If we had ham, we could have ham and eggs, if we had eggs. Another classic "this will be easy as long as we have unobtanium" concept.
I've been baffled, though, by the insistence on this kind of antimatter production. Antimatter production is inherently expensive because we are fighting conservation of baryon number, conservation of lepton number, et al.
Physics does have one theoretical method around this, which never seems to be addressed for these proposals, and that's the baffling issue of black holes having no hair. You throw whatever past the event horizon, all that is conserved is mass, angular momentum, and charge. Baryon number, lepton number, strangeness ... all lost. Re-emission as Hawking radiation, it is thought, would simply be this sort of thing, redistributed without regard to what went in, so long as mass, angular momentum, and charge are accounted for. You would conceivably get out as much antimatter as matter.
Now, that's worth looking at. And not from a "we JUST need to capture an itty black hole" (the word "just" does an enormous amount of lifting here) perspective. Rather, passage through the event horizon somehow strips off (we think, some think it might be preserved in some fashion) all of the variables which account for matter versus antimatter. And yet the event horizon isn't a hunk of matter, it's a ... membrane, a boundary, generated by matter at some distance (as a function of our usual three variables). Somehow, this warpage of spacetime operates on matter, shaving it so it has no hair.
That's what fascinates me, in the sense of the theoretical having some extremely juicy practical results.
Baryon number, lepton number, strangeness ... all lost.
Even for classical black holes I don't think that's the consensus among physicists. The general assumption seems to be that quantum numbers are still conserved when you throw stuff into black holes, just like electrical charge.
Now, as for Hawking radiation, it's worth pointing out that Hawking's calculation only works for large black holes (low curvature near the event horizon). Once a large BH has shrunken down to a tiny BH (-> high curvature at the event horizon), the calculation no longer works and it is unclear what will happen. Some people say the BH will evaporate completely, some say there will be a remnant – who knows. (Both solutions have their issues.)
All in all, I'm skeptical of the "shaving" you describe.
It's right there in the Wikipedia article on the No Hair Theorem:
"Suppose two black holes have the same masses, electrical charges, and angular momenta, but the first black hole was made by collapsing ordinary matter whereas the second was made out of antimatter; nevertheless, then the conjecture states they will be completely indistinguishable to an observer outside the event horizon. None of the special particle physics pseudo-charges (i.e., the global charges baryonic number, leptonic number, etc., all of which would be different for the originating masses of matter that created the black holes) are conserved in the black hole, or if they are conserved somehow then their values would be unobservable from the outside"
Now, this is all still hypothetical, as we haven't a black hole on hand, but this has been the mainstream view on black holes for decades.
Wasn't LHC supposed to create the occasional microscopic black hole? What are the logistics on capturing one of those, keeping it fed, and making some definitive observations?
Wasn't LHC supposed to create the occasional microscopic black hole?
That was discussed but AFAIR nobody really believed this was actually going to happen.
What are the logistics on capturing one of those, keeping it fed, and making some definitive observations?
Generally speaking, the logistics are that you hope that will never create a black hole. You can't really "capture" a BH: It will fall down (towards Earth) like everything else and then start eating its way to the core…
Unless… you manage to create an electrically charged black hole. Then you might be able to confine it e.g. between two condensator plates, by calibrating the voltage in such a way that electric and gravitational force on the BH cancel out.
Now, one problem would be that we expect small black holes to radiate heavily (Hawking radiation), meaning we would have to keep feeding the BH to prevent it from evaporating. (Unless we believe in black hole remnants, see my other comment.) This whole endeavor would make stabilizing the BH between the condensator plates much more challenging. And we'd also still have to worry about what all that radiation will do to our equipment…
Comments
If we had ham, we could have ham and eggs, if we had eggs. Another classic "this will be easy as long as we have unobtanium" concept.
I've been baffled, though, by the insistence on this kind of antimatter production. Antimatter production is inherently expensive because we are fighting conservation of baryon number, conservation of lepton number, et al.
Physics does have one theoretical method around this, which never seems to be addressed for these proposals, and that's the baffling issue of black holes having no hair. You throw whatever past the event horizon, all that is conserved is mass, angular momentum, and charge. Baryon number, lepton number, strangeness ... all lost. Re-emission as Hawking radiation, it is thought, would simply be this sort of thing, redistributed without regard to what went in, so long as mass, angular momentum, and charge are accounted for. You would conceivably get out as much antimatter as matter.
Now, that's worth looking at. And not from a "we JUST need to capture an itty black hole" (the word "just" does an enormous amount of lifting here) perspective. Rather, passage through the event horizon somehow strips off (we think, some think it might be preserved in some fashion) all of the variables which account for matter versus antimatter. And yet the event horizon isn't a hunk of matter, it's a ... membrane, a boundary, generated by matter at some distance (as a function of our usual three variables). Somehow, this warpage of spacetime operates on matter, shaving it so it has no hair.
That's what fascinates me, in the sense of the theoretical having some extremely juicy practical results.
Even for classical black holes I don't think that's the consensus among physicists. The general assumption seems to be that quantum numbers are still conserved when you throw stuff into black holes, just like electrical charge.
Now, as for Hawking radiation, it's worth pointing out that Hawking's calculation only works for large black holes (low curvature near the event horizon). Once a large BH has shrunken down to a tiny BH (-> high curvature at the event horizon), the calculation no longer works and it is unclear what will happen. Some people say the BH will evaporate completely, some say there will be a remnant – who knows. (Both solutions have their issues.)
All in all, I'm skeptical of the "shaving" you describe.
It's right there in the Wikipedia article on the No Hair Theorem:
"Suppose two black holes have the same masses, electrical charges, and angular momenta, but the first black hole was made by collapsing ordinary matter whereas the second was made out of antimatter; nevertheless, then the conjecture states they will be completely indistinguishable to an observer outside the event horizon. None of the special particle physics pseudo-charges (i.e., the global charges baryonic number, leptonic number, etc., all of which would be different for the originating masses of matter that created the black holes) are conserved in the black hole, or if they are conserved somehow then their values would be unobservable from the outside"
Now, this is all still hypothetical, as we haven't a black hole on hand, but this has been the mainstream view on black holes for decades.
Wasn't LHC supposed to create the occasional microscopic black hole? What are the logistics on capturing one of those, keeping it fed, and making some definitive observations?
That was discussed but AFAIR nobody really believed this was actually going to happen.
Generally speaking, the logistics are that you hope that will never create a black hole. You can't really "capture" a BH: It will fall down (towards Earth) like everything else and then start eating its way to the core…
Unless… you manage to create an electrically charged black hole. Then you might be able to confine it e.g. between two condensator plates, by calibrating the voltage in such a way that electric and gravitational force on the BH cancel out.
Now, one problem would be that we expect small black holes to radiate heavily (Hawking radiation), meaning we would have to keep feeding the BH to prevent it from evaporating. (Unless we believe in black hole remnants, see my other comment.) This whole endeavor would make stabilizing the BH between the condensator plates much more challenging. And we'd also still have to worry about what all that radiation will do to our equipment…
Long story short: Don't do it!