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    The Simpsons: cartoon black hole physics vs real black hole physics.
    By Hontas Farmer | October 7th 2012 07:33 PM | 22 comments | Print | E-mail | Track Comments
    About Hontas

    Currently I am a adjunct professor in physical sciences at the City Colleges of Chicago with a MS from DePaul University. My research focuses on...

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     Things everyone should know about real black holes in  comparison to fictional black holes.  Most importantly they don't suck things into them.   

    Black holes do not suck everything in like some kind of vacuum cleaner.   A mini black hole like the one created by Springfield's collider would start out with the mass-energy of two sub atomic particles.  Gravitationally it would not be more attractive than those particles were, which is not at all.  

    They don't float.  However they can have an effective surface charge and if rotating a magnetic field.  (These are called Kerr-Newman black holes.)   

    Last but not least, they don't stick around long enough to do anything.  Stephen W. Hawking,  as Homer once called him "that wheel chair guy", figured out that black holes radiate particles.  As they radiate they evaporate.  The smaller the black hole the faster it evaporates.  A tiny black hole will disappear almost as soon as it's created.  





    I must add, they did a pretty decent job with time travel and alternate universes.  

    Comments

    ... actually black holes do suck mass that is a relative stationary velocity, but in the universe objects rotate around black holes because they are not stationary

    Hfarmer
    Not in the way that the Simpsons and other popular media show.  A black hole only attracts objects to itself with the force of gravity.   That gravity is no stronger than the gravity of the objects that went into it.    If you took a ordinary baseball and compressed it down to a size comparable to an atom or molecule it would become a black hole.  However, that black hole would no more suck things into it than the baseball did.  :)
    Science advances as much by mistakes as by plans.
    vongehr
    A mini black hole like the one created by Springfield's collider would start out with the mass-energy of two sub atomic particles.
    This is misleading, and in an obviously biased way (giving the clear impression that you aim to downplay a threat)! Their kinetic energy can be far above that of atomic particles.

    About the whole post: All according to the theories you believe in. Science never had a single small black hole to experiment with (nor did it ever experiment close to large ones, and the astronomical observations are consistent with any theory that provides black stars). Who knows how close to the event horizon GR breaks down to be a good description; who knows how much a small black hole would suck; who knows whether Hawking radiation is going to be empirically verified? We do not!
    Hfarmer
    To your point about energy and mass.  My short answer is that I wrote mass-energy.  Even two particles at LHC energies have a tiny tiny mass-energy compared to, say, a good sized asteroid.  A Olympic long jumper could probably jump into an orbit around an asteroid.   
    Ah, but we can know from observations of black holes out in the universe that our theories, at least at the classical level, are totally correct.  We can know from experiments that our theories about quantum physics, leaving out gravity, are correct.  There is a good chance that either string theory or theories such as LQG or group field theory are correct.  When it comes to quantum black holes none predict that they will persist long enough to do any damage to us.  

    They are just such a sexy plot device for destroying the world.  

    Now if a real, astronomical black hole got near our solar system that would be interesting. 
    Science advances as much by mistakes as by plans.
    vongehr
    I wrote mass-energy
    Mass and energy are equivalent, so this is either a bad mistake, or, if you mean "restmass-energy", it is precisely misleading in the way I told you, because restmass is negligible in collider experiments.
    know from observations of black holes out in the universe that our theories, at least at the classical level, are totally correct.
    This is wrong and naive scientism dogma! There is absolutely no empirical evidence whatsoever for that anybody can freely fall through an event horizon or for that black regions in the real universe do not start "sucking" a micrometer in front of the event horizon! Is such indicated by our theories? No. Are our theories anywhere close to being finished? Hahaha!
    We can know from experiments that our theories about quantum physics, leaving out gravity, are correct.
    Black holes are all about gravity.
    Hfarmer
    So are space and time but people still use space-time. 
    Science advances as much by mistakes as by plans.
    vongehr
    Meaning what? That quantum mechanics as confirmed empirically implies that mini black holes do not "suck"? You forget that Homer's black hole would have exploded in an UV/X-ray/gamma ray/particle explosion if not quantum sucking trapped the Hawking radiation. So there!
    Thank you friend the simpsons should be ban

    Sascha is correct but it should be extended to we have absolutely no idea if "mini-black hole" are even remotely possible let alone how they would behave. There are a bunch of theories that say it could happen that are on very very slippery slopes most in various string theories.

    You comment above attempts to invoke the certainty of "classic physics" but you leave out the problem under "classic physics" you can't make a "mini black hole" so if one was to exist I am not sure classic physics is going to offer much insight or confidence as to what may or may not happen.

    The correct answer is we won't really know until we make one or have a correct theory that can predict what is going to happen and trying to judge who is right you or the simpsons with absolutely no data is pretty pointless.

    Hfarmer
    You say that under classical physics we cannot make a mini black hole.  That isn't true.  
    While we do not know what quantum effects might kick  classical black hole theory does not break down when the mass is small.  Some serious theorist even consider that electrons may be mini black holes.   Practically naked singularities, that are stable due to quantum effects.   If they are right, then my posting is only wrong about one thing.  The overall message, that black holes, that could be created in a accelerator, are harmless, stands. 


    Based on well accepted theory my posting is just right. 






    Science advances as much by mistakes as by plans.
    What would it take for a black hole composed of one molecule to "attract" and 'consume" another atom?

    Seems to (uneducated) me: Gravitational force at that scale is just about negligible (classical or quantum), and the Schwarzchild radius has got to be itty-bitty, like, wild guess, about the same radius as an atomic nucleus. Particles could pass very near a mini-BH and never even notice. So it seems to me you'd have to aim a particle very, very directly at the mini-BH for it to "fall in." And wouldn't the electrical fields interfere a lot with that? If a mini-BH fell to the center of the earth - why would it interact with anything on the way down?

    Is it even possible, in nature, for a mini-BH to accumulate another atom?

    And what if it did? Would a mini-BH of 2 atomic masses (plus energy) become somehow deadly if it somehow accumulated a third atom?

    blue-green

    I have no idea what was reported by the Simpsons, however, since Homer works at a nuclear power plant, he must know a lot ….kind of like the way Representative Paul Broun serves on the Committee on Science, Space and Technology.

    "God's word is true. I've come to understand that. All that stuff I was taught about evolution and embryology and the big bang theory, all that is lies straight from the pit of Hell," said Broun, who is an MD. "It's lies to try to keep me and all the folks who were taught that from understanding that they need a savior."

    "You see, there are a lot of scientific data that I've found out as a scientist that actually show that this is really a young Earth. I don't believe that the earth's but about 9,000 years old. I believe it was created in six days as we know them. That's what the Bible says."

    Hfarmer
    Basically they had a black hole going around sucking things into it like a giant drain hole.  Black holes just don't work that way.  
    Science advances as much by mistakes as by plans.
    blue-green

    Perhaps Hank or “News Staff” can clarify how Paul Broun serves on the Committee on Science, Space and Technology. After googling “Springfield collider” I realized that the Simpson episode is a colorful spoof of the end of the world according to Mayan folklore. I'll try to make time to see it. It looks vastly more funny and less scary than the nuclear power plant meltdown by Homer's namesakes in Japan.

    The basic formula for the evaporation time of a black hole has it being proportional to the cube of its mass. The formula assumes that the black hole is initially all alone in an empty space with nothing more than quantum fluctuations to feed it. It is more like a half-life calculation. In a single situation, there is an equal probability for it to absorb or spit out virtual particles and evaporate in a longer or shorter time. …. If it happened to absorb enough to triple its mass, then it would take 27 times longer to evaporate its new excess weight … and that's just a statistical average. There is still a chance for a runaway chain reaction. You cannot state with scientific certainty that it is zero. You can only say that the odds are very small, which isn't going to go down well with a population willing to let Paul Broun be its representative.

    A little digging into how a black hole "works" quickly gets one into holography ... grist for a followup episode ... in which our 2-dimensional cartoon characters are presented on screens …. oh wait, that's already happening.

    Hfarmer
    Actually something like your last point has been shown on there.  The classic scene where homer gets into the 3rd dimension.   It's funny. 


    Homer 3D by Columbia-Pictures


    What you say about the black hole absorbing mass if it's around and taking longer to collapse is a good and true point.  If one did get out of an accelerator it might be able to absorb a molecule here or there before still evaporating in a short time.  27 times longer than a pico second or microsecond isn't long enough to do any real damage.  :)

    Now that I think of it, this video gives a pretty decent idea of what a real black hole would be like.  It's wrong in the sense that a black hole is a spherical region of 3D space that light cannot escape from, not a 2D hole.  Other than that, the nature of it's force is well represented there.  Objects simply fall into the hole.  
    Science advances as much by mistakes as by plans.
    Since Hawkin radiation modifies the event horizon, would it be possible for something (small) to briefly visit inside the event horizon and then escape?

    Does this shrinking of event horizon let mass out of black hole? If it did, that would cause a chain reaction which would continue without virtual particles help? And if it did not, we would actually know something inside the event horizon (mass distribution)?

    Hfarmer
    Well yes and no to your first question.  Once something is inside the event horizon it's in.   On the other hand the information it takes to reconstruct the object is still available and released into the universe as hawking radiation.   So the object itself is lost, but if we had enough ability to decode the scrambled up information we could Humpty Dumpty it back together.  
    The thing about Hawking radiation is it does not come out of the black hole.  It comes from just outside the event horizon.  Pairs of virtual particles are being created and destroyed all around us.  When a black hole is present one of the particles in a pair will be caught by the event horizon.  The other particle escapes and becomes real.  In the process taking mass-energy and information about the black hole back into the universe.

    Entropy, information, and black holes are a fascinating subject.  In fact reproducing the results Hawking found is one of the litmus test for any theory of quantum gravity.    

     
    Science advances as much by mistakes as by plans.
    Let me try to be a bit more verbose. Assume some tiny particle p with motion which just barely takes it inside the event horizon at radius r0. Then some Hawking radiation takes place and as a result event horizon radius shrinks a little to r1. While p was inside r0, could it be outside r1?

    Hfarmer
    Once p is inside r0 the only path it can take, classically is into the center of the black hole.  Going to the center of the black hole for a particle inside the event horizon is as inevitable as going forward in time is for us.
    Now, if we think of this quantum mechanically things get interesting.  The location of the event horizon and of the particle become fuzzy.  They both become a distribution of probabilities with some chance the particle is inside and outside the horizon at any given moment.  







    Science advances as much by mistakes as by plans.
    Particles if they do anything in this universe are not 'virtual'. That anyone would depend on particles that don't exist outside of the field of math (because the math doesn't work or give the right answer without it) and can't be observed to prove the physical existence of anything amazes me. REAL particles have physical extension, and can only interact with other REAL particles, not imaginary or virtual ones.

    Hfarmer
    The problem with your argument is that quantum field theory is the best tested theory in all of science and predicts the results of experiments to a degree of accuracy rivaled only by General Relativity. 
    Virtual particles are only virtual because they exist for such a short time, not because they aren't real and cannot be observed.  We see their effects all around us.  
    Science advances as much by mistakes as by plans.
    blue-green
    The only thing more amazing is that you would expect the Lamb Shift and QED vacuum to conform to your simplistic wishes. Virtual particles do quite a bit that doesn't match your ideals.

    http://en.wikipedia.org/wiki/QED_vacuum