Gravity is Energy

The laws of thermodynamics decree that each quantity of en^rgy has a characteristic quaUty called entropy associated with it. The entropy measures the degree of disorder associated with the energy. Energy must always flow in such a direction that the entropy increases. Thus, we can arrange the different forms of energy in an "order of merit," the highest form being the one with the least disorder or entropy. Energy of a higher form can be degraded into a lower form, but a lower form can never...

 Entropy in our Everyday Lives: Active Stability

Because things naturally move to disorder over time, we can position ourselves to create stability. There are two types of stability: active and passive. Consider a ship, which, if designed well, should be able to sail through a storm without intervention. This is passive stability. A fighter jet, in contrast, requires active stability. The plane can’t fly for more than a few seconds without having to adjust its wings. This adjustment happens so fast that it’s controlled by software. Ther...

 Unlike Physics, Biology Can't Ignore Information

Physicists love to think about systems that take only a little information to describe. So when they get a system that takes a lot of information to describe, they use a trick called 'statistical mechanics', where you try to ignore most of this information and focus on a few especially important variables. For example, if you hand a physicist a box of gas, they'll try to avoid thinking about the state of each atom, and instead focus on a few macroscopic quantities like the volume and total en...

 Teaching Temperature

Outside Temperatures. Place a thermometer outside a window so students can make daily calculations and keep a chart reporting the actual temperature and the temperature change from the previous day. Students will see that the change can be a negative number without the temperature falling below 0—an often-confusing concept that is clarified by these observations. An achievable-challenge extension could include barometers, and students who need more advanced work can learn how negative—or...

 The Sensation of Pressure

We feel pressure on our skin, when we place our hand over the outlet of a bicycle pump, for example, as a kind of springy push. Actually, pressure is the summed bombardments of thousands of molecules of air, whizzing about in random directions (as opposed to a wind, where the molecules predominantly flow in one particular direction). If you hold your palm up to a high wind you feel the equivalent of pressure - bombardment of molecules. The molecules in a confined space, say, the interior of a...

 Q

The hypothesis of {108} abstraction says that every living creature is characterized by a number Q which is a measure of the complexity of the creature. To measure Q, we do not need to know anything about the internal structure of the creature. Q can be measured by observing from the outside the behavior of the creature and its interaction with its environment. Q is simply the quantity of entropy produced by the creature's metabolism during the time it takes to perform an elementary respons...