Tuesday, March 3, 2009

James Clerk Maxwell

This year is the 150th anniversary of Charles Darwin's book, Origin of Species. But it is another 150th anniversary for science, one of monumental proportions. Though I have heard much of Darwin in the media, I have not seen a word about this man and his work.

The man is James Clerk Maxwell, and his picture hung on the wall of Einstein's study. He was born in Scotland and in his 48 years was, as Einstein put it, the most influential scientist since Isaac Newton.

He even outdid himself, in that one of his works, that of mathematically describing electromagnetic energy, overshadows his accomplishment of exactly 150 years ago. But first, in 1859, he brought into physics a concept that is crucial to our understanding that was not even conceived at the time. He brought statistical analysis into physical law.

The first ever statistical analysis of physics was the Maxwell distribution of molecular velocity introduced in 1859. Though later modified by Ludwig Boltzmann, the Maxwell-Boltzmann distribution still stands today. It has to do with ideal gas movements and how they relate to volume, pressure and temperature. Though molecules collide and have different velocities, there is a predictable statistical percentage that have the same velocities within a range. When temperature changes, velocities change in a statistical way. Though other scientists had started to understand the properties of ideal gases, Maxwell's contribution was a key piece to the puzzle. It fit into the understanding of statistical mechanics and thermodynamics. Mechanics provides information on physical things and how they are affected by forces. Statistical mechanics then describes those physical forces and their effects at a molecular level.

There is an endearing description of Maxwell on Wikipedia when he was three years old and already an inquisitive child. Of almost all things he asked his father, "What's the go 'o that?"

The distributions of velocity were worked out for ideal gasses, but there are kinetics to consider in liquids as well. The collisions of atoms and molecules cause random movements.

The structure of elements and molecules affect their chemistry. In the next few posts I will talk about some of the specific structures which make up biological organisms.

No comments: