What do Marcellin Jobard, William Robert Grove, Frederick de Moleyns and Alexander Lodygin have in common with Thomas Edison? The answer is that they all have a credible claim to have invented the lightbulb. Then again, so do 16 other people.
When we think about inventors and invention we tend to picture the lone genius sitting in their laboratory — or under the apple tree, or in the bath. Suddenly, there is a moment of inspiration, or just a happy accident, and the world is changed for ever.