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Black Holes From the LHC Could Last For Minutes 672

Posted by kdawson
from the becoming-greyer dept.
KentuckyFC writes "There is absolutely, positively, definitely no chance of the LHC destroying the planet (or this way either) when it eventually switches on some time later this year. And yet a few niggling doubts are persuading some scientists to run through their figures again. One potential method of destruction is that the LHC will create tiny black holes that could swallow everything in their path, including the planet. Various scientists have said this will not happen because the black holes would decay before they could do any damage. But physicists who have re-run the calculations now say that the mini black holes produced by the LHC could last for seconds, possibly minutes. Of course, the real question is whether they decay faster than they can grow. The new calculations suggest that the decay mechanism should win over and that the catastrophic growth of a black hole from the LHC 'does not seem possible' (abstract). But shouldn't we require better assurance than that?"
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Black Holes From the LHC Could Last For Minutes

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  • It's Crazy (Score:5, Funny)

    by LinuxWhore (90833) * on Friday January 23, 2009 @12:06PM (#26575321) Homepage Journal
    I can't help but think of one of my favorite The Soup clips [] every time I hear about the LHC now.
  • by MyLongNickName (822545) on Friday January 23, 2009 @12:08PM (#26575341) Journal

    1. My Barber
    2. My urologist during my vasectomy.
    3. The LHC scientists during the first collisions.

    • Re: (Score:2, Funny)

      by eclectro (227083)

      How can an LHC scientist say oops if their vocal cords have entered another dimension of space and time?

    • by Gareon (1253358) on Friday January 23, 2009 @12:31PM (#26575737) Homepage
      I wonder if they are taking any bets on the probability of an "oops" incident.

      Source: July 16, 1945: Trinity Blast Opens Atomic Age @ Wired []
      "The Trinity test, as it was known, was the culmination of the American effort to win the race against Germany (and, ultimately, the Soviet Union) in building an atomic bomb. A mere three weeks after the test, the United States used atomic bombs to destroy the Japanese cities of Hiroshima and Nagasaki.
      But prior to the 16th, none of those involved in the project knew if they had built a devastating new weapon or a spectacular dud.
      With gallows humor, the Los Alamos physicists got up a betting pool on the possible yield of the bomb. Estimates ranged from zero to as high as 45,000 tons of TNT. Enrico Fermi, who won the Nobel Prize for Physics in 1938 for his work on nuclear fission, offered side odds on the bomb destroying all life on the planet."

      • by MoonBuggy (611105) on Friday January 23, 2009 @12:48PM (#26576065) Journal

        I think that pretty much sums up the way that the scientists on these kind of projects really think about these things, and I find it reassuring. They are just as unenthusiastic about the prospect disappearing into nothingness as you are. They are smarter than me. They are also almost certainly smarter than you. If they are comfortable enough to joke/make bets then I'm not worried.

      • Re: (Score:3, Interesting)

        by hitmark (640295)

        was there not some calculations done at the time that suggested that the atmosphere itself could be ignited?

      • by kenj0418 (230916) on Friday January 23, 2009 @01:10PM (#26576575)

        Enrico Fermi, who won the Nobel Prize for Physics in 1938 for his work on nuclear fission, offered side odds on the bomb destroying all life on the planet.

        Assuming he's betting on the "No" side, he probably should have got a prize for economics too. If you're right -- you win money. If you lose -- everyone's dead anyway so you don't have to pay! Its a win-win proposition.

        (Ok maybe win-win isn't the right term here)

      • Re: (Score:3, Interesting)

        If there is no time limit to these side odds of Enrico Fermi's--then odds could very well happen if we saw a WW3.

        I suppose it'd be pretty hard for man to technically wipe out all life with current technology. However, all of man and most large critters is close enough in my book. Hell, even knocking man back to the stone age is enough in my book.

        I wonder--did anyone bet on that one and side with annihilation? what were the odds he gave? :)

        • Re: (Score:3, Interesting)

          by HiThere (15173)

          Actually, it wouldn't be *THAT* difficult to wipe out all life on Earth, if that was your intention, and you controlled a major country (or equivalent) and you could afford to be patient. Asteroid orbits aren't *THAT* difficult to perturb. You might have to make a few orbital corrections, but I think that a solar powered mass driver on a large asteroid could probably perturb the orbit in a way that would wipe out all life on Earth within a century...though possibly some of the bacteria that live deep unde

    • by Joce640k (829181) on Friday January 23, 2009 @12:39PM (#26575887) Homepage

      If they're right the benefit to humanity could be enormous.

      If they're wrong then it's the end of the economic crisis, unemployment, conflict in the Middle East and world hunger.

      So, on balance ... I think they should do it.

    • by postbigbang (761081) on Friday January 23, 2009 @12:39PM (#26575889)

      I said it before: Lake Hadron. New shoreline real estate for sale, soon.

      Don't mind the Schwarzchild radius, come on in!

    • by MrMunkey (1039894) on Friday January 23, 2009 @12:48PM (#26576055) Homepage
      My urologist was actually quite funny. When he was done he said, "Well, I've finished with the second one... but I found a third." I was a bit confused and shocked and then he laughed and said he was just kidding.
      • Re: (Score:3, Insightful)

        by syphax (189065)

        I was so not in a joking mood at the end of that experience-

      • Re: (Score:3, Funny)

        by darthnoodles (831210)
        When I had mine done I asked him how many he'd performed. He said several thousand. So I commented that he could probably do it with his eyes closed. He offered to try...I declined.
  • And I'm not just talking about the glowing accretion disk around the hole. If we do generate black holes that swallow the Earth, at least worrying about that will take our minds off the economy!

  • by tnk1 (899206) on Friday January 23, 2009 @12:09PM (#26575365)

    There is absolutely, positively, definitely no chance of the LHC destroying the planet (or this way either) when it eventually switches on some time later this year. ...

    But physicists who have re-run the calculations now say that the mini black holes produced by the LHC could last for seconds, possibly minutes. Of course, the real question is whether they decay faster than they can grow.

    Well its good to know that despite their uncertainty about the the data, they are absolutely certain of their conclusions.

    • by MozeeToby (1163751) on Friday January 23, 2009 @12:42PM (#26575953)

      Even if the black holes lasted indefinately, their cross sectional area is too small to pick up any significant amount of matter. The Earth would be swallowed up by the sun long before the black hole began to threaten Earth in any way.

  • Well... (Score:5, Insightful)

    by AltGrendel (175092) <> on Friday January 23, 2009 @12:09PM (#26575369) Homepage
    ...there's one sure way to find out.

    Fire it up, boys!
  • cosmic rays (Score:5, Insightful)

    by cats-paw (34890) on Friday January 23, 2009 @12:09PM (#26575371) Homepage

    I thought that this entire line of doomerism had been dispensed with thanks to cosmic rays.

    Since cosmic rays are striking the earth all the time, and a decent percentage of them have a much higher energy level than anything the LHC can produce, we should have already seen such a phenomena.


    • Re:cosmic rays (Score:5, Interesting)

      by secPM_MS (1081961) on Friday January 23, 2009 @12:26PM (#26575655)
      Small black holes are far less dangerous than made out to be. I wouldn't like to be very near one due to its Hawking radiation (virtual photon creation near the event horizon where one of the virtual photons is absorbed and the other turns real as it escapes), but the fear mongers of black holes forget the limiting factor. Matter falling into a black hole is compressed and gets hot. The hot matter radiates light / gamma rays. While in some cases this radiation might be captured as well, it is far more likely that the radiation pressure will limit the rate of matter absorption by the black hole. The radiation pressure effect is known as the Eddinton effect and is a major factor in stellar stability. In the case of a small black hole, the size of the black hole is far smaller than the absorption length of gamma rays, preventing advection of the gammas. Since a non-rotating black hole is likely to convert on the order of 1% of the absorbed mass into gamma radiation, such a source would be more than capable of creating a near vacuum of hot matter about itself.

      If such stable black holes were creatable / existed, we should see rather remarkable things with old white dwarfs and neutron stars, which would be greatly affected by such energy sources.

      • Re:cosmic rays (Score:5, Interesting)

        by davolfman (1245316) on Friday January 23, 2009 @12:48PM (#26576075)
        What I find more interesting is that if these miniature black holes can give off a minute of Hawking radiation then it means the final seconds of a black hole look less like a bomb and more like a really bright flashbulb. This is great news for some science fiction authors as it means potential Hawking radiation reactors are actually NOT suicidal for a species to build.
        • Re: (Score:3, Funny)

          by bonch (38532)

          Thank goodness we built the LHC to provide science fiction authors another MacGuffin.

      • by PinkyDead (862370) on Friday January 23, 2009 @01:41PM (#26577161) Journal

        Small black holes are far less dangerous than made out to be.

        A while back we had a family of small black holes living in our basement, and I found that if you didn't bother them, they wouldn't bother you.

        The wife wanted rid of them, but I said no, they're not doing any harm to anyone - and anyway we never used that part of the basement.

        Eventually they just moved on.

    • Re:cosmic rays (Score:5, Informative)

      by whathappenedtomonday (581634) on Friday January 23, 2009 @12:28PM (#26575689) Journal
      That's what I thought, too, and in the comment section you'll find a comment from Geoffrey A. Landis [], scientist at the NASA John Glenn Research Center, stating:

      Jeez - read the abstract. Its a calculation based on a theoretical model using some very speculative physics for which there is NO EVIDENCE WHATSOEVER. Really. Ignore it.
      The main thing to keep in mind is, cosmic rays have energies vastly higher than the LHC. If the LHC could produce black holes, then there would be black holes floating around everywhere.

    • Re:cosmic rays (Score:5, Insightful)

      by Goldsmith (561202) on Friday January 23, 2009 @12:45PM (#26575999)

      There is no need for comments on this article other than the parent. In fact, this article should just be put into idle.

      As a physicist, this whole thing has been an embarrassing reminder of just how bad physicists are at public relations and the failure of many people to think logically. I'm not the biggest fan of LHC, but I'd like to see some intelligent criticism out there (Is this really where we should be putting our smartest scientists? Are particle accelerators the best way to do this measurement?), not this junk.

      • Re:cosmic rays (Score:5, Insightful)

        by Thiez (1281866) on Friday January 23, 2009 @01:26PM (#26576859)

        > Is this really where we should be putting our smartest scientists?

        What gives us the right to decide where to 'put' 'our' smartest scientists? They belong to themselves, right? It is their choice what to do with their brains (cure cancer or get drunk or work at the LHC).

        If you insist on asking a question I guess you could ask 'Do we really want to fund the LHC?'.

        • Re: (Score:3, Interesting)

          by Goldsmith (561202)

          I wish the government shared your point of view! As a scientist, I'm not entitled to a lab, or funding, or students. I have to ask the government for the ability to do research and their permission to do the research I'd like to do (they regularly check on what I'm doing). If there's no government agency (or private company) that wants to fund me to do what I'd like, I have to do what they want me to do to pay the bills. Occasionally, you can slip some research in that's not supported, but you're not go

      • As a physicist, this whole thing has been an embarrassing reminder of just how bad physicists are at public relations...

        Take heart, your peers in climatology and meteorology haven't been able to convince the US that global warming is real, in spite of the fact that several key politicians picked up the cause.

        If being unable to convince people that a black hole *won't* happen is the worst you've done, count your blessings.

    • Re: (Score:3, Insightful)

      by 0xABADC0DA (867955)

      What I object to is exactly that kind of reasoning.

      I'm not a particle physicist, so I don't know the math and formulas and such, but what I do know for sure is that they are incomplete. Our physics doesn't completely account for everything in the universe so there is no way you can say that just because high energy particles have been hitting the planet for eons that LHC can't destroy the planet. For instance, when was the last time a high energy particle hit the earth near a torus of high energy particle

    • Re:cosmic rays (Score:4, Informative)

      by khallow (566160) on Friday January 23, 2009 @01:12PM (#26576607)

      Actually cosmic rays don't fully replicate the black hole problem. Keep in mind that a black hole in the LHC would be fed for some bit of time by the stream of high energy particles in the LHC before it leaves the beam path and that black holes apparently have a relatively large cross section compared to subatomic particles. In theory, if you can feed a black hole more mass than it loses, you'll eventually grow it large enough to cause a problem, if you drop it into the Earth.

      Having said that, neutron stars are a better case study. They have densities far above that of Earth. For example, the average density of Earth is somewhere around 5.5*10^3 kg/m^3, presumably a little more in the core and around 2.5-3 kg/m^3 near the surface (I guess). The surface of a neutron star [] can have densities around 10^9 kg/m^3. That's almost a million times as dense. The interior can be far higher, somewhere above 10^17 kg/m^3. That's a factor of 10^14 more. Glancing at wikipedia [], the power output of a black hole is proportional to the inverse square of the mass. The cross-section area is proportional to the 2/3 power of the mass (mass is proportional to volume which is proportional to 3/2 the power of the cross-sectional area). That leads to the tricky observation that the ratio of mass sucked to mass lost is proportional to 8/3 power power of mass. So a black hole formed by such a cosmic ray immediately interacts with mass roughly 10^6 denser than the surface of the Earth. Neutron stars obviously have a massively greater acceleration (10^12 stronger roughly), so velocities will be a lot faster. Let's suppose that means that a black hole on a neutron star intercepts 10^18 (=10^12 * 10^6) times as much mass as it would on Earth. For a black hole on a neutron star to have the same ratio of mass in to out as one in Earth would have, it'd need a mass almost 10^7 times smaller.

      Some natural cosmic rays are known to have energies above 10^20 eV. In comparison, the energy of lead ions (the highest energy particles mentioned in the wikipedia article) in the LHC will be somewhere around 10^15 eV. At a stab, that means black holes in neutron stars ought to form with initial masses of around 10^20 eV and dissipate, else the neutron star would rapidly go away. So to generate black holes with equivalent mass in/out ratios to those on a neutron star generated by the most powerful cosmic rays we've observed, we'd need around 10^12 lead ion particles crammed into the black hole to duplicate a black hole we know dissipates on the surface of a neutron star. While there's probably that many in the beam, it doesn't strike me that the black hole will intercept many of them before it is knocked out of the beam path. The black hole might even escape Earth's gravity altogether since it is likely to start with a velocity that is a significant fraction of the speed of light. I ignore the initial velocity in the above calculation because the speed has to slow to below escape velocity before there is a problem of black hole growth.

  • by JCSoRocks (1142053) on Friday January 23, 2009 @12:09PM (#26575375)
    Hey guys, we thought the first nuclear bomb might burn up the atmosphere and we survived that! Guys?
    • by Goaway (82658)

      We didn't think any such thing.

      • by Muad'Dave (255648) on Friday January 23, 2009 @12:25PM (#26575631) Homepage
        Teller did. According to this article [], he showed that igniting the atmosphere was possible, but unlikely. He just didn't cover up the data fast enough, and it got out.

        Teller also raised the speculative possibility that an atomic bomb might "ignite" the atmosphere, because of a hypothetical fusion reaction of nitrogen nuclei.[citation needed] Bethe calculated, according to Serber, that it could not happen. However, a report co-authored by Teller showed that ignition of the atmosphere was not impossible, just unlikely.[6] In Serber's account, Oppenheimer mentioned it to Arthur Compton, who "didn't have enough sense to shut up about it. It somehow got into a document that went to Washington" which led to the question being "never laid to rest".[7]

  • Assurances (Score:5, Informative)

    by truthsearch (249536) on Friday January 23, 2009 @12:10PM (#26575387) Homepage Journal

    But shouldn't we require better assurance than that?

    What better assurance can we get than mathematical formulas? Unfortunately the only other way to find out is to run an experiment, right? I just hope their formulas and the assumptions they are based on are correct.

  • by egcagrac0 (1410377) on Friday January 23, 2009 @12:10PM (#26575389)

    And there's no possible way that Stimpy would be stupid enough to press the beautiful, shiny button - the jolly, candy-like button.

    and nothing of value was lost?

  • by Mindwarp (15738) on Friday January 23, 2009 @12:10PM (#26575393) Homepage Journal
    The Sun in conjunction with the Earth's atmosphere has been colliding particles with WAY higher energies that the LHC could ever manage for billions of years now. As far as I know we've not been consumed by a mini black hole yet.
  • by Anonymous Coward on Friday January 23, 2009 @12:10PM (#26575395)
    This could be why we do not see Advanced Alien Civilizations - their technological sophistication gets to a point where they eventually play with some sort of basic question of physics and have a planet ending disaster. Yet another reason to colonize Mars, and do this type of research there.
  • already happens (Score:2, Insightful)

    by Anonymous Coward

    Anything that could happen due to the LHC, already happens daily. The collisions in the LHC aren't as energetic as collisions that occur in the upper atmosphere from cosmic rays, etc ALL OF THE TIME. The reason to build the LHC and other accelerators is that it's kind of a pain in the ass to mount detectors on balloons and *hope* that your detector intercepts some of said cosmic rays...

  • Assurances (Score:2, Informative)

    What about the assurances in the fact that protons with energies on the order of the energy in the LHC, and several orders of magnitude larger, have been bombarding the planet for billions of years without any stable black hole forming, ever? I'm sure that for almost any event you can find some incredibly unlikely scenario of it triggering a sequence of events that will doom humanity. But it's not generally seen as a reason to stop doing things. Because it's never happened despite things going on for quite
    • Re: (Score:3, Insightful)

      by jespley (1006115)
      To put some numbers on this, the LHC [] will produce protons with 10^14 eV of energy. At that energy, we expect [] more than 1 per m^2 per year. I haven't seen any black holes recently in the square meters of the Earth's surface I routinely interact with. You? I wish the numerical illiterate would stop scare-mongering.
  • Like, "It seriously is un-possible dude!"

  • by PolygamousRanchKid (1290638) on Friday January 23, 2009 @12:16PM (#26575467)

    Yeah, I would really feel a lot better if the LHC deployed Bruce Campbell, with a shotgun during those Black Hole experiments:

    Evil Witch/Black Hole: "I'll swallow your soul! I'll swallow your soul!"

    Bruce points his shotgun at the Evil Witch/Black Hole:

    Bruce: "Swallow this."


  • by phrostie (121428) on Friday January 23, 2009 @12:17PM (#26575481)

    when they say seconds and minutes is that in normal earth time or according to the time inside the micro event horizon?

    • Re: (Score:3, Insightful)

      by AndersOSU (873247)

      I would think you'd need a quantum theory of gravity to express the effects time dilation in or near a black hole of this scale.

  • Finally! (Score:3, Funny)

    by nizo (81281) * on Friday January 23, 2009 @12:17PM (#26575493) Homepage Journal

    Finally, we may have resolved the Fermi Paradox [].

  • by xav_jones (612754) on Friday January 23, 2009 @12:21PM (#26575561)
    There will be no black holes, well except for very tiny ones that will wink out of existence in mere nanoseconds. Certainly no more than a couple of microseconds. At most a second. Likely tops of a minute. Absolutely can't be more than seven minutes ...
  • by Anonymous Coward on Friday January 23, 2009 @12:21PM (#26575567)

    Everyone wins a free trip to France.

  • by John Hasler (414242) on Friday January 23, 2009 @12:26PM (#26575659) Homepage

    > Various scientists have said this will not happen because the black holes would decay
    > before they could do any damage.

    The argument is stronger than that. Even if the holes don't decay at all their collision cross-sections are so small that they cannot get big enough to matter before the sun turns into a red giant and swallows the Earth.

    An even stronger argument is that if the LHC can create such holes so can cosmic rays and yet we are still here.

  • by dazedNconfuzed (154242) on Friday January 23, 2009 @12:27PM (#26575675)

    A black hole is just the gravity well of a given mass compressed into a sufficiently small space. In this case, the given mass is miniscule, so very little (practically nothing, hence the "evaporation" issue) will be drawn to it.

    You have more to worry about from the gravitational pull of your shoes.

  • by SilentBob0727 (974090) on Friday January 23, 2009 @12:29PM (#26575713) Homepage

    It's the ice-9 strangelets that have me worried.

  • by The Fun Guy (21791) on Friday January 23, 2009 @12:30PM (#26575715) Homepage Journal

    If you bothered to go past the Slashdot summary of the arXiv blog summary of the paper's abstract summary, and actually RTFA by Casadio et al. [], you would find the following:

    We can conclude that black holes created at the LHC under the warped brane-world scenario and described according to Ref. [4] would always remain microscopically small in mass and radius when traversing through the Earth.

    and also this:

    We conclude that, for the RS scenario and black holes described by the metric (6), the growth of black holes to catastrophic size does not seem possible. Nonetheless, it remains true that the expected decay times are much longer (and possibly â 1 sec) than is typically predicted by other models, as was first shown in Ref.[4].

    Possibly, potentially, maybe, under certain conditions, they might be longer lived than expected. They still can't grow.

    Go back to worrying about your 401Ks.

  • by Trails (629752) on Friday January 23, 2009 @12:45PM (#26576001)

    If the LHC manages to create mini blck holes, let's be clear here, tese will be very very mini. A black hole weighing what? Same as a couple atoms of carbon?

    Consider that even if matter collapses to a singularity, its gravitational effect is still just proportional to its mass. Given that the LHC is a vacuum where the collisions are occuring, the blackhole could only ever mass the sum total of the mass of the particles used in the collision. From a casual outside observer you wouldn't even notice, and the black hole would decay before it could acquire more mass.

  • Cosmic Rays anyone? (Score:4, Informative)

    by nukeade (583009) <> on Friday January 23, 2009 @12:51PM (#26576145) Homepage

    The most energetic particle that the LHC can create is 574 TeV/particle lead nuclei. Nature has been bombarding our solar system with a significant flux of particles as powerful as 100 million TeV for as long as it's been around. If it was possible to spawn a black hole capable of consuming a planet from a collision with a particle a mere thousand TeV in energy, then it is all but certain that we would have seen every large body in our solar system converted from billions of years of bombardment from cosmics ray 100,000 times more energetic (caveat: much more energy is available for consumption into a black hole should two particles collide "head-on" with opposing momenta versus a fast particle with a stationary target).

    Though, the above reasoning does not exclude the possibility that black holes that may last minutes but yet not consume planets.


  • by hAckz0r (989977) on Friday January 23, 2009 @12:52PM (#26576171)
    ... that the LHC is not in my back yard.

    Actually this is great! Being across the pond, I should have the benefit of at least a femtosecond to be the first to write and publish a paper on the effects of gravity waves before I go. After all, those Europeans are going to be pretty much getting all the glory and making it much harder for us on this side to be recognized for any new discoveries. With this type of discovery, and it being so close to home, they likely won't even see it coming. And for a Scientist there is surely nothing like getting really embedded into your work to make you forget to publish. But face it, sometimes its just better to distance yourself for a more objective look at a situation.

  • by SpuriousLogic (1183411) on Friday January 23, 2009 @01:12PM (#26576601)
    The LHC black holes are not new. Physicists have seen super-heavy particles hitting the upper atmosphere for some time. These particles are huge (something like half the plank mass, but memory is a bit fuzzy ), and moving very fast. It is not known where these particles originate from, but the idea of the black holes in the LHC is based on the same mechanism. The LHC black holes would get generated very similarly to the mechanism that these super heavy particles possibly generate black holes in the upper atmosphere. See [] and [] for more info
  • by MrLizard (95131) on Friday January 23, 2009 @01:12PM (#26576615)

    I find it hilarious how people say, "Before we run an experiment, we need to know what will happen!" Hello, McFly! You run experiments to FIND OUT WHAT WILL HAPPEN. That's, uhm, the whole FRAKING DEFINITION OF THE SCIENTIFIC METHOD! You can do the math, you can form theories, you can hypothesize... but you never know FOR SURE until you flip the switch.

    People like the OP were probably standing around in caveman days, saying, "Ugh. No make fire. What if fire is monster, kill everyone? Bad thing. Not make fire unless know not monster."

  • Figure it out... (Score:3, Informative)

    by Genda (560240) <> on Friday January 23, 2009 @06:34PM (#26582223) Journal

    As others have said many times, nature dramatically exceeds any test we've ever done on an almost daily basis. If microscopic black holes were going to gobble up the earth, it would have happened long ago, in fact, all the stars and planets in the universe would now be black holes. You may have noticed, this hasn't happened. ergo...

    Think about it... the sun, 186,000 miles across reduces to a black hole, and the radius of the event horizon would be measured in mere dozens of miles. Now squish an atomic nucleus (even carrying the mass of all that acceleration), the resulting black hole and it's event horizon would vanish down to dimensions comparable to the Plank Length. At that dimension, the distance between any particles is beyond imagining. With a lifespan of even hours the best such an object could hope to do is gravitationally disrupt a few atomic nuclii.

    This simply isn't a threat to anyone or anything.

  • Answer: no (Score:3, Insightful)

    by toriver (11308) on Friday January 23, 2009 @07:49PM (#26583171)

    But shouldn't we require better assurance than that?

    The doomsayers have grabbed onto this idea of horrible black holes, but the proof that these will even appear are from the same scientists that try to convince them that any black holes, in the unlikely case they will appear, will be harmless. "Assurance" seems to be a requirement directed at only one side of the fence while the other is free to do its unscientific fantasizing without any need to provide actual proof.

    I mean after they have proven that the Earth will not be swallowed by a black hole when they perform the experiments, what next?

    Prove that a dimensional gate will not open, letting in Yog-Sothoth from the great beyond.

    Prove that the collision will not exterminate the (ultra-rare) unicorns.

    Prove that the collider doesn't employ Goa'uld technology.

    It never ends.

    Meanwhile, said doomsayers carry mobile phones in their pockets even though it hasn't been proven that the radiation doesn't cause infertility and cancer. They drive cars even though the probability of getting killed that way is many orders of maginitude higher than the black hole forming hypothesis...

You are in a maze of little twisting passages, all different.