String theory: A beginner's guide - physics-math - 15 April 2009. String theory is one of the most famous ideas in modern physics, but it is also one of the most confusing.
At its heart is the idea that the fundamental particles we observe are not point-like dots, but rather tiny strings that are so small that our best instruments cannot tell that they are not points. It also predicts that there are extra dimensions to space beyond the obvious length, breadth and depth, but we do not experience them because they are bunched up in tiny spaces. String Theorists Squeeze Nine Dimensions Into Three.
A simulation of the early universe using string theory may explain why space has three observable spatial dimensions instead of nine.
The leading mathematical explanation of physics goes beyond modern particle theory by positing tiny bits of vibrating string as the fundamental basis of matter and forces. String theory also requires that the universe have six or more spatial dimensions in addition to the ones observed in everyday life. Explaining how those extra dimensions are hidden is a central challenge for string theorists. “This new paper demonstrates, for the first time, that our 3-D space appears naturally … from the 9-D space that string theory originally has,” says Jun Nishimura of the High Energy Accelerator Research Organization in Tsukuba, Japan.
He and his colleagues will publish their findings in an upcoming issue of Physical Review Letters.