history of mathematics
Can you measure information? It's a tricky question — but people have tried and come up with very interesting ideas. 

To celebrate the release of more English translations of Einstein's papers, we revisit one of his previously unknown models of the Universe. 
The selftaught Indian genius would have turned 127 this month. 
A little trig helps to find the relative distance to the Sun and Moon. 
How to derive the famous quadratic formula from pictures, just like the Babylonians did. 
Euclid's fourth axiom says that all right angles are equal. But isn't that obvious? 

Does light have weight? Newton thought so. His laws predicted that gravity would bend light, two centuries before Einstein's revolution. 