This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
My grandfather, Iyah, told me stories.
He told me how, when Ganesha, the elephant-headed deity, was asked to circle the universe three times, he traced three circles around his parents. He told me how Rama protected all fearful children, how his breath, dancing in the resonant flute he carried, produced a song so beautiful it could still any trembling. Iyah told me about Saraswati, the goddess he had dedicated a temple to, how she was the goddess of knowledge and education, how education was the most sacred gift in the world.
He told me that during the catastrophic Indian Ocean tsunami of 2004, the seawater had burst 50 feet past the Hindu temple on Chennai's beach. The open-air granite shrines remained intact despite the massive debris the torrents carried ashore on every side.
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“Come here, I’d like to speak with you,” Iyah began one evening. His hair was gray, and his skin was furrowed like his wrinkled handkerchief. He occasionally dabbed his moist, blind right eye. I followed him to the couch in the living room of his home in Queens, and his body heaved slightly into the cushion. The sofa cover was faded and worn, but through the fray of tattered cloth lay the vestiges of a vibrant pattern: colorful circles concealed by age.
Iyah told me that on September 21, 1995, Ganesha had given a sign to human beings and made himself known in a gesture that thrilled millions of Hindus around the world. While most worshippers leave basins of milk around the base of Ganesha’s shrine, one man in New Delhi attempted early that morning to feed the deity. The devotee was astonished to see the liquid disappear from the metal spoon he tipped towards Ganesha’s lips. He woke the neighborhood priest, who confirmed the man’s observation with a trial of his own.
As the news spread, thousands of people soon lined up at temples in India, and abroad to serve the God of New Beginnings, also known as the Remover of Obstacles, and watch him drink. Milk sales in New Delhi jumped more than 30 percent on that day. One store sold more than 25,000 pints. So many people flooded to pray at temples across the country, especially in New Delhi, that the crowds brought traffic to a standstill. Bearing bells, incense, tin containers, and garlands strung with yellow marigolds, people visited their local temples and knelt before Ganesha’s shrine, thanking him for his revelation.
Scientists, of course, were skeptical about the idea of celestial intervention. Researchers from India’s Ministry of Science and Technology visited the temple to test a different hypothesis: the milk was disappearing due to capillary action—the propensity of liquid to flow into narrow spaces without the assistance of, or even in opposition to, external forces like gravity. The scientists arrived at the original temple where the “miracle” had first been reported to perform an experiment with milk that had been dyed with food coloring.
As the level of liquid in the spoon diminished, the colored milk diffused into the statue, coating it with the same hue.Scientists explained that the statue had been absorbing milk this way all along. However, because a thin layer of milk is nearly colorless, the diffusion of the liquid had not been previously visible. A New York Times headline from September 22, 1995, declared, in a subtitle infused with a healthy dose of snark: “Some Hindus Flock But Scientists Mock.”
But despite the gullibility implied by the sonic harmony of the Times subhead, capillary action is not a widely understood scientific principle. It rests on the principles of adhesion, cohesion and surface tension, which are properties shared by many liquids. Cohesion describes the tendency of water molecules to attract one another. For instance, a drop of water seems to form a spherical shape because each water molecule is surrounded by other water molecules. Adhesion describes the tendency of water molecules to attract other substances. The combination of adhesion and cohesion explain the "stickiness" of water, which can also be observed in the droplets that stick to a window after a rainstorm.
Finally, surface tension is the property of the surface of a liquid that allows it to resist an external force because of the cohesive nature of its molecules. For example, when you fill a cup or beaker with water, the water dips slightly when you look at the surface edge-on. This dip, also known as the meniscus, is caused by the surface tension of the water. Cohesion of the water molecules to each other and adhesion of the water molecules to the glass cause the surface "line" of the water to slope.
Capillary action occurs when the adhesion to a container is stronger than the cohesive forces between the liquid molecules. And the height to which capillary action will carry water is controlled by surface tension and gravity. Liquid can travel skyward, driven simply by the ratio of adhesion to cohesion and the forces of surface tension. The thinner the tube, the more relative surface area inside the tube, enabling capillary action to pull liquid up higher than in larger diameter tubes. In the case of Ganesha's miracle, the surface tension of the milk was pulling the liquid up and out of the spoon before gravity caused the milk to drip down the front of the statue. Since the statues of deities in temples are often made of porous materials such as ceramic or stone, and decorated with flowers, stems and twigs, there are plenty of thin openings that could draw in the milk with capillary action.
Although capillary action is ubiquitous in the natural world, it was not formally identified until the late 15th century by Leonardo da Vinci—the first of several renowned scientists who became preoccupied with the phenomenon. In 1660, more than a century later, Robert Boyle, an Irish chemist, performed experiments to investigate it. However, it was not until the early 19th century that two investigators presented a quantitative explanation. Thomas Young and Pierre Simon-Laplace derived the Young-Laplace equation for capillary action in 1805. In 1830, Carl Friedrich Gauss tweaked the mathematical expression. (Technically, he factored in "conditional boundaries" relating to the "liquid-solid interface.") And in 1900, Albert Einstein submitted a paper titled, "Consequences of the observations of capillarity phenomena" to Annalen der Physik, one of the world's oldest scientific journals for physics. It was the first paper Einstein published.
Besides the history of celebrated researchers who explored capillary action, it is worth noting that the phenomenon occurs all the time, everywhere, and when you stop to think about it, its manifestations are awe-inspiring. Of course, the anomalous case of Ganesha’s ostensibly divine act is just one instance of capillary action beyond the confines of a science laboratory.
Another example is when your eye waters. It is capillary action that allows the tear ducts in our eyes to release tear fluid. The process cleanses the eye and clears all the dust and particles around the ducts of the eye. Capillary action is also responsible for a vital step plants take to feed themselves. Plant a seed, and when that seed sprouts—when the roots take hold of the soil—you feed the bud by pouring water into the base of the pot, or the floor of the garden. The roots of plants absorb the moisture in the dirt through capillary action. Trees take in water, provide oxygen to our atmosphere, branch heavenward, flower and bear fruit, because of capillary action.
Although they are merely theorizing at this point, scientists have imagined using capillary action to create renewable energy. The idea is that water could climb upward through capillaries, evaporate when it reaches the top, condense and then drop back down to the bottom, spinning a turbine on its way to creating energy. Capillary action could in effect create electricity.
Did Ganesha drink milk on September 21, 1995? We have plenty of scientific evidence to suggest otherwise; capillary action was once again in play. But does that mean that reverence has no place in our experiencing the phenomenon? Perhaps an understanding of the science and history behind capillary action can actually imbue the quotidian with wonder—the role of capillary action in sustaining an apple orchard or in restoring a field suffering from the aftershock of a wildfire. There need not be an irreconcilable dichotomy between "science" and "wonder," as the New York Times headline suggests.
Iyah used to live in this constant wonder: “God is not only everywhere, but in everyone and everything,” he said. Iyah believed that God existed in all people, making human interaction sacred. "Kindness to others is like praying at their temple," he would say. Iyah believed God permeated every part of the natural world—even the architectural miracle behind capillary action. For him, there would have been no conflict between faith on the one hand and an extraordinary scientific phenomenon on the other. Capillary action, which demonstrates the most elementary kind of attraction, is crucial to the sound functioning of our bodies and our environment. Surely it is something to marvel at—and maybe even something to “flock” for.