The Fabric of the Cosmos

The Fabric of the Cosmos

Author: Brian Greene

Publisher: Vintage Books, USA

Pages: 541

Dedication: To Tracy

Rating:

Presentation: 5, Language: 3, Relevance: 4, Depth: 4, Reputation: 4

Brian Green’s excellent book on cosmology and the new trends in cutting edge science is a must read for those who want to stay in touch with what is happening around them. The examples, illustrations, diagrams and presentation are truly relevant to the topics and cleverly chosen so as to produce the greatest convincing effect. He discusses the origin of the universe, fundamental forces of nature and the quest to find a unified theory which can describe all the forces, string/M theory, relativity, concepts of time travel etc.

Some of the quotations from the book are

Difference between classical and quantum physics

A core feature of classical physics is that if you know the positions and velocities of all objects at a particular moment, Newton’s equations , together with their Maxwellian updating, can tell you their positions and velocities at any other moment, past or future. Without equivocation, classical physics declares that the past and future are etched into the present. This feature is also shared by both special and general relativity. Although the relativistic concepts of past and future are subtler than their familiar classical counterparts, the equations of relativity, together with a complete assessment of the present, determine them just as completely

By the 1930’s, however, physicists were forced to introduce a whole new conceptual schema called quantum mechanics. Quite unexpectedly, they found that only quantum laws were capable of resolving a host of puzzles and explaining a variety of data newly acquired from the atomic and subatomic realm. But, according to the quantum laws, even if you make the most perfect measurements possible of how things are today, the best you can ever hope to do is predict the probability that things will be one way or another at some chosen time in the past. The universe, according to quantum mechanics, is not etched into the present; the universe, according to quantum mechanics, participates in a game of chance.

A curious thing about special relativity

Special relativity declares that the combined speed of any object’s motion through space and its motion through time is always precisely equal to the speed of light. At first, you may instinctively recoil from this statements since we are all used to the idea that nothing but light can travel at light speed. But that familiar idea refers solely to motion through space. We are now talking about something related, yet richer: an object’s combined motion through space and time. They key fact, Einstein discovered, is that these two kinds of motion are always complementary. When the parked car you are looking at speeds away, what really happens is that some of its light-speed motion is diverted from motion through time into motion through space, keeping their combined total unchanged. Such diversion unassailably means that the car’s motion through time slows down.

Tachyons

Special relativity forbids anything that has ever traveled slower than light speed from crossing the speed-of-light barrier. But if something have always been traveling faster than light, it is not strictly ruled out by special relativity. Hypothetical particles of this sort are called tachyons. Most physicists believe tachyons don’t exist, but others enjoy tinkering with the possibility that they do. So far, though, largely because of the strange features that such a faster-than-light particle would have according to the equations of special relativity, no one has found any particular use for them- even hypothetically speaking. In modern studies, a theory that gives rise to tachyons is generally viewed as suffering from an instability.

A curious thing about entropy

Etched into a tombstone in the Zentralfriedhof in Vienna, near the graves of Beethoven, Brahms, Schubert, and Strauss, is a single equation, S=k log W, which expresses the mathematical formulation of a powerful concept known as entropy. The tombstone bears the name of Ludwig Boltzmann, one of the most insightful physicists working at the turn of the last century. In 1906, in failing health and suffering from depression, Boltzmann committed suicide while vacationing with his wife and daughter in Italy. Ironically, just a few months later, experiments began to confirm that ideas Boltzmann had spent his life passionately defending were correct.

Higgs Field

There are matter fields and force fields, but in addition to that, many physicists believe that there is yet a third kind of field, one that has never been experimentally detected but that over the last couple of decades has played a pivotal role both in modern cosmological thought and in elementary particle physics. It is called a Higgs field, after the Scottish physicist Peter Higgs.

Casimir force

Think about two plain, ordinary, uncharged metal plates in an empty region of space, facing one another. As their masses are tiny, the gravitational attraction between them is so small that it can be completely ignored. Since there is nothing else around, you naturally conclude that the plates will stay put. Casimir concluded that the plates would be gently guided by the ghostly grip of quantum vacuum fluctuations to move toward one another. When Casimir first announced these theoretical results, equipments sensitive enough to test his predictions didn’t exist. Yet, within about a decade, another Dutch physicist, Marcus Spaarnay, was able to initiate the first rudimentary tests of this Casimir force, and increasingly precise experiments have been carried out ever since.

Overall rating: 4/5