Ideas that changed the World : The invention of printing & the printing press like many innovations evolved over time but there was one seminal moment when the printing press exploded on the scene and changed society forever.
Concrete is not a modern material. Did you know the Romans used it? But who discovered it and how long ago was it used?
Solar cells, or photovoltaic cells, convert energy from sunlight into electricity… but how? What principles lie behind this technology?