Strange physical effects are discovered from mediocre tea cups

Someone said that the real signal for a scientific discovery is not "Eureka!" but "Huh . really .".

This is true of Sebastian Bianchi: a normal cup of tea led him to very interesting things, and countered the surface tension of water.

When he was a student of physics at the University of Havana in Cuba in 2008, Bianchi noticed a few strange things when mixing a cup of mate - a popular tea in South Africa. To mix mate, you need to pour hot water into a cup of mate leaves and allow them to absorb. Usually, everything always flows downstream, but somehow he sees some mate leaves appear in the kettle. Somehow, they ran upstream into the kettle.

Bianchi went to an adviser at Havana's physics council, Ernersto Alshuler, who helped him do some experiments, even though they had never published their conclusions.

The experiment consisted of two water tanks placed next to each other, one of which would be placed higher than the other.

The experiment consisted of two water tanks placed next to each other, one of which would be placed higher than the other. Two barrels of water are connected together through a pipe, from which water can flow from the higher barrel to the lower one. Then they released mate leaves and lime pollen on the water in the lower bin. And then, tea leaves and pollen grains found the way to the higher bin:

Tea leaves do not ignore gravity; they are simply responding to the fluid dynamics of liquids. In a report published in the Proceedings of the Royal Society, physicists concluded that this behavior is a result of many factors: namely, differences in water surface tension and eddy currents.

The culprit is the Marangoni effect, discovered in 1855 by James Thomson - who is Lord Kelvin's brother.

This is another "cool" moment: Thomson sees droplets and water flow into a glass of wine while having dinner and then doesn't understand why this happens - especially wine with alcohol content. high. Wine is almost exclusively alcoholic and water, and alcohol has a smaller surface tension than water. So the water will tend to flow out of the high-alcohol, high-alcohol liquid bag by a little difference in surface tension.

And then capillary happens, where the surface tension will pull the liquid up a narrow channel (or the wall of the container, like a wine glass) until it is heavy enough to flow backwards. Capillary-based plants convert water and nutrients from the trunk to the leaves. It also appears in the "wick effect" of the oil lamp: the oil will run upwards in a wick so that the fire burns steadily and slowly.

With wine (or any high alcohol beverage), the liquid will hit the glass wall and start running up, thanks to capillaries, forming a thin layer. Both alcohol and water will evaporate in this process - except that they evaporate at different speeds. This will reduce the level of alcohol in the area, increase the surface tension, so the alcohol will run up more, forming drops and eventually heavy enough to flow down into the stream.

The same thing happens with tea leaves and pollen grains, combined with the fact that they will drive in the whirlpool formed. We all see whirlpools created when stirring milk, blowing smoke, or when drawing water from the sink.

Wine is almost exclusively alcoholic and water, and alcohol has a smaller surface tension than water.

This is not a new phenomenon, but it is surprising that they can be combined to create enough force to push the leaves away from the stream. Physicists' conclusions can also explain waste sometimes running upstream on a slow-flowing river.

Bianchi's "cool" moment is not the first time a physical experiment is inspired by tea. A few years ago, Daniel Ives, a mechanical student in Colorado, conducted an experiment to find out how hibiscus tea leaves were soaked in water. He placed a cup of hot water in front of a blank sheet of paper and dropped some tea leaves on the surface of the water, then photographed each step of the soaking process.

Ives found that tea leaves sucked water and hatched, and the amount of moisture absorbed pulled the water-soluble particles out of the tea, allowing them to dissolve in the water, gradually diffusing outward, and down, until the tea reach balance. Tea leaves, denser than water, will be pushed up by the amount of water they occupy, according to Archimedes' principle - the first "Eureka! " Moment. But gravity also pulled down the seeds in the tea leaves. Although it was only a small effect, it was enough to make the water saturated with the escaping particles gradually sinking to the bottom of the cup.

One day, Ives and other physicists could try out a perfect cup of tea together. Now, it's not very cool when we can get some interesting things about nature from a simple cup of tea.