Having been on the 'net for a very long time, I get asked often to look at some rather outrageous claims being made by a lot people, many of them in need of serious psychiatric help. This one is a doozy from quite a few years ago.
A guy had a coil of wire stuffed into a cylinder (I think a brass cylinder). The two ends of the wire stuck out on the opposite ends of the cylinder. The cylinder was suspended from the ceiling by some cables. He then connected a heating element to the end of the wire at the bottom of the cylinder. The moment he turned on the heating element, he started time. He has a thermocouple of some kind monitoring the temperature at the other end of the wire. As soon as the temperature had risen by 50 C (I don't quite remember the exact number so I made this up), he stopped time. Call this Time A.
Next, he connected the heating element to the top end of the wire. He repeated the experiment, this time monitoring the temperature of the bottom end of the wire till the temperature has changed by 50 C also. Call this Time B.
He noticed that Time A is shorter than Time B. He said that this means that the heat in the conductor can travel faster upwards than downwards. His conclusion was that he has discovered an anti-gravity effect, and that there was an anti-gravity component to heat. [Honest! This is what was said! You can't make up idiotic statements like this!]
This is where having just a little knowledge can result in something hysterical. Anyone who has studied physics can immediately see two very obvious problems (there may be more) with this interpretation:
1. Convection. The inside of the cylinder is at atmospheric pressure and not in some level of a decent vacuum. So by heating from below, a heat convention can easily carry some of the heat upwards, thus heating the top end faster.
2. Cooling gradient. This is the more important aspect. I asked this person (yeah, I actually made contact with him) if he waiting for the wire to cool down back to room temperature before he did the 2nd part of the experiment. He said, no, he continued right on. This means that he had no clue that the rate of heat loss depends on the temperature gradient of an object with its surrounding. Heating an object in air from 20 C to 70 C is not the same as heating it from 50C to 100 C, even though the temperature change is identical. As the temperature of the object increases, the temperature difference between it and the surrounding also increases, and so will the rate of heat loss. This is straight-forward law of cooling. So of course he would take longer to heat the 2nd part since he is starting off at a higher temperature!
We teach physics majors all the things that are known and can already be explained, NOT because we want them to be able to mimic and repeat all of them when they become physicists. We teach them those things so that they will KNOW when they encounter something new and unexplained. You cannot know what you are observing or discovering is new if you don't already have a clear idea of what are known and can already be explained! This person that I just described lacked the knowledge to know that what he thought was "new" can, in fact, be explained quite simply based on existing ideas. He certainly had a vivid imagination, but it is nothing more than mere ignorance of the knowledge he did not have.
Zz.
No comments:
Post a Comment