Oil floats on water, that much we know, right?
Well, physicists are about to turn your world upside down (again): under certain conditions, water can actually float on oil.
Using a theoretical model, the scientists calculated the forces acting on water when it is dripped onto an oil surface. Taking into account surface tension, the property that allows some insects to walk on water, they showed that a water droplet can "hang" from the oil's surface. The oil surface droops like a rubber membrane, allowing the above air—which is much lighter than oil and water—to extend beneath the surface's average level. With help from the surface tension, this air pocket balances the weight of the water droplet, preventing it from sinking. The scientists confirmed the model's predictions in tests and found that water droplets up to 170 microliters in volume could float on oil
Previously on Neatorama: 5 Really Weird Things About Water