Tabletop Black Hole Yields Evidence of Hawking Radiation

By Anna Nowogrodzki | August 15, 2016 4:27 pm

(Credit: NASA-JPL / Caltech)

Black holes aren’t perfectly black.

For the first time, using a model of a black hole that traps sound instead of light, scientists have seen spontaneous evidence of what comes out of them.

These particles are so few and faint that it’s not feasible to observe them for an astrophysical black hole, so Jeff Steinhauer at Technion–Israel Institute of Technology made a tabletop version of a black hole that sucks in sound instead of light.

Using this, he’s the first to see evidence for particles that escape a black hole, called Hawking radiation.

In 2014, using the same tabletop black hole equipment, Steinhaeur saw an induced form of Hawking radiation, in which something hit the black hole’s event horizon to cause the Hawking radiation. But this is the first time anyone has seen spontaneous Hawking radiation. Steinhauer published the results in Nature Physics Monday.

Hawking radiation is named for Stephen Hawking, who in 1974 theorized its existence, calculating that black holes shouldn’t suck in absolutely everything. A few lucky particles should be able to escape. This is because, according to quantum theory, pairs of particles spontaneously come into being all over the universe: a particle and its antimatter counterpart. Normally, they obliterate each other, but if they happen to pop into being in exactly the right place, one will be sucked into a black hole and the other will escape it.

Steinhaeur’s tabletop black hole is made of a very thin cylinder of liquid confined in the space of a laser beam. Because the liquid is flowing faster than the speed of sound, no sound waves should be able to escape, except for Hawking radiation. Here, the Hawking radiation consists of pairs of sound waves, one falling into the black hole, and the other coming out.

Hawking’s calculations also show that the particles should be quantum entangled with each other, and Steinhaeur’s experiment showed evidence that they are. He collected observations of many pairs of Hawking particles, and for each pair, the particles had exactly the same energy value, except that one was positive and the other was negative. When he graphed the particles’ energies, “I knew it must be entangled just as soon as I saw it,” he says.

Steinhauer says his goal is “to learn as much as we can about real black holes,” but that’s not the ultimate purpose. “People are not trying to understand the black hole,” he says; “they’re trying to understand the laws of physics more.” No one has yet reconciled our understanding of gravity with the fundamental uncertainty and randomness of quantum mechanics.

“We understand gravity on a classical level,” Steinhaeur says. “But we’d like to understand it more deeply, understand the randomness of gravity… In this search for the laws of quantum gravity, Hawking’s radiation is considered an important first step.”

To this end, Steinhauer has worked on the sonic black hole model for seven years straight. “I’ve been working on this continually since 2009. Only this, all day, every day.” To gather the data for this most recent study, he had to repeat the experiment 4,600 times, the equivalent of 6 continuous days of measurements.

When asked how he celebrated the first ever observation of spontaneous Hawking radiation, Steinhauer said, “I quickly wrote a paper—that’s a form of celebration.”


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CATEGORIZED UNDER: Space & Physics, top posts
  • Alberto Carvalhal Campos

    Para os que pretendem aprender o universo corretamente, sugiro ler o blog :”Olhando o Universo”. Tire suas conclusões.

    • jonathanpulliam

      Nao sinto obrigado a concluir porra nenhuma

  • Alberto Carvalhal Campos

    For those who want to learn the universe properly , I suggest reading the blog: ” Looking at the universe.” Draw your conclusions .

  • Uncle Al

    A hypo-piddly 0.001 solar mass black hole has a naked radiative lifetime of 2.1×10^58 years and a viewed temperature of 6.2×10^(-5) kelvin. Cosmic background radiation is blackbody 2.725 kelvin. Heat only spontaneously flows downhill, hotter to colder. No real world persistent black hole can do anything but feed. There is no real world black hole Hawking radiation. Other than empirical fact, no problem.

    • Antony Clements

      Absence of real world evidence is not to equal to evidence of real world absence. Hawking radiation is and will be for the foreseeable future theoretical. Also, your statement that a real world black hole can only feed is erroneous at best. Mass and energy are not just equivalent, they are also interchangeable. One is derived from the other and vice versa. Energy does indeed escape a real world black hole, which then indeed can and will condense into atoms.

      • jonathanpulliam

        You GO girlfrien’

    • zlop

      “Heat only spontaneously flows downhill, hotter to colder.”? — Potential Temperature tends to equalize.

      Will small back holes act as black bodies?

      • Uncle Al

        A clean event horizon has no electronic structure or selection rules – good blackbody. They are dirty, interstellar space containing about 300 atoms/liter. Reverse calculate (xaonon,dyndns,org),

        T = 2.725 kelvin. M = 2.26×10^(-8) solar masses or 0.75% Earth mass. 4.26×10^(-14) cal/sec luminosity. Naked radiative lifetime of 2.4×10^44 years. How does one assemble that 0.134 millimeter diameter black hole?

        • zlop

          “A clean event horizon has no electronic structure or selection rules”

          Structure is the size of the black hole. Much less than quarter wavelength, little interaction.

          And inside the black hole, gravity decreases. What goes on at the center of the black hole?

          • Uncle Al

            Sub-wavelength emitters have no emission problems, doi:10.1016/j.mee.2015.03.072

            LIGO event GW150914, 30 and 35 solar mass binary black hole merger, briefly exceeded the entire universe’s summed stellar electromagnetic emission energy. Equilibrium occurred within 0.2 seconds with no quantized addenda, no infinite redshfits, no firewall, and no angular momentum glitches. 100% classical relativity. Strop Occam’s razor!

            A black hole is 100% its (curved) two-dimensional event horizon. No singularity, no internal volume, and no thickness to externally-viewed forever penetrate. All black hole information trivially resides in its “surface.” Call it a 2-D graviton condensate, removing composition. Was that so difficult?

          • zlop

            “No singularity, no internal volume, and no
            thickness to externally-viewed forever penetrate.”

            I am confused — Without structure how can it
            have angular momentum?

          • Uncle Al

            I propose all the BH mass-equivalent is in a 2D spherical shell. It has maximum possible angular momentum re gyroscope or potter’s wheel foot disk mass distribution. The limit to 2-sphere’s equatorial tangential spin speed is its binding energy.

            v_lim = sqrt[(2)(S)/(rho)]

            where S is the yield strength and rho the density. For an infinitesimally thin surface element, stresses are tangential as radial stresses go to zero on the surface. Said tangential stresses still yield a radial force component for a curved surface. From the theory of elasticity: given a surface element with area dA and thickness dt, tangential stresses present in the surface, the normal (to the surface) force acting on this element,

            dF_s = (S1/R1 + S2/R2)*dAdt

            and it goes on for another 40 lines or so to give the starting equation. Looks to me that a BH being a 2-sphere is an uncomfortably good fit.

            Somebody kick a physicist to calculate it the physics way. I’m a chemist.

          • zlop

            Unless we have a model of the near center of a black hole, where gravity is near zero, what do we know?

          • Uncle Al

            Given two LIGO observations of binary BH mergers, I suggest there is no BH center (singuarity) and there is no BH volume. A BH is nothing but its 2D event horizon, a 2-sphere graviton condensate whose description requires two physical coordinates (re latitude, longitude. and Earth’s 2-sphere surface) not 3 or 10 or 26 or more.

            Unlike 50 years of quantized gravitation and particle theory, this can be empirically validated or falsified. Physics can calculate the radiated binding energy of mass and mass-equivalent falling into a BH. Physics can calculate the maximum BH equatorial spin rate to remain bound. Plug the numbers into my model, do a formal calculation with all footnotes appended, and see if idiot simple v_lim = sqrt[(2)(S)/(rho)] is respected.

            It either blows or goes. If it goes, there’s the clean, neat, simple answer that satisfies all observations and leaves nothing else to be unexplained. Hey physics – shut up and calculate.

          • zlop

            Thanks for the motivation.

  • Zeb Mason

    A sonic black hole in the lab. Don’t tell the public otherwise the hippies will try to shut it down before it escapes and sucks all the music out of the world!

    • Brad Moore

      Queue Don Mclean

    • jonathanpulliam

      Kanye West and Taylor Swift have already managed that feat.

  • Dan Sutton

    So, let’s see… something which isn’t a black hole does this with something which isn’t light, thus real black holes will do this. I note a few anomalies, such as the absence of time dilation, spacetime distortion, neutrino jets and so forth… and the fact that the fast-flowing liquid in this guy’s living room is about as different from a black hole as it’s possible to get… but apart from that, I’m sure it’s all fine.

    Now – about that new stereo equipment I was thinking of making…



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