Black holes not black after all

May 12th, 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


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  • 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.
  • Ragtime - May 12, 2008
    • Rank: 1.8 / 5 (5)
    This is simply how the Aether theory works. Wave spreading in the flowing matter, no math babbling - just robust observable physics, which I've explained here many times. Images and videos can be downloaded from http://www.genima...mar.html You can read about hydraulic jump model of white holes here, for example. http://www.st-and...bre.html
  • Ragtime - May 12, 2008
    • Rank: 3 / 5 (2)
    You can understand the white hole model even with using of relativity. The common black hole is "black" because of vacuum density gradient, which is behaving like glass sphere or semitransparent mirror due the total reflection phenomena near the event horizon. The larger the black hole is, the larger the curvature of space should be, right? But we shouldn't forget, every space-time curvature has its own energy density by Einstein equations, and such energy is behaving like aditional matter due the E=mc^2 equivalence. The dense vacuum is surrounding black hole and it's balancing its internal mass density by such way, it decreasing surface density gradient (compare the negative-frequency waves in the water sink model above quoted).

    If the black hole become sufficiently large, then the mass density of vacuum above BH will compensate the mass density below event horizon, so nearly no density gradient can appear here. Therefore the vacuum density gradient will not reflect the energy from inside anymore and whole the object will change into giant glowing star, emanating both energy, both matter from inside, so called the quasar.

    By Aether Wave Theory most of sufficiently large gallaxies inside of our Universe were created by evaporation of quasars, and the Milky Way is no exception. The black hole siting at the center of most of galaxies is cold remnant of quasar, which has evaporated the excessive matter. This is because only black holes larger then certain mass limit can evaporate their matter by the above mechanism.
  • 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.
  • Alexa - May 13, 2008
    • Rank: 3.5 / 5 (2)
    On the surface of water stream the environment is moving too, while the waves aren't influenced by such motion necessarily. The so called capillary waves are driven by surface tension and their motion doesn't depend on the environment motion (or quite slightly). With respect to such waves the water surface gradient is behaving like thin elastic membrane, similar to foam membrane.

    We can make an undulating waves on foam bubble, but the motion of such waves will not be dragged by wind. This is quite natural behavior of matter, and nothing strange is about it. It just requires to compose whole environment of thin foam - the more thin, the better.

    This can give as clue, how the Aether model of vacuum is working: because of immense Aether density the Aether gradients and surface wave spreading are pronounced heavily, therefore the motion of matter/energy doesn't depend on the motion of its environment at all (or just quite slightly). It's quite easy to comprehend, if you know something about surface wave spreading.
  • Alexa - May 13, 2008
    • Rank: 3.5 / 5 (2)
    All previous models of Aether were quite naive. The Aether cannot be formed by thin gas, because such environment cannot spread the energy of arbitrary density. Instead of it, the Aether must be extremely dense, to be able to spread even the energy waves inside of atom nuclei.

    http://superstrun...er02.gif

    Inside of such environment, the energy will spread nearly exclusively along surfaces of thin density fluctuations ("membranes and strings"), which are similar to foam inside of condensing supercritical fluid.

    http://superstrun...crit.gif

    As we can see, this is nothing new, some people has knew about this model whole years, but the physics has never consider it seriously, albeit it's quite trivial. This is because of blind adherence of physicists to abstract, ad hoced models of relativity and quantum mechanics without deeper understanding of their connections with classical mechanics.
  • 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!

May 12th, 2008 all stories
Physics / General Physics

Comments: 11
Rank: 4.1/5 after 55 votes

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