Black holes, white holes, sinks and sources

There is hope for mankind when the Universe can be modelled in your kitchen!

From New Scientist

A black hole is a dense concentration of mass surrounded by an extremely powerful gravitational field. Nothing that falls within a certain radius surrounding it, known as the event horizon, escapes. A white hole is the opposite: its event horizon allows things to escape but prevents anything from entering. However, so far white holes only exist in theory, so cannot be studied observationally.

Horizon effects with surface waves on moving water is a  new paper by Germain Rousseaux1, Philippe Maïssa1, Christian Mathis1, Pierre Coullet1, Thomas G Philbin2 and Ulf Leonhardt2 (Affiliations 1 Université de Nice-Sophia Antipolis, France, 2 School of Physics and Astronomy, University of St Andrews, UK ), 2010 New J. Phys. 12 095018

doi: 10.1088/1367-2630/12/9/095018

From Wired Science:

The ring-like ridge formed when a stream of fluid hits a flat surface behaves like a white hole event horizon (Image: Germain Rousseaux/U. Nice-Sophia Antipolis)

The ring-like ridge formed when a stream of fluid hits a flat surface behaves like a white hole event horizon (Image: Germain Rousseaux/U. Nice-Sophia Antipolis)

When a stream of tap water hits the flat surface of the sink, it spreads out into a thin disc bounded by a raised lip, called the hydraulic jump. Physicists’ puzzlement with this jump dates back to Lord Rayleigh in 1914. More recently, physicists have suggested that, if the water waves inside the disc move faster than the waves outside, the jump could serve as an analogue event horizon. Water can approach the ring from outside, but it can’t get in.

“The jump would therefore constitute a one-directional membrane or white hole,” wrote physicist Gil Jannes and Germain Rousseaux of the University of Nice Sophia Antipolis in France and colleagues in a study on ArXiv Oct. 8. “Surface waves outside the jump cannot penetrate in the inner region; they are trapped outside in precisely the same sense as light is trapped inside a black hole.”

The analogy is not just surface-deep. The math describing both situations is exactly equivalent. But so far, no one had been able to prove experimentally that what’s going on in the kitchen sink really represents a white hole.

plumber in the sky

plumber in the sky

If fluid mechanics provides the correct analogy for physics, then a black hole can be considered a “sink” and a white hole is then a “source”. In fluid mechanics flow is always out of a source and into a sink. So black holes in the universe provide the way out of the universe for matter into some great Cosmic Drain exhausting into some other universe. Then white holes must be the taps from which matter flows into our universe from the Great Unknown.

The only time that a backflow of fluids occurs through a sink is when the drains are backed up or a reverse pressure surge drives fluid back through the sink-hole.

Which begs the question: “What happens in a black hole when the Cosmic Drain gets clogged?”.

Which in turn leads to the answer “Just call the Great Plumber in the sky”!

 
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