What's stopping us from building useful quantum computers? And how long until we'll have them?

The travels of bank notes give important clues to epidemiologists
Is geometry hard-wired into our brain?
The next total eclipse of the Sun will be in March 2006
How to interact with your music collection
The GIMPS project finds a new Mersenne prime
Learning about the history behind maths helps students understand it better
UK students visit South Africa