A Brief History of Time: From the Big Bang to Black Holes is a popular-science book on cosmology by British physicist Stephen Hawking. It was first published in . #1 NEW YORK TIMES BESTSELLER A landmark volume in science writing by one of the great minds of our time, Stephen Hawking's book explores such. A Brief History of Time book. Read reviews from the world's largest community for readers. In the ten years since its publication in , Stephen.
|Language:||English, Arabic, Hindi|
|Genre:||Academic & Education|
|ePub File Size:||29.58 MB|
|PDF File Size:||19.43 MB|
|Distribution:||Free* [*Registration needed]|
A Brief History Of Time by Stephen Hawking, , available at Book Depository with free delivery worldwide. Hawking's discovery that black holes emit particles caused great excitement among astronomers. In this succinct overview of current theories of the cosmos, the. physicists in history, wrote the modern classic A Brief History of Time to help of its contents stretch the reader further than is usually expected in a book of this .
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?
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.
Frequently bought together
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 download 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. 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. As Hawking points out, there are four forces that have been identified: 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.
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.
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.
Book review: A Brief History of Time
I have also commented on this book in my review on Interstellar. View all 24 comments. View all 13 comments. 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 Hawking wrote the book for nonspecialist readers with no prior knowledge of scientific theories.
Dec 17, Simon Clark rated it it was amazing Shelves: 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 This is an absolutely magical book, both objectively and for me specifically. 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. I know. I both loved and hated this book. I definitely should never have read this book, cut the pages, opened the box, etc.. Look, no doubt the guy is a genius and has a fantastic story ALS, computer voice, nurses, Black Holes, strippers, movies, etc.
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. Nov 22, Manny rated it it was ok Shelves: 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. Then download A Brief History of Rhyme.
View all 29 comments. I've had this on my shelf for years, but somehow I've never got round to actually reading it. Time to see what it's all about! View 1 comment. Aug 30, Matthew rated it it was ok. 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 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. 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. View all 17 comments. 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! Being Indian, I loved this - because we are strong champions of cyclical time. Also, if time and space are both curved, Manny says this book is in the "bought but not read" category for most people.
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!
View 2 comments. Dec 08, Trevor rated it really liked it Shelves: 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. 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.
If you're into stuff like this, you can read the full review. On Horse-Flies: For starters, I'm great at killing horse-flies by hand. Should I get some black pyjamas and a balaclava and become a ninja? And there was me thinking that the horse-fly's all round vision and short nerve pathway had something to do with their reaction speed. Move aside Hawking!
Dec 20, Shine Sebastian rated it it was amazing Shelves: Without a doubt a masterpiece! It's just incredible how Hawking explains to us the complex and mindboggling secrets and concepts of physics and our universe, with amazing wit , clarity, and simplicity.
Stephen Hawking: Why you might want to give A Brief History Of Time another go
The questions that we all used to ask to ourselves and to our parents, about god, about time, life and it's meaning, the sky, stars, about who created our universe and about it's beginning, about our fate But there are quite a few people, whose curiosity and desire to find out more, to explore the truths of this vast universe, never dies.
They are always always on the lookout for answers to questions deemed unanswerable , and then to ask new questions , that one by one, fills the gap between us and the truth and makes our understanding of this universe and it's secrets a bit more clearer and deeper, Stephen Hawking is one such blessed genius!
In this book, Hawking familiarise us with the possible beginning of the universe or space-time , which is called the Big Bang Singularity, the Black Holes with extremely strong gravitational force so that even light can't escape from it, the reasons why we are at this time and space of the universe [ this might be because that the present condition, universe if there are other universes , and dimensions are the only configuration which allows the existence of intelligent beings like us who can observe and ask these questions], the long quest for a Grand Unification Theory that will explain the whole universe completely which still continues, and so many more fascinating and incredible stuff.
The writing style is highly enjoyable, Hawking is a great teacher and a wonderful writer, his wit and engaging writing makes me forget that I'm reading a scientific book! Highly recommended to everyone who wants to know a little more about this universe and it's secrets. Jul 23, Nikki rated it liked it Shelves: Stephen Hawking's book is easy to read, but harder to comprehend. In every chapter came a point where my brain couldn't hold another permutation of a theory, and as the book progressed, I ended up taking the same approach as I do when reading a Norse saga for the first time.
With sagas, I just read, even if my brain doesn't seem to retain all the information about who is related to who and what they named their horse. Inevitably, at the end, I have a reasonable basic grasp of the saga, and then Stephen Hawking's book is easy to read, but harder to comprehend.
Inevitably, at the end, I have a reasonable basic grasp of the saga, and then I have to read it over again to fit more information into that basic understanding. I don't know if the same will hold true here, but it's a nice hope. Sep 29, Michael Finocchiaro rated it it was amazing Shelves: A classic text where the amazing Stephen Hawking explains string theory and quantum mechanics "for dummies. I need to go back and read this one again myself! Oct 07, Mohammed rated it liked it.
View all 20 comments. Sep 26, Miquel Reina rated it it was amazing Shelves: Oh, this is definitely one of my favorite books of science and my favorite one of Stephen Hawking. I love the way Hawking explains concepts so abstract and difficult to understand as time or black holes. It's a science book for the general public; you don't need to know math or physics to understand the amazing concepts about the Universe he tries to explain us.
Spanish version: Lo recomiendo a todo el mundo, no solo a los amantes de la ciencia. All I can really tell you with certainty is 'A Brief History of Time' is very logically organized, but as each chapter described a series of linked discoveries and what it all meant, unfortunately it mostly was still opaque to me. Topics are introduced logically as Stephen Hawking describes in plain English the discoveries of scientists. He usually begins with observable phenomena which have led to verified maths not actually detailed demonstrating very likely how the Universe, and presumably All I can really tell you with certainty is 'A Brief History of Time' is very logically organized, but as each chapter described a series of linked discoveries and what it all meant, unfortunately it mostly was still opaque to me.
He usually begins with observable phenomena which have led to verified maths not actually detailed demonstrating very likely how the Universe, and presumably Time with it, came into existence. Hawking does not detail the math in 'A Brief History of Time', but he tries to explain the significance of the observations. The Universe operates in a manner which can be predicted once the math formulas are sussed out from the objects being observed, or at least the side effect of an unseen act can be observed.
Each discovery builds on older discoveries, which leads to more knowledge. I can tell I grasped only the surface of how each discovery led to a more holistic understanding of many separate ideas from many separate pieces. To me, it seems like each scientist was figuratively designing a personal knitted pattern for an afghan square observation, experiment and math , which is ultimately tried on to fit into a larger, but incomplete, afghan of many other formerly disparate squares, placing it where to the scientists' best judgement the square seems to work out or sometimes not, and sometimes the mismatched piece has to be unraveled and redesigned, or moved elsewhere.
But I have difficulty in understanding some of the individual designs of the pieces, and I don't know sometimes why scientists have decided this piece must fit there in that location; however, I understand the ultimate description of conclusions reached which have been the result from the fit of the pieces. I can see Astronomy is where everything learned since the Ancient Greeks, but especially from the discoveries of Galileo Galilei, Isaac Newton and Albert Einstein, has been like adding cars to a train engine, delivering more and more understanding about the size of the universe, its age, its chemistry and its elements, and how stars and galaxies came into being from a variety of small elemental particles responding to forces; all of which shockingly behave in a manner which can be mathematically described and reproduced.
Sadly, I understood only half of the book despite reading it cover to cover and studying the included illustrations, and referring again and again to the included glossary and index in back. No, not. Actually I'm not kidding. Reading this did not cause my brain to fizz, or jizz.
If a high frequency light is used, the light can find the position more accurately but the particle's speed will be unknown because the light will change the speed of the particle. If a lower frequency light is used, the light can find the speed more accurately but the particle's position will be unknown. The uncertainty principle disproved the idea of a theory that was deterministic, or something that would predict everything in the future.
Here is a picture of a light wave. How light behaves is also talked more about in this chapter. Some theories say that light acts like particles even though it really is made of waves; one theory that says this is Planck's quantum hypothesis.
A different theory also says that light waves also act like particles; a theory that says this is Heisenberg's uncertainty principle. Light interference causes many colors to appear. Light waves have crests and troughs. The highest point of a wave is the crest, and the lowest part of the wave is a trough. Sometimes more than one of these waves can interfere with each other - the crests and the troughs line up. This is called light interference. When light waves interfere with each other, this can make many colors.
An example of this is the colors in soap bubbles. Chapter 5: Elementary Particles and Forces of Nature[ edit ] Quarks and other elementary particles are the topic of this chapter.
Quarks are very small things that make up everything we see matter. There are six different "flavors" of quarks: the up quark, down quark, strange quark, charmed quark, bottom quark, and top quark. Quarks also have three "colors": red, green, and blue. There are also anti-quarks, which are the opposite of the regular quarks. In total, there are 18 different types of regular quarks, and 18 different types of anti quarks.
Quarks are known as the "building blocks of matter" because they are the smallest thing that make up all the matter in the universe.
A particle of spin 1 needs to be turned around all the way to look the same again, like this arrow. All particles for example, the quarks have something called spin. The spin of a particle shows us what a particle looks like from different directions. For example, a particle of spin 0 looks the same from every direction. A particle of spin 1 looks different in every direction, unless the particle is spun completely around degrees.
Hawking's example of a particle of spin 1 is an arrow. A particle of spin two needs to be turned around halfway or degrees to look the same. The example given in the book is of a double-headed arrow. All of these particles follow the Pauli exclusion principle. Pauli's exclusion principle says that particles cannot be in the same place or have the same speed.
If Pauli's exclusion principle did not exist, then everything in the universe would look the same, like a roughly uniform and dense "soup". This is a proton. It is made up of three quarks. All the quarks are different colors because of confinement.
Particles with a spin of 0, 1, or 2 move force from one particle to another. Some examples of these particles are virtual gravitons and virtual photons. Virtual gravitons have a spin of 2 and they represent the force of gravity.
This means that when gravity affects two things, gravitons move to and from the two things. Virtual photons have a spin of 1 and represent electromagnetic forces or the force that holds atoms together. Besides the force of gravity and the electromagnetic forces, there are weak and strong nuclear forces. Weak nuclear forces are the forces that cause radioactivity , or when matter emits energy. Strong nuclear forces are the forces that keep the quarks in a neutron and a proton together, and keeps the protons and neutrons together in an atom.
The particle that carries the strong nuclear force is thought to be a gluon. The gluon is a particle with a spin of 1.
The gluon holds together quarks to form protons and neutrons. However, the gluon only holds together quarks that are three different colors. This makes the end product have no color. This is called confinement. Some scientists have tried to make a theory that combines the electromagnetic force, the weak nuclear force, and the strong nuclear force. This theory is called a grand unified theory or a GUT.
This theory tries to explain these forces in one big unified way or theory. Chapter 6: Black Holes[ edit ] A picture of a black hole and how it changes light around it. Black holes are talked about in this chapter. Black holes are stars that have collapsed into one very small point.
This small point is called a singularity. Black holes suck things into their center because they have very strong gravity.
Some of the things it can suck in are light and stars. Only very large stars, called super-giants, are big enough to become a black hole. The star must be one and a half times the mass of the sun or larger to turn into a black hole. This number is called the Chandrasekhar limit. If the mass of a star is less than the Chandrasekhar limit, it will not turn into a black hole; instead, it will turn into a different, smaller type of star.
The boundary of the black hole is called the event horizon. If something is in the event horizon, it will never get out of the black hole. Black holes can be shaped differently. Some black holes are perfectly spherical - like a ball. Other black holes bulge in the middle. Black holes will be spherical if they do not rotate. Black holes will bulge in the middle if they rotate. Black holes are difficult to find because they do not let out any light. They can be found when black holes suck in other stars.
When black holes suck in other stars, the black hole lets out X-rays , which can be seen by telescopes. In this chapter, Hawking talks about his bet with another scientist, Kip Thorne. Hawking bet that black holes did not exist, because he did not want his work on black holes to be wasted. He lost the bet. Hawking realized that the event horizon of a black hole could only get bigger, not smaller. The area of the event horizon of a black hole gets bigger whenever something falls into the black hole.
He also realized that when two black holes combine, the size of the new event horizon is greater than or equal to the sum of the event horizons of the two original black holes.
This means that a black hole's event horizon can never get smaller.
Disorder, also known as entropy , is related to black holes. There is a scientific law that has to do with entropy.
This law is called the second law of thermodynamics , and it says that entropy or disorder will always increase in an isolated system for example, the universe. The relation between the amount of entropy in a black hole and the size of the black hole's event horizon was first thought of by a research student Jacob Bekenstein and proven by Hawking, whose calculations said that black holes emit radiation.
This was strange, because it was already said that nothing can escape from a black hole's event horizon. This problem was solved when the idea of pairs of "virtual particles" was thought of. One of the pair of particles would fall into the black hole, and the other would escape.
This would look like the black hole was emitting particles. This idea seemed strange at first, but many people accepted it after a while. Chapter 8: The Origin and Fate of the Universe[ edit ] The Big Bang and the evolution of the universe How the universe started and how it might end is discussed in this chapter. Most scientists agree that the universe started in an expansion called the Big Bang. The model for this is called the "hot big bang model". When the universe starts getting bigger, the things inside of it also begin to get cooler.
When the universe was first beginning, it was infinitely hot. The temperature of the universe cooled and the things inside the universe began to clump together. Hawking also discusses how the universe could have been.
For example, if the universe formed and then collapsed quickly, there would not be enough time for life to form. Another example would be a universe that expanded too quickly. If a universe expanded too quickly, it would become almost empty. The idea of many universes is called the many-worlds interpretation. Inflationary models and the idea of a theory that unifies quantum mechanics and gravity also are discussed in this chapter. Each particle has many histories. This idea is known as Feynman's theory of sum over histories.
A theory that unifies quantum mechanics and gravity should have Feynman's theory in it. To find the chance that a particle will pass through a point, the waves of each particle needs to be added up. These waves happen in imaginary time. Imaginary numbers, when multiplied by themselves, make a negative number. Chapter 9: The Arrow of Time[ edit ] In this chapter Hawking talks about why "real time" as humans observe and experience it in contrast to the "imaginary time" in the laws of science seems to have a certain direction, notably from the past towards the future.
The things that give time this property are the arrows of time. Firstly, there is the thermodynamic arrow of time. According to this, starting from any higher order organized state, the overall disorderliness in the world always increases as time passes.
A Brief History of Time
This is why we never see the broken pieces of a cup gather themselves together to form a whole cup. Even though human civilizations have tried to make things more orderly, the energy dissipated in this process has created more overall disorder in the universe.
The second arrow is the psychological arrow of time. Our subjective sense of time seems to flow in one direction, which is why we remember the past and not the future. Hawking claims that our brain measures time in a way where disorder increases in the direction of time.
We never observe it working in the opposite direction. In other words, the psychological arrow of time is intertwined with the thermodynamic arrow of time. Thirdly there is the cosmological arrow of time, the direction of time in which our universe is expanding and not contracting.
Hawking believes that in order for us to observe and experience the first two arrows of time, the universe would have to begin in a very smooth and orderly state. And then as it expanded, it became more disorderly. So the thermodynamic arrow agrees with the cosmological arrow. Because of the "no boundary" proposal for the universe, after a period of expansion, the universe will probably start to contract. It will probably not go backwards in time to a more smooth, orderly state.
The thermodynamic arrow in the contracting phase will not be as strong. As for why humans experience these three arrows of time going in the same direction, Hawking postulates that humans have been living in the expanding phase of the universe. He thinks that intelligent life couldn't exist in the contracting phase of the universe. Only the expanding phase of the universe is suitable for intelligent beings like humans to exist, because it contains a strong thermodynamic arrow.
Hawking calls this the "weak anthropic principle". Chapter The Unification of Physics[ edit ] The fundamental objects of string theory are open and closed strings.
Physicists have come up with partial theories to describe a limited range of things, but a complete, unified and consistent theory which can take into account all of these partial theories remain unknown.
Hawking is cautiously optimistic that such a unified theory of the universe may be found soon. Such a theory must combine the classical theory of gravity with the uncertainty principle found in quantum mechanics.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.
Rating details. Black holes are difficult to find because they do not let out any light. In the ten years since its publication in , Stephen Hawking's classic work has become a landmark volume in scientific writing, with more than nine million copies in forty languages sold worldwide. It was assumed that since some stars are red shifted, some stars would also be blue shifted.
- J2EE 1.4 PROJECTS BLACK BOOK PDF
- NOVEL LUPUS BETE PDF
- LIVRO WICCA PARA INICIANTES PDF
- TWILIGHT BOOK IN FRENCH
- SOLAR ENERGY SYSTEM PDF
- OXFORD TEXTBOOK OF PALLIATIVE MEDICINE PDF
- MODERN CHESS OPENINGS 15TH EDITION PDF
- ANTENNA BY JD KRAUS PDF
- NATIONAL TREASURE BOOK OF SECRETS IN HINDI
- DIGITAL WATERMARKING PDF
- LAGU EBIET G ADE BERJALAN DIHUTAN CEMARA