I just got one of those anonymous e-mail warnings—this one about the supposed perils of heating water in a microwave. If you believe the text, some hapless Gen X-er—the son of the friend of the wife of the anonymous e-mail writer—suffered horrible burns after a cup of microwaved water blew up in his face. And to eliminate the reader's doubt, the science teacher of the victim's mother's friend's husband verified it can actually happen!
Okay—it's true that heated water can erupt spontaneously. Most engineering students learn about a phenomenon called superheating in school. Water can become superheated if there is a lack of nucleating sites that trigger the formation of steam bubbles that normally form at boiling temperature. Any slight disturbance can cause the water to boil explosively.
According to the science teacher in the e-mail, "Superheating can happen any time water is heated." Uh-huh. Fact is, it requires a fairly specific set of conditions, namely: still water, a cup with a near-flawless surface, and no impurities. I don't know about you, but this state of affairs would be practically impossible to reproduce in my kitchen.
Nevertheless, the doctor of the e-mail burn victim boldly asserts that "Superheating is a fairly common occurrence, and water alone should never be heated in a microwave." So I talked with Amana, a leading microwave maker. Director of Public Relations Russ Maharis told me that the firm does not discourage heating water in a microwave. In fact, the owner's manual includes tips for doing it safely. Stir the liquid; leave a non-metallic spoon in the cup; use a cup with sloping walls; or add in a pinch of coffee, etc. I guess you could also spit in the cup first!
E-mail messages like this one are what's wrong with the Internet today. When people who are technologically unsophisticated use e-mail to proliferate bad information, or exaggerate the facts, they mislead others to believe that technology is extremely dangerous and should be avoided at all costs. Worse yet, they undermine the credibility of real engineers, whose word may be treated as less believable than an anonymous source on the Internet.
Karen Auguston Field firstname.lastname@example.org