Tuesday, February 1, 2011

Are physicists wasting their time hunting for a theory that unites the forces of nature?

In Ancient Greece, Pythagoras and his followers believed nature was a mathematical puzzle, constructed through ratios and patterns that combine integers, and that geometry was the key to deciphering it. The idea re-emerged in the late Renaissance, although Galileo Galilei, Johannes Kepler and Isaac Newton believed the mathematical description of nature could be found through the painstaking application of the scientific method, where hypotheses are tested by experiments and observations, and then accepted or rejected.
But that’s really only half the story. According to Newton, God was the supreme mathematician and the mathematical laws of nature were Creation’s blueprint.
And while the notion that God interfered with natural phenomena faded with the march of science, the idea that nature’s hidden code lay in wait to be discovered did not.
Modern Incarnations of unified field theories come in two flavours. The more traditional version, the so-called Grand Unified Theory, seeks to describe electromagnetism and the weak and strong nuclear forces as a single force, and the first of these theories was proposed in 1974 by Howard Georgi and Sheldon Glashow.
The more ambitious version seeks to include gravity in the unification framework. Superstring theory tries to do this by abandoning the age-old paradigm that matter is made of small, indivisible blocks, substituting them with vibrating strings that live in higher-dimensional spaces.
Like all good theories in physics, grand unified theories make predictions. One is that the proton, the particle that inhabits all atomic nuclei, is unstable. But for decades, experiments of increasing sensitivity have looked for decaying protons and failed to find them.
As a consequence, the models have been tweaked so that protons decay so rarely as to be outside the current reach of detection. Another prediction fared no better: bundled-up interacting fields called magnetic monopoles have never been found.

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