In one example I use bond energies to calculate the energy per mole of sucrose and TNT (the explosive trinitrotoluene). Most students expect that TNT has more energy, but it turns out the two have about the same. So why is TNT an explosive (actually a conflagration)? TNT burns rapidly and involves a huge volume change. It is the rate of reaction (chemical kinetics) and the rapid volume change that causes the explosive damage. Then I can move to the thermodynamics overview.Read More
When I start into heat capacity I contrast the temperature of a substance with the feeling of hot and cold. A thermometer will tell you the temperature of a substance, but that does not tell you how much heat is present. If you touch something, you can tell if it is hotter or colder than your hand, but what about two substances at the same temperature?
Suppose outside it is -10 C (14 F) and there you find a piece of steel and a piece of Styrofoam. Which is colder? If you touch the steel it feels colder than the Styrofoam, but they are both at the same temperature. If you placed the steel on the Styrofoam, no heat will flow between them (Third Law of thermodynamics). Since your hand is much hotter than the objects, heat must flow from your hand into them.Read More
Although the obvious “pro” of recording is to give students the chance to listen numerous times; review the material; and listen to missed lectures, there is a huge “con” and that is they skip class and opt to listen to my lectures at home. Last year the attendance dropped to half because lectures are available on line, but this year the time has been shifted to 8:30 a.m. from 10:30. I am going to predict that very few will want to attend at that hour.Read More
HOW do we know the other particle “magically assumes” the opposite state, rather than it just had the opposite state all the time?
The answer is “nobody knows because it makes no physical sense”. When a physicist is asked how this happens, they indeed invoke the word “magic” as in quantum magic or quantum weirdness.Read More
One day I am sure that physics will view Nature as real. Throughout history initial ideas of non-local effects, also called “action-at-a-distance”, have been repudiated and replaced with something more physically reasonable. The most well-known examples are the early attempts to understand gravity and electromagnetism. So it will be with non-locality between entangled particles.Read More
This complementary nature of states with non-commuting operators, (σX, σY ,σZ), is the basis for the Copenhagen Interpretation of Quantum Mechanics (CI). It states, basically, that if the Z states exist then the X do not, and vice versa. I would rather conclude that it is impossible to determine experimentally if spin has more than one axis of quantization.Read More