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May 12, 2008
Volume 86, Number 19
p. 64
Image Title Heather Mul
Bob Wolke

Science Friction with Bob Wolke

This column could be titled ???A Little Science is a Dangerous Thing.??? Here are a few of the resulting BOMBS I???ve run across.

• The authors of several popular science books seem to have difficulty explaining the difference between temperature and heat. An example: “Temperature is not really a reliable guide to how hot something is.” The author goes on to make his point by describing the relatively painless experience of putting one’s hand briefly into a 400 °F oven versus the sensation of dipping it into boiling water at only 212 °F. This supposedly shows that the water is in some sense “hotter.” (Should we throw away our thermometers and just use our hands?) If we held our hands in the oven long enough for them to come to thermal equilibrium with the air, we’d sure find out which is hotter.

• Speaking of heat, the same book states baldly that “metal is a less efficient transmitter of heat than oil.” This statement is made in an attempt to show that one can cook vegetables at “very low heat” in a bare frying pan, but when oil is present, the vegetables fry at a higher temperature.

• And here’s a perfectly straightforward chemistry lesson: “When baking soda is added to an acid, a chemical reaction occurs that produces air bubbles.”

• Cookbooks are a much-too-common source of scientific bombs. One know-it-all author informed us that cucumbers are 20 °F cooler than their surroundings. That’s obvious, isn’t it? Just place a slice of cucumber against your forehead, and you’ll see that it is indeed “cool as a cucumber.”

Well, let’s think about that.

If a cucumber is able to stay cooler than its surroundings, that means it can somehow shrug off whatever heat it might acquire from the environment. This opens the possibility of cucumbers as a source of energy.

Say we build a large, hollow box out of cucumbers. After a period of equilibration, the air inside the box will be approximately 20° cooler than the air outside. We can then place a smaller cucumber box inside the first one and so on until we will have created a very cold space.

We can now construct a heat engine based on the temperature difference between the ambient air (a heat source) and the cold air inside the box (a heat sink). Heat will flow spontaneously from the former to the latter, perhaps doing work along the way, such as vaporizing a liquid whose vapor pressure can then move a piston. Instead of growing corn to make ethanol, then, we could solve the world’s energy problems by growing lots and lots of cucumbers.

All we’d have to do is petition our congressional representatives to repeal the First Law of Thermodynamics (and don’t think some of them wouldn’t try) because, as you have undoubtedly perceived, we would be getting energy out of a system without having put any energy into it.

• Several cookbooks explain that bakers roll out their pastry dough on marble slabs because they don’t want the shortening (lard, Crisco, butter) to melt from the heat generated by rolling, and marble is cooler than any other kitchen surface. Shades of cucumbers! Here we go again.

Can marble stay cooler than its surroundings? Of course not. It’s just that marble is a better heat conductor than, say, wood, and it conducts the generated heat away more rapidly. So it does help keep the shortening from melting, but not for the popularly believed reason.

• A best-selling microwave cookbook explains to us laypersons why microwaves cook food faster than conventional ovens. It’s “because microwaves are so short they travel quickly.”

The following three bombs are from an award-winning “food science” book written by a television personality.

• “Any time you find an acid bound to an alkaline, you’ve found yourself a salt.”

• “Radiation simply refers to energy that travels in waves, be they visible (photoelectrons) or not (microwaves).”

• “Fire is a physical reaction wherein a fuel (oxygen) combusts in the presence of a catalyst (a chunk of charcoal).”

Distortions such as these do not amuse me; they make me angry. When science is “explained” by authors who don’t understand science themselves (and they are legion), readers who are similarly handicapped will swallow it without question. No wonder so many people think science is just a lot of mumbo jumbo.

Bob Wolke can be reached at

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