Saturday, February 04, 2006

A Different Universe - Reinventing Physics from the Bottom Down

Nobel Prize Winner R B Laughlin describes the new physics of emergence

Robert B Laughlin, co-winner of the 1998 Nobel Prize in physics for his explanation of the Fractional Quantum Hall Effect, is a professor of physics at Stanford University. In his first popular publication, Laughlin describes his ground breaking research into "emergent phenomena" - the complicated effects that emerge when simple laws interact - has lead to him to question the typical reductionist view of physics.

The reductionist view is that by progressing further and further towards the fundamental laws of physics, we are able, by default, to understand everything in the universe simply in terms of these basic laws. Laughlin, a long time opponent of this viewpoint, points out that this view is essentially an arrogant myopia on the part of many modern scientists and science popularizes.

While we often think of the cutting edge of physics lying in deep space, or at the first fraction of a second after the big bang or at energies far in excess of the energies accessible to today's largest particle accelerators or on length scales so small that they lie orders of magnitude below what our most sensitive devices can detect, Laughlin provides numerous examples of phenomena that lie far from these edges that are, none the less, so far unexplained.

Even something as simple as ice becomes an emergent mystery in Laughlin's hands - he points out that there are at least eleven distinct types of ice (crystalline phases), not one of which has properties that can be correctly determined by a first principle calculation! Ice is also an example of another of Laughlin's theses - that the microscopic rules are often irrelevant in macroscopic behavior "because what we measure is insensitive to them or ... overly sensitive to them ... Bizzarely, both can be true simultaneously."

In the case of ice, we don't know enough about the microscopic properties of H2O to calculate the properties of the eleven types of ice, but we don't need them to calculate the general macroscopic properties of ice.

From everyday emergence phenomena, like phases of matter, Newton's Laws (which should be correctly thought of as emerging from the laws of quantum mechanics when objects are made to be macroscopic in size) and the existence of life itself, Laughlin also takes us on a tour of emergence in areas of physics that are more removed from normal experience. He discusses how the vacuum of space behaves like a solid, how strange "gargoyle" features can appear, at microscopic scales on the surfaces of metals imaged by electron microscopes and the amazing parallels between antimatter and the electrons moving in every transistor and diode in every electronic device on the planet!

Interspersed between the wonderfully lucid explanations of complex physics are passages where Laughlin describes events in his life - family trips, hikes through Yellowstone park, the night his cul-de-sac in Boston froze solid with a foot of water - and his philosophical musings on life and the nature of physical law. In "Picnic Table in the Sun" Laughlin describes a day long interdisciplinary symposium held at Stanford that brought together academics and experts from the sciences, the arts, law and politics to discuss emergence. That almost the entire morning was occupied with discussing just what emergence actually was is testament to how young this idea really is and how important it will be in the years to come.

In another chapter, entitled "The Dark Side of Protection," Laughlin describes how perhaps nature is setup in such a way that the final results are protected from many of the microscopic details of things. This protection makes many important things possible, but can hide the realities of the universe from scientists who are not asking exactly the right questions.

Laughlin's book is well written and eye-opening. He has struck a strong blow against the reductionist culture of physics (and other sciences), in what has been a bitter and long fought battle between those who seek to push physics ever towards higher energies and smaller and smaller scales of matter in the search of ultimate laws and those who, like Laughlin, want to understand things at our scale - pointing out that no matter how accurate string theory (or what ever replaces it) might become, there are still many things that cannot be calculated from first principles.

I feel that these two sides misunderstand each other - some of the antagonism comes from recent history of physics: events like the cancellation of the Superconducting Super-Collider (SSC) in 1993 and competition for funding in a post-cold war/war on terror climate where fundamental research funding is suffering. The SSC was the darling of reductionist thinkers - hoping to use the tremendous energies it would have achieved to probe matter at smaller and smaller scales. It was cancelled by congress due to a combination of undercutting by anti-reductionist thinkers and (mostly) massive cost overruns.

No comments: