4 ms·

IANAP (physicist, just an Engineer) but any sort of reaction like this is probably pretty hard to control so you won’t get twice the energy. Just like with comb

IANAP (physicist, just an Engineer) but any sort of reaction like this is probably pretty hard to control so you won’t get twice the energy. Just like with combustion engines, you’re probably looking at some significant percentage loss (~50%?) in efficiency from various things. (I’m sure there are other things that would also hinder the 2x outlook you are asking about)

JoshTriplett 2y ago
Yeah, as the article here notes, the energy released is effectively an explosion, and harnessing that energy into something more useful is a substantial challenge. As is the concept of turning energy into specific (anti-)matter, which we have no idea how to do at the moment. This is more a theoretical question of whether any law of physics makes this impossible (e.g. you can't create unpaired particles), or whether this is theoretically possible but it's difficult to get enough efficiency to make it net positive. (We currently haven't even gotten fusion to be reliably net positive; practicality is as always a set of concerns all its own.)
- api 2y ago
  Project Orion style pusher plate nuclear pulse designs can handle turning big boom boom into space propulsion but as the parent said you are not 100% efficient.
  - JoshTriplett 2y ago
    More interested in electrical power than propulsion, in this case.
    - lazide 2y ago
      The classic stand-in of boiling a bunch of water, then spinning turbines is likely our best bet.
- ben_w 2y ago
  > This is more a theoretical question of whether any law of physics makes this impossible (e.g. you can't create unpaired particles), or whether this is theoretically possible but it's difficult to get enough efficiency to make it net positive. It's theoretically impossible, with the slight problem that there seems to be more matter than antimatter in the universe today and nobody really knows why. Either the theory is wrong (and it being a conservation rule, then by Noether's theorem there's an equivalent symmetry* you'd have to violate if the conservation doesn't hold), or the initial value that's getting conserved wasn't ever zero. * the wikipedia page says this is specific to continuous symmetry; but integers aren't continuous, so has this been generalised, or is it just assumed?
EA-3167 2y ago
You have a solid intuition, in addition to the usual efficiency losses, a large amount (20%-50% would be usual, up to 80% in some cases) of the energy released during annihilation is in the form of... neutrinos. I don't foresee a realistic means of harnessing that energy any time soon, even where "soon" indicates quite a stretch of time.

JoshTriplett 2y ago

Yeah, as the article here notes, the energy released is effectively an explosion, and harnessing that energy into something more useful is a substantial challenge. As is the concept of turning energy into specific (anti-)matter, which we have no idea how to do at the moment. This is more a theoretical question of whether any law of physics makes this impossible (e.g. you can't create unpaired particles), or whether this is theoretically possible but it's difficult to get enough efficiency to make it net positive. (We currently haven't even gotten fusion to be reliably net positive; practicality is as always a set of concerns all its own.)

api 2y ago
Project Orion style pusher plate nuclear pulse designs can handle turning big boom boom into space propulsion but as the parent said you are not 100% efficient.
- JoshTriplett 2y ago
  More interested in electrical power than propulsion, in this case.
  - lazide 2y ago
    The classic stand-in of boiling a bunch of water, then spinning turbines is likely our best bet.
ben_w 2y ago
> This is more a theoretical question of whether any law of physics makes this impossible (e.g. you can't create unpaired particles), or whether this is theoretically possible but it's difficult to get enough efficiency to make it net positive. It's theoretically impossible, with the slight problem that there seems to be more matter than antimatter in the universe today and nobody really knows why. Either the theory is wrong (and it being a conservation rule, then by Noether's theorem there's an equivalent symmetry* you'd have to violate if the conservation doesn't hold), or the initial value that's getting conserved wasn't ever zero. * the wikipedia page says this is specific to continuous symmetry; but integers aren't continuous, so has this been generalised, or is it just assumed?

EA-3167 2y ago

You have a solid intuition, in addition to the usual efficiency losses, a large amount (20%-50% would be usual, up to 80% in some cases) of the energy released during annihilation is in the form of... neutrinos. I don't foresee a realistic means of harnessing that energy any time soon, even where "soon" indicates quite a stretch of time.