6 ms·

> Studying antimatter is particularly cool, because at the face value it is one of the most efficient ways to store energy (Basically 100% of matter gets conver

> Studying antimatter is particularly cool, because at the face value it is one of the most efficient ways to store energy (Basically 100% of matter gets converted to energy). In theory, a black hole is also a 100%-efficient converter of matter into energy, via the Hawking radiation. A microscopic BH might radiate very large amounts of Hawking radiation. The bonus is that, unlike antimatter, you can make (or at least fatten up) a BH directly from ordinary matter, without spending energy as a prior step (anti-matter is energy storage, a black hole is an energy source - if you're willing to spend some dirt as "fuel"). Of course, the problem of storage is just as bad, if not worse.

wyager 13y ago
I hadn't thought about black holes as an energy source. Cool idea. But where does the energy actually "come from"? With M/AM interactions, the M/AM is annihilated, which creates harvestable photons. Does the energy given off by a black hole come from the change in entropy from structured matter to unstructured Hawking radiation or something? It seems almost too easy if we can just feed any old matter into a black hole and get energy out...
- maxerickson 13y ago
  If it is a traditional black hole, it has to have a pretty large mass to have a manageable energy output (they burn faster as they lose mass). On the other side, if it is too large, the energy output is miniscule.
- waps 13y ago
  The energy comes from virtual particles. You should think of it this way : anything has a certain chance of happening, but must follow conservation laws. Conservation of energy, conservation of mass, conservation of ... (the "real" conservation laws are more complex, but ... E.g. only mass+energy+entropy is constant, not mass, nor energy, nor entropy). But small, "short term" violations are possible. Now imagine there are particle pairs that, when added together have zero mass, zero energy, zero ... These would pop into existence in pairs everywhere and be anihilated soon after. Same is true for triples, quadruplets, ... with different probabilities. Surprise : these particles "exist" (normally for very short times). So particle a and particle b come into existence, both particles on a path that separates them from eachother. However, because opposite charges attract (and other effects related to other forces) they will fall back into eachother after a while, anihilating eachother and leaving nothing. These are generally referred to as "virtual" particles. Except of course if something comes between them while flying on their path. This results in multiple effects, like the Casimir pressure, and hawking radiation. The Casimir pressure is simpler. Suppose you have 2 straight plates, and you bring them close together. So close that these virtual particles have a good chance of impacting one but not the other. If the plates are metal, the particles will generally "merge" with it (like electrons). So a tiny percentage of the virtual particles between the plates become real. This does not affect virtual particles that are not between the plates. So there is a clear differential between vacuum interactions outside of the plates and inside. This results in a massive pressure pushing the plates together, like removing gas particles in a container results in a pressure on the outside of the container (and, in an athmosphere of large molecules, if you move plates closer together than the size of the gas molecules, there will be a pressure that pushes the plates completely together). Likewise, in black holes what comes between the particles is an event horizon. Event horizons "erase" quantum information, only the black hole as a whole has quantum information (the reason for is that black holes are physical, localized, manifestations of the end of time : they don't have an inside as far as anything outside the black hole can detect), no individual parts of a black hole have quantum state. So if an electron crosses the event horizon the charge of the entire black hole changes instantaneously, and the point charge of the electron disappears. That means the charge pulling the particles back together (assuming an e+ and e- virtual particle pair) becomes much more distant to the particle, and if it has enough speed and a convenient direction it will fly away from the black hole. Due to conservation laws the net result is that the black hole has eaten a somehow negative-mass charged particle, and the mass has decreased. A particle has been created outside of the black hole and is flying away to infinity. The vast majority of these particles are photons of a specific frequency, and, surprisingly, the smaller the black hole, the larger the effect (and the higher the frequencies). So spaceships would have to carry "heavy" black holes to get a decent output and would have to "feed" the black holes to avoid exploding (millions of tonnes as least, and you have to shovel in matter at a rate of 10+ kg per second to keep it stable. Or you could reflect hawking radiation back in). And of course, large black holes have large inertia (plus : how do you hold on to one ? Electrical fields can do it, but it would have to be a field so huge it baffles the imagination ...). A 1kg black hole would be converted into energy in less than a planck second by this effect and there is nothing, even theoretically, that can hold back that energy. Such an explosion might even do what people were "afraid" would happen with CERN's Higgs experiments and disrupt the Higgs field, causing a cascading conversion of the energy "powering" inertia into photons (the higgs field is something like a magnetic field that opposes all velocity changes in mass). If this were to happen, it would look one hell of a lot like a big bang.
  - maaku 13y ago
    Thanks... now I'm going to have trouble sleeping at night.
  - bjelkeman-again 13y ago
    Thanks for that explanation. Seems it isn't very practical with a black hole as your energy source/storage. Not surprising I suppose.
  - tempestn 13y ago
    Is there a similarly simplified explanation for why the black hole tends to 'eat' the negative-mass halves of the virtual particle pairs but not the (or at least more often than the) positive-mass ones? Just going by your explanation above, it seems just as likely that the positive-mass particle would be captured by the black hole, emitting the negative mass one, but since the black hole loses mass through this radiation, that must not be the case.
    - grkvlt 13y ago
      They're not 'negative mass' particles, they are anti-particles, which have the same (positive) mass as the normal particle, but opposite charge.
      - xerophtye 13y ago
        well by his definition they HAVE to be negative mass. Because when these particles unite, they end up having ZERO mass, energy, entropy etc. So all of their properties must be inverses of each other, including mass
    - Florin_Andrei 13y ago
      There is no "positive" or "negative" mass. They are both virtual. Their sum-total energy is zero. Virtual pairs appear and disappear all the time. They are like water boiling in a pot making foam; there are virtual "bubbles" everywhere around you. As long as they disappear back into nothingness, everything about them is virtual. It's only that the event horizon throws a snag into the mechanism, and swallows up one of the particles, thereby preventing recombination. The only way for that to happen is that if the other particle gets promoted from virtual to real. The only way that could happen is if the black hole itself provides the required energy to make that particle real. Again, the BH does not pick "positive" vs "negative" mass. It just swallows up one random member of a virtual pair. The other member, left alone, cannot recombine; it sucks up some energy from the BH's gravitational field and becomes a real particle, with positive energy and mass. To sum it up, it's the virtual pair "foam" that slowly sucks up energy from the BH.
- wcoenen 13y ago
  The energy comes from the mass energy equivalence E=mc^2. The idea is to use a black hole as an engine for converting mass into (other kinds of) energy.
darkmighty 13y ago
Interesting; though with antimatter you can control the emission by controlling M/AM recombination rate, whereas the best you could do with a BH is optimize when you feed your BH so that it's output is mostly when you need it (from what I remember the decay rate increases rapidly with decreasing size; not sure about absolute energy output though time).
kristianp 13y ago
Microscopic Black Holes are cooler than anti-matter if you ask me. We are only centuries of progress away from this: "Are Black Hole Starships Possible", http://arxiv.org/abs/0908.1803 http://arxiv.org/abs/0908.1803 My question is, how long before we can build an accelerator that deliberately aims at creating black holes, so we can understand the Quantum effects? (In space hopefully).
dhughes 13y ago
I remember reading about this on io9 quoting Louis Crane and Shawn Westmoreland of Kansas State University. (2009) >A black hole that would survive the entire trip would have a radius of 0.9 attometers, would have a mass of 606,000 tonnes, and a power output of 160 petawatts. The lifespan of the black hole could be extended by feeding it mass, too. http://io9.com/5391989/a-black-hole-engine-that-could-power-spaceships http://io9.com/5391989/a-black-hole-engine-that-could-power-...
hartror 13y ago
The novel Earth by David Brin uses this energy source. It also has a lot of other tech in it that has come about since its publication in 1990. http://en.wikipedia.org/wiki/Earth_(Brin_novel) http://en.wikipedia.org/wiki/Earth_(Brin_novel)
zephjc 13y ago
This is basically the power source on Romulan starships :)

wyager 13y ago

I hadn't thought about black holes as an energy source. Cool idea. But where does the energy actually "come from"? With M/AM interactions, the M/AM is annihilated, which creates harvestable photons. Does the energy given off by a black hole come from the change in entropy from structured matter to unstructured Hawking radiation or something? It seems almost too easy if we can just feed any old matter into a black hole and get energy out...

maxerickson 13y ago
If it is a traditional black hole, it has to have a pretty large mass to have a manageable energy output (they burn faster as they lose mass). On the other side, if it is too large, the energy output is miniscule.
waps 13y ago
The energy comes from virtual particles. You should think of it this way : anything has a certain chance of happening, but must follow conservation laws. Conservation of energy, conservation of mass, conservation of ... (the "real" conservation laws are more complex, but ... E.g. only mass+energy+entropy is constant, not mass, nor energy, nor entropy). But small, "short term" violations are possible. Now imagine there are particle pairs that, when added together have zero mass, zero energy, zero ... These would pop into existence in pairs everywhere and be anihilated soon after. Same is true for triples, quadruplets, ... with different probabilities. Surprise : these particles "exist" (normally for very short times). So particle a and particle b come into existence, both particles on a path that separates them from eachother. However, because opposite charges attract (and other effects related to other forces) they will fall back into eachother after a while, anihilating eachother and leaving nothing. These are generally referred to as "virtual" particles. Except of course if something comes between them while flying on their path. This results in multiple effects, like the Casimir pressure, and hawking radiation. The Casimir pressure is simpler. Suppose you have 2 straight plates, and you bring them close together. So close that these virtual particles have a good chance of impacting one but not the other. If the plates are metal, the particles will generally "merge" with it (like electrons). So a tiny percentage of the virtual particles between the plates become real. This does not affect virtual particles that are not between the plates. So there is a clear differential between vacuum interactions outside of the plates and inside. This results in a massive pressure pushing the plates together, like removing gas particles in a container results in a pressure on the outside of the container (and, in an athmosphere of large molecules, if you move plates closer together than the size of the gas molecules, there will be a pressure that pushes the plates completely together). Likewise, in black holes what comes between the particles is an event horizon. Event horizons "erase" quantum information, only the black hole as a whole has quantum information (the reason for is that black holes are physical, localized, manifestations of the end of time : they don't have an inside as far as anything outside the black hole can detect), no individual parts of a black hole have quantum state. So if an electron crosses the event horizon the charge of the entire black hole changes instantaneously, and the point charge of the electron disappears. That means the charge pulling the particles back together (assuming an e+ and e- virtual particle pair) becomes much more distant to the particle, and if it has enough speed and a convenient direction it will fly away from the black hole. Due to conservation laws the net result is that the black hole has eaten a somehow negative-mass charged particle, and the mass has decreased. A particle has been created outside of the black hole and is flying away to infinity. The vast majority of these particles are photons of a specific frequency, and, surprisingly, the smaller the black hole, the larger the effect (and the higher the frequencies). So spaceships would have to carry "heavy" black holes to get a decent output and would have to "feed" the black holes to avoid exploding (millions of tonnes as least, and you have to shovel in matter at a rate of 10+ kg per second to keep it stable. Or you could reflect hawking radiation back in). And of course, large black holes have large inertia (plus : how do you hold on to one ? Electrical fields can do it, but it would have to be a field so huge it baffles the imagination ...). A 1kg black hole would be converted into energy in less than a planck second by this effect and there is nothing, even theoretically, that can hold back that energy. Such an explosion might even do what people were "afraid" would happen with CERN's Higgs experiments and disrupt the Higgs field, causing a cascading conversion of the energy "powering" inertia into photons (the higgs field is something like a magnetic field that opposes all velocity changes in mass). If this were to happen, it would look one hell of a lot like a big bang.
- maaku 13y ago
  Thanks... now I'm going to have trouble sleeping at night.
- bjelkeman-again 13y ago
  Thanks for that explanation. Seems it isn't very practical with a black hole as your energy source/storage. Not surprising I suppose.
- tempestn 13y ago
  Is there a similarly simplified explanation for why the black hole tends to 'eat' the negative-mass halves of the virtual particle pairs but not the (or at least more often than the) positive-mass ones? Just going by your explanation above, it seems just as likely that the positive-mass particle would be captured by the black hole, emitting the negative mass one, but since the black hole loses mass through this radiation, that must not be the case.
  - grkvlt 13y ago
    They're not 'negative mass' particles, they are anti-particles, which have the same (positive) mass as the normal particle, but opposite charge.
    - xerophtye 13y ago
      well by his definition they HAVE to be negative mass. Because when these particles unite, they end up having ZERO mass, energy, entropy etc. So all of their properties must be inverses of each other, including mass
  - Florin_Andrei 13y ago
    There is no "positive" or "negative" mass. They are both virtual. Their sum-total energy is zero. Virtual pairs appear and disappear all the time. They are like water boiling in a pot making foam; there are virtual "bubbles" everywhere around you. As long as they disappear back into nothingness, everything about them is virtual. It's only that the event horizon throws a snag into the mechanism, and swallows up one of the particles, thereby preventing recombination. The only way for that to happen is that if the other particle gets promoted from virtual to real. The only way that could happen is if the black hole itself provides the required energy to make that particle real. Again, the BH does not pick "positive" vs "negative" mass. It just swallows up one random member of a virtual pair. The other member, left alone, cannot recombine; it sucks up some energy from the BH's gravitational field and becomes a real particle, with positive energy and mass. To sum it up, it's the virtual pair "foam" that slowly sucks up energy from the BH.
wcoenen 13y ago
The energy comes from the mass energy equivalence E=mc^2. The idea is to use a black hole as an engine for converting mass into (other kinds of) energy.

darkmighty 13y ago

Interesting; though with antimatter you can control the emission by controlling M/AM recombination rate, whereas the best you could do with a BH is optimize when you feed your BH so that it's output is mostly when you need it (from what I remember the decay rate increases rapidly with decreasing size; not sure about absolute energy output though time).

kristianp 13y ago

Microscopic Black Holes are cooler than anti-matter if you ask me. We are only centuries of progress away from this: "Are Black Hole Starships Possible", http://arxiv.org/abs/0908.1803 http://arxiv.org/abs/0908.1803 My question is, how long before we can build an accelerator that deliberately aims at creating black holes, so we can understand the Quantum effects? (In space hopefully).

dhughes 13y ago

I remember reading about this on io9 quoting Louis Crane and Shawn Westmoreland of Kansas State University. (2009) >A black hole that would survive the entire trip would have a radius of 0.9 attometers, would have a mass of 606,000 tonnes, and a power output of 160 petawatts. The lifespan of the black hole could be extended by feeding it mass, too. http://io9.com/5391989/a-black-hole-engine-that-could-power-spaceships http://io9.com/5391989/a-black-hole-engine-that-could-power-...

hartror 13y ago

The novel Earth by David Brin uses this energy source. It also has a lot of other tech in it that has come about since its publication in 1990. http://en.wikipedia.org/wiki/Earth_(Brin_novel) http://en.wikipedia.org/wiki/Earth_(Brin_novel)

zephjc 13y ago

This is basically the power source on Romulan starships :)