Monday, April 03, 2006

Mini Black Holes

The last days I was at the conference Strangeness in Quark Matter, which was strange indeed. It was nice to meet all the people, and surprising how many I knew. Walter Greiner's 70iest birthday was an occasion to tell some funny stories. As so often, I got the impression that the Heavy Ion community is actually a large family, where people stick together even though they can not stand each other, and bad habits get passed on to the next generation.

Anyway, before I begin to wonder why I kicked myself out of the field, let me come to the reason of this post. My PhD adviser Horst gave a talk about Black Hole production at the collider. I had an earlier post 'Risky Black Holes' where I told you about the governmental guy who was concerned about the danger of Black Hole production at the LHC. He wrote back several times, asking for exact probabilities for every possible scenario, and circled around the question what probability to destroy the whole planet when LHC is switched on is acceptable? 0.001% ? 0.000000000000000000000000001 % ?

Also, last week I received an email from a guy writing for a German newspaper who apparently is about to plan an article about extra dimensions and black holes for the Sunday edition.

Some of you might know that the reasons I worked on black holes are quite obscure, and that I repeat at least twice a year that I don't want to work on it any more. What's so complicated about quitting is that the interest in the topic is so large! Black holes always make a good topic at BBQs, and everyone thinks he has something to say about extra dimensions. Even though I appreciate the discussion, I can't avoid having the impression that the scientific content is in most cases entertaining but doubtful. E.g. I learned that cosmic rays are black holes that are created on our brane, then go into the extra-dimensions, grow there, then come back to our brane and make an ultra high energetic cosmic ray. Sounds exciting, huh? But is that scientific?

So here is a quite general statements:

If the Hierarchy problem (the gap between the Elektroweak and the Planck scale) is only an apparent problem and the Planck scale is much lower, then black hole production is one of the most general predictions that we can make about what is going to happen. The assumptions are plain and simple, too much energy in too little space leads to a collapse.

However, though we think we know how the Hawking radiation looks like, we have no idea what the final decay looks like. Therefore, most details of the black hole's signature are strongly model dependent and should be treated carefully.

In addition to this, the required models with extra dimensions are not really understood, esp. regarding the stabilization, the evolution in the early universe (or time dependence in general), and at least I don't feel comfortable with the mechanisms to confine particles to the brane. Also, extra dimensions are surely not a theory of everything, so there should be more about it.

This is not to say that one should not investigate speculative ideas, just that one should try to stay as close as possible to reliable assumptions. I don't think there is any point in examining weird and even weirder scenarios on shaky ground. That's nice for a BBQ party but not really scientific.


  1. <<< My PhD adviser Horst gave a talk about Black Hole production at the collider. >>>

    Guess who's supposed to write the proceedings.


    I fully understand you. I know too well the moment when you are trying to explain your field of work to a non-physicist (yes, indeed, physicists actually talk to non-physicists, they even have them as friends!) and you mention the two words "black hole" in a mere subordinate clause, and the person you are talking to is immediately interrupting you and asking more: "Black holes? Really? How?" I know how depressing it is since LXDs is not all about black holes, black holes are just a possible observable, and that only in the case of very favourable parameters and in a semi-classical approximation.

    I think the whole point is that "black hole" sounds stylish in some way (praise the inventor of the phrase, otherwise we would still call it space-time singularity or something) and gives people the feeling they could at least remotely understand what we are doing in the ivory tower. And that is also the reason why the newspapers (we also talked to that FAZ-guy here in Frankfurt) and the rest of the physical community is so interested in it. (imo there is not much difference between non-physicists and non-expert-physicists in that respect.)

    But isn't that rewarding too? Doesn't that give us some confirmation and social support for the "useless" work we are doing? I feel the black hole somehow connects the scientific world with the everyday world, even though that connection may be only a faint resemblance of the hard scientific problem behind it. And isn't that a very rewarding prospect?

  2. I think a lot of actors have
    the same problem. Once they
    are famous for this on special
    kind of movies, nobody would
    ever accept that they are doing
    something different now.

  3. I learned that cosmic rays are black holes that are created on our brane, then go into the extra-dimensions, grow there, then come back to our brane and make an ultra high energetic cosmic ray.

    BTW, I have found "the source" of this story, it is mentioned in a recent book by some Stephen Webb,
    Out of This World: Colliding Universes, Branes, Strings, and Other Wild Ideas of Modern Physics, on page 262 - in case your amazon "look inside" works, it is the 9th hit when searching for "cosmic rays"; that is how I have found it.

    That book, from the table of contents, treats an amazingly wide range of topics, including M theory and the holographic principle. I always wanted to understand what this AdS/CFT/holography stuff is all about. Maybe I should try to read it ;-)...

  4. Hi Uli,

    yes, it is definitely rewarding! That is why I DON'T quit doing the black hole stuff. I also think its in general a good thing to communicate the stuff I am doing to other people, physicists or not. Not so much to advertise it, but because it actually is inspiring and feedback is always useful.

    As far as I know black holes were originally named 'frozen stars', which sounds more poetic (but would have spoiled our joke with the black holes in the governmental budget for the xmas-party movie...).

    Stefan, thanks for the book info. I ordered the book at amazon to see how bad it is... Will let you know.

    Uli, BTW, have a look at Lisa Randall's book, its really nice and says something about black holes as well.



  5. Stefan, thanks for the book info. I ordered the book at amazon to see how bad it is...

    Why do you assume it is bad?

  6. Seems the amazon package arrived already last week. I put it on my fridge and forgot it. Still have not read the book, sorry, no news.

    So, I can't tell whether its good or bad, that's why I want to have a look at it. From what I have heard so far, it seems to be very speculative. Though I would say I am fairly open minded for new ideas, I don't think its so good to mix up serious research with weird ideas in popular science books. The avergage reader won't be able to tell the difference.

  7. just think of the LXD-BHs as a source of energy!

  8. just think about how much energy it takes to run the LHC...

  9. The Large Hadron Collider [LHC] at CERN might create numerous different particles that heretofore have only been theorized. Numerous peer-reviewed science articles have been published on each of these, and if you google on the term "LHC" and then the particular particle, you will find hundreds of such articles, including:

    1) Higgs boson

    2) Magnetic Monopole

    3) Strangelet

    4) Miniature Black Hole [aka nano black hole]

    In 1987 I first theorized that colliders might create miniature black holes, and expressed those concerns to a few individuals. However, Hawking's formula showed that such a miniature black hole, with a mass of under 10,000,000 a.m.u., would "evaporate" in about 1 E-23 seconds, and thus would not move from its point of creation to the walls of the vacuum chamber [taking about 1 E-11 seconds travelling at 0.9999c] in time to cannibalize matter and grow larger.

    In 1999, I was uncertain whether Hawking radiation would work as he proposed. If not, and if a mini black hole were created, it could potentially be disastrous. I wrote a Letter to the Editor to Scientific American [July, 1999] about that issue, and they had Frank Wilczek, who later received a Nobel Prize for his work on quarks, write a response. In the response, Frank wrote that it was not a credible scenario to believe that minature black holes could be created.

    Well, since then, numerous theorists have asserted to the contrary. Google on "LHC Black Hole" for a plethora of articles on how the LHC might create miniature black holes, which those theorists believe will be harmless because of their faith in Hawking's theory of evaporation via quantum tunneling.

    The idea that rare ultra-high-energy cosmic rays striking the moon [or other astronomical body] create natural miniature black holes -- and therefore it is safe to do so in the laboratory -- ignores one very fundamental difference.

    In nature, if they are created, they are travelling at about 0.9999c relative to the planet that was struck, and would for example zip through the moon in about 0.1 seconds, very neutrino-like because of their ultra-tiny Schwartzschild radius, and high speed. They would likely not interact at all, or if they did, glom on to perhaps a quark or two, barely decreasing their transit momentum.

    At the LHC, however, any such novel particle created would be relatively 'at rest', and be captured by Earth's gravitational field, and would repeatedly orbit through Earth, if stable and not prone to decay. If such miniature black holes don't rapidly evaporate and are produced in copious abundance [1/second by some theories], there is a much greater probability that they will interact and grow larger, compared to what occurs in nature.

    There are a host of other problems with the "cosmic ray argument" posited by those who believe it is safe to create miniature black holes. This continuous oversight of obvious flaws in reasoning certaily should give one pause to consider what other oversights might be present in the theories they seek to test.

    I am not without some experience in science.

    In 1975 I discovered the tracks of a novel particle on a balloon-borne cosmic ray detector. "Evidence for Detection of a Moving Magnetic Monopole", Price et al., Physical Review Letters, August 25, 1975, Volume 35, Number 8. A magnetic monopole was first theorized in 1931 by Paul A.M. Dirac, Proceedings of the Royal Society (London), Series A 133, 60 (1931), and again in Physics Review 74, 817 (1948). While some pundits claimed that the tracks represented a doubly-fragmenting normal nucleus, the data was so far removed from that possibility that it would have been only a one-in-one-billion chance, compared to a novel particle of unknown type. The data fit perfectly with a Dirac monopole.

    While I would very much love to see whether we can create a magnetic monopole in a collider, ethically I cannot currently support such because of the risks involved.

    For more information, go to:


    Walter L. Wagner (Dr.)

  10. Micro Blackholes

    Walter there is more on this topic by Bee there.


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