Black holes not black after all

May 12, 2008

International scientists have used flowing water to simulate a black hole, testing Stephen Hawking's theory that black holes are not black after all.

The researchers, led by Professor Ulf Leonhardt at the University of St Andrews and Dr Germain Rousseaux at the University of Nice, used a water channel to create analogues of black holes, simulating event horizons.

An event horizon is the place in the channel where the water begins to flow faster than the waves. The scientists sent waves against the current, varied the water speed and the wavelength, and filmed the waves with video cameras. Over several months the team painstakingly searched the videos for clues. They wanted to see whether the waves show signs of Stephen Hawking's famous prediction that the event horizon creates particles and anti-particles.

Professor Ulf Leonhardt, from the School of Physics and Astronomy, explained, "It is probably impossible to observe the Hawking radiation of black holes in space, but something like the radiation of black holes can be seen on Earth, even in something as simple as flowing water."

Black holes resemble cosmic drains where space disappears like water going down a plughole. Space seems to flow, and the closer one gets to the black hole, the faster it flows. At the event horizon space appears to reach the speed of light, so nothing, not even light, can escape beyond this point of no return.

The experiments were carried out at the Genimar laboratory near Nice which houses a 30-metre-long water channel with a powerful pump on one end and a wave machine on the other. The normal business of Genimar is testing the environmental impact of currents and waves on coasts or the hulls of French submarines, but the scientists turned the machinery to testing black holes.

The team demonstrated that something as simple and familiar as flowing water might contain clues of the mysterious and exotic physics of black holes. In a forthcoming paper in New Journal of Physics, the scientists report observed traces of "anti-waves" in their videos.

Professor Leonhardt continued, "Flowing water does not create anti-particles, but it may create anti-waves. Normal waves heave up and down in the direction they move, whereas anti-waves do the opposite.

"We definitely have observed these negative-frequency waves. These waves were tiny, but they were still significantly stronger than expected. However, our experiment does not completely agree with theory and so much work remains to be done to understand exactly what happens at the event horizon for water waves."

Source: University of St Andrews

4.2 /5 (57 votes)  

Filter


Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

thales
May 12, 2008

Rank: 1.3 / 5 (4)
How does this make black holes not black? Do virtual particles have a non-black color? Do "anti-waves" have a non-black color? In summary: what the crap?
Lord_jag
May 12, 2008

Rank: 3 / 5 (3)
uh... i think black holes are considered "black" because no energy that can be detected is emmitted. If there are any particals including the wierd ones expelled, then they can be detected on something making them non-black over all spectrums.
brant
May 12, 2008

Rank: 2.3 / 5 (3)
"However, our experiment does not completely agree with theory and so much work remains to be done to understand exactly what happens at the event horizon for water waves."

YOUR THEORY IS BROKEN!!!!!

How stupid do you have to be.... Ding ding, LIGO the non gravity wave detector.... Looking for non existent entities..

I have never said that about science before, but its definitely getting there...
WolfAtTheDoor
May 13, 2008

Rank: 3.4 / 5 (5)
I agree this seems a little obtuse. Not that I think I'm smarter than these guys or anything, but you're dealing with two completely different systems that are not governed by the same forces. I don't see how anything meaningful can come out of it.
bobwinners
May 13, 2008

Rank: 1 / 5 (2)
Just one comment: Space doesn't move. Matter moves, energy moves. Space is where this takes place. It is infinite.
Soylent
May 13, 2008

Rank: 3 / 5 (1)
Just one comment: Space doesn't move. Matter moves, energy moves. Space is where this takes place. It is infinite.


Spoken like a true classical physicist.

May I direct you to the theory of general relativity which is now very well entrenched and has succesfully made many, very accurate predictions and welcome you to the 20th century.

Space is no longer regarded as a static scene on which 'actors' play out, it is an active participant. Curvature in spacetime tells matter how to move and matter tells spacetime how to curve.

It's not at all known whether the universe is infinite; it's not even known if the universe is simply connected.
googleplex
May 13, 2008

Rank: 5 / 5 (1)
Some people might mock such a simplistic anologue to black holes.
Let me tell you that I modelled a nuclear reactor in my backyard using potatoes instead of neutrons. Sure enough when I passed the nuclear cross section threshold I achieved critical Mash!
Rank 4.2 /5 (57 votes)
Tags

Related Stories
Relevant PhysicsForums posts
  • Does light travel for ever?
    created1 hour ago
  • Infinity by Particles
    created2 hours ago
  • what does negative resistivity mean
    created2 hours ago
  • Calculating Electrostatic force between parallel plates
    created4 hours ago
  • Strength of induced magnetic field inside an inductor
    created7 hours ago
  • increasing time of daylight
    created8 hours ago
  • More from Physics Forums - General Physics

More news stories

Putting the squeeze on planets outside our solar system

(PhysOrg.com) -- Using high-powered lasers, scientists at Lawrence Livermore National Laboratory and collaborators discovered that molten magnesium silicate undergoes a phase change in the liquid state, abruptly ...

Physics / Condensed Matter

created 7 hours ago | popularity 4.8 / 5 (4) | comments 0 | with audio podcast

Hovering not hard if you're top-heavy, researchers find

Top-heavy structures are more likely to maintain their balance while hovering in the air than are those that bear a lower center of gravity, researchers at New York University's Courant Institute of Mathematical Sciences ...

Physics / General Physics

created 8 hours ago | popularity 5 / 5 (1) | comments 1 | with audio podcast

SLAC, Stanford team focuses on high-energy electrons to treat cancer

Accelerator physicists at SLAC and cancer specialists from Stanford are working on a new technology that could dramatically reduce the time needed for cancer radiation treatments. The team ran an initial experiment ...

Physics / General Physics

created 11 hours ago | popularity 5 / 5 (1) | comments 0

Measurements from high-energy collisions lead to better understanding of why meson particles disappear

For several years, physicists at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL), USA, have studied an unusual state of matter called the quark–gluon plasma, which they ...

Physics / General Physics

created 11 hours ago | popularity 5 / 5 (1) | comments 0

Explained: Sigma

It's a question that arises with virtually every major new finding in science or medicine: What makes a result reliable enough to be taken seriously? The answer has to do with statistical significance -- but ...

Physics / General Physics

created Feb 09, 2012 | popularity 5 / 5 (16) | comments 48


Google users warned of threat to smartphone wallets

Users of Google smartphone wallets were being warned on Friday that there is a way to crack pass codes intended to thwart thieves from going on illicit shopping sprees.

Anonymous knocks CIA website offline (Update)

The website of the Central Intelligence Agency was inaccessible on Friday after the hacker group Anonymous claimed to have knocked it offline.

Complex wiring of the nervous system may rely on a just a handful of genes and proteins

Researchers at the Salk Institute have discovered a startling feature of early brain development that helps to explain how complex neuron wiring patterns are programmed using just a handful of critical genes. ...

New error-correcting codes guarantee the fastest possible rate of data transmission

Error-correcting codes are one of the triumphs of the digital age. They’re a way of encoding information so that it can be transmitted across a communication channel — such as an optical fiber o ...

The power of estrogen -- male snakes attract other males

A new study has shown that boosting the estrogen levels of male garter snakes causes them to secrete the same pheromones that females use to attract suitors, and turned the males into just about the sexiest ...

NASA sees wide-eyed cyclone Jasmine

Cyclone Jasmine's eye has opened wider on NASA satellite imagery, as it moves through the Southern Pacific Ocean.