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While I do believe our knowledge of particle physics is still incomplete, the money spent plumbing its depths seems disproportionately high. When was fusion ene

While I do believe our knowledge of particle physics is still incomplete, the money spent plumbing its depths seems disproportionately high. When was fusion energy meant to be produced again?

PavlikPaja 8y ago
Nuclear fusion won't work, because stars are not powered by fusion. What happens in the stars is that heavier elements capture protons, until they eventually reach lead, where it keeps cycling - lead 206 captures proton, turns into bismuth 207, which decays into lead 207, captures another proton, turns into bismuth 208, captures yet another proton, turns into polonium 209, which either decays into lead 205 (releasing a helium core), or captures another proton and the resulting astatine 210 decays into polonium 210, and the polonium 210 decays back into lead 206 + a helium atom. Which is why direct fusion of hydrogen/deuterium will never work at expected temperatures and controllable speed, it can only work in explosions, if at all.
- jerf 8y ago
  If what you say was true, the bombs wouldn't work either. The bombs are based on the same math as stellar physics.
  - deleted 8y ago
    [deleted]
  - PavlikPaja 8y ago
    They're explosions though, they can't be controlled. And they contain heavy elements as the trigger.
    - jerf 8y ago
      Neither of those sentences is relevant to, or contradicts, what I said.
- ivalm 8y ago
  Nearly everything you said is wrong. First of all, we can do/have done fusion on earth (from H-bombs, which are quite calculable, to ICF, also quite calculable). Second, proton capture for heavy nuclei is endothermic (so you cool down) and there is no way "cycling" can produce energy since that would be a perpetual energy source. That's why fusion stops in iron rich stars (fusion is exothermic until you reach Fe-56). We have A LOT of astro observations to back this up. The heavy elements that do get produced are generally produced by neutron capture, not proton capture (r-process). This is an endothermic process and happens during large energy releases such as neutron star mergers and potentially core collapse supernovae (although there still needs to be more experimental evidence).
  - PavlikPaja 8y ago
    > ICF, also quite calculable). It doesn't seem to be working, so it's reasonable to expect it's wrong. >Second, proton capture for heavy nuclei is endothermic (so you cool down) No, it isn't. Whoever calculated that Iron is where it ends forgot to add the binding energy of the added proton. The binding energy per nucleon decreases, but there is one nucleon more, so it's still a net gain. > there is no way "cycling" can produce energy since that would be a perpetual energy source. It wouldn't you're using up hydrogen. >We have A LOT of astro observations to back this up. There are also observations of lead rich stars.
auntienomen 8y ago
When did particle physicists promise you fusion? Those are largely separate areas of research.

While I do believe our knowledge of particle physics is still incomplete, the money spent plumbing its depths seems disproportionately high. When was fusion energy meant to be produced again?

PavlikPaja 8y ago

Nuclear fusion won't work, because stars are not powered by fusion. What happens in the stars is that heavier elements capture protons, until they eventually reach lead, where it keeps cycling - lead 206 captures proton, turns into bismuth 207, which decays into lead 207, captures another proton, turns into bismuth 208, captures yet another proton, turns into polonium 209, which either decays into lead 205 (releasing a helium core), or captures another proton and the resulting astatine 210 decays into polonium 210, and the polonium 210 decays back into lead 206 + a helium atom. Which is why direct fusion of hydrogen/deuterium will never work at expected temperatures and controllable speed, it can only work in explosions, if at all.

jerf 8y ago
If what you say was true, the bombs wouldn't work either. The bombs are based on the same math as stellar physics.
- deleted 8y ago
  [deleted]
- PavlikPaja 8y ago
  They're explosions though, they can't be controlled. And they contain heavy elements as the trigger.
  - jerf 8y ago
    Neither of those sentences is relevant to, or contradicts, what I said.
ivalm 8y ago
Nearly everything you said is wrong. First of all, we can do/have done fusion on earth (from H-bombs, which are quite calculable, to ICF, also quite calculable). Second, proton capture for heavy nuclei is endothermic (so you cool down) and there is no way "cycling" can produce energy since that would be a perpetual energy source. That's why fusion stops in iron rich stars (fusion is exothermic until you reach Fe-56). We have A LOT of astro observations to back this up. The heavy elements that do get produced are generally produced by neutron capture, not proton capture (r-process). This is an endothermic process and happens during large energy releases such as neutron star mergers and potentially core collapse supernovae (although there still needs to be more experimental evidence).
- PavlikPaja 8y ago
  > ICF, also quite calculable). It doesn't seem to be working, so it's reasonable to expect it's wrong. >Second, proton capture for heavy nuclei is endothermic (so you cool down) No, it isn't. Whoever calculated that Iron is where it ends forgot to add the binding energy of the added proton. The binding energy per nucleon decreases, but there is one nucleon more, so it's still a net gain. > there is no way "cycling" can produce energy since that would be a perpetual energy source. It wouldn't you're using up hydrogen. >We have A LOT of astro observations to back this up. There are also observations of lead rich stars.

auntienomen 8y ago

When did particle physicists promise you fusion? Those are largely separate areas of research.