It may not seem strange to us today that there is a thing called energy that is conserved in all physical interactions. Energy is a concept we have all grown up with. A hundred and fifty years ago it was not so evident that there should be an intimate, quantitative relationship between such appar- ently unrelated phenomena as motion and heat. The discovery that heat and motion can be seen as different forms of the same thing—namely energy—was the first and biggest step toward understanding the concept of energy and its conservation. Count Rumford of Bavaria, in 1798, was the first to realize that work and heat.
