We already carry smartphones – do we actually need wearable computers or are they just a fashion faux pas?

The first surprising thing about Google Glasses is that anybody thinks this is a new idea (just have a look at this history of mobile augmented reality). Steve Mann, a Canadian known as the father of wearable computing, has been developing systems since the 1980s with obvious industrial, medical and military applications. One example is the Battlefield Augmented Reality System, where having information overlayed on your view of the world could be a matter of life and death.