Hidden extra dimensions are causing measurements of the strength of gravity at different locations on Earth to be affected by the planets magnetic field, French researchers say. This is a controversial claim because no one has ever provided experimental evidence to support either the existence of extra dimensions or any interaction between gravity and electromagnetism. But lab measurements of Newtons gravitational constant G suggest that both are real.Newtons constant, which describes the strength of the gravitational pull that bodies exert on each other, is the most poorly determined of the constants of nature. The two most accurate measurements have experimental errors of 1 part in 10,000, yet their values differ by 10 times that amount. So physicists are left with no idea of its absolute value.
http://www.newscientist.com/news/news.jsp?id=ns99992814
