Roger Penrose
THE ROAD TO REALITY
A Complete Guide to the Laws of the Universe


The purpose of this book is to convey to the reader some feeling for
what is surely one of the most important and exciting voyages of discovery
that humanity has embarked upon. This is the search for the underlying
principles that govern the behaviour of our universe. It is a voyage that
has lasted for more than two-and-a-half millennia, so it should not surprise
us that substantial progress has at last been made. But this journey
has proved to be a profoundly diYcult one, and real understanding has,
for the most part, come but slowly. This inherent diYculty has led us
in many false directions; hence we should learn caution. Yet the 20th
century has delivered us extraordinary new insights—some so impressive
that many scientists of today have voiced the opinion that we may be
close to a basic understanding of all the underlying principles of physics.
In my descriptions of the current fundamental theories, the 20th century
having now drawn to its close, I shall try to take a more sober view.
Not all my opinions may be welcomed by these ‘optimists’, but I expect
further changes of direction greater even than those of the last century.