If you had to pick one image to sum up the modern world, it might be the glowing LED. This simple light shows how we moved from a dim, stagnant past to a bright, fast-changing present. For about two thousand years, life stayed mostly the same. To illustrate this, picture the everyday life in the year 1500: the average person consumed roughly 2,000 calories per day, barely enough for subsistence, and travel was extremely slow, with horse-drawn carriages averaging just 5 miles per hour. (Horse ...
