If it doesn’t have an event horizon, it’s not a black hole. However, the event horizon will be extremely tiny-- It scales linearly with the mass.
The question about a black hole in the core of the Earth that’s large enough to remain stable is extremely interesting, but very difficult to answer, since although the black hole itself is simple, the core of the Earth is very messy indeed. But even in vacuum, a black hole of human mass would last roughly a second, which might be enough time to swallow a human mass of core.
Oh, and no matter what happens, we can already be completely, 100% confident that it won’t destroy the planet, since naturally-occurring cosmic rays have been observed with hundreds of times as much energy as anything the LHC can do. If particles of such an energy were going to destroy the Earth, they would have already done it.
Let me see if I’ve got this straight. If you compress my fat ass down to a black hole, then I will go POOF one second later in a burst of 226 pounds (as of this morning) of Hawking radiation? This sounds like a nifty way to conveniently transport a lot of potential energy in a handy, compact form. Any way this could be used for rocket propulsion or anything else useful? Maybe we want to figure out a way to make some black holes?
IF we could make a hole big enough that we could keep it stable then yes there would be all sorts of uses. But that’s well beyond our present ability, and quite possibly always will be. You’d need a way to make the hole, then shove a huge amount of mass-energy down something the size of an elementary particle faster than it is radiating energy back out. Or come up with some clever way around the problem.
Unfortunately this would be very expensive, and the constructs would last for barely enough time to allow a wide variety of interest groups from OPEC to PETA to slap an injunction on you. You’re better off trying to figure out how to make muon-catalyzed fusion viable.
From everything I’ve read, worrying about the LHC is just about as ignorant as worrying about 2012. As Chronos said, the Earth has already seen much more exciting natural phenomena.
Well, it would be. If you find carrying around 226 lbs plus the mass of whatever you would need to contain the black hole so it doesn’t drop though the floor.
For that matter, how would we know if there wasn’t already a small black hole at the center of the Earth’s core? How long would it be until there was a noticeable effect on the surface?
Wait, how does this even work? I can extract work from your fat ass’s gravitational collapse. (Or, say, an ass large enough to collapse on its own.) And then you burst into light that I can extract more energy out of? Is this a free lunch?
A tiny black hole doesnt “suck” anything into it so to speak. It is on the size of an atom. Its only going to “eat” things that run into it. Thats a pretty small target to hit.
Weight of the earth = 1.31695337 × 10^25 pounds. Chronos said that a 226 pound black hole would last a second and devour 226 pounds. Therefore, assuming linearity, that black hole would take 5.8272273 × 10^22 seconds or 1.84657634 × 10^15 years. Too long to worry about.
Make the black hole a million times larger. That brings it down to 1.84657634 × 10^9 years. Still too big.
But even 1% of the earth’s mass would be an issue. That’s 1.84657634 × 10^7 years. Nope. Can’t worry yet.
There is no such thing as a small black hole that would make any difference in under geologic time.
Stop asking this question. Do a search for the 1.84657634 × 10^15 previous threads. Read them. You’ll have plenty of time while your silly black hole does nothing.
One thing I wanted to point out is that the Earth can’t just collapse into a [sufficiently large] black hole at its center. It’s got a bunch of rotational momentum, after all. It will have to radiate all of that off like a quazar before it can collapse. It will get very hot as that happens. As a side-note, I wonder if the crust can stay in place during much of this.
Very simply, the LHC cannot do anything as big and bad that nature already hasn’t done a billion times already. Gamma rays bombard our own atmosphere with more energy than whatever the LHC can cook up. These very microscopic black holes have been created over and over again in the Earth’s upper atmosphere. If we haven’t been sucked into a microscopic black hole yet, it isn’t because the universe hasn’t been trying.
So, if we have more tremendous energy collisions going on now on this very planet than whatever the LHC can produce, why bother with the LHC?
Simple: Because the LHC will produce these collisions in a single spot which is surrounded by big giant sensors. The gamma radiation, although much more energetic, can hit our atmosphere at anywhere and at anytime it’s hard knowing exactly where to look before it happens.
If I didn’t live in the U.S., I’d create a webpage allowing people to bet that we’d be sucked into a black hole as a result of the LHC. I’m willing to give these people 100:1 odds (and maybe 200:1 that we’ll be destroyed by a strangelet). Not only am I completely confident that the LHC won’t destroy us. I also figure even if I’m wrong, I still won’t have to pay a cent.
