A Random Walk
The Campfire:One of life's most pleasant experiences is to sit around a campfire in the outdoors as dusk falls, watching the flames lead an dance. If you many notice that the colors of the coals, in the fire changes, depending on how hot the fire is. They are ordinarily red, but in a roaring blaze, they can be white. Then, as the fire starts to go out and people start to unroll their sleeping bags and get ready for bed, the coals glow a dull orange and, eventually stop glowing altogether.
However, even when the coals are not glowing they are giving off energy in the form of infrared radiation, which you can feel if you put your hand out to the fire. Even the next day, you can still feel the radiation given off by the cooling embers.
Believe it or not, a phenomenon like this campfire, led the twentieth-century scientists to a completely new understanding of the structure and history of the universe in which we live.
