The Grand Design (Reprint)

Difficult to understand but ,if you were a physician title says what is inside the book

Un gran libro de vulgarizacion científica, que necesita un minimo de formación científica para poder entenderlo. Me gusto mucho y lo aconsejo.

The authors in presenting the prevailing scientific thinking that has evolved over the last ten to twenty years argue that the universe or to be more precise the multiverse that is a virtual infinity of universes each with its own specific set of laws is not the result of divine intervention but rather a spontaneous genesis due to quantum events. The questions the authors address in the book are profound:why is there something rather than nothing? why do we exist? why this particular set of laws and not some other? The slim volume of less than 200 pages and small format addresses the general reader and does not include a single mathematical equation or formula. It is written clearly and concisely but on instances the reader is intimated on subtle distinctions. The reader is introduced gradually to the various relevant concepts while their theory is articulated in the concluding chapter which is the briefest of the lot but the most rigorous with closely weaved arguments. The authors adopt a view they call model-dependent realism:the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations. This is the framework with which to interpret modern science. According to model-dependent realism it is pointless to ask whether a model is real, only whether it agrees with observation. An additional element is that it might be that to describe the universe, we have to employ different theories in different situations. Each theory may have its own version of reality but according to model-dependent realism, that is acceptable so long as the theories agree in their predictions whenever they overlap, that is, whenever they can both be applied. We are intimated to Feynman's original insight that a system has no just one history but every possible history and quantum theory, and in particular, the approach to quantum theories called alternative theories. In that view, the universe does not have just a single existence or history but rather every possible version of the universe exists simultaneously in what is called quantum superposition. Quantum physics might seem to undermine the idea that nature is governed by laws, but that is not the case. Instead it leads us to to accept a new form of determinism:given the state of a system at some time, the laws of nature determine the probabilities of various futures and pasts rather than determining the future and past with certainty. The book reaches its climax in the concluding chapter in which M-theory the candidate for a complete theory of the universe is presented. The elements and arguments comprising and leading to M-theory are: Any set of laws that describes a continuous world such as ours will have a concept of energy, which is a conserved quantity, meaning that it does not change in time. One requirement any law of nature must satisfy is that it dictates that the energy of an isolated body surrounded by empty space is positive, which means that one has to do work to assemble the body. If the total energy of the universe must always remain zero, and it costs energy to create a body, how can a whole universe be created from nothing? That is why there must be a law like gravity. Because gravity is attractive, gravitational energy is negative. Because gravity shapes space and time, it allows space-time to be locally stable but globally unstable. On the scale of the entire universe, the positive energy of the matter can be balanced by the negative gravitational energy, and so there is no restriction in the creation of the whole universe. Because there is a law of gravity the universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing. The ultimate theory must be consistent and must predict finite results from quantities that we can measure. There must be a law of gravity, and that for a law of gravity to predict finite quantities, the theory must have what is called supersymmetry between the forces of nature and the matter on which they act. M-theory is the most supersymmetric theory of gravity. For these reasons M-theory is the only candidate for a complete theory of the universe.

Il libro è veramente fenomenale, spiegato con il solito stile irresistibile di Hawking. Un must per gli appassionati del genere. Inoltre impaginazione ottima su carta spessa e con illustrazioni a colori. Veramente ben fatto.

Came in a great quality 10/10

I bought it in second hand "condition was acceptable" written on the page. But when i received my book it was in NEW condition, doesn't seemed to be touched. I am in love with the quality.