I, however, am not worried about this. Why not, you ask? Well, since you asked so nicely. . .
Under ordinary (to us) circumstances, there are four main forces that make things happen around us. None involve midichlorians, thankfully. These forces are, from weakest to strongest:
1) Gravity
2) The weak force (about 10,000,000,000,000,000,000,000,000 times stronger than gravity)
3) Electromagnetism (about 100,000,000,000 times stronger than the weak force)
4) The strong force (about 100 times stronger than electromagnetism)
You'll notice that this make gravity about 1,000,000,000,000,000,000,000,000,000,000,000,000 times weaker than the strong force. And yet gravity is the one that we're all the most familiar with. Why is this?
Mainly this is due to a matter of scale. The strong force is much, much stronger. . .for as far as it will reach. But the distance that it can reach is so small that we can never actually tell it exists without using really fancy equipment. Gravity, on the other hand, goes on forever. If you were to take an atom and put it on one side of the universe, its gravity would reach all the way to the other side of the universe. Gravity happens at a scale that we can see.
Because gravity is so weak, though, the gravitational pull between those two universe-apart atoms would be so tiny as to basically not exist. The further away you get from an object, the less its gravitational attraction becomes. And that lessening happens very, very fast. Gravity works in what is sometimes known as an “inverse square law”. Imagine that there is a particle floating around in space, and that you are standing ten meters away from it. We'll say that this particle's gravitational pull on you is 100 (we won't worry about 100 whats; the units aren't important, and I just chose the number 100 because it is easy to work with for this example). If you were then to double your distance to twenty meters away, you might guess that the gravitational force would be halved, down to 50. But it isn't. Because of the inverse square law, when you double the distance the gravitational force becomes the square root of the original amount. So if at ten meters it is 100, then at twenty meters it is actually 10. And if you were to increase your distance the same amount again, then it would drop down to the square root of 10 (about 3.2), and then to 1.8, and so on. You'll never actually get to 0, but by this point the gravitational pull from that particle is almost nothing in comparison to what it was when you started.
How, then, do we take the weakest of forces, one that fades away so rapidly with distance, and create the infamous all-devouring black holes from which even light cannot escape?
By weight of numbers.
If we take just one atom floating alone in space and send a photon of light zinging by it, the gravity from that atom won't do much to the photon. It might bend the path of the photon by an immeasurable amount, but the photon will keep going on its way (we're assuming that the photon doesn't smash directly into the atom, of course).
In that picture, the photon brushed past the 3.2 gravitational pull limit of that atom, but 3.2 wasn't strong enough to do anything to the photon.
The gravitational pull of a single atom is just too weak. But gravitational pull is connected to mass. The more mass something has, the more gravitational pull it has. So, the more atoms you can get together, the more gravity. Since gravity gets weak so quickly, though, you also want to get those atoms as close together as you can. That way there will be as many atoms as possible as close as possible to any photon going by.
Let's suppose we took that photon again, but this time we sent it by two particles. The two particles each have their own gravitational field, and the fields overlap.
This time the photon again just passes within the 3.2 gravity pull range of the first particle. . .but at the same time, it is also well within the 1.8 gravity pull range of the second particle. So there is a cumulative pull of 5 on the photon, and the photon is turned slightly from its straight path. It still will continue on its way, but it isn't going to go in the same direction that it was before.
So we add a few more particles, each with yet another gravity field. Now the photon at that point hits a gravity pull of close to 10, and is pulled even further off course.
If we keep adding more particles, we keep adding more gravitational pull. And as the photon has to pass through more and more gravitational pull, it gets pulled more and more off course. Eventually, we reach a certain point.
In that picture, the combined gravitational pull of all of those particles is pulling on that poor photon with a cumulative amount of “a whole lot”. So much so, in fact, that the photon's course is bent into either a perfect circle (in which case the photon will be stuck in orbit around the particles) or even more (in which case it will spiral down into the mass of particles). The photon can no longer pass through the gravitational fields and escape. The particles have now combined into a black hole.
So, what you need to make a black hole is a lot of particles in one place. Well, the Earth has lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots of atoms all gathered together, right? So why isn't the Earth a black hole?
Because it's not just having a lot of atoms all gathered together, it's having them all gathered very closely together. Remember, gravity gets weak very quickly as you move away from its source. You need to have the sources of the overlapping gravity fields all sitting right next to each other, otherwise you get something like this:
The strong parts of the gravity fields aren't overlapping, so there isn't enough concentrated gravity to make a black hole. And that's what the situation is on/in Earth, or any other planet, or the sun. The atoms are all spaced out at a distance from each other. This is due to two things: the fact that the positively-charged nucleus of each atom repels the positively charged nucleus of every other atom, and something called Pauli repulsion. Pauli repulsion gets rather complicated, so I'll explain it as follows: weird sciencey stuff shows that only a certain number of electrons like to be in the same area at the same time.
To get the atoms' nuclei closer together, and to get the electrons to allow other electrons into their space, you need energy. A very large amount of energy, pushing or pulling all of the atoms together.
In the case of the familiar common black holes that used to be stars, this energy comes from gravity. If a star is large enough, it has enough atoms in it that, even with gravity being so weak at a distance and with the atoms repelling each other, the total amount of gravity is still enough to overcome the atoms' repelling. The only reason why the star was able to be a star before turning into a black hole was because of nuclear fusion. As the gravity was shoving the atoms together, nuclear fusion happened before enough atoms were gathered up to form a black hole. And when nuclear fusion happened, it produced a lot of heat and energy in a sudden blast. And that blast pushed the other atoms apart. As long as there were still enough atoms that could come together in fusion, there would be enough energy being released to keep pushing the other atoms apart again. But when the star ran out of atoms that could be easily fused, then there wasn't enough energy pushing against gravity. The star collapsed, the atoms got all squished, their gravity fields all merged together as strongly as possible, and a black hole was formed.
A star or other object has to be of a certain mass to manage this, though. Otherwise it won't turn into a black hole, and will instead become something else. Nothing in our own solar system, not even the sun itself, is large enough to become a black hole.
Amazingly enough, the Large Hadron Collider isn't as massive as the sun. It's not even as big as the Earth. Obviously, then, the worries about the LHC making black holes is based on some other method of black hole production.
The LHC does one of two things: it either sends two streams of individual protons zapping along at each other to make protons collide, or it sends two streams of lead atom nuclei to do the same thing. And these protons or lead nuclei are moving along at a very high speed, faster than mankind has ever been able to send protons or lead nuclei before (in a controlled manner, at least). So when these particles smash into each other, there is a lot of energy involved. And energy, remember, is what is needed to squash particles together and form a black hole.
Does the LHC, then, crunch particles together with enough energy to compress them into a black hole? Well, the LHC does represent the current pinnacle of mankind's ability to smash things together quickly and break them. But if there's one thing that history has taught us, it is. . .umm. . .not to live in Carthage during the Second Century BC. And if there's another thing that history has taught us, it is that mankind is rather feeble in comparison to nature. A lesson that holds true in this case, too.
The collisions at the LHC are, on the grand scale of things, indeed high-energy events. But there are higher ones, and they happen all around us all the time. As do lower-energy ones, and ones of equivalent energy. The LHC may be the best and latest for us, but nature has been doing the same and better for longer than mankind has even been around.
The main example of natural events being even more energetic than the LHC is the collision of cosmic rays with. . .other stuff. All around us, cosmic rays are flying through space with a huge amount of energy within them. And all around us, these cosmic rays are colliding with rocks and random hydrogen atoms and squirrels and nachos. This is going on now, and has been for as long as we're able to tell. Every second there are about 10,000,000,000,000 of these collisions taking place, each one of them with more (often much more) energy than the collisions taking place in the LHC. The LHC, on the other hand, only fires off a few billion particles to collide during each experiment. If the LHC was able to continuously perform four experiments every second (which is not likely at all), then it is estimated that it would need to run nonstop for approximately 7,922,238,852,586,021,570,799 years to match the same number of collisions as these cosmic rays have made.
As you may have noticed, the Earth hasn't been destroyed by black holes. Nor does any other planet in this solar system appear to have been, nor has the sun. Swarms of rogue black holes don't appear to be crowding the universe. All black holes that we have discovered seem to have been formed by the gravitational collapse of really big stars, not by cosmic ray collisions.
So, it appears that cosmic rays don't have the energy to create a black hole through collision. If they don't, then the LHC certainly doesn't.
(A minor side note for those who were wondering: the scientists at the LHC have worked out that the highest energy collisions that they will be creating, the proton-proton collisions, will have an energy of about 7 TeV. . .about the same energy released when two mosquitoes collide in mid-air. The important difference between colliding protons and colliding mosquitoes is that in the former case all of the energy is concentrated on two tiny protons, while in the latter it is spread out over two whole mosquitoes. So while the energy is the same, the effect isn't. Though I would still love to see CERN set up a Large Mosquito Collider one day.)
But let's pretend that the LHC (or my proposed LMC) was capable of producing enough energy to create a black hole. After all, just because the approximately 10,000,000,000,000,000,000,000,000,000,000,000,000,000 cosmic ray collisions (that's the actual official estimated number) that have occurred haven't produced any known black holes doesn't mean that collision number 10,000,000,000,000,000,000,000,000,000,000,000,000,001 won't make one, right? And if a cosmic ray collision could then make a black hole, perhaps the LHC could make one as well, even though it is of much lower power?
If the LHC was to produce a black hole, then it would be different from the collapsed-star type in one major way: it would be incredibly tiny. A black hole's mass doesn't really change when it turns into a black hole. The collapsed star black hole still has the mass of that star within it, meaning that it has a truly unimaginable amount of mass. A black hole made out of two protons colliding, though. . .would have the mass of two protons at most. Instead of the unimaginably vast amount of mass, we're going with an unimaginably puny amount of mass. It's the total opposite end of the spectrum. This sort of black hole is commonly called a micro black hole, and is still totally theoretical. Nobody has ever detected one.
So, our colliding protons (or mosquitoes) have produced a micro black hole. What does the micro black hole do now? Does it go flying out of the LHC, to destroy and pillage and burn? Does it sit quietly in the middle of the machine, stealthily warping time and space about itself until it unleashes our doom upon us? Does it listen to Soundgarden albums and play sudoku?
Actually, none of the above. It disappears almost immediately. And by “almost immediately”, I mean within less than a millisecond. As it turns out, the theories about micro black holes show that they will fall apart due to various reasons that don't bother their larger cousins. One likely reason for the micro black hole to fall apart is because black holes, in spite of being black holes, still apparently radiate some energy out from themselves. And as you may remember from science class or just from the equation E = mc², energy and mass are equivalent. So losing energy is the same as losing mass to a black hole. With the large black holes made out of stars, this isn't much problem. They have a huge amount of mass, so they can afford to radiate away a bit of themselves without it really making much difference. Plus, they are able to replace the lost mass. For a micro black hole, however, they barely have any mass at all, and they needed to borrow energy from someplace else just to form. Once they start to radiate, they'll immediately lose everything they have and disappear.
A second reason for micro black holes to be unstable is another one of those very complicated “weird sciencey stuff” things. Basically, it says that due to the nature of what makes up a micro black hole, the black hole will automatically try to revert back to what it originally was. So a micro black hole made out of two collided protons will automatically turn itself back into a pair of protons (and a bunch of energy). This doesn't apply to the large black holes, because they were made in a different matter. This only applies to micro black holes.
One might argue, however, that these theories could be wrong. Maybe the micro black hole wouldn't radiate, or maybe it wouldn't revert. But the theories that predict these ends to the micro black holes are the exact same theories that are used to predict the possible formation of the micro black holes. If the theories are wrong, then you're not even going to get the micro black holes in the first place.
But for the sake of argument, let's pretend that not only does the LHC have enough energy to produce micro black holes, but it will also produce stable ones. Where does that leave us? Will that finally destroy the world and kill us all?
Perhaps. Around the same time as the world would be destroyed anyway by our own sun.
A popular conception of black holes is that they float around through space, sucking up anything and everything in the area like the Vacuum Cleaners of the Gods. This isn't quite true, though. The “suction” power of a black hole is its gravity. As was mentioned earlier, gravity and mass are related. The more mass, the more gravity. The greater the gravity, the greater the mass. So a black hole's suction power is based on its mass. And a black hole starts off with about the same amount of mass as it had before it was a black hole. Meaning that it will have about the same amount of gravitational pull.
Our own sun doesn't have enough mass to turn itself into a black hole. But if it did have enough mass, and it did turn into a black hole, what would happen to the rest of the solar system? Would all of the planets and asteroids and comets suddenly be sucked up into it? No. Since it has the same amount of mass as a black hole as it had as a star immediately before it changed, it would have the same gravity pull. The planets would still be attracted towards it the same amount as they are now. They'd all keep on orbiting around as they are now. The only real difference that we'd notice would be that after a bit over eight minutes it would suddenly get really dark, and then it would start to get very, very cold. We might all die from freezing or starvation or one final hedonistic spree of overeating on junk food, but the black hole's gravitational pull wouldn't bother us at all.
A black hole isn't going to attract to it anything that the pre-black hole object wouldn't have attracted to it. The only difference is that while a star or whatever would then possibly let the whatever go free afterward, a black hole will always keep it and add it to its own mass. And so black holes will gradually build up mass and grow bigger and stronger.
Now, consider the mass of a micro black hole produced by the LHC. The absolute largest ones possible will have a mass less than that of some atoms. The average dust mote will have a mass billions of times greater than these black holes; when was the last time that a dust mote floating by you had a noticeable gravitational pull on you? A micro black hole will only be able to eat up the most tiny little bits of matter, and so will grow veeeeeeery slowly. It's actually possible to calculate just how slowly. As it turns out, a magically-stable black hole produced with that sort of mass can eventually grow big enough to threaten the world. . .but it would take billions of years. By that time, we'd have other naturally-occurring threats to the world already to worry about. Assuming that we're even still here.
So, the Large Hadron Collider doesn't have the energy to produce black holes. Even if it did, the black holes wouldn't last long enough to do any damage. Even if they did, they'd take so long that it wouldn't matter.
I think that we have better things to be worrying ourselves about. Such as your donation to my new project, the Large Mosquito Collider. Why haven't I received your cheque yet?
