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Man-Made Black Holes Looming?

Posted by michael on from the danger-will-robinson dept.

camusflage writes: "The New York Times has a story that some physicists think it might be possible to make black holes at the under construction Large Hadron Collider at CERN, slated to come online in 2006. Trying to allay concerns about a man-made black hole blipping us out of existence, they say "The same calculations ... predict that around 100 such black holes a year are `organically' and apparently safely produced in the earth's atmosphere in cosmic ray collisions." As long as we can keep critters from building nests in the singularity, we should be okay."

3 of 300 comments (clear)

  1. Gravity is a really weak force... by dido · · Score: 5, Informative

    As everyone knows, gravity is the weakest of all the fundamental forces by a very very long way, something like 40 orders of magnitude weaker than the weakest of the nuclear forces. I remember reading an article here long ago (can't find it and put a link to it because Slashdot search is down...grr) that talked about some speculation that gravity is so weak because the universe has more dimensions than the four that we see (this is also a prediction of superstring theory), and while the other three forces are only capable of propagating there, gravity is able to propagate through these extra dimensions, making it seem weaker. These dimensions are supposed to be curled up small so we don't normally notice them, so one of the implications of this theory is that the value of the universal gravitational "constant" should shoot up dramatically when you try to measure it at smaller scales; the smallest scale at which gravity has been measured so far is on the order of centimeters only. Another implication is that it should be possible to create low mass black holes with less energy than the weakness of gravity as we know it predicts. So if these scientists are successful in making such small black holes, it could go a long way to validating this theory.

    --
    Qu'on me donne six lignes écrites de la main du plus honnête homme, j'y trouverai de quoi le faire pendre.
    1. Re:Gravity is a really weak force... by dragons_flight · · Score: 5, Informative

      You're essentially right.

      The original theory expected curled dimensions on the order of a Planck Length (10^-33 m), but some people later showed that is was possible to modify the theory for dimensions of arbitrary size. The question then falls to experimentalist to say how large they might be. As it turns out, it's easy to show that they aren't as large as a meter (unless you modify string theory in some really weird ways that few people consider plausible). Thus we can easily confirm everyone's ordinary perceptions that life at our scale is 3D. However the types of experiments to test this don't scale well, so the best that experiments can say so far is that there are no hidden dimensions on the order of a millimeter.

      Scientists that think that hidden dimensions are really only just beyond the horizon of where we know they aren't are a pretty scant minority right now. Most people expect that they probably are down near the Planck Length and well out of reach. However, the neat experiments and effects (such as black holes) that could be done with access to large extra dimensions make them worth looking for, just in case.

  2. ~Why Black Holes Go Away~ by deathcow · · Score: 5, Informative
    Remember that the gravity is proposed to be this Extra-Ordinarily intense only at these "quantum distances". The point was -- you can make the black hole with almost no matter whatsoever, if you can get the particles to play nice at these infinitesimally small quantum distances.

    Fast forward a few years, scientists make a black hole. Why doesnt it destroy the earth?

    1) The black hole weighs no more than the particles slammed together to make it. It has essentially zero pull on anything. A grain of salt would make an incredibly more effective attractor.

    So you say, yes, but the black hole will persist and continue to grow in mass by swallowing more and more particles.

    But the scientists in the Times article say the black hole will "evaporate".

    The following paragraph, from this page, states it well:

    Since the 1970s, it has been known that black holes are not completely black. In fact, they emit very low-energy radiation called Hawking radiation. The lower the mass of a black hole, the higher the energy of the emitted Hawking radiation. As a black hole radiates, its mass decreases, and it starts emitting more and more radiation, causing it to evaporate more and more rapidly. Eventually, it shrinks to around the Planck mass, the point at which its DeBroglie wavelength is equal to the Schwarzschild radius. At this point, we no longer know what happens, since to describe physics at the Planck scale requires a theory of quantum gravity.