Build Your Own Universe

[evenwolf]

Hey this is strange.   I was listening on the radio and caught this broadcast. 

http://www.npr.org/templates/story/story.php?storyId=6545246

Click the "listen" icon.

Scientists in a Hadron Collider in Switzerland are attempting to create blackholes.   They hope to use these blackholes to create their own universe!    This would answer so many questions about our own existence.  I don't expect them to be successful anytime soon, but has anybody heard of anything like this?   Making a universe out of a watermelon?

[Rui 'Trovatore' Pires]

I'd heard of "trying to create blackholes", but that's as far as my hearing got me. I thought it was a baaaaaaaaaaaaaaaaaaaaaaaaaad idea even then.

[Traveler]

Why would it be a bad idea?

[scotch]

Because people are scared about the idea of a black hole growing and sucking in the entire world I guess. Like in the 30s people worried that if we created a nuclear explosion there'd be a chain reaction and the whole world would go nuclear. I don't know what the scientists are trying to do exactly, but it's almost certainly not as exciting as it sounds, generally the science media sucks if you want to find out exactly what is going on.

[vict0r]

With the new "Personal Universe", everyone can be a god.
Sounds like a great idea^-^

But how are they supposed to control it? As far as i know, the universe we have today expands with every second that pass. What if the universe they made would expand and eat up everything around?

[Traveler]

 

Well, scientists would have to be resourceful to even come close to anything like that.

A black hole is nothing but an object with immense density. One can actually create a black hole from a few atoms - given that these atoms are pressed sufficiently close to each other.

Creating such a black hole would have no bad effects at all: the mass is still the mass of the few atoms that were compressed together so the gravity that awakens from such a black hole would be miniscule. Such a small black hole would also evaporate very quickly - in a fraction of a second. (Black holes radiate because they have a temperature. Given enough time, a black hole can evaporate completely - a smaller black hole evaporates a lot faster.)

It would be a great step forward if physicists succeeded in creating a very small black hole - the result could confirm that black holes really exist (right now we don't know it for a fact, we just have predictions that seem to be all right.) In turn, this would confirm (again) that general relativity is correct. It would also confirm parts of quantum electrodynamics.

The fear of black holes comes from the stories regarding their gravity, but gravity is strong only for large masses - the larger the mass, the greater its gravity is. (Or the more it distorts spacetime.) If you move close enough to a black hole (crossing the event horizon), you would be torn apart and sucked down. But if you kept the distance, nothing would happen to you. Of course, keeping the distance is more difficult the closer you are.

What do you think would happen to Earth if you suddenly replaced the Sun with a black hole of equal mass?

Answer:

Spoiler

Nothing. It would be dark, of course, and cold, so it wouldn't be very comfortable for life, but nothing else would happen. Since the mass of our black hole is equal to the mass of the Sun, it'd generate the same gravity at the same distance. So Earth (and Moon, Mars, Jupiter, etc.) would keep moving in their orbit exactly as before.

[close]

On the other hand, if you'd replace the Sun with a black hole of equal size, that would be a completely different story - the mass of such a black hole would be enormous - maybe thousands of Suns (this is just a guess, I didn't actually calculate it.)

The problem with small black holes (like the ones they're trying to create at the LHC) is not really controlling but creating them. Such a tiny black hole could be controlled quite easily, since its mass is very small, but achieving the necessary density is a monumental task and requires a lot of energy.

[MillsJROSS]

Even if a stable black hole were "released" on earth, and consistently gaining mass, it would take a really long time for it to affect the earth in adverse ways. David Brin tackles this issue in his book Earth, and while it is science fiction, he does have his doctorate in astrophysics and has consulted for NASA. But there really isn't much to worry about. We're far more likely to die from Nuclear warfare, than black holes.

At the moment I couldn't get to the link but my internet has been slow recently.

-MillsJROSS

[Raggit]

I just play The Sims.

[Erenan]

Anyone up for gambling? I bet $5 that this project will destroy all of existence. Any takers?

[lo_res_man]

I'll take that bet what are the odds?

[Traveler]

It's a sure win for you. I didn't take his bet because it felt unethical, knowing that.

[Rui 'Trovatore' Pires]

Why would it be a bad idea?

Been pretty much answered, but I'll say it anyway. Because black holes are still mostly an enigma of a conundrum wrapped in a mystery. And the idea of something that somehow sucks matter into it and somehow makes it gone, something that is like a hole in the very fabric of the universe in a much more brutal way than LOOM put it... it scares me that it's out there at all, it terrifies me that anyone can actually try and create such a thing artificially. I have no guarantees it won't get out of control.

Same like some years ago when some scientists were trying to recreate the very first steps of the Big Bang... maybe it was a first step in this very experiment, actually. Anyway, that scared the hell out of me, for much the same reasons. How much can you control something like this? We've messed with radioactivity before we knew what we were dealing with, and the result is patches of land that still show the effects of radioactivity... er... activity. Now we want to mess with things we barely pretend to know a thing about?

[Erenan]

It's a sure win for you. I didn't take his bet because it felt unethical, knowing that.

I was, of course, making an allusion to the betting that was done on the Trinity test.

Betting pools were set up among the observers for the results of the test. Some predictions ranged from zero, a dud, to 18 kilotons of TNT (predicted by I. I. Rabi), to destruction of the state of New Mexico, to ignition of the atmosphere and incineration of the planet (fortunately, this result was calculated to be almost impossible beforehand, though for a while it caused some of the scientists some anxiety). As it turned out, Rabi won the bet.

[EagerMind]

Why would it be a bad idea?

Haven't you ever seen Event Horizon?

[Vince Twelve]

Why would it be a bad idea?

Haven't you ever seen Event Horizon?

Watching Event Horizon, now that's a bad idea!

[Traveler]

I was, of course, making an allusion to the betting that was done on the Trinity test.

I'm sorry, I didn't realize that. In that case, it was a good one.

Haven't you ever seen Event Horizon?

Unfortunately, I have. It was a bad, bad movie. I thought it was sci-fi, when it's really a bad horror flick. I rue the day when I watched it.

it scares me that it's out there at all, it terrifies me that anyone can actually try and create such a thing artificially. I have no guarantees it won't get out of control.

Same like some years ago when some scientists were trying to recreate the very first steps of the Big Bang... maybe it was a first step in this very experiment, actually. Anyway, that scared the hell out of me, for much the same reasons. How much can you control something like this?

It's very easy to control them in theory. In practice, it's technically very complicated (I mostly don't know/understand the actual details) but the most problems arise out of generating the amount of energy necessary to create the right conditions. Most of these experiments involve less than 100 atoms; in many cases, less than 10 atoms. Conditions at the Big Bang were extreme (just like they are in creating black holes) and achieving them is a big task even for a couple of particles: it requires a lot of energy to speed the particles up so that they'll have temperatures close to those in the Big Bang.

Now even if you imagine that an experiment goes wrong, which is certainly a possibility, what could potentially happen if ~100 highly charged particles get released? Nothing special, 100 atoms is nothing on our human scales. Of course, equipment (like generators, cooling systems) might blow up as well, that might cause some damage and kill some people, but that would be local and probably not much different from an oil truck blowing up. (It's bad, of course, since people die in such events, but my point is that such accidents are always very localized.) Even if the entire particle accelerator blows up (which would be pretty exceptional!), it'd still be mostly local.

With black holes, if scientist created small black holes from a few atoms (which is already very complicated), it could fly right through you and you wouldn't know about it. Absolutely nothing would happen, because the mass of it is very very small and so the gravity that it generates is miniscule.

In nature, a black hole may be born under extremely hot conditions or when a very large mass is involved. For mass, you'd need about 3 Suns to create a black hole - this would be a sizable beast, but given our resources (and the size of our planet), this is not going to happen anytime soon in a lab.

Under extremely hot conditions, a black hole might be created, if atoms are smashed together - this is what scientists try to do. But nature doesn't make it easy to do this: atoms don't like to be that close to each other, so scientists have to use a lot of energy to really smash them together so they stick. This is the reason that large black holes cannot be created in labs: even creating a small one is a challange.

If you're willing to read (and spend some time understading it), I'd recommend "Black holes & time warps" by Kip S. Thorne and "The brief history of time" by Stephen Hawking. These are very good books that explain a lot of the theory behind astrophysics, without using a lot of math.

I'm sorry for being so long-winded - I find physics fascinating, because it makes one understand the world. I'm not a physicist but lately I read a lot of physics and it gives me a sense of accomplishment when I look at something and suddenly realize that I understand it (well, mostly    .) It's most definitely better than being scared of nature.

Edit: fixed typo and factual error.

[Rui 'Trovatore' Pires]

Oh. Ok, I'm reassured.

[Nikolas]

Let me see if I know this correctly:

Black holes are something for which we have little, or no info. They are called that because there is this "strong" phenomenon: The gravitational forces are so strong that do not allow the light to escape.

So what I think is happening is that these black holes are ever expanding, since they attract more atoms, and more mass all the time. Since the mass is growing the gravity (and the radius) is growing.

If we manage to create a black hole with 10 atoms... wouldn't these 10 atoms be enough to pull a 11th into them? Then the 11 ones wouldn't be strong enough to pull another one and another one and another one...

So from a kind of ignorant side of view, it seems like a bad idea...

[Traveler]

So what I think is happening is that these black holes are ever expanding, since they attract more atoms, and more mass all the time. Since the mass is growing the gravity (and the radius) is growing.

If we manage to create a black hole with 10 atoms... wouldn't these 10 atoms be enough to pull a 11th into them? Then the 11 ones wouldn't be strong enough to pull another one and another one and another one...

No, it'd be impossible. Gravity is a very very weak force as compared to the electromagnetic and the strong nuclear forces. Imagine it like this (an example from Richard Feynman): imagine that there is the entire gravity of Earth, which is pretty strong, right? Try to jump up, you fall back right away because of gravity. Try to throw up a ball, it falls back. To leave the planet, the ball would need to fly by ~11 km/s - we need rockets to reach that kind of speed and be able to escape the gravity of Earth. That's strong, right?

Now imagine that you're standing on a concrete pavement. Concrete is made up of atoms, just like your shoes. These atoms are actually not very close to each other, because they repel each other, because of the electromagnetic force (like if you try to force together like ends of magnets, they repel each other, that's the electromagnetic force again.)

And now to the point: you standing there don't even make a dent in the concrete pavement, even though you're pulled by the entire gravity of Earth! That's how weak gravity is. The repulsion of atoms in matter (to resist being compressed) is so much stronger that our objects withstand the gravity of the entire planet. That's why our buildings don't collapse. That's why we can stand up and walk. Just imagine the strength of your muscles and skeleton: they withstand the pull of the Earth plus the weight of the atmosphere above you.

There is one big difference between gravity and the EM force, though: gravity does not repel, because it doesn't have two opposite charges: it always adds up. So if you keep increasing the mass, its gravity will grow ever stronger - slowly, but steadily. That's why you need the mass of ~3 Suns to create a black hole:  at that mass gravity becomes so strong that atoms cannot resist the pull anymore and they collapse into a black hole.

So to answer your question again: it'd be impossible for those 10 atoms to grab an 11th one. That's exactly the problem scientists face when they want to create such very small black holes: it's extremely hard to pack 10 atoms together so tightly so that they finally form a black hole.

Correction: you need the masses of ~3 Suns for that mass to collapse into a black hole. I fixed my previous post.