Tuesday, May 21, 2013

Lord Kelvin

In 1900 the great physicist Lord Kelvin (William Thomson) announced that everything that could be known was known in the field of physics.  There were only two “small clouds” on the horizon which he believed would soon be cleared away:  the failure of the detection of the “ether,” (the Michelson and Morley experiment), and the explanation of the spectrum of the so-called black body radiation, the radiation given off by heated materials.  He couldn’t have been more wrong.  The absence of the ether gave rise to Einstein’s  theory of relativity, and the second problem spurred the development of quantum theory, both theories that are viewed as the core of the revolution in physics  at the beginning of the 20th century.

Now scientists, including the French physicists Gilles Cohen-Tannoudji and Sylvain Hudlet argue that we are on the verge of a new revolution in physics.  Today, physicists and astrophysicists are faced with much bigger ‘clouds’ than those perceived by Kelvin.  The first one is that both relativity and quantum theory are valid in their own domain, but are not represented by a single theory.  The second unresolved problem is the nature of dark matter and dark energy.  Another conundrum is what exactly caused the “inflation” of the universe right after the Big Bang, an idea needed to explain the structure of the universe.

For many years now scientists have tried to develop a Grand Unification Theory (GUT), also known as a theory of everything,  that would reconcile gravitation and relativity with the quantum world, more specifically, the Standard Model of particles and their interactions.  One of the current attempts is string theory, which tries to build up a model of the universe on mathematical principles.  However, a growing number of  physicists have started viewing the idea of unifying quantum theory with gravitation as doomed to fail.  They argue that both space and gravitation are not fundamental  but emergent phenomena, reflections of a yet hidden reality.  Emergence, the idea that a physical system can have properties that aren’t just the combination of the properties of its components, but are new. The existence of  “emergent” properties is now increasingly, albeit reluctantly, accepted by the scientific community.

In this blog I will explore the telltale signs that a revolution in physics is imminent. I will talk to physicists and astrophysicists whose  research on open questions in physics  might contain the seeds of the next scientific revolution.  Stay tuned to this blog...