The World within the World [Hardcover]

The World Within the World also addresses some other interesting philosophical questions that have been inspired by developments in modern physics. For example, within the infamously counter-intuitive world of quantum mechanics we find that when neutrons are fired at a screen with two openings, even when fired one at a time, they arrive at a target screen behind the double-slit screen like particles would be expected to, making distinct hits on the target screen, yet creating an overall interference pattern which is exhibited in wave phenomena such as water or sound waves. When golf balls are 'fired' in this way through a double-slit screen they do not create an interference pattern. This wave-particle duality is often taught to be a characteristic of light, but it applies to all elementary particles on the subatomic scale. Water and sound waves are waves of a medium--of water and air, respectively. But what does it mean to say that light or a neutron is a wave when these can exist in a vacuum? They are not waves of a medium; rather, they are waves of probability--of information--telling us the probability of finding a photon or a neutron in a particular place when we make a measurement. Heisenberg's Uncertainty principle also tells us that when we try to measure both the position and momentum of a particle, not only are we incapable of measuring both simultaneously, but, far more incomprehensibly, both the position and momentum cannot exist at the same time! This implies that such properties, which we are inclined to think of as inherent properties of the particles, do not exist until they are measured. This is known as the Copenhagen Interpretation of quantum mechanics, which holds that particles are really nothing more than probability wave functions that expand infinitely across the universe and simply have a far higher likelihood of being measured at a certain spot; in other words, the actual location of a particle does not exist until it is measured! In the terminology of quantum mechanics, the act of measurement collapses the wave function.

There is one way out of this dilemma which is consistent with quantum mechanics and allows the position of a particle to be a real property of the particle and not merely a measured property existing only when a measurement takes place. However, while the alternative keeps the observer separate from the observed, it is equally troubling: The Many Worlds Interpretation of quantum mechanics implies that every time the measurement of a particle's position or momentum is made, all possible results obtain--the result we measure obtains in our world, and all the other possible results obtain in an infinite number of worlds for that single act of measurement. This implies that there are an infinite number of versions of you existing in these parallel worlds making these measurements! And you thought science fiction was strange! Perhaps at this point the best option is to maintain that--despite its unprecedented success in explaining the physical world--quantum mechanics is incomplete and therefore neither of the two interpretations adequately characterize the real world. The fact that we have yet to develop a successful quantum theory of gravity suggests that either general relativity or quantum mechanics is incomplete, if not both.

Barrow addresses other interesting issues in modern physics in this book: the categorization of the hundreds of particles that have been discovered into three basic types based on their interactions with the four forces of nature; the possibility of the existence of 10 or 26 dimensions and why only 3 dimensions of space grew larger than microscopic size; the attempt to unify the four forces of nature into a 'Theory of Everything' (TOE); a brief overview of superstrings, a possible candidate for a TOE; some practical diffulties in actually finding a TOE; features of cosmology that make it uniquely different from other sciences; whether the universe is infinite or finite in extent; the evidence that the universe began with the Big Bang; the difficulties in determining whether the universe with expand forever and die a 'Heat Death' or whether it will collapse to a 'Big Crunch'; and the different 'arrows of time' that cosmologists employ. There is also a very interesting dialogue debate in chapter 5 (p. 247-254 in the paperback edition) about whether abstract objects such as numbers exist independently of the mind in some Platonic realm outside of the physical universe, outlining the arguments for and against Platonic abstract objects.

In this book the aim is not simply to pick again upon one of these esoteric fields at the frontiers of fundamental science and attempt to expalin it in simple terms. Rather, it is to pick upon the traitional unspoken assumptions to which we owe all these abstract and pragmatic developments: that the Universe is ordered, that it is logical, that it is mathematical, that it is predictable, that it is governed by something outside ourselves which is the same everywhere, but which has a deep resonance with the workings of our own minds: to explore something of the origin and possible meanings of the idea that there exist "laws of Nature" and some of the unsuspected realms that such an idea has led us.

So, with this being said, I found that unless you have some science background you will not get much use from this book as it is. Also, there is a message in the book, although laws of Nature may be necessary for such grand explanations, broken symmetries, organizing principles, selection effects, and human categories of thought all play essential and irreductible role in augmenting any law of Nature to determine a picture of the Universe in which we live.

This book has seven parts and each of these has various topics that are discussed in detail, giving the reader a dose of historical context along with cutting edge science. From inner space to outer space, there are mathematical laws of Nature that explain what nature is. A changeless world of order and certainty, impartial to our actions and desires.

I found the book can get difficult at times and I had to stop and ruminate, contemplate, and engage in serious thought... not that that wasn't a good thing. This is a book that will make you think.