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Miscalculation Invalidates LHC Safety Assurances
Posted by
timothy
on Wed Jan 28, 2009 06:07 PM
from the philosophy-of-science dept.
from the philosophy-of-science dept.
KentuckyFC writes "In a truly frightening study, physicists at the University of Oxford have identified a massive miscalculation that makes the LHC safety assurances more or less invalid (abstract). The focus of their work is not the safety of particle accelerators per se but the chances of any particular scientific argument being wrong. 'If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect,' say the team. That has serious implications for the LHC, which some people worry could generate black holes that will swallow the planet. Nobody at CERN has put a figure on the chances of the LHC destroying the planet. One study simply said: 'there is no risk of any significance whatsoever from such black holes.' The danger is that this thinking could be entirely flawed, but what are the chances of this? The Oxford team say that roughly one in a thousand scientific papers have to be withdrawn because of errors but generously suppose that in particle physics, the rate is one in 10,000."
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Black Holes From the LHC Could Last For Minutes 672 comments
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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Voodoo Science (Score:5, Insightful)
This is voodoo science. And I don't mean the LHC experiments.
I mean the TFA that in essence claims that because an expert may be wrong, any probability the expert assigns to a risk can be ignored and inflated by as much you feel like it. Talk about bias.
--
The 5 Steps to a Great Startup Idea [fairsoftware.net]
Re:Voodoo Science (Score:5, Funny)
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"That isn't right" (Score:5, Interesting)
"It isn't even wrong..." [wikipedia.org]
What if they are so far off, that not only do they not produce black holes, they do nothing, but dim the lights in Switzerland?
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An excerise in stating the bloody obvious (Score:5, Insightful)
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Re:An excerise in stating the bloody obvious (Score:5, Funny)
Yes, yes, but what is it if I look inside the box?
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Re:Uncertainty and certainty (Score:5, Funny)
How many times can we roll the dice before our luck runs out?
Every single time. After that, there won't be any more dice to roll, or anyone to roll them if they did exist.
If we had some dice, we could roll them, if we existed.
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Re:Voodoo Science (Score:5, Funny)
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Re:Voodoo Science (Score:5, Funny)
No need for that. You can subscribe to this RSS feed
http://www.hasthelhcdestroyedtheearth.com/rss.xml [hasthelhcd...eearth.com]
This is funny too
http://www.hasthelhcdestroyedtheearth.com/robots.txt [hasthelhcd...eearth.com]
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Re:Voodoo Science (Score:5, Insightful)
This is voodoo science. And I don't mean the LHC experiments.
It's not science, it's just probability. It's senseless to try to assess any statistical estimates *themselves* based on Physics, just the probability that they could be wrong based on some very broad assumptions. Specifically, any estimate is arrived at by a chain (rather, DAG) of logic. What you CAN estimate is the probability that any Physics-oriented estimate is based on incorrect assumptions, by (presumably) analyzing that chain of reasoning down to first principles and assuming that a "logic error" might have been made at any point. I hope that the authors aren't taking it further than this, in which case, this is statistical masturbation.
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Re:Voodoo Science (Score:5, Insightful)
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Re:Voodoo Science (Score:5, Insightful)
Actually, this isn't that much voodoo.
It's just saying that, if someone has a 1/10,000 chance of being wrong, their assurance that there is a 1/1,000,000,000 chance of something isn't that good of a bet. In other words, if you want the latter level of certainty, you don't really have it, because of the fallibility of the research itself.
This is actually rather obvious. If Jimbo tells you that there's a 1% chance that your tire will go flat if you don't fix it, that's not 1% if Jimbo is wrong 50% of the time. At best, it's 50.5%. Or something like that.
Assuming his brother Jethro is just as bad (but uncorrelated) with him, then their dual recommendation that it will go flat only gets you 25.25% certainty, not 1% (or 0.01%). The numbers may not be exactly right (my stats are rusty), but you get the point.
Basically, they're saying that the research provides a wider error bound than it may claim, assuming that scientists uniformly make logical mistakes--which they very probably do.
The implication, then, is that the LHC estimates should be independently done by other teams. This is, well, the basis of the scientific method, so essentially this study provides a statistical analysis of what we already know--after enough work, science gets results. Of course, the base theories assumed by all of the researchers could be wrong, which would be unfortunate, but the LHC is going to nail that one pretty quickly. :)
This is not surprising, but not voodoo either.
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Re:Voodoo Science (Score:5, Funny)
Yeah it is voodoo. If I calculate that there is a 1:10^20 chance an asteroid will destroy the earth this month, and someone else figures there is a 1:50 chance I am wrong, that does not make the odds of an asteroid destroying the earth 1:50. As wrong as the person calculating the odds are, the odds are still going to be incredibly small.
If what you were saying was true we could destroy the earth by having a 10 year old do the calculations since they would almost certainly be wrong.
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Re:Voodoo Science (Score:5, Insightful)
Actually the point the article makes is not that there is a 1/1000 chance that the LHC will destroy the world but rather it is meaningless to say that the odds are as small as they safety reports etc say because the chance of the reports being wrong is greater than their predictions.
It basically boils down to saying that the scientists are saying there is a one in a billion chance that the LHC is dangerous then turning round and saying that there is a 1/1000 chance that that figure is wrong. Basically the point is that neither statistic is very helpful. Since the 2nd invalidates the first but tells you nothing about the actual probability of a dangerous event.
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Re:Voodoo Science (Score:5, Funny)
I have calculated that there is almost no chance of money spontaneously raining out of the sky above me. However, I was drunk when I made those calculations, so they are most certainly wrong.
*waits expectantly*
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Re:Voodoo Science (Score:5, Insightful)
But for the LHC, arguably there is no accurate prior because nothing in that energy range has ever been done before
How many natural events involving hadrons in LHC+ energy ranges do you need?
99% of cosmic rays are made of hadrons (mostly protons and helium nuclei, but heavier nuclei are known), and they regularly collide with other objects made of hadrons (most of the mass of the visible universe) at LHC-plus energies.
Want me to worry about the LHC? Tell me when a cosmic ray collision has turned the Sun into a black hole or strange matter or new Big Bang or whatever your LHC disaster scenario is.
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Re:Don't fear the hadron (Score:5, Insightful)
Black holes do not require lots of mass, they require lots of density. If matter is packed into an area less than that matter's Schwarzschild radius, you have a black hole. There is a real theory that this experiment will create a black hole. However, the same theory that says that a black hole could be created also says that black holes should be created all the time in Earth's upper atmosphere. Small black holes are harmless because they rapidly evaporate. Regardless of what will be created, the LHC is just recreating events that occur all the time in our upper atmosphere, so saying that it could be harmful is kinda stupid -- if there were a significant risk, we would already be dead.
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Re:Voodoo Science (Score:5, Insightful)
But for the LHC, arguably there is no accurate prior because nothing in that energy range has ever been done before.
We are regularly bombarded with particles with 10^6 times more energy than the LHC produces. We can observe interactions much more intense than that in the visible universe.
Supposing all the scientists are wrong about their risk estimates, we should've observed the naturally occuring events at some point.
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Voodoo posting (Score:5, Insightful)
Okay seriously?
The probability that Jimbo is wrong is unrelated to the probability of your tire failing. If jimbo says that you have a 1% chance of your tire failing, but there's a 50% chance that jimbo is wrong we can reach the following conclusion: There is a 50% chance that your tire has a 1% chance of failing. There is a 50% chance that your tire has some other probability of failing. Some other probability of failing includes values such as 0%, .5%, and 2%. It also includes a 100% probability of your tire failing.
However, we have to assume that Jim isn't pulling the 1% figure out of his ass. If your tire was 100% likely to fail, we can still assume that Jim based his statement on a reasonable analysis. Perhaps Jim didn't notice a nail in your tire, but without knowing the quality of Jim's inspection of your tire, or without having access information Jim doesn't have, it's hard to say that he has a 50% chance of being wrong.
Finally, in some cases a professional will include a certain amount of leeway in his figure. Chances are, Jim fully inspected the tire and doesn't see any reason why it would fail prematurely. Chances are, that 1% is left as wiggle room in case of invisible manufacturing defect or a mistake in his evaluation. In this case, Jim has already factored into his evaluation the chances that he's incorrect.
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Re:Voodoo Science (Score:5, Insightful)
If you took the ten seconds needed to read the abstract, you'd clearly see it's the former:
"... If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect. We develop this idea formally, explaining how it differs from the related distinctions of model and parameter uncertainty. Using the risk estimates from the Large Hadron Collider as a test case, we show how serious the problem can be when it comes to catastrophic risks and how best to address it."
In other words, since the upper bounds of a catastrophic outcome is a least the probability that they were wrong, it's important to estimate the missing factor.
Of course, the problem underlying this is the fact that if one _could_ calculate the missing factor, it wouldn't be an issue. In the case of the LHC, it is (probably :P) far more likely that the world would be destroyed by some yet-unknown physics (e.g. "the doctor" from Ender's Game) than by black holes. But, since it's impossible to predict the likelihood of something we don't know anything about, at some point one just has to throw the switch and see what happens.
Bad journalism, solid (enough) science. As always...
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Re:Voodoo Science (Score:5, Insightful)
This is patently ridiculous. If I write a relatively small piece of software where I have carried out a formal mathematical proof of the algorithms used in that software, I should obtain a much better bug ratio than the industry average, which includes work done by code monkeys working 90 hour work weeks.
Put another way, it's not clear to me that the statistical results for papers where an error might mean a measured loss of academic status are relevant to papers where the analysis regards the possible destruction of the Earth. So far the sample size on the latter is pretty small but the ones that have predicted the absence of global life-ending catastrophe have been 100% accurate. Of course they would have to be or we wouldn't be around to speculate about it, so we can't really make a conclusion from that either. But the point is that the foundation of this paper's statistical argument is itself invalid.
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Frequency of outcome vs. degree of belief (Score:5, Insightful)
No, it's not a mistake. It all comes down to the fact that there are two general types of interpretations of probability:
Basically, you're treating this as an argument about probability in the first sense, when it is really about probability in the second sense. The argument is that even if your formulas lead you to asssign a degree of confidence of .00000000000001 to the proposition that the LHC will not destroy the Earth, that means very little if we assign a degree of confidence of .000001 to the proposition that you are wrong.
The point now, which other posters in this thread have made in other ways, is that the frequency model for probability theory is not relevant here, because this situation is not like a coin toss. For the situation to be like a coin toss, we would have had to do something like run the LHC a gazillion times, and observe how many of those times it ended up destroying the Earth. Therefore, the probabilities must be interpreted as degree of belief, and the number produced by any formula must be tossed out if the probability of getting the formula wrong is bigger than that number.
The assumption you're making here is that the number is the "probability of the event." Again, it is not; it is the degree of belief warranted to a specific proposition, given some other information.
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Re:Voodoo Science (Score:5, Insightful)
then you have to use the odds of them making a mistake as the probability of the event happening.
This isn't what the actual study states, though the summary seems to hint that way. To quote from one-of-the-FA's:
Which means we are left with the possibility that their argument is wrong which Ord reckons conservatively to be about 10^-4, meaning that out of a sample of 10,000 independent arguments of similar apparent merit, one would have a serious error.
Of course, this doesn't mean that the LHC is dangerous, only that there is no reasonable assurance of safety which, as Mark Buchanan writing in New Scientist this week says, is not the same thing at all.
To sum it up, they say that if a researcher predicts an occurrence rate for an event that is less than the researcher's own error rate, then the occurrence rate remains unknown ('cannot be assured')... not that it is equal to the researcher's error rate.
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Re:Voodoo Science (Score:5, Insightful)
I mean the TFA that in essence claims that because an expert may be wrong, any probability the expert assigns to a risk can be ignored and inflated by as much you feel like it. Talk about bias.
Bias? Hype, maybe. Actually, this does make some sense, IMO. Say I was offering to shoot an apple off the top of your head and I told you I'd calculated there was only a 1 in 1 million chance of the bullet hitting you instead. Now if you knew (somehow) that there was a 1 in 10 chance I'd gotten the calculation wrong, you're going to look at it as more of a 1 in 10 chance of getting hit ... or at least way more than one in 1 million.
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Re:Voodoo Science (Score:5, Insightful)
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Are they good for anything? (Score:5, Interesting)
Maybe I just like Romulans, but when I hear that the LHC will be making black holes I don't think about "woo, the earth is gunna get swallowed!" I wonder if there are any cool ways to use them for power generation.
Re:Are they good for anything? (Score:5, Interesting)
There is.
Matter being drawn into the black holes should be accelerated to damn close to the speed of light, and will emit massive amounts of gamma radiation, with a conversion rate that's higher than even fusion.
If we could harness the energy of the gamma emissions around artificial black holes, we'd be have vast energy generating capability, without the pesky fast neutrons that most fusion reactions generate.
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Re:Are they good for anything? (Score:5, Insightful)
I don't see the problem, facts:
1) We will all die some day.
2) The solar system will stop working some day.
So what's the problem? Sure it may kill us and all life on the planet, but does it really matter? We're screwed anyway.
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Re:Are they good for anything? (Score:5, Funny)
Who would remember if we all died?
The race of intelligent beings who, millions of years from now, finds a small black hole orbiting a star, with a flag on its moon.
Honestly, if the human race has to end, that is exactly how I want us to go out.
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Re:Are they good for anything? (Score:5, Funny)
I'm fuzzy on the whole good/bad thing. What do you mean "bad"?
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Meh.... not really a problem (Score:5, Insightful)
The purpose of the LHC is noble, and results could be what we need to get off this rock and really dominate the galaxy. If they destroy the Earth... meh, it was a good try. Maybe next time.
Something here is flawed (Score:5, Informative)
and I don't think it's the assurance that the LHC won't produce black holes that swallow the earth. There reason the whole LHC black hole rubbish is dismissed out of hand is simply because we have already obvesrved particles colliding with much higher energies than the LHC can produce and they didn't form black holes. Where did we observe these collions - in earth atmosphere. We built the LHC so that we could study the collisions in a controlled manner not because they are of particularl high energy.
Re:Something here is flawed (Score:5, Informative)
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This is dumb as shit. (Score:5, Insightful)
Opponent: Oh crap, you're whacking things together, it could destroy the earth, crazy scary technology we don't understand!
Proponent: That could never happen.
Opponent: OMG yes it could you don't know wtf you only have studied this shit your whole life you're not a sane normal rational person like the boys in Alabama!
Proponent: Look, we've done tons of calculations; we've compared this against real-world natural occurrences; we've considered the number of times the conditions we've come up with have occurred in our lifetimes, and it's huge. We're just scaling it down to a laboratory level so we can observe it in a controlled environment. It can't break anything.
Opponent: BUT YOU COULD BE WRONG!!!!
Bring it on! (Score:5, Funny)
My retirement fund is pretty much crushed at this point.
Being consumed by black holes created by a multibillion dollar scientific whiz-ma-gig is sounding like a pretty good exit plan.
I call BS - RTFA - it's about probability, not LHC (Score:5, Informative)
~kulakovich
In the words of Dr Brian Cox (Score:5, Funny)
He's a particle physicist from my physics department (Manchester), and hence let it be known Oxford physicists are twats!
Heart of Gold (Score:5, Funny)
'If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect,'
But if the improbability is large enough, and you hook it up to a nice, hot cup of tea; then we'll travel instantaneously through every point of the Universe, and possibly create a worried-looking whale and a bowl of petunias.
Sensationalist BS (Score:5, Insightful)
The article is a pile of BS topped by a sensationalist (and completely wrong) headline. The paper abstract is interesting, but that's it.
Essentially the blog article makes the jump from 1 in 1000 papers being withdrawn because of "an error", any error, to the idea that the safety of the LHC is "invalid" due to a "massive miscalculation."
How can a hypothetical miscalculation be "massive?" Anyway, you can't just take an average retraction rate for papers and assume it applies to anything you like. The arguments for the LHC being safe are based on well established science. That is, for the LHC to destroy the world not only would ONE paper have to be wrong, but a LOT of papers would have to be wrong, and all in the same direction.
Flawed, invalid, wrong, confused, or just nonsense (Score:5, Interesting)
If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect.
The headline says "Miscalculation Invalidates LHC Safety Assurances", yet the quote from the abstract seems to say that because arguments are sometimes "flawed" (terribly squishy word, that), it follows that for crucially important calculations we have to...well, the abstract doesn't say what we should do, and there's no link to the actual article. (Maybe there's a good reason for the latter.)
This amounts to the assertion that if an estimate is about something very important, then we can't trust the estimate, because some estimates are mistaken. In other words, we can't make estimates about important things—just trivial ones.
Unless someone produces the article in question, and unless it actually makes a more substantial argument than I quoted, I vote this a waste of my time on the part of whoever submitted it. May the rats eat your mail.
Of course (Score:5, Interesting)
The the safety of the LHC does not depend on a single calculation.
For a black hole created by the LHC to destroy the earth essentially requires everything we know about physics to be wrong.
First, can it even create them? The Standard Model says no - not even close. A certain category of String Theory models say maybe. This same models predict that these black holes are everywhere, being created all the time, even here on Earth.
Will black holes evaporate? They certainly should. If we are wrong about this than in all probability we are wrong about being able to create them at all as well - and we should hope we are, since they'd have swallowed up the universe by now if they were dangerous.
Is a stable micro black hole even dangerous? The numbers I've seen show a black hole like this would behave more or less like a neutrino. Maybe hitting an atom every few thousand or million years. The sun will enter its red giant stage, destroy Earth, and shrink down to a white dwarf before the black hole gains any significant mass. I don't think we will care much at that point.
awesome logic (Score:5, Insightful)
paranoid person: The LHC is going to cause a black hole!
scientist: No, the LHC is not going to cause a black hole.
paranoid person: The chances of a scientist being wrong is 10%, therefore there is a 10% chance that the LHC will cause a black hole!
TLDR: Article is a massive troll. (Score:5, Insightful)
Seriously, nothing to see here. This is truly an embarrassment to Slashdot (if that's even possible). Just move along.
Why I'm not worried (Score:5, Informative)
The Pierre Auger Observatory (http://www.auger.org/observatory/ [auger.org]) records one 10^19 eV hit per km^2 a year, just on earth. If that hasn't turned up any major anomalies in our solar system or even in the major mass centers in our close vicinity over the billions of years it's been happening then I would like an explantion why.
Every day.... (Score:5, Informative)
Every single day the earth is bombarded with particles of far higher energy than those the LHC could ever come close to producing. We've observed cosmic rays with energies that are several orders of magnitude higher than the LHC can ever come close to producing. The Pierre-Auger project will probably reveal that we're hit by far more of them, and might even tell us where they're coming from. So if the LHC were capable of producing a world ending event, we already wouldn't be here. Sure, "scientists meddle with forces they don't understand" sells papers, (and let's face it, if we DID understand them, we wouldn't need to meddle) but we all do that. How many of you know exactly how the computer sitting on your desk works, down to the excitation states of silicon? Yet you still use them and don't worry about them causing the world to end, because you know that it just isn't possible. The same analysis works for the LHC.
Clarifications (Score:5, Informative)
As one of the authors of the paper in question, I'd like to point out that the headline and summary are very misleading. We have *not* identified any particular miscalculation and nor have we claimed to. Indeed, we are impressed by the recent safety report and agree that it is very unlikely that there will be a disaster.
The basic point of our paper is that what we really want to know is the chance of the disaster happening, but the reports give us the chance of it happening given a large number of physical assumptions. These probabilities are not the same, because there is a small but real chance that there is a flaw in these assumptions. This need not be due to any mistake on behalf of the physicists but may be like Lord Kelvin miscalculating the age of the Earth because nuclear fission and fusion were not yet known. Think of it this way: in a random sample of 1,000,000 cutting edge scientific articles that look as reliable as the LHC safety report, how many of them are likely to have flaws that invalidate their reasoning? This is especially pertinent as the safety report for the LHC's predecessor (the RHIC) failed to take into account anthropic considerations.
Of course even if the argument is flawed, we are still probably safe. We have indeed dealt with this point in the paper. The overall risk is very small, but larger than the raw calculations suggest, and non-negligible when there are 6.5 billion lives at stake. We thus urge caution and a reassessment of the safety of the LHC taking these considerations into account.
I encourage you all to read the actual article, which goes into many of these points in detail:
http://arxiv.org/pdf/0810.5515v1 [arxiv.org]
Re:My first thought from reading this (Score:5, Funny)
I STILL don't think the LHC will kill us all but the fact we're debating it says something.
I don't know what you're trying to imply here.
People are still debating evolution.
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Re:My first thought from reading this (Score:5, Funny)
I am sorry, The THEORY of evolution and the THEORY of creation both imply that I am somehow related to the people who make LOL cats and I just can not accept that. I CAN NOT accept that.
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Re:My first thought from reading this (Score:5, Insightful)
> I STILL don't think the LHC will kill us all but the fact we're debating it says something.
Yes, it says that people are easily scared by things they do not understand. See also: wireless, mobile phones, things that have a 'chemical' smell... Ask some random people what would happen if the sun were to be replaced instantaneously by a black hole with a mass equal to that of the sun (moving in the same direction as the sun with the same speed, etc). Most people will reply that the earth would get 'sucked' in the black hole... if you don't even understand gravity you have no place in a debate concerning the LHC.
Everyone is entitled to an _informed_ opinion.
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Re:hubris (Score:5, Informative)
If I had seen what they were doing beforehand I would have said 5:1 in favor. That place was a hell-hole.
Among other things the reactors had no containment vessels, was designed so badly that it required core cooling even after a shutdown. The control rods were so poorly designed that the core reaction rate actually increased while they were being inserted. The operators were performing a power failure test (on a live reactor!) where the steam turbines were to be used to generate electricity for the coolant pumps as they spun down. A previous similar test conducted under better conditions failed miserably. This previous failure was swept under the rug because it would have delayed commissioning the plant, meaning the plant's constructors would not get bonuses.
This new test was also planned in secret, without approval of the Soviet nuclear regulatory board.
During the run-up to this insane test a problem with the Kiev grid forced a delay in the test plan; rather than scrub and reschedule the plan was conducted with an unprepared night shift. The engineer in charge of operation of the control rods that night was a new employee with only 3 months of experience in that role. One of the documents associated with this disaster reads:
"One operator rings another and asks: What shall I do? In the programme there are instructions of what to do, and then a lot of things are crossed out. His interlocutor thought for a while and then replied: Follow the crossed out instructions."
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Re:A simple reason (Score:5, Informative)
Except that even if the LHC did create a black hole, the effects on the earth or any people are basically nil. The amount of mass/energy that's going to be involved in the LHC is practically nothing compared to the black holes that astronomers are looking for out in space. If a black hole happened to be created in an LHC particle collision, it would be incredibly tiny. Smaller than an atom tiny.
A newer but reasonably well respected theory about black holes has them emitting "Hawking radiation", and one of the ways that this stuff works is that the smaller a black hole, the more quickly it radiates away its energy/mass, and a minuscule black hole like we're potentially talking about here would evaporate almost instantly. For more information about Hawking radiation, ask the internet.
Even if we assume that hawking radiation doesn't exist, and that black holes last forever, a minuscule black hole created by the LHC would not be particularly dangerous. First off, when you smash things together in an particle accelerator, the resulting particles usually end up moving very quickly. A black hole that happened to be created would likely be moving in a random direction at a speed well above escape velocity, and would quickly fly off into space and we'd never hear from it again.
But let's assume again that it just so works out that a black hole is created, doesn't evaporate, and it ends up with very little momentum, and just starts slowly drifting around inside the earth. The black hole would have very little mass, and it's gravity would be negligible, it wouldn't "suck" in matter. For it to absorb another particle, it would have to actually bump into it. It's important to understand how very tiny this black hole would be. The event horizon would be many times smaller than even the diameter of an atom. And although we generally consider matter to be reasonably solid and dense stuff, an atom is almost entirely empty space. The black hole could pass through billions and billions of atoms without actually hitting and absorbing a nucleus.
So worst case, we end up with an extremely tiny black hole hanging out around the center of the earth, and on rare occasions, happening to absorb a particle and increasing its mass a tiny bit. Perhaps many billions of years from now it will grow large enough that we might be able to detect it somehow, but it's more likely that the earth will have been destroyed by an expanding sun before then.
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