on 9 May 2013, 2:00 PM
Another day, another groundbreaking physics experiment about bubbles. Although scientists have long understood the behavior of a single soap bubble, they have not been able to mathematically describe the behavior of clusters of bubbles, otherwise known as foams. As you can see in the photo above, when one bubble pops in a group like this, the other bubbles quickly rearrange themselves to balance out the cluster—but because the forces behind all that shapeshifting are different from the forces determining when each bubble pops, it's difficult to make a computer model that can incorporate all phases of a foam's life. Now, scientists have solved the problem by taking a hint from climate models, which have long struggled to figure out how local events (a volcanic eruption in Hawaii or a single bubble in a foam popping) influence more widespread changes (global temperature changes or the foam entirely collapsing). The new model splits up a foam's life into three phases, the researchers report online today in Science: rearrangement, in which the group of bubbles slip and slide around each other to achieve stability; drainage, in which gravity draws the fluid inside a bubble's membrane toward the earth; and rupture, in which a bubble's membrane becomes so uneven that it finally pops, forcing the remaining bubbles to rearrange themselves and allowing the cycle to begin again. While the researchers tested their model using—you guessed it—soap bubbles, they hope their work will help materials scientists better understand and control the properties of solidified foams made of metal and plastic, which are vital for applications that require materials that are both light and strong—like prosthetic limbs.
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Caffeine For Imprisoned Twins
In the late 18th century, King Gustavus III of Sweden was rumored to have carried out a strange experiment to determine the harmful health effects of coffee. Two identical twins who had been condemned to death had their sentences commuted to life in prison on the condition that one would drink three pots of coffee per day, and the other three pots of tea, for the rest of their lives. The only problem was that the doctors assigned to monitor the cases died before either of the patients did, their observations lost--as the story goes, the tea drinker died first, and there's no record of the coffee-drinker's death. The experiment proved nothing, suffering from a lack of rigor (to say the least). Source: Uppsala University, "Coffee - rat poison or miracle medicine?"
Simulated Anthrax On The Subway
In June 1966, the U.S. Army's Special Operations Division secretly dispersed harmless bacteria in the New York Subway system to model the effects of an outbreak of more harmful germs. According to Army reports, "Test results show that a large portion of the working population of New York City would be exposed to disease if one or more pathogenic agents were disseminated covertly in several subway lines at a period of peak traffic." Source: Deadly Cultures: Biological Warfare Since 1945. Wheelis, Rózsa, and Dando. Harvard University Press, 2006.
Weaponized Fleas In The Desert
Operation Big Itch, 1954, was an attempt to discover the potential of weaponized fleas. The operation, part of the Cold War-era United States biological weapons program, took place at Dugway Proving Ground in Utah. According to "Using the flea as weapon," an article in the Army Chemical Review, "In the United States, the plague flea concept was competing against the use of mosquitoes, flies, ticks, and lice. Of these concepts, the United States put most of its energies behind weaponizing yellow fever in combination with the Aedes aegypti mosquito."
Food Through A Hole In The Stomach
U.S. Army Surgeon William Beaumont (above) found an extraordinary patient in Alexis St. Martin, a Canadian trapper who was injured in a hunting accident and left with a hole in his belly that led directly into his stomach. Beaumont attached a string to various foods, including oysters and rare roast beef, and introduced them into the wound to observe the rates of digestion. Despite the unorthodox techniques, this research would later lead to the discovery of the importance of stomach acid in digestion, earning Beaumont the epithet "father of gastric physiology." Source: Experiments and observations on the gastric juice, and the physiology of digestion. Beaumont, Martin and Combe. Maclachlan & Stewart, 1838
Candy For Mental Patients
In 1945, Sweden's new National Dental Service commissioned research, now known as the Vipeholm experiments, in which researchers gave subjects large amounts of sticky sugary candy in order to study the development of cavities. This might not have been so controversial, except that the subjects couldn't give consent to their participation: "The use of mentally handicapped subjects was criticized in the Swedish press and all studies on mentally handicapped individuals were stopped in 1954," according to Topics In Dental Biochemistry by Mark Levine (Springer, 2010).