Cats can be simultaneously solid and liquid because of their ability to adopt the shape of their container, according to this year’s Ig Nobel Physics Prize winner.

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Cats that behave like liquids, tampons that play music, and other ‘advances’ honored with Ig Nobel Prizes

CAMBRIDGE, MASSACHUSETTS—Are cats liquid or solid? That’s the kind of question that could win a scientist an Ig Nobel Prize, a parody of the Nobel Prize that honors research that “makes people laugh, then think.” But it wasn’t with this in mind that Marc-Antoine Fardin, a physicist at Paris Diderot University, set out to find out whether house cats flow.

Fardin noticed that these furry pets can adapt to the shape of the container they sit in—think of a cat in a vase—similarly to what fluids such as water do. So he used the principles of rheology, the branch of physics that deals with the deformation of matter, to calculate cats’ relaxation time, or the time it takes for them to take up the space of a vase or bathroom sink.

The conclusion? Cats can be either liquid or solid, depending on the circumstances, Fardin reported in the Rheology Bulletin in 2014. (The awards don’t recognize the strangest research of the year, but strange research in general.) A cat in a small box will behave like a fluid, filling up all the space, but a cat in a bathtub full of water will try to minimize its contact with it and behave very much like a solid. For this achievement, Fardin was awarded this year’s Ig Nobel Physics Prize before an audience of more than 1000 people, including genuine Nobel laureates, during a ceremony here at Harvard University’s Sanders Theatre.

The event was presided over by Marc Abrahams, editor of the science humor magazine Annals of Improbable Research, and included the premiere of The Incompetence Opera, a show about the Peter principle and the Dunning-Kruger effect, which both seek to explain why incompetent people rise to the top. Abrahams was joined on stage by a dozen of awardees, who each received a cash prize of 10 trillion dollars—in the form of a Zimbabwean bill whose value is just a few U.S. cents.

Fluid dynamics got the lion’s share of the awards: In addition to Fardin’s study on house cats, a second prize went to Jiwon Han, a sophomore majoring in physics and astronomy at the University of Virginia in Charlottesville, who, as a high school student in South Korea, analyzed why people tend to spill coffee as they walk. It turns out that gripping the body of a cup or holding it by the handle makes coffee careen violently into its sides and eventually slosh, Han reported last year in Achievements in the Life Sciences. The fix, however, is quite easy: Han recommends carrying coffee cups from the top or walking backward, both of which help coffee move gently around the inside of the cup, preventing spills.

Heavy coffee drinkers have another reason to rejoice: The winners of this year’s Ig Nobel Peace Prize might have figured out how to get better sleep. In a paper published in 2005 in The BMJ, Swiss researchers showed that regularly playing the didgeridoo, an Australian aboriginal wind instrument, reduced sleep apnea, which leads to snoring, broken sleep, and daytime exhaustion. Practicing the didgeridoo may strengthen the muscles of people’s airways, the scientists say, making them less likely to collapse during sleep and helping snorers—and their partners—rest easy.

But in nature there are couples that have to face bigger challenges than a few hours of poor sleep: The Biology Prize–winning team found a type of Brazilian cave-dwelling insect whose copulation can last up to 70 hours, with females “deeply penetrating” the opening that leads to the males’ sperm storage organ using spiny, penislike structures called gynosomes. Female bugs use their gynosomes to receive not only sperm, but also a cocktail of highly nutritive substances, the team reported in 2014 in Current Biology. The competition to get this precious supplement may have favored the evolution of females with pseudopenises and, as a consequence, males with “vaginas,” the scientists say.

More traditional sexual organs were honored by this year’s Obstetrics Prize, awarded to a team of Spanish researchers for showing that a human fetus responds more strongly to music that is played inside the mother’s vagina than to music that is played on the mother’s belly. The findings, published in 2015 in Ultrasound, have inspired the development of a patented Fetal Acoustic Stimulation Device: basically, a music-playing tampon. Its name? “Babypod.”

Despite their entrepreneurial endeavors, these scientists didn’t get this year’s Economics Prize. That award went to two Australian researchers who tested how contact with a live crocodile affects people’s willingness to gamble. The duo asked people visiting a Queensland crocodile farm to either hold a 1-meter-long crocodile or not. Then, they asked the visitors to fill a survey about their mood and play a slot machine. People with problematic gambling behaviors, such as gambling addiction, placed higher bets after holding a crocodile, unless they were in a negative mood, in which case they bet less than people who didn’t hold the crocodile, the team reported in the Journal of Gambling Studies in 2010. Although the research might seem pointless, it shows how emotions, such as the excitement of holding a crocodile, can influence our decisions, study author Matthew Rockloff, a psychologist at Central Queensland University in Rockhampton, Australia, told Science. “People think they’re in control when they gamble,” he said. “But that’s not true.”

Other winners included psychologists who showed that identical twins are no better than outsiders at recognizing photos of each other’s faces, especially when they see them for a fraction of a second (Cognition Prize), a team of researchers that used brain scanning to understand why some people hate cheese (Medicine Prize), zoologists that found human blood in the diet of the hairy-legged vampire bat (Nutrition Prize), and a medical doctor who reported that older men tend to have bigger ears (Anatomy Prize).