DARK matter? Hidden strings of pure energy? Multidimensional membranes? Modern physics is nothing if not wild. Starting a hundred years ago with the advent of relativity and quantum theory, physics has steadily gathered an increasing number of extraordinary ideas.
Each one flows from our deep desire to understand everything around us. Yet each in some way disguises the fact that there鈥檚 still plenty we don鈥檛 know, and on page 28 Paul Davies explores seven of the biggest questions facing physicists today. How to answer them?
Well, ever-more sophisticated equipment would help, so physicists would probably say more funding is crucial. But there may be a more fundamental issue to address.
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There has always been a friendly rivalry between those who generate theories and those who test them. Theorists argue that they are the leaders. Experimentalists point to those moments when unexpected discoveries 鈥� such as the first detection of an electron 鈥� totally changed our view of reality. And such rivalry is fine as long as the two sides talk. Unfortunately communications seem to have broken down.
Take a meeting this month on 鈥淭he unsolved Universe: challenges for the future鈥�. There, French scientists proposed some experiments to resolve disparities in the value of Newton鈥檚 gravitational constant, G, when it鈥檚 measured in different labs (see 鈥淐an Earth鈥檚 magnetic field sway gravity?鈥�). Those disparities, they argued, might be caused by the influence of the Earth鈥檚 magnetic field on gravity itself. This is a fascinating idea because discovering how gravity is linked to the other forces of nature is one of the great mysteries of physics.
But some theorists were dismissive because the notion did not fit their models. They saw no value in doing the experiments, arguing that we would have noticed the link long ago if it was there. Several also presented ideas based on incredibly convenient assumptions in which experimental data played a minimal role. There was little debate because the two sides were speaking different languages.
It was a sobering episode, and by no means unique. It highlighted the fact that it鈥檚 no bad thing for the theories that we hope will explain the Universe to be subjected to reality checks. Experiments may yet refute those ideas. And if we move too far ahead of testable theories, the wild ideas of physics will cross the boundary into science fiction. That will be no help at all to physicists, whatever their persuasion.