The LHC’s dodgy dossier?


There’s no reason to worry about the Large Hadron Collider that is due to to be switched on later this year for the second time. The chances of it creating a planet-swallowing black hole are tiny. Hardly worth mentioning really.

But last month, Roberto Casadio at the Universita di Bologna in Italy and a few pals told us that the LHC could make black holes that will hang around for minutes rather than microseconds. And they were rather less certain about the possibility they the  black holes could grow to catastrophic size. Far from being utterly impossible, they said merely that this outcome didn’t “seem” possible.

This blog complained that that was hardly the categorical assurance we’d come to expect from the particle physics community. The post generated many comments, my favourite being that we shouldn’t worry because of the Many Worlds Interpretation of quantum mechanics. If the LHC does create Earth-destroying black holes, we could only survive in a universe in which the accelerator broke down.

Thanks to Slashdot, the story got a good airing with more than few people pointing out that we need better assurances than this.

Now we can rest easy. Casadio and co have changed their minds. In a second version of the paper, they’ve removed all mention of the black hole lifetime being many minutes (”>> 1sec” in mathematical terms) and they’ve changed their conclusion too. It now reads: “the growth of black holes to catastrophic size is not possible.”

What to make of this? On the one hand, these papers are preprints. They’re early drafts submitted for peer review so that small problems and errors can be ironed out before publication. We should expect changes as papers are updated.

On the other, we depend on the conclusions of scientific papers for properly argued assurances that the LHC is safe. If those conclusions can be rewritten for public relations reasons rather than scientific merit, what value should we place on them?

Either way, we now know that a few minutes work on a wordprocessor makes the LHC entirely safe.

Ref: On the Possibility of Catastrophic Black Hole Growth in the Warped Brane-World Scenario at the LHC version 2

Thanks to Cap’n Rusty for pointing out the new version

22 Responses to “The LHC’s dodgy dossier?”

  1. K says:

    Theorist predict shit like this with as much success as they do trying to get laid. Once in a blue moon if they’re lucky and it’s probably with a fugly chick. period.

  2. Sean Carroll says:

    Sorry, but this is a bit silly. The reason why physicists think the LHC is safe is not because their models predict that black holes will evaporate away, even in the unlikely event they are produced. It’s because the LHC won’t do anything the universe hasn’t done countless times before. If the LHC were going to do anything dramatic to Earth, we should have seen similarly dramatic things elsewhere in the universe. And we don’t.

    Particle physicists do not have much motivation to be sloppy about the possibility of destroying the Earth. There are much more interesting and dangerous things to worry about in life than LHC disaster scenarios.

  3. Charles Q. Choi says:


    I’ve interviewed scientists who talked through this brou-ha-ha the first time. There are a number of fairly reasonable arguments why the LHC won’t destroy the Earth beside the oft-cited “higher-energy collisions happen in the Earth’s atmosphere all the time, and the planet hasn’t been destroyed yet.”

    Below is the story I wrote, which appeared on MSNBC, etc.:

    In short, even if the models that suggest that LHC will generate black holes are right, and even if these black holes don’t evaporate immediately as Hawking predicted, and even if these black holes don’t go zipping off the Earth (because, after all, they were created in the aftermath of a high-speed collision) and somehow magically sink into the Earth — these black holes are subatomic, and would take longer than the lifetime of the sun to devour the Earth.


    Good news! Black hole won’t destroy Earth
    Fears raised collider would create black holes that could swallow planet

  4. srph says:

    “Either way, we now know that a few minutes work on a wordprocessor makes the LHC entirely safe.”

    Great attitude for a scientist to have. People shouldn’t be allowed change their opinions, or correct their errors?

  5. tulcod says:

    I have to agree with the criticism in other responds here: why does the validity of a paper depend on opinions? I know, it’s a problem embedded in all science, but this is one of the more extreme cases, and peer review should have reviewed this paper more deeply.
    That aside, arxivblog shouldn’t switch opinions this easily either. Where are the real, objective scientists these days?

  6. wcoenen says:

    Glad you liked my many-worlds comment ;-) (

  7. gs says:

    IMO it’s a good thing to have a forum where scientists can think out loud in depth. IMO it’s good to have a visitors’ gallery for the public that funds the science.

    But that implies that the boom will not be lowered, by the public or by their peers, if brainstormers change their minds.

    Our host’s tut-tutting would be well taken if a published, peer-reviewed paper were followed by flip-flopping corrigenda.
    So as not to be a killjoy here, I’ll note an LHC cataclysm has an upside: if the earth begins to be devoured, presumably there will be time and rationale to award a series of Nobel Prizes for black hole physics.

  8. This article has been added to the Astronomy Link List.

  9. Zephir says:

    /*’s because LHC won’t do anything the universe hasn’t done countless times before…*/

    Well, I’m not aware of observational evidence of many LHC experiments in Universe, just the presence of many black holes in it. This could serve rather as an evidence of the opposite, don’t you think?

    Be more serious, LHC collisions are exceptional by their low symmetry combined with particle jet density. During supernovae explosions most of matter moves in the same direction, huge gradients in radial momentum can never occur here. Therefore as the only relevant analogy of LHC can serve just another collider.

    Personally, I don’t consider risk of black hole very significant, because risk of strangelet formation is way more significant here, as it can occur at much lower energy densities and by recent Fermilab dimuon events we even observed it already.

    Anyway, this doesn’t change the fact, theorists can alter meaning of their deductions by removal of few sentences from it up to level, which illustrates clearly, how firm and relevant their stance really is.

  10. R.. Mirman says:

    Brane worlds are nonsense thus so are the arguments. See proof that a universe is possible only in dimension 3+1 (which eliminates branes) in book
    Our Almost Impossible Universe:
    Why the laws of nature make the existence of humans extraordinarily unlikely

  11. “CERN does not insure it’s truth.” -inductive logic

  12. The standar model is not even a “s t a n d a r d” model.

    LHC/cosmic ray cross sectional data are incomplete, indeterminate and inconclusive. You fail.

    “The Grand aim of all science is to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms.” -Albert Einstein

  13. Angus says:

    @Zephir: The same sort of collisions that happen at the LHC also happen in Earth’s upper atmosphere (and on everything else in space) due to cosmic rays. We don’t see the Earth being devoured by black holes from cosmic ray collisions.

  14. ZEPHIR says:

    Nope Angus, this sort of collisions exhibits an exceptional symmetry, which is a product of billion years long evolution of human race, nothing else. You cannot find a situation, where so many particles are moving in opposite directions with the only exception: during brane collisions, which are supposed to form our universe generation. By AWT everything in our Universe is symmetry driven.

    So you cannot consider energy density only, but the geometry of collisions and the resulting momentum of collisions products, too, simple chaos based thermodynamics doesn’t work well here. For example, strangelet formation can never occur as a consequence of cosmic rays collisions with Earth atmosphere, simply they’re always formed by individual proton particles, not by collimated proton jets.

  15. ZEPHIR says:

    /*..brane worlds are nonsense thus so are the arguments…*/
    By AWT brane worlds can be interpreted even in 3D geometry, because AWT is invariant to high dimensional models. Every interaction in many dimensions can be replaced by interaction, whose force constant doesn’t fulfill inverse square law. For example personal relationships (which are working at very long distance) can be considered as an interactions in extremely high number of dimensions. From this perspective, our world is full of hidden dimensions, we just don’t realize it.

    Conversely, from exsintric perspective every highly dimensional particle system appears like simple system of nested particle fluctuations (atom nuclei, orbitals, and so on). Therefore from exsintric perspective of outer observer such brane collisions appear like normal collisions in 3D, we can even observe them from outside during pulsar formation.

  16. ZEPHIR says:

    I can try to explain the source of misunderstanding once again. For example, neutrons are conditionally stable particles, which are decomposing slowly and at presence of strong gravity fields at the center of neutron stars the decay of neutrons into protons and electrons can be suppressed completely.

    But the same result, like extreme gravity can exhibit the surface tension of tiny dense droplets of pure neutrons (so called the neutron fluid) due their strong positive surface curvature. From this perspective, common atom nuclei are neutron droplets too, they’re just balanced by excess of protons, which are making them more stable. Because pure neutrons droplets lacks the repulsive force of protons, they can have a tendency to expel protons from neighboring atom nuclei, thus changing them into another strangelets in avalanche like reaction.

    The neutron fluid model can be extended into second and third generation of quarks as well, because the surface tension mechanism can stabilize dense clusters of every unstable particles under formation of tiny quark starlets (containing high number of strange quarks), so called the strangelets. Because these strangelets are expected to be more stable, then individual particles (which are forming them), we can expect the very same avalanche reaction even at the level of second and third generation of quarks.

    It means, from perspective of thermodynamics the possibility of formation of large cloud of tiny dense neutron starlets is much more possible, then the formation of single black hole or neutrino star, albeit it can release a lower amount of energy, then just black hole formation. Unfortunately for mankind, strangelet mechanism still doesn’t provide any alternative for terrestrial life anyway, because energy released during avalanche propagation of strangelets will be still comparable to nuclear fusion reaction.

    We can see, while the risk of black hole formation is rather low (because it requires the formation of highly unstable black holes, which are evaporating fast by Hawking mechanism), the strangelet mechanism considers droplets of particles, which can be prepared and handled even at room temperature and pressure, so to say. My personal problem is, this possibility wasn’t taken into account in security analysis of LHC experiments, so until now we have no clue about probability of such chain reactions during LHC collision.

  17. The LHC collisions would be symmetric. Cosmic rays are asymmetric. Simply…no comparison.

    For such large artifacts CERN did not check their astronomical arguments (which are anyway only weak). It is also clear, that the collisions of cosmic rays in the atmosphere do not create Quark-Gluon-Plasmas. Cosmic rays sometimes consist from iron-nuclei, which are 4 times smaller than those of gold (used at RHIC) or lead (to be used at LHC). And even if they would be created, there would be only ONE single iron nucleus colliding, quite in contrast to the LHC where packages of 10e11 nuclei are smashed within <10e-11 seconds in exactly the same place. A small difference, uhh? It is easy to imagine, that around 50% of the 10e11 lead nuclei are collected by an Quark-Gluon-Plasma, i.e. around 10^10. As said, any of the lead nuclei contain around 207 protons/neutrons. Now let us proceed conservatively, only 1% of the mass remain in the QGP, do to perturbations, jets etc. Still the mass of the QGP would be 2*10^10 protons. That is 10′000*1′000′000 more than calculated by the CERN safety papers. Any synchronization effect like “flocking”, hypersonic compression or others are addition ally to be taken into account. It is not only not difficult to imagine that a QGP collapsing into a black-hole is not so micor any more, it is almost sure that these objects will NOT behave as suggested by Giddins/Mangano/LSAG.

    The incalculable “black hole rex” showed it’s teeth at RHIC in 2005 w/ a 10th of the amount of energy available at LHC…

    “The RHIC fireball as a dual black hole”

    “Lab fireball may be black hole”

    And Heim predicted the neutrino masses 20 years ago when many physicists still thought they had zero mass:

    Until now, Heim’s unified field theory must be considered the most successful one, since in physics there are no better results for the properties of elementary particles yet, since Higgs-bosons have not yet been found and physical properties of strings can not yet be determined. Therefore, it should to be checked by specialists. Since this theory requires exceptional mathematical knowledge, Heim’s theory is only accessible to few theorists. But the many results of this theory which correspond with experiments, in our opinion, justify all efforts of a preoccupation with it – contrary to many other modern theoretical ideas.

    So Heim theory, with the mass formula nd artificial gravity predictions, has already many more predictions than String theory or Loop Quantum gravity (who have essentially no concrete easily measurable predicitons).

    Heim got another shot in the arm (well his successors, as he died some years ago) recently when Martin Tajmar discovered what seems to be artificial gravity, more or less confirmed by a group in Canterbury, NZ, and the ‘anomalous’ results of the Gravity Probe B satellite. Droscher and Hauser found that Heim’s gravito-photons could explain this, as his theory has just 2 extra forces compared to the usual 4, both gravitational: this gravito-magnetism via gravito-photons and a weaker long range force, resembling dark energy. Heim’s theory predicts a way to improve on Tajmar’s effect that could lead to a new space drive. Tajmar quotes the Heim mechanism as one of 2 or 3 candidate theories of his effect, in his papers (search Arxiv etc.).

  18. Zephir says:

    Yep, my stance is exactly the same. Even sucessull finding of Higgs bosons or some SUSY artifacts will not enable to compute mass of particles better, then 30 years old Heim’s theory enables. In fact, SUSY artifacts are closely related to strangelet concept, so that sucessfull confirmation of SUSY may become the very last success of civilization at all.

    Contemporary high energy physics is driven by politics and short-seeing interests, so its separated from interests of the rest of society like black hole. Which is the main reason of its undergoing crisis.

  19. [...] The LHC’s dodgy dossier? the physics arXiv blog Could the LHC produce a dangerouse black hole when it is switched on again later this year. A paper currently in preprint suggests that black holes could be generated which may last for a few minutes. It has since been rewritten to state that they could be created, but will last for only a short amount of time. [...]

  20. Warren Platts says:

    The reason for the difference between the two versions is that the equations are designed to be used with natural (Planck) units. The first version apparently used SI units for the calculations–that’s what threw everything off by several orders of magnitude. In the second version, the calculations were done with natural units, and then reverted to SI units.