Einstein’s Final Riddle

Why does the Universe expand the way it does? Why does it accelerate? Einstein’s equations offer an explanation of gravity that works on the scale we know, but do they work on the grandest scales of space and time? Humanity now has a way to find out. The General Theory of Relativity predicts the behaviour of gravity, and includes a term known as the cosmological constant.  Einstein added this term to make the universe static and unchanging, as he believed it was.  But when the expansion of the universe was discovered by Edwin Hubble, Einstein regarded it as ‘the greatest blunder...

The Real Discovery of Neptune

Have you ever read the story of the discovery of Neptune? It truly is a triumph of science and mathematics, and part of the reason it is my favourite planet (a hard choice to make).  The story goes like this: It all starts with the discovery of Uranus in 1781 by William Herschel.  This was the first ever discovery of a planet, as the Earth and the five visible planets have been known of since the dawn of history. Thanks to Isaac Newton working out the laws of gravitation and the mechanics of the solar system, mathematicians could easily calculate the properties...