3 ms·

> Since hydrogen fusion lies at the heart of hydrogen bombs, the researchers were quite naturally alarmed at their findings. So much so that they considered not

> Since hydrogen fusion lies at the heart of hydrogen bombs, the researchers were quite naturally alarmed at their findings. So much so that they considered not publishing their results. But subsequent calculations showed that it would be impossible to cause a chain reaction with quarks because they exist for too short a period of time—approximately one picosecond—not long enough to set off another baryon. They decay into much smaller, less dangerous lighter quarks. This must be either some kind of inside joke that was lost on the reporter, or a really poor reporting. You simply cannot accumulate stuff that decays in the order of picoseconds: if you can, you already have a bomb. No chain reaction needed. After all, when they say "they decay into much smaller, less dangerous lighter quarks," it means they release all this dangerous energy. It's like saying "Fortunately, this TNT decays into a much less dangerous mixture of inert nitrogen, water vapor, and carbon monoxide." Well, duh, it's exactly the process of decaying that makes TNT so dangerous.

dogma1138 9y ago
No if they decay into lighter quarks it doesn’t mean they release all that energy just the energy difference between the states. Say you have 2 10meV particles that can fuse into a single 12meV particle this means that 8meV of energy has to be released in the process. If they also have a decay route that say decays into a 9meV particle it means that only 2meV are released in the decay process. If we take a real world example then hydrogen fusion releases about 14.5meV of excess energy on top of the helium atom when 2H and 3H fuse, deuterium (2H) is stable, tritium (3H) is not and it’s beta decay only releases 0.0018meV of energy. This means that the energy released in a fusion reaction is about 8000 more than the beta decay of the tritium. The product of the decay/fusion is also important the beta decay of tritium releases an electron and a neutrino the energy that goes into the neutrino is effectively sunk since it’s a weakly interactive particle which is basically harmless. The electron is what you need to worry about in this case.
goalieca 9y ago
Sure, but it’s the chain reaction that is needed to make the nuke.
AnimalMuppet 9y ago
OK, but you have one picosecond to assemble your bomb. Let me know how much explosive power you manage to accumulate in that time. Also let me know how far away from your manufacturing facility you manage to move it before it goes off...
- tantalor 9y ago
  Perhaps a precursor reaction could be used to generate the necessary ingredients "just in time", like how a fission type of explosion is a precursor to a fusion explosion.
  - AnimalMuppet 9y ago
    That's not a bad idea, but I still don't think it would work. There are at least two problems. First is the rate at which you can generate the precursors. How many can you generate in a picosecond? That's how big your explosion can be. Or rather, the explosion will be as big as how many you can generate in a picosecond, times however many picoseconds you can sustain generating them (plus the force needed to make the fusion reaction happen). The second problem is that generating the ingredients probably takes at least as much energy as you get out of the fusion reaction. At that point, whatever you're using to generate the energy can be your weapon, without needing the intermediate step of the quark fusion reaction. (As the Schlock Mercenary web comic says, "Any sufficiently advanced technology is indistinguishable from a really big gun.")
- yongjik 9y ago
  Maybe I should have said "you have an explosion". I agree that this isn't really a bomb in the usual sense.
ckozlowski 9y ago
If we were talking fission, then yes, you'd already have it. Once critical mass is achieved, then you have a reaction. But for fusion, there is no critical mass as the ingredients (from a nuclear standpoint) are inert. So it's a matter of keeping them present and around long enough that it can be weaponized. Early hydrogen bombs had this problem as they used cryogenic fuel. There was a real challenge of keeping the fuel from boiling off and having nothing to fuse. Of course, that problem was solved. Not to suggest the challenge to keep a quark around for longer will prove to be as simple, but give it some decades...and things will be interesting.
- otakucode 9y ago
  Hydrogen bombs are already of any desired variable strength. It would make no sense to pursue 'bigger' bombs. The hydrogen bombs we have now are already so large that no legitimate military target could ever exist which called for one. They're purely weapons of genocide with no reasonable military use. That's why Oppenheimer opposed their development in the 70s (and was burned for it).
  - ckozlowski 9y ago
    " The hydrogen bombs we have now are already so large that no legitimate military target could ever exist which called for one." Which is why all of the large ones have been decomissioned. Ironically, eliminating "bigger" bombs in favor of smaller ones is being cited as a danger in and of itself. Because the threshold to using nuclear weapons currently is so high (even in the 170-300kt range as they are now), pursing accurate weapons in the tens of kilotons range is seen as destabilizing because it's seen as being more acceptable to use against say, a remote, hardened target.
  - excalibur 9y ago
    Could be useful for blowing up an incoming asteroid. We're currently stuck in a dilemma where if the rock is small enough for a missile to actually wipe it out, it won't be dangerous enough to merit nuking in the first place. If we had a reliable and lightweight bomb that could take out a rock the size of Ceres, we would have a much better chance of defending our planet. Of course we would still have to refrain from annihilating ourselves.

dogma1138 9y ago

No if they decay into lighter quarks it doesn’t mean they release all that energy just the energy difference between the states. Say you have 2 10meV particles that can fuse into a single 12meV particle this means that 8meV of energy has to be released in the process. If they also have a decay route that say decays into a 9meV particle it means that only 2meV are released in the decay process. If we take a real world example then hydrogen fusion releases about 14.5meV of excess energy on top of the helium atom when 2H and 3H fuse, deuterium (2H) is stable, tritium (3H) is not and it’s beta decay only releases 0.0018meV of energy. This means that the energy released in a fusion reaction is about 8000 more than the beta decay of the tritium. The product of the decay/fusion is also important the beta decay of tritium releases an electron and a neutrino the energy that goes into the neutrino is effectively sunk since it’s a weakly interactive particle which is basically harmless. The electron is what you need to worry about in this case.

goalieca 9y ago

Sure, but it’s the chain reaction that is needed to make the nuke.

AnimalMuppet 9y ago

OK, but you have one picosecond to assemble your bomb. Let me know how much explosive power you manage to accumulate in that time. Also let me know how far away from your manufacturing facility you manage to move it before it goes off...

tantalor 9y ago
Perhaps a precursor reaction could be used to generate the necessary ingredients "just in time", like how a fission type of explosion is a precursor to a fusion explosion.
- AnimalMuppet 9y ago
  That's not a bad idea, but I still don't think it would work. There are at least two problems. First is the rate at which you can generate the precursors. How many can you generate in a picosecond? That's how big your explosion can be. Or rather, the explosion will be as big as how many you can generate in a picosecond, times however many picoseconds you can sustain generating them (plus the force needed to make the fusion reaction happen). The second problem is that generating the ingredients probably takes at least as much energy as you get out of the fusion reaction. At that point, whatever you're using to generate the energy can be your weapon, without needing the intermediate step of the quark fusion reaction. (As the Schlock Mercenary web comic says, "Any sufficiently advanced technology is indistinguishable from a really big gun.")
yongjik 9y ago
Maybe I should have said "you have an explosion". I agree that this isn't really a bomb in the usual sense.

ckozlowski 9y ago

If we were talking fission, then yes, you'd already have it. Once critical mass is achieved, then you have a reaction. But for fusion, there is no critical mass as the ingredients (from a nuclear standpoint) are inert. So it's a matter of keeping them present and around long enough that it can be weaponized. Early hydrogen bombs had this problem as they used cryogenic fuel. There was a real challenge of keeping the fuel from boiling off and having nothing to fuse. Of course, that problem was solved. Not to suggest the challenge to keep a quark around for longer will prove to be as simple, but give it some decades...and things will be interesting.

otakucode 9y ago
Hydrogen bombs are already of any desired variable strength. It would make no sense to pursue 'bigger' bombs. The hydrogen bombs we have now are already so large that no legitimate military target could ever exist which called for one. They're purely weapons of genocide with no reasonable military use. That's why Oppenheimer opposed their development in the 70s (and was burned for it).
- ckozlowski 9y ago
  " The hydrogen bombs we have now are already so large that no legitimate military target could ever exist which called for one." Which is why all of the large ones have been decomissioned. Ironically, eliminating "bigger" bombs in favor of smaller ones is being cited as a danger in and of itself. Because the threshold to using nuclear weapons currently is so high (even in the 170-300kt range as they are now), pursing accurate weapons in the tens of kilotons range is seen as destabilizing because it's seen as being more acceptable to use against say, a remote, hardened target.
- excalibur 9y ago
  Could be useful for blowing up an incoming asteroid. We're currently stuck in a dilemma where if the rock is small enough for a missile to actually wipe it out, it won't be dangerous enough to merit nuking in the first place. If we had a reliable and lightweight bomb that could take out a rock the size of Ceres, we would have a much better chance of defending our planet. Of course we would still have to refrain from annihilating ourselves.