Thursday, November 24, 2011

String Theory

The reports of neutrinos moving faster than the speed of light and the entanglement of electrons lead to the possibility of additional dimensions. Extra dimensions could also help explain the possibility of dark matter and dark energy, which seem to be necessary to explain the makeup of the universe, although there is no physical evidence of them.  One response to this possibility is string theory. 

To see the possibility of additional dimensions, think about trying to figure out our three dimensional universe by looking at two dimensional shadows.  By looking only at the shadows, it would be very difficult to figure out exactly what the three dimensional shadows casting the shadows looked like.  A sphere, for example would cast a circular shadow, but so would a cylinder, if it was held the right way.  An egg could cast a circular shadow or an oblong shadow, and so on. 

For string theory, consider drawing a line on a sheet of paper.  If you look at the edge of the paper, you would only see a dot, where the line started, but if you could look down on the paper, you might see an infinitely long line, if the paper was infinitely long.  Or, you could draw a line that started at one point on the edge of the paper, then then went in crazy curves all over the paper, before coming back to the edge.  If you looked only at the edge, you would see only two points, one where the line started and one where it ended.  You would think these were separate points, but in fact they would be part of the same line.  This concept could explain the idea of entanglement, which says that if you know the state of one electron in a pair, you instantly know the state of the other.  In the line case, you would think you are looking at two separate points, but in fact you are looking at two ends of the same line.  Therefore, if one point was blue, for example, you would know that the other point would also be blue, because they are part of the same line.  But from looking only at the two points on the edge of the paper, it would be impossible to know what the line did between those two points, whether it went in a relatively smooth curve from one to the other, or went for miles and miles in all sorts of crazy curlicues between the two points.