# Thread: Could a black hole be used to produce free quarks

1. ## Could a black hole be used to produce free quarks

Could a black hole be used to seperate out individual quarks? The mechanism I'm imagining is shooting a meson (particle composed of one quark and one antiquark) at a significant portion of the speed of light on a trajectory so that it partially (less than half) intersects the event horizon on a tangent. Ideally sometimes this partial intersection will take the form of only one the two constituent particles actually being in the event horizon while the other would be outside the event horizon and going fast enough to get away.

Or would imparting the energy required to escape from a black hole from within a meson's width of the event horizon just result in that energy just turning the meson into a baryon or something and spoiling the experiment before it even got to the black hole?

2. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Bohandas
Could a black hole be used to seperate out individual quarks? The mechanism I'm imagining is shooting a meson (particle composed of one quark and one antiquark) at a significant portion of the speed of light on a trajectory so that it partially (less than half) intersects the event horizon on a tangent. Ideally sometimes this partial intersection will take the form of only one the two constituent particles actually being in the event horizon while the other would be outside the event horizon and going fast enough to get away.

Or would imparting the energy required to escape from a black hole from within a meson's width of the event horizon just result in that energy just turning the meson into a baryon or something and spoiling the experiment before it even got to the black hole?
I think the event horizon is quantum fuzzy, such that a particle either hits or misses. That and the whole "a one kilogram black hole evaporates in 10^-19 seconds" makes the whole thing pretty moot if you ask me to guess, and I ain't doing the maths.

3. ## Re: Could a black hole be used to produce free quarks

In the end, it does not really matter. Whatever clever mechanism you imagine to rip quarks apart, you will still not get free quarks. The reason that free quarks do not exist is not that they are impossibly hard to separate. The energy binding them is finite and quantifiable. The reason you cannot have a free quark is that this energy required to separate them is so large that you would just create more quark-antiquark pairs out of nothing. Which would then immediately bind to the two halves that you ripped apart, thus forming a complete hadron again.

4. ## Re: Could a black hole be used to produce free quarks

Originally Posted by halfeye
I think the event horizon is quantum fuzzy, such that a particle either hits or misses. That and the whole "a one kilogram black hole evaporates in 10^-19 seconds" makes the whole thing pretty moot if you ask me to guess, and I ain't doing the maths.
The thing is that a meson isn't a true particle as such so much as a quark plus an antiquark. The idea is that one of these could hit while the other missed. Similarly to what occurs with hawking radiation, in which pairs of virtual particles are separated

5. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Bohandas
The thing is that a meson isn't a true particle as such so much as a quark plus an antiquark. The idea is that one of these could hit while the other missed. Similarly to what occurs with hawking radiation, in which pairs of virtual particles are separated
The point I was trying to make is that the ease of determining a black hole's mass depends on the mass, the smaller the mass, the easier you can determine what that mass is, and thus the radius of the EH. However small black holes erupt.

I'm guessing you could try scanning a beam of mesons past a black hole and see if the last one not to be engulfed was a quark, but then you need to avoid the collector falling in.

6. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Seppl
In the end, it does not really matter. Whatever clever mechanism you imagine to rip quarks apart, you will still not get free quarks. The reason that free quarks do not exist is not that they are impossibly hard to separate. The energy binding them is finite and quantifiable. The reason you cannot have a free quark is that this energy required to separate them is so large that you would just create more quark-antiquark pairs out of nothing. Which would then immediately bind to the two halves that you ripped apart, thus forming a complete hadron again.
Which actually could be a very interesting way of extracting energy from a black hole. If the rest mass of a meson is that much lower then that of a single free quark, you get much more then you put in from a clean split through event horizon. The question is, what is a probability of such a reaction even for ideal aim?

7. ## Re: Could a black hole be used to produce free quarks

Which actually could be a very interesting way of extracting energy from a black hole. If the rest mass of a meson is that much lower then that of a single free quark, you get much more then you put in from a clean split through event horizon. The question is, what is a probability of such a reaction even for ideal aim?
Where are you "getting" energy? You are throwing additional stuff into the hole! Or if you wonder where the seemingly "free" quarks come from (after all, you start with 2 quarks outside, and end up with 2 quarks inside and 2 quarks outside): As I said, it does not really matter if the mechanism that you used was a black hole or anything else. The energy for the new quarks is still the energy used to rip the two starting quarks apart. In this case, it comes from whatever mechanism you used to "hold" the one quark and prevent it from falling into the hole.

8. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Seppl
In this case, it comes from whatever mechanism you used to "hold" the one quark and prevent it from falling into the hole.
That mechanism is the event horizon, so indeed the black hole could do the work for us. I cannot make direct calculations for this scenario, but I see no reason for it to be impossible. After all, it works perfectly well with virtual particles, which I would think are more difficult to tear away from each other. The probability of such a situation is most likely stupidly small in comparison to a clean fly-by or the whole meson falling into the black hole, but I do believe it to be non-zero. Depending on the actual value it might or might not be a viable energy extraction method.

9. ## Re: Could a black hole be used to produce free quarks

As a chemist I'm having trouble picturing this situation. Gravity is a force with a long reach, it doesn't decline very fast over distance. Atomic and sub-atomic particles are really small, the distance between their components is tiny. Even near a black hole, how much of a gravity gradient could you really get that's strong enough to split a particle rather than get all of it swallowed by the hole or have all of it escape? Alternatively, how weak are mesons?

10. ## Re: Could a black hole be used to produce free quarks

That mechanism is the event horizon, so indeed the black hole could do the work for us.
The event horizon is not "doing" anything. It's not a magic wall and anyone crossing it does not even note that anything special happened (because there is nothing special). What you are doing here is bringing your particle close to something where half of it gets "stuck" and then you rip off the other half by whatever means. That is where the work is done and it does not really matter if your sticky bit was a black hole or anything else.

Think of it this way: In the end, your black hole will be heavier by at least three quarks, and you will end up with the same number of quarks that you started with. If you had somehow extracted energy from the hole, how would this be possible? Where is that energy?

11. ## Re: Could a black hole be used to produce free quarks

In the OP's proposed experiment, you're sending the meson in with very high kinetic energy, and you'll get a meson out with lower kinetic energy. The net difference in energy will be energy that the black hole gains.

12. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Seppl
Where are you "getting" energy? You are throwing additional stuff into the hole! Or if you wonder where the seemingly "free" quarks come from (after all, you start with 2 quarks outside, and end up with 2 quarks inside and 2 quarks outside): As I said, it does not really matter if the mechanism that you used was a black hole or anything else. The energy for the new quarks is still the energy used to rip the two starting quarks apart. In this case, it comes from whatever mechanism you used to "hold" the one quark and prevent it from falling into the hole.
I'm not super familiar with the behavior of quarks the forces interacting between them.

But if you were to try a similar things with say a deuterium nucleus, this setup would be ignoring the strong force. Two neutrons traveling in parallel very close together could result in one neutron falling into the event horizon and the other neutron continuing on an escape trajectory. But if you have a deuterium nucleus and one of the two particles falls into the event horizon, it would pull the other particle with it because they hold on to each other by the strong force.
The only thing that could tear the two particles apart would be the tidal forces due to gravity. Are the tidal forces outside of a stellar mass black hole strong enough to rip apart atoms?

If groups of quarks behave similar to groups of neucleons, then the event horizon wouldn't matter in this thought experiment. Only tidal forces.

13. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Yora
I'm not super familiar with the behavior of quarks the forces interacting between them.

But if you were to try a similar things with say a deuterium nucleus, this setup would be ignoring the strong force. Two neutrons traveling in parallel very close together could result in one neutron falling into the event horizon and the other neutron continuing on an escape trajectory. But if you have a deuterium nucleus and one of the two particles falls into the event horizon, it would pull the other particle with it because they hold on to each other by the strong force.
The only thing that could tear the two particles apart would be the tidal forces due to gravity. Are the tidal forces outside of a stellar mass black hole strong enough to rip apart atoms?

If groups of quarks behave similar to groups of neucleons, then the event horizon wouldn't matter in this thought experiment. Only tidal forces.
As black holes get smaller, the tidal forces at the event horizon rise. If they didn't go *very bang!* this might almost be a testable hypothesis.

14. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Yora
I'm not super familiar with the behavior of quarks the forces interacting between them.

But if you were to try a similar things with say a deuterium nucleus, this setup would be ignoring the strong force. Two neutrons traveling in parallel very close together could result in one neutron falling into the event horizon and the other neutron continuing on an escape trajectory. But if you have a deuterium nucleus and one of the two particles falls into the event horizon, it would pull the other particle with it because they hold on to each other by the strong force.
The only thing that could tear the two particles apart would be the tidal forces due to gravity. Are the tidal forces outside of a stellar mass black hole strong enough to rip apart atoms?

If groups of quarks behave similar to groups of neucleons, then the event horizon wouldn't matter in this thought experiment. Only tidal forces.
Yes, overall I doubt the proposed mechanism would even work. Local spacetime near the event horizon of a decently sized black hole (say: a stellar remnant or larger) is actually surprisingly flat. You would need to go much deeper into the hole. But I did not do the maths, it is just a rough estimate. Also, there is no reason in the first place to assume anything special about the event horizon when looking at tidal forces.

But as I said in my first answer: It does not really matter what kind of mechanism one imagines, thus I did not dwell on the particulars of this method. The basic premise of the original poster was wrong. Producing free quarks is not about finding a method to apply great forces to the quarks. Quarks are confined not because it is super-hard to rip them apart but because the very act of ripping them apart creates a new confinement.

15. ## Re: Could a black hole be used to produce free quarks

It's not a matter of applying forces, its a matter of the quark inside the horizon being unable to communicate with the quark outside of it

16. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Bohandas
It's not a matter of applying forces, its a matter of the quark inside the horizon being unable to communicate with the quark outside of it
There is nothing special happening locally at the event horizon. It's just normal spacetime for the hadron falling in. Before it falls in, someone from the outside could decide to "rescue" one of the quarks by ripping it off from the others but there is nothing going on there that you could not replicate in a lab on earth.

An event horizon is not a magic membrane as it is often portrayed in movies. True, strange things happen there if you look from far away, but when you are actually there it is just a place as any other.

Concerning your plea that the quark "inside" cannot communicate with the quark "outside": It does not and it does not have to. We do actually have to go a bit beyond the simple arguments above to solve this one, though some special relativity should suffice: By its very nature, anything crossing the event horizon is falling at the speed of light (think about that!). Thus, we are dealing with infinite time/length-dilation when observing it from the outside, i.e. we are not actually observing anything.

17. ## Re: Could a black hole be used to produce free quarks

The event horizon is the last point to turn back, and accordingly the last location from which outside observers can observe anything. It's not an object. Just a region from which no light (or anything else) emerges.

18. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Seppl
By its very nature, anything crossing the event horizon is falling at the speed of light (think about that!).
strictly speaking, no. What defines the event horizon is that crossing back would require travelling at the speed of light or faster, which is impossible for solid matter due to relativity.

19. ## Re: Could a black hole be used to produce free quarks

Originally Posted by hamishspence
strictly speaking, no. What defines the event horizon is that crossing back would require travelling at the speed of light or faster, which is impossible for solid matter due to relativity.
And as a direct consequence, everything going into it must also travel at the speed of light at that point…

20. ## Re: Could a black hole be used to produce free quarks

That's not how it works. It's possible to cross the event horizon while travelling at a relatively low speed, especially if the black hole is sufficiently big.

It's only achieving escape velocity at Event Horizon Distance that would require travelling at the speed of light. And since it requires infinite energy to travel at the speed of light, it's impossible to orbit that close.

Look at Earth. An object falling to Earth does not have to be travelling at escape velocity. Similarly, an object falling to a singularity (having crossed the event horizon) does not have to be travelling at the speed of light. In fact, being solid matter, it can't be.

21. ## Re: Could a black hole be used to produce free quarks

Sorry, but that is not how it works. There are just no space-time paths through the event horizon that do not involve the object traveling at speed of light.

PS: I am aware that this sounds like an exchange of "I am right; No, I am right; …". I guess, the only real solution would be to explicitly demonstrate the math. But do I have to? That stuff is hard and it's been a while since I heard that lecture. The topic is not really relevant for the thread.

PPS: All of that is only from the perspective of an outside observer, mind you. The object itself does not notice anything special in its frame of reference. That was, after all, the whole point of all my posts.

22. ## Re: Could a black hole be used to produce free quarks

I am fully with hamishpence on this. You can pass through the event horizon at any speed.

It doesn't really have anything to do with speed. The event horizon is simply the distance at which all possible paths curve into the singularity. Even if you were to go faster than light somehow, there is simply no direction you can travel in that does not lead into the singularity.

23. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Yora
I am fully with hamishpence on this. You can pass through the event horizon at any speed.

It doesn't really have anything to do with speed. The event horizon is simply the distance at which all possible paths curve into the singularity. Even if you were to go faster than light somehow, there is simply no direction you can travel in that does not lead into the singularity.
If that were true, an outside observer could see something crossing the horizon because light sent from that object outwards would move, well, at the speed of light away from that object. But that is against the very definition of the event horizon. Therefore, anything falling into the hole is seen approaching the speed of light until it disappears (i.e. it gets dimmer and dimmer until you cannot see it any more; you never observe it actually reaching the speed of light).

It is all about speed, because the horizon is that sphere, where something with the speed of light can no longer escape.

Also, if you were hypothetically to move faster than light, you could actually escape. Not all paths curve into the singularity, just all future paths. Going faster than light is essentially the same as moving backwards in time.

24. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Yora
It doesn't really have anything to do with speed. The event horizon is simply the distance at which all possible paths curve into the singularity. Even if you were to go faster than light somehow, there is simply no direction you can travel in that does not lead into the singularity.
Not so, (although the escape velocity would continue to increase the closer you got to the singularity))

In the Penrose diagram the vertical axis is time, and the horizontal axis is space. curves that are less than 45 degrees from vertical represent velocities lower than that of light and curves more than 45 degrees from vertical represent speeds greater than the speed of light. The boundry of an event horizon is oriented at 45 degrees in this diagram. Before one passes it one can always remain outside of it by moving at some speed less than or equal to that of light. At the horizon one could remain indefinitely by moving AT the speed of light. Inside the horizon even the speed of light is insufficient to avoid the singularity, BUT, as we can clearly see, if one could somehow muster the infinite energy required to accelerate past lightspeed (which would be represented by a curve more horizontal than vertical) then one could still avoid the singularity even from inside the horizon

25. ## Re: Could a black hole be used to produce free quarks

I don't mean to be disruptive or anything to the discussion about black hole escape velocities (should be escape accelerations, really) and such. And I'm not particularly informed on the topic or anything, but it seems to me that talking about speed around black holes or at the event horizon is a bit muddy. For one thing, speed doesn't always mean the same thing to different people. That's the whole point of relativity.

Is there a reason why nobody is discussing black hole event horizons in terms of acceleration? I mean, it's a bit more fiddly as a concept than "speed", but it has the advantage of being more accurate and maybe a bit more clear. If you say, for instance, that the event horizon is the point at which you need infinite acceleration away from the black hole in order not to fall in, that seems to be a bit more clear that you're talking about the perspective of the person on the edge of falling in. They could appear to be (hypothetically at least), stationary relative to their background to someone watching them.

As far as I am aware, talking about the event horizon with "Speed" only makes sense in the abstract sense that matter cannot reach the "speed" of light. That is, talking about the event horizon as a "speed" barrier is an oversimplification that only works because light itself has a fixed "speed" which we understand represents the upper "speed" barrier of all matter. But it's not really a speed barrier. It's really an acceleration barrier, for which a black hole is massive enough to create for its surroundings.

Also, as for "crossing" the event horizon, as far as I know the math says the matter would undergo "infinite acceleration" and thus be traveling "faster than light" or some such thing across the barrier. But as a general rule I don't think most real scientists would be comfortable with using the output of a clearly broken mathematical model in order to make statements about events in the broken-math-region. To be clear, any path drawn that "crosses the event horizon" is a path into a broken-math-region. If you're deliberately breaking models to end up making statements about physics, I think it's entering a realm of semi-useless, pointless speculation. I'm looking at you, negative-mass fans.

When infinities show up in mathematical models, I think it tends to indicate a limitation of the model.

26. ## Re: Could a black hole be used to produce free quarks

As I understand it the problem is that any discussion about acceleration and escape velocities is based on Newtonian physics in which gravity is an accelerating force that pulls masses towards each other. This works well enough when dealing with stars and planets, but to understand what is happening in black holes you need to use Einsteinian physics and treat gravity as a curving of spacetime.

Things passing beyond the event horizon accelerating past the speed of light could perhaps be a possible interpretation of what an outside observer is seeing. But that seems to me the same misrepresentation that leads to the claim that time stops at the event horizon. (Which I've even seen as reasons to claim that black holes can not exist because they can not form.) But just because no more photons are reaching an outside observer does not mean that no more photons can leave the object that has passed the event horizon. All of the possible paths of such photons take them into the singularity, but time is still moving inside the event horizon.

27. ## Re: Could a black hole be used to produce free quarks

Escape velocity (or more properly, escape speed) is irrelevant. You can get arbitrarily far away from a massive object without ever once exceeding its escape speed, and you can get infinitely far away from a massive object without ever once exceeding its surface escape speed. Escape speed is only relevant if you're trying to escape by imposing a single instantaneous impulse and then coasting the rest of the way, and why would you want to do that?

The better explanation is that there is no timelike path from the inside of the hole to the outside. This can be interpreted as meaning that there is no path from the inside to the outside at less than the speed of light. But it does not mean that there is no path from the outside to the inside at less than the speed of light. Going in at any sublight speed is trivial.

28. ## Re: Could a black hole be used to produce free quarks

There's another angle to this. The reason free quarks don't exist in nature is because the strong nuclear force actually behaves in the opposite manner to the gravitational and electromagnetic forces - it actually gets stronger the farther apart the quarks are, not weaker. And if you apply enough energy to overcome that, there's enough energy to spontaneously create a quark-antiquark pair, one for each half of the hadron you're trying to split. Thus in the situation you're describing, where the tidal forces of the black hole apply enough energy to overcome the strong force and split the meson, you will instead end up with two mesons - one that ends up trapped in the black hole, and another that heads off into space.

Edit: So to answer the question plainly, no, but only because free quarks can't exist in nature.

29. ## Re: Could a black hole be used to produce free quarks

You all misunderstand me. I'm not relying on the tidal forces to pull the meson apart, I'm relying on the fact that in the situation I've described the gluons that carry the strong force can only move in one direction

30. ## Re: Could a black hole be used to produce free quarks

Originally Posted by Bohandas
You all misunderstand me. I'm not relying on the tidal forces to pull the meson apart, I'm relying on the fact that in the situation I've described the gluons that carry the strong force can only move in one direction
That's the exact same thing though. Tidal forces are the difference between paths particles can take through space-time under gravitational influence. Its energy is expressed as how curved space-time is, and thus which paths particles follow.

Regardless of the method you attempt, you run up against color confinement. Any particle that can participate in strong force interactions must, by its nature, remain in strong force interactions, and inputting enough energy into the system to overcome the strong interaction (regardless of its source) is enough energy to start creating new particles to fill the gaps.

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