Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Artificial Black Holes, again

  1. May 29, 2006 #1
    Wikipedia http://en.wikipedia.org/wiki/Micro_black_hole" [Broken] that hawking radiation is a controversial theory which very well may not be true. Correct me if I'm wrong, but doesn't this mean that if we are able to create micro black holes at the Large Hadron Collider, and if Hawking radiation is wrong, we are effectivly destroying all of humanity and this entire solar system? Won't scientists at the collider try and create micro black holes? Isn't this a bit reckless on the part of the scientists to endanger all of human existence based on very theoretical science? All of this just to possibly learn a bit more about black holes. Doesn't make too much sense if you ask me...

    I'm just trying to understand the thinking in all of this, thanks.
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. May 29, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    This argument comes back sometimes. Of course, each time something new is tried, there can always be some imaginary (or real) catastrophy anticipated. But the aim of the LHC is not to create black holes, and probably won't.
    There have been more catastrophic scenarios, one being that the vacuum state of the universe is an unstable one, and that a collision of high enough energy might "trigger" the sudden phase transition to another vacuum state (like the sudden freezing of an undercooled liquid). That would not only destroy the earth and the solar system, but the entire visible universe. The advantage is that death in this case is totally painless.
    Last edited by a moderator: May 2, 2017
  4. May 30, 2006 #3


    User Avatar

    Wikipedia dodges another blow!!
  5. May 30, 2006 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    No, even if it formed and didn't evaporate, a micro black hole would not destroy the solar system, humanity, or even the laboratory. The interaction cross section (if approximated by the horizon area) of a micro black hole is absolutely miniscule (at least in the theories I've seen).
    Last edited by a moderator: May 2, 2017
  6. May 30, 2006 #5
    As much fun as it must be to "play" with the LHC, the energies it's capable of reaching don't come close to what occurs naturally in the universe. Since the universe has been round for awhile, and since it's still here, I suspect the notion of existence being torn assunder by the experiments we puny humans do as a tad unjustified.
  7. May 30, 2006 #6
    Even if it didn't evaporate and it did manage to interact with matter enough to suck in the entire planet (that's two enormous if's which go against GR and interacting quantum field theories) then it wouldn't destroy the Sun, it would form a black hole the mass of the Earth orbiting the Sun. Even the Moon wouldn't really notice any change, because all it notices is the Earth's gravity and the black hole would just fall to the centre of the Earth and absorb it all. The Moon would continue orbitting because the gravity wouldn't change.

    As already said though, that's almost certainly not going to happen anyway. It's just too many people hear "black hole" and think "Giant, unstoppable cosmic vacuum cleaner that devours everything around it".
    Last edited: May 30, 2006
  8. May 30, 2006 #7


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Yes, as long as it escapes with sufficient momentum. But if it is produced at low enough momentum, so that it falls down, right through the earth, and back, it is supposed to slowly eat out what it finds on its way, no ?
    So like each time eating out a very very thin needle of "earth" along a diameter, wouldn't this end up (I have no idea how long it would take, it's maybe only 5 protons eaten up per voyage) eating up all of earth ?
  9. May 30, 2006 #8
    Considering there are particles that are hitting the Earth's atmosphere with several orders of magnitude more energy than what will be produced at the LHC, and also considering that we're not all dead yet, I'd say we're pretty safe.
  10. May 30, 2006 #9
    So the argument for "this is safe" are as follows:

    1.) That even if we produce black holes, and they don't evaporate, they won't interact with matter and get any bigger.

    This is wrong because eventually it will absorb matter, grow bigger and absorb it faster untill it consume all of earth.

    2.) That we won't have enough energy to produce black holes anyway.

    Too risky because it is theorized that if string theory is correct, we will in fact have enough energy to create a micro black hole in our accellerator.

    3.) It is safe because particles hitting our atmosphere from space have more energy than particles will have in the accellerator, so the accellerator experiments must be safe.

    Who's to say this is true, do we know this for sure? And couldn't the different aspects of the matter and energy be different in the experiment from the interacations that happen naturally in our atmosphere, such that our experiments would create black holes?

    In other words, none of the arguments for why this whole black hole experiments are safe are so rock solid definite that it is safe to jepordize everything just for the sake of some science experiment.
  11. May 30, 2006 #10
    Well, we have large amounts of evidence that it is indeed happening in the atmosphere. I'll just link to the Wiki article, but you can Google for it and get all sorts of results:

    These lines in particular:
    "It was most likely a proton travelling with velocity almost equal to the speed of light..."
    "Since the first observation, by the University of Utah's Fly's Eye Cosmic Ray Detector, at least fifteen similar events have been recorded, confirming the phenomenon."

    And the LHC will be accelerating hadrons (protons and heavy ions). The max energy for a proton in the LHC will be around 10^10 eV, whereas the Oh-My-God particles peak at around 10^20 eV. That's 10 orders of magnitude.

    Another quote from a different source:
    "The frequency of air showers ranges from about 100 per m^2 per year for energies >10^15 eV to only about 1 per km^2 per century for energies beyond 10^20 eV."

    So, there are about 100 events per year on every square meter of the Earth with 10,000 times as much energy as the events that will occur in the LHC. That works out to about 5x10^16 events over the whole Earth per year. 2.5x10^26 events over the lifetime of the Earth.

    So, therefore, if the LHC kills us, it would be an event that happens in only 1 out of every >10^26 interactions. I think we can take our chances... :)
  12. May 30, 2006 #11
    Also: The most energetic particles produce "showers" of particles (MANY particles, ~10^11), many of which are still much greater in energy than what the LHC could possibly produce.
  13. May 30, 2006 #12


    User Avatar
    Staff Emeritus
    Science Advisor

    I think you may be missing the timescale involved here. The sun will turn into a red giant long before such a tiny black hole could eat the Earth.

    See for example

    http://curious.astro.cornell.edu/question.php?number=572 [Broken]

    That was worked out for a billion ton black hole that did not evaporate, much larger than anything a particle accelerator could create.

    Yes, another poster has already posted some references to a MUCH more energetic events that already occur in nature.

    Worry about getting struck by a meteorite on the way to work, or if you like global destruction, the next "Dinosaur killer" impact, it's more logical than worrying about creating a black hole in a particle accelerator.

    (It would be even more logical, of course, to worry about getting in a traffic accident, or slipping on your bathtub, or choking on your food).
    Last edited by a moderator: May 2, 2017
  14. May 30, 2006 #13
    We are safe IF the current hypotheses are true. We can't know that they are true without performing the experiment, and if they aren't true, then... well... you know.

    The conserved momentum of naturally ocurring impacts would send a subsequently formed black hole clean through the earth before it could accrue any meaningful mass. Therefore the argument that the earth is constantly being bombarded anyway, is rather meaningless.

    The CERN created black holes will have little (if any) relative momentum to the earth. They'll just hang around, causing what damage they might.

    Should these things fall into the Earth's core, they will be in an environment where the average densisty is 811.6 pounds per square foot, the pressure is about 52 milliion pounds per square inch and it's about 11,000 degrees farenheit!

    Imagine all of that crushing pressure just looking for an escape route! The real concern then isn't what might "fall" into the nano black hole, but rather what might be pushed in.

    As far as planetary destruction is concernd, how do we know that the asteroid belt wasn't the result of a black hole orbiting the center of mass of a former planet?

    It has been supposed under GR that we'd need about 620 orders of magnitude more energy than CERN to create nano black holes. It can only work if string theory is correct and the energy required comes from other dimensions.

    Unfortunately, it's looking like the energy requirements aren't as high as originally supposed. In fact, they think they've already created one at another collider (reference).

    Side note: Did you know that if the sun became a black hole its event horizon would be like 1.9 kilometers wide, but if Earth became a black hole its event horizon would only be around a centimeter wide?

    You might doubt black hole formation at CERN, but the way they are talking about it, they have little doubt. They are expecting to make thousands of 'em at a time (reference).

    Personally, I agree that the risk here is seemingly small. However since we are literally risking everyone and everything, I think the risk is too great. Just ask yourself: What if they're wrong?

    I say let's wait to do these experiments off-world, safely away from our only earth.

    Last edited: May 30, 2006
  15. May 31, 2006 #14


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Although I agree with you, we should be cautious here. To even produce black holes at TeV energies, we need compactified extra dimensions, and this can greatly increase the Schwarzschild radius of a micro black hole. If the Planck scale is ~1 TeV, the Schwarzschild radius of a planck mass black hole works out to:


    where the "pl0" subscript refers to the standard planck quantities. This works out to around 10-19 m -- still smaller than the billion ton black hole, but not by much. The timescale would be very long, much longer than that estimated in your link. While in 4-D the horizon size scales as the mass, higher-dimensional spaces have a scaling that goes less dramatically with mass (M2/7 in 10-D). More info here:

    http://xxx.arxiv.org/abs/hep-ph/0106219" [Broken]

    Anyway, I otherwise agree with you completely. It's true that, if the earth existed eternally and the black hole remained bound, it would eventually "swallow" the earth, but the timescales are so long that it's not even worth thinking about. Other things will get us (and even the earth) before then.
    Last edited by a moderator: May 2, 2017
  16. May 31, 2006 #15
    That's what I was getting at: all the hypotheses that "prove" that these black hole experiments are safe are simply to weak and newly hypothosized to risk our entire future for some discretionary science experiements. In other words, no matter what explanation anyone has for why micro black hole experiments are safe, it's not good enough because it's not proven. The only thing that is known is that black holes here on earth can end our entire existence, so I think it's safe to say we need quite a bit of undeniable, undebatable proof that these experiements are safe before we can resonably justify the risks involved. I'm sorry but just saying that "Hawking radiation theory is probably right" isn't good enough for me, not when the entire world's existence hangs in the balance.

    In simple mechanical engineering, any unknown factor like material strength or long term strain is treated with caution to ensure it is not a danger and safety threat. But here, we are dealing with the most unproven, theoretical physics, often based just on hypothesese, and yet these people expect to mess around with this stuff as if it's no big deal, and not as if it has a chance of ending our entire existence. The whole thing just seems ludacris.
  17. May 31, 2006 #16
    I have to say I'm uncomfortable about the LHC. Particularly when I read Michiu Kaku saying energies seen not since the Big Bang.
  18. May 31, 2006 #17


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Hey, thanks, that was exactly my question in my previous post...
    Last edited by a moderator: May 2, 2017
  19. May 31, 2006 #18

    ...Or maybe not to cause destruction, but a "flip" of time. (I'm laughing right now, so you might too...) :smile:

    So, in some weird kind of way all the physical processes, all the chemical reactions go backwards - a crazy, crazy, crazy world.
    Now imagine that there are only few civilisations in the Universe (maybe 6-7), so when some of them researches technology to such level that they can try it (make such experiment) - they "filp" the time for the whole Universe, and for all of the rest of the civilisations in existance! Maybe some of those civilisations function in the other "flip" of the time - so it seems as a normal logic of things for them (like some other culture would see some other numeric system as logical and use it (instead of decade system like us)). Maybe some of them can function in both directions of time (or they developed a technology to overcome such problem). Maybe not. Maybe we all play a weird intergalactic game of ping-pong. Switching it backward and forward, and so on... Until some of them figure this out (SOMEHOW!), so they must make an intergalactic quantum telescope just to figure-out where the punny little imbeciles actually are; and then they must make a quantum telecomunication device, and a quantum device that can manipulate matter at predetermined distance, so they could finaly make a pohone call in the nick of time yelling in their native thongue: "STOP it! You idiots! What a heck do you think you're doing?!?!! You'll have us all FLIPPED!!!". ...And if some of them decide to make phisical contact with those which function in other direction of time, someone suddenly realize that they might be made of anti-matter, and so he says "Don't touch them!!! They might explode!"
    Oops... to late... a few teratons of explosion force... nothing really...

    Heh... Highly unprobable, but makes a good story for "a comedy movie of cathaclismical proportions".
    (if somebody uses this idea without my prior consent I'LL SUE! :smile: )
    Last edited: May 31, 2006
  20. May 31, 2006 #19
    Don't you hate when it happens... I thought I've lost the original post so I've wrote it all over agen up there, but then I've found it after all...

    Or, maybe not cause a destruction, but a reversal of time (in some way we are still ignorant of, because we (let's be objective) still have a whole load of missconceptions (not being aware of it (BELIEVING differently) is a part of the concept of "missconception")))? (I'm laughing on this, so you might too)

    ...Imagine: all the physical laws being wierdly reversed (but somehow normal for some other type of logic (like some other culture could have another numeric system (insted of decade like us))), all the chemical reactions (by some weird logic) going backwards - a crazy crazy world - world where there is no process of decission for our type ("flip") of inteligence, because first there are ideas, and then they aren't (instead of normaly). So - imagine that totaly crazy concept in context of this: that there are a few civilisations (6-7) in whole of Universe, so they (in a way) play an intergalactic game of ping-pong: first one of them who see all of that crazy reversed as normal and live in those reversed conditions flip the time in Universe, then the other do it and set them straight (asrev eciv <-) a perplexed mix-up of different out-comes for all of them in that "crazy game". (all that until some of them (!SOMEHOW!) realize this and then make a quantum comunication machine which can also manipulate matter on a predermined distance (so you must first have a gigantic "quantum telescope" to first see where the punny little far away imbeciles which are in our "filip" actualy are)) - and finaly make a phone call in the nick of time - yelling on it in their native languge "You idiots! What the **** are you doing!?!? Do you want us all FLIPPED!"

    (Then you find those other beings in other "flip" state of the Universe - some of them functioning in that different logic, some of them being victimes of it (some of them being able to go both ways?!?!?); and you find-out that some of them are made of anti-matter - so you must say "Stop! Don't touch them! They'll explode!!")

    (A good material for a comedy... totaly unprobable, but makes a good story...)

    (where "****" = "heck")
  21. May 31, 2006 #20
    I strongly disagree. While realistic prudence is necessary, timidity beyond reason is unwarranted and foolish. By that logic, Columbus should not have set sail, lest he anger the sea monsters that lived near the edge of the world so they would destroy all ships on the sea. Nor should we do research on biological mutations, lest we create a superbug that will infect everyone and wipe out all mammals. Hey, we probably shouldn't be broadcasting radio waves out to the universe, since that might alert the hostile K'zini to our presence and invite all the extraterrestrials to come and conquer us. After all, those are all possibilities that we cannot preclude (well, except for the sea dragons maybe, but there's still a lot of unexplored territory under the oceans). We just don't know enough to take such risks when the whole world is at stake, right?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook