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IgNobels 2013! Could you walk on water?

The views expressed are those of the author and are not necessarily those of Scientific American.


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Some might say there’s only one person who could do that. But it turns out it might not be so impossible. The real trick to it? An exotic locale. Not Tahiti or Costa Rica. The moon.

Minetti et al. “Humans Running in Place on Water at Simulated Reduced Gravity” PLoS ONE. 2012.


(Figure 1. For SCIENCE!)

There are things that can walk on water in this world. What kid hasn’t been shocked by water striders, sliding effortlessly over the surface of a pond? One of the big moments in wildlife documentaries, where the music swells and the electric guitars kick in, is the moment when you see a lizard go splashing wildly across a pond in high-def slow-mo.


(The other part of figure 1)

So why can’t humans? We are too big, and too weak. Water striders have tiny body weights that can be supported (if you spread the weight out) by the surface tension of the water. Other animals, like the basilisk lizard and the grebe (best courtship display ever?) get away with being heavier by being really FAST. They have big wide feet to spread the weight out, and move them very quickly, slapping the water so fast they can go along on top.

But humans? We are big. And we have narrow feet, no good for hustling along on top of the water. To move our legs fast enough to stay up, we’d have to be moving more than 30 m/s, 67 miles an hour! Even Usain Bolt is no good for that one.

So how to get around this? Well, I suppose we could try flippers or some other device to increase flotation, the kind that Da Vinci envisioned.

The other thing you could try is reducing gravity. Or, if you want to ensure success…try both!

The authors of this study used both computer models AND humans in a pool to test whether humans could ever run on water. They gave them regular old swim flippers, and held them up in a harness to simulate different levels of gravity. The fin size was designed to be close in proportion to that of the basilisk lizard, the one that runs on water.

And it worked! At 0.22 (22%) of earth gravity, a human on the run could stay above the water. The best results were at 0.1 (10%) of earth gravity, where everyone could pull a Jesus (or a basilisk lizard), but at 0.22 it got a lot harder and only the “most skilled and fit” could do it (what does it mean to be skilled at running on water in fins? Is that something you can put on your resume?).

I really wish they had video of this happening (of course, to appropriately heroic music), but while they showed video at the awards ceremony, they didn’t have it in the supplemental info. :(

And so if you, and your fins, and the water, were on the moon, you too could run on water! And not just on our moon, you could also do it on any of the moons of Jupiter (Io, Ganymede, Callisto, Europa), the Saturn moon Enceladus, Pluto, and another 126 celestial objects in the Solar System. Who knows, if space travel becomes a real thing some day, maybe there will be a sport! Get ready to compete in the 3013 water running Olympics!

Scicurious About the Author: Scicurious is a PhD in Physiology, and is currently a postdoc in biomedical research. She loves the brain. And so should you. Follow on Twitter @Scicurious.

The views expressed are those of the author and are not necessarily those of Scientific American.





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