

4) Why are so many scientists atheists
While reading this book I could not get past about how complex this universe is and it made me wonder why it is, with the mathematical precision of the universe, and the complexity that lies therein, that so many scientists seem to argue that it all came about by chance. Even Hawking argues, using the second law of thermodynamics, that the universe cannot move from a state of disorder to a state of order – a broken plate simply cannot mend itself. However, the argument also goes that with the Big Bang Theory (not the television show) that the universe began in a state of disorder and moved to a state of order, however the laws of physics seem to suggest otherwise because what the big bang did was sent in motion a series of laws that caused the universe to come about to what we have at the moment. However, to go into details would require some intense theoretical physics, something which I have do desire to delve into at the moment.

5) Scientists assume the speed of light is a constant
The truth is that it is not. Okay, if light were travelling through a vacuum where there are no external forces acting upon it, then it is a constant, but that is very rarely the case. Take for instance this phenomena:



The reason light behaves thus is because when it hits the prism it SLOWS DOWN, and when it slows down it refracts. Thus my point is proven, the speed of light is only a constant when there are no external forces acting upon it.

So, what external forces may act upon light in space. Well, first of all there are black holes. When light hits a black hole the force of gravity is so strong that it will actually prevent light from escaping. Thus, gravity is a force that effects light and slows it down. Then there is the concept of dark matter, which are clouds of matter that do not emit light and float between the star systems. Okay, we know very little about the stuff (and it is also a theory, so it has not been proven) but my hypothesis is that if this stuff exists then would it not have an effect upon light, namely by slowing it down, which means that there is a possibility that our calculations as to the distance of stars from our own Sun could actually be wrong?

6) Scientists do not know as much as we think they know
One of the things that Hawking stresses in this book is that theories are not actually proven. A theory is an idea that has some foundation based on mathematical calculations and empirical evidence. Therein lies the problem. Much of our understanding of the universe is based upon mathematical calculations, and it appears that if an event comes about which causes this mathematical calculation to break down, they immediately set out to try to find another mathematical equation to plug the hole.

Take light for instance. For years we believed that light acted as a wave and suddenly it was discovered that it also behaves like a particle (a particle of light is called a photon). The same goes with matter – for years we believed that they were particles when all of the sudden we discovered that they can also behave like waves. As such, our understanding of the universe suddenly breaks down (meaning that we are not necessarily made up of atoms, but have wavelike properties as well).

Mathematical equations have been very destructive in out modern world. Take the Global Financial Crisis for instance. A bunch of apparently really smart people create complex mathematical equations to determine when to buy and sell shares and how to make billions of dollars. However what these equations did not take into account was the fact that people could not simply continue to accumulate debt without having to pay it back and when people began to default on their loans enmass, the whole concept broke down and we were taken to the brink of financial armageddon.

Another point goes back to Ancient Greece. Here we have the theory of Democritus, namely that matter was not infinitely indivisible (the smallest piece of matter is an atom), and then the theory of Aristotle, that is that matter is infinitely divisible. Scientists preferred Democritus' theory, however they soon discovered that you could break down the atom into protons and neutrons, and you could even break them down to quarks. So, maybe Aristotle was right after all.

7) We accept their theories because our gadgets work
It goes without saying that their research and discoveries have lead to the computer that I am writing this on, the energy that powers our devices, and the bombs that can level entire cities. We know how to make a nuclear bomb, as well as a smart phone, so we don't question what they say, because it obviously works. However, as a friend of mine once said, it is still all based on theory, and just because something works does not necessarily mean that the theory is correct. Remember that penicillin was discovered by blind chance.

8) Nobel Prizes are simply shiny baubles that have no merit
Okay, maybe the people that win these prizes are actually really smart, but then again, the guys who set up Long-Term Capital Management also won a Nobel prize, which proves my point.

9) Nobody really knows how gravity works
Gravity is one of those odd forces that doesn't seem to connect with any of the other forces in our universe. As Hawking points out, there are four forces that have been identified: electro-magnetic, strong nuclear, weak nuclear, and gravity. Out of those four forces (five if you divide electric and magnetic, but since electricity will create a magnetic force, they are effectively combined) only gravity stands out. This is probably why Hawking spends so much time talking about black holes because black holes are where the gravitational pull is so strong that not even light can escape from its grasp. The other thing is that gravity does not, at least in our knowledge, have an opposing force. Gravity basically sucks, and that is all it does – it doesn't repulse as the other forces can.

It is interesting that in some texts that I have read (maybe it is speculative science-fiction but I simply cannot remember off the top of my head) some people have suggested that gravity is actually a force from another universe that affects our universe and what it is effectively doing is sucking our universe into their universe. However, as I have said, that is incredibly speculative, and since I am not a theoretical physicist I can't really say any more on the subject.

10) The God of the Gaps is a cop-out
The idea of the God of the Gaps is that where there are gaps in our knowledge we simply say 'oh, God did that' and think nothing more of it. This goes back to the days of paganism (and Medieval Europe) where all of the unknown forces, such as the weather, was attributed God (or the gods) and we could not know anything beyond that fact. However I am arguing that it is a cop out. Creation scientists who resort to this argument are at best lazy and at worst dangerous. The reason I say that is that it discourages research into areas that we do not understand. Okay, we may never be able to control the weather, or predict earthquakes, but that does not mean that we should throw our hands up in the air and say 'this is too hard'.

While I may be taking a swipe at creation scientists here, I would also take a swipe at the atheists who claim that there is no God. The reason I say that is because there seems to be a fear within the scientific community that suggests that we may not be able to know everything, or that our understanding of the universe may be wrong. The problem that arises is that if we throw the idea of God out of the window and claim that the universe came about by chance, then we deny the fact that we live in an incredibly ordered universe that we can learn and understand through the development of mathematical formulae. If a formulae turns out to be wrong, that does not mean that the universe will collapse in on itself – it won't – it just means that we have to go back to the drawing board and start over from scratch.

11) Why are Creation Scientists so dogmatic
Why is it that some members of the scientific community insist that we must take the Bible literally? The Bible is not a scientific text, and it was never meant to be a scientific text. It is a theological text that tells us how we should live with one another and how we should view God. Science exists beyond the Bible, and neither contradicts the other. Okay, granted, God has intervened in this world and done things that break the laws of science, but doesn't he have a right to do that – he created the universe? However, what the Bible tells us is that God is a god of order, and if he is a god of order then does it not make sense that the universe that he created is an ordered universe?

So, maybe you are looking for a whiz bang conclusion to my exposition on this book, but all I can say is that what I have written above pretty much sums up what I have learnt from this book. In a nutshell (hey, this is me in a nutshell), all I can say is that what I have learnt from this book is that the world is an amazingly ordered place in which we live, and having now completed this book I am just as committed to my Christian faith as I ever was. However, if theoretical physics fascinates you, then this is certainly a book that you should give a read (though you have probably done that already).

This review also appears on my blog. I have also commented on this book in my review on Interstellar.

Simon Clark

Rating: really liked it
This is an absolutely magical book, both objectively and for me specifically. I first read it when I was about 9 or 10, and ever since I've assumed that I didn't understand a thing, and read it as a childish boast. Fast forward nearly twenty years, degree and PhD in physics in hand, and I decided to give it a proper read. Much to my surprise I found that the book had permeated my brain! I remembered a huge number of the explanations, and the book resonated with the way I've thought about physics my entire academic career - I think I took in a great deal more than I first thought!

As a primer to physics (I would say modern physics, but the book is a little out of date) you really couldn't ask for anything better than this. Especially when it comes to cosmology, this is possibly the best popular physics book that I've ever read. It really is a classic for a reason. It's such a concise, understandable introduction to the field that I'm determined to get my girlfriend (a linguist with no real interest in physics) to read it. Not just because I think she'll understand it, but because I think she will enjoy it!

One peculiarity of the text is Hawking returning to the concept of God (with a capital G) over and over again. In some ways this feels like a transitional text, marking the passing of the public generation for whom the church determined the order of all things, and the coming of the current, secular generation. Unlike other authors (looking at you, Dawkins) Hawking always does so in a way that feels respectful while also forcefully stating his scientific case. It's quite feat of writing, much like the rest of the work.

You really should read this, it's fantastic.

Manny

Rating: really liked it
Apparently this book tops the world list of "bought but not read", which may explain why it's so universally acclaimed as a work of genius. If you know anything much about relativity or cosmology, it comes across as a potboiler, admittedly a well-written one with a great final sentence. I wasn't impressed.

But... without it, we would never have had MC Hawking. If you haven't come across him, start with the lyrics to "E = MC Hawking". Then buy A Brief History of Rhyme.

Darwin8u

Rating: really liked it
“The universe doesn't allow perfection.”
― Stephen Hawking, A Brief History of Time



I know. I know. I both loved and hated this book. I definitely should never have read this book, cut the pages, opened the box, etc.. Somehow Stephen Hawking has written a book that gently fluffs the tail on Schrödinger's cat (or perhaps Schrödinger's cat is fluffing Dr. Hawking).

Look, no doubt the guy is a genius and has a fantastic story (ALS, computer voice, nurses, Black Holes, strippers, movies, etc). My problem is the wussification of a large scientific narrative by one of Big “P” Physics primary scientists. Let someone else write a pop-GUT/Blackhole/Big Bang story. Let another writer do the pop-up Children's book with the scratch-n-sniff singularity, the rotating black hole, the pull-out universe.



I want Dr. Hawking doing smart stuff. Let Bill Bryson write the summary science. But it is too late for me. I already crossed the damn event horizon. I've just become entangled with his book, so my "observer state" now corresponds to the damn book and the damn book review being both five stars and 1 stars is no longer a possibility; my reader state is entangled or linked now with my own review so that the "observation of the book review's state" and the "review's state" correspond with each other. I am finished.

Hey, now to go see some movies about blackholes and wormholes and assholes.

Muhammad Abdullah

Rating: really liked it
This is the first book I have ever read about science.This is one of the best selling book of the century.I have found it really infomative and my interest in science seems to build. This book is free from mathematical equations (except E=mc2) which is the best thing about the book. This book is so simple that even a lay person with basic knowledge of science can understand it.

Stephen Hawking, the author of the book, is one of the well renowned scientists of the century after Einstein. Some people even called him the successor of Einstein due to his work in the field of science. In this book, Hawking talks about black holes, worm holes, time travel, cosmic background radiation (CBM), uncertainty principle, expansion of universe, space and time (or simply space-time), origin and fate of the universe, forces of nature and the most important The Grand Unification Theory (the theory of everything) which is the biggest unsolved mystery of the present time.


A brief intro to author, Stephen Hawking

This book is really amazing and is popular in both science and non-science related people. I enjoy it a lot and I would like to recommend it to all the science and nature loving people. And I hope they will also enjoy it.

Luís

Rating: really liked it
This popularization book provides us with a portrait of the latest discoveries that have shaken the scientific world over the past hundred years: General relativity, quantum mechanics, the Principle of uncertainty, black holes, quarks, string theory, etc., enough to answer many questions: what will become of the the our universe? How was it formed? Why is CERN so determined to accelerate particles in a tunnel several kilometres long in Switzerland?
I will not claim to have assimilated all the concepts in a single reading. Still, the book allows me to have a good idea of the stakes and the research. Therefore, I recommend it to any science lover, especially as some of the theories explained will soon celebrate their century of existence and have not yet reached ordinary people.

Nandakishore Mridula

Rating: really liked it
Manny says this book is in the "bought but not read" category for most people. Well, I'm proud to say that I bought and read it, that too in nearly one sitting - back in my geeky days, when I used to get a sexual high just from solving a hard maths puzzle.

Unfortunately, I don't remember much of it (time for a re-read!) but I remember taking away the idea that time is a sphere. Being Indian, I loved this - because we are strong champions of cyclical time. Also, if time and space are both curved, it creates the possibility of jumping from one place and time to another; which is just delicious.

(I bought a pirated edition of this book for 25 rupees from the roadside at Connaught Place in New Delhi. The vendor asked for 50, I said 25, and the bargaining was just starting when he spied a policeman approaching - so he let me have it for whatever I was offering! "Time" was on my side.)

Matthew

Rating: really liked it
Hawking is a brilliant physicist and a true expert in explaining highly complex aspects of our physical universe in terms that can be understood by most lay people.

Where Hawking fails, in my opinion, is his hubris. He proceeds in to the realm of metaphysics and religion in several portions of this book. For instance, in his chapter on the "arrow of time", he states that, essentially, the universe can only move in one direction of time. It cannot go backwards. He also states that this limits the powers of God himself. Now, Hawking never qualifies those statements by defining "God". However, if he is talking about the Biblical God, how can you honestly think you're so intelligent as to place limits on a limitless being? If God is so powerful as to have created the universe and all the physical laws, why wouldn't he be powerful enough to change those laws any time he chooses? It is the same concept as a scientist creating a computer simulation of the universe. The scientist can, at any time during the simulation, alter the underlying framework of the simulation, effectively changing the physical laws that simulated universe operates under.

Now, whether you believe in God or not, the mere fact that Hawking has the audacity to think he can assign limits on a limitless being should cause you some concern. Hawking, because of his fame and brilliance, is a man that people listen to when he speaks. That gives him immense power over the minds of his readers. He should be more careful in choosing his words.

When Hawking sticks to his strengths, however, the book is second to none. Hawking truly has a gift of explaining the powerful forces that shape our lives in ways anyone can understand.

If this book had been edited better, it would have received a few more stars from me, but I can't reward stubborn scientific pride resulting in false assumptions.

Trevor

Rating: really liked 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.

Orhan Pelinkovic

Rating: really liked it
Theoretical Physics from the master himself. It's a great summary, but you need a little background knowledge to understand all the chapters. It's a summary of astrophysics, theoretical physics, and cosmology, and it's hard grasping it all in 200 some pages. I wish it was a little longer.

The definitions at the end of the book are very useful. You will not regret reading the book, but you need some peace and quiet while reading it in order to hopefully understand it.

I've read the A Bantam Book Edition published April 1988 / A Brief History of Time by Stephan W. Hawking / 226 pages / 56,997 words.