# The opposite of black holes can be seen in your kitchen sink

14/10/2010

Scientists have long known that the kitchen sink can create a white hole. And now, they have confirmed this experimentally.

Turn on the faucet, and when the water reaches a steady stream of washing, there is a circular disc. This CD has unusual properties: it is surrounded by a circular rim, where the height of the water suddenly changes.

This so-called hydraulic jump, which is already at least a century puzzling physics (John Strutt, the third Baron Rayleigh, published the first mathematical description of the phenomenon in 1914). Hydrodynamic problems of this type are difficult to resolve.

In recent years, the study of hydraulic jumps accelerated by the fact that some physicists have indicated that they are examples of a much more exotic objects: white holes, temporal contrasts of black holes. The white hole is a region of space that can emit waves and particles, but where those waves and particles can not enter. Although the hypothesis is of great interest, so far no one has managed to prove it experimentally.

But Jill Dzhennes from the University of Nice - Sophia Antipolis in France, managed to find the proof, which have been looking for. White holes exist if the water is flowing through the hydraulic jump faster than waves can flow. This means that waves can come out of the hole, but can not enter into it upstream.

But to prove this, you need to measure both the characteristic properties of the white hole: the flow of oxen in a circular disk and the speed at which the waves move on the surface of the water.

The problem is that the water layer is extremely thin, and it is difficult to carry out measurements with the required accuracy.

Dzhennes found a solution to this problem. Instead of measuring these values directly, you can find their ratio, measuring the "Mach cone associated with supercritical flow of the inland region the jump."

It sounds complicated, but in reality, everything is easier. Poke your finger into a flat disk of water and the resulting v-shaped flow around it and will Mach cone. The angle of the cone is the value that should be measured (see picture).

Dzhennes told that their measurements show that the hydraulic jump really has unusual properties attributed to him. "We conducted an experimental demonstration that the circular hydraulic jump represents a hydrodynamic white hole" - he said.

This is a striking result. He suggests that it is possible to reproduce the characteristics of the most unusual objects in the universe in a normal kitchen sink. We’ll tell you the top news of science and technology, more detailed and interesting.

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