14/1/03: Introduction

To see the world in a grain of sand
And heaven in a wild flower,
Hold infinity in the palm of your hand
And eternity in an hour.
William Blake

The history of human civilization is the history of man's discovery of different solid states and their applications:
2 million BC -- 8000 BC: Old Stone Age
8000 BC -- 3000 BC: New Stone Age [pottery, use of copper]
Around 1500 BC: Bronze Age
Around 1000 BC: Iron Age
19th century: The era of steel
20th century: The era of plastics and semiconductors
21st century: The era of biological materials, nano materials, smart materials ???

Condensed matter physics is the physics of everyday life, about things which are normal, ordinary, human-scale - but the theories developed to explain these things is hardly ``ordinary''.

The number of Nobel prizes awarded for work in condensed matter physics is an indication of the importance and subtlety of ``every-day'' physics - interesting physics is not an exclusive monopoly of of the very small scale (particle physics) or the very large scale (astrophysics, cosmology).
Some Nobel Laureates in Condensed Matter Physics.

What is surprising is the prevalence of ``order'' throughout nature - as seen in the periodic arrangements in objects as diverse as snowflakes and crystals of salt. We see periodic or semi-periodic patterns all around us - in seashells, animal coats, vortices in a boiling liquid. Such periodic structures imply some kind of symmetry present in the system. Crystal symmetry, as observed e.g. in minerals is the simplest framework on which to base our study of materials.

One of the first questions we have to try to answer is: can we explain this order ? Disorder is easy to explain - using the laws of thermodynamics. But explaining the emergence of order is more difficult.

Are there fundamental questions in Condensed Matter Physics ? Yes. Even if the "theory of everything" is discovered one day, that does not mean it can explain everything of importance in condensed matter physics. Take for example the case of Langton's ants, a simple computer game where the "theory of everything" (in the sense of the complete set of microscopic rules of behavior) is known. Yet, we can still ask important questions about this very simple system which have not yet been answered. For details see:
``The Ultimate in Anty-Particles" by Ian Stewart
The reason why condensed matter physics is fundamentally different from being just an application of the principles discovered by elementary particle physicists to a system of large number of particles is explained in:
``More is Different'' by P. W. Anderson
This article also marks the transformation of "solid state physics", which was mostly involved with applying quantum mechanical principles to understand the properties of metals, alloys and semiconductors, into "condensed matter physics", which studies almost the entire range of materials known to man (solids, liquids, glasses, polymers, etc) using general principles of conservation laws and broken symmetry.

Further reading: Chaikin & Lubensky, Chapter 1: pp 1-16.