Imagine a piece of string wrapped around the Earth's equator - that's about 40,000km. How much MORE string would you need for it to sit 15cm above the ground, all the way around? The important ...

Alan Davies and Marcus Du Sautoy get to grips with the problem of measuring the exact length of a piece of string. They visit the National Physics Laboratory, look at how a metre is defined now ...

String theory aims to explain all fundamental ... along with two co-authors, added a new piece to this puzzle: They have proven a conjecture related to so-called 4-graviton scattering, which ...