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Radiothermal heating of planetary cores is established scientific fact. It's not a fission reactor because there's no chain reaction, just a lot of unstable ele

Radiothermal heating of planetary cores is established scientific fact. It's not a fission reactor because there's no chain reaction, just a lot of unstable elements in one place. Some details are controversial, but not the basics. (I have a geochemistry PhD)

foobarbecue 4y ago
Ok I just read a bit more and apparently there are some fringe geophysicists who think it really is more like a reactor. I didn't know that.
- sidewndr46 4y ago
  Yes, I think that is the where the debate is over the exact nature of things. Fission happens spontaneously, even the bismuth in Pepto Bismol has a bit of a fission going on, slowly decaying into thallium.
  - amluto 4y ago
    ²⁰⁹Bi decay to ²⁰⁵Tl is alpha decay — the bismuth nucleus splits into an alpha particle (helium) and a thallium nucleus. I think you’d be hard pressed to find a nuclear physicist or engineer who calls that “fission”. Here’s the Wikipedia article on fission. It’s a rather different process: https://en.m.wikipedia.org/wiki/Nuclear_fission https://en.m.wikipedia.org/wiki/Nuclear_fission
- saboot 4y ago
  Can you link to what you are reading? I am a nuclear engineer, I suspect they are using a very loose definition of critical, one that would imply the entire universe itself is critical.
  - nonrandomstring 4y ago
    Maybe the fault is with me for using the word "reactor" a bit loosely. I don't think anyone knows for sure what is going on down there. My theory is that it's both critical and quiescent, with a violent dynamic at play. Gravity will concentrate the heaviest and least stable elements as you'd expect. As that happens pockets of dense matter in close neutron proximity will approach critical and heat billions of tons of matter which then convects outwards, dispersing the mixture. Think of a lava lamp.
    - pencilguin 4y ago
      Geochemists say uranium concentrates in the crust, for chemical reasons -- which is, in fact, where we find it.
pas 4y ago
are there estimates for how much heat is produced this way? any other way? (solar magnetic field interaction?) how much is the residual heat dissipation? edit: ah, just read the title of the link posted in the top level comment. apparently it's "half of the heat" :)
yummypaint 4y ago
Yes. Alpha decay in particular is also the source of essentially all helium on earth, and the reason helium is captured from gas wells.

foobarbecue 4y ago

Ok I just read a bit more and apparently there are some fringe geophysicists who think it really is more like a reactor. I didn't know that.

sidewndr46 4y ago
Yes, I think that is the where the debate is over the exact nature of things. Fission happens spontaneously, even the bismuth in Pepto Bismol has a bit of a fission going on, slowly decaying into thallium.
- amluto 4y ago
  ²⁰⁹Bi decay to ²⁰⁵Tl is alpha decay — the bismuth nucleus splits into an alpha particle (helium) and a thallium nucleus. I think you’d be hard pressed to find a nuclear physicist or engineer who calls that “fission”. Here’s the Wikipedia article on fission. It’s a rather different process: https://en.m.wikipedia.org/wiki/Nuclear_fission https://en.m.wikipedia.org/wiki/Nuclear_fission
saboot 4y ago
Can you link to what you are reading? I am a nuclear engineer, I suspect they are using a very loose definition of critical, one that would imply the entire universe itself is critical.
- nonrandomstring 4y ago
  Maybe the fault is with me for using the word "reactor" a bit loosely. I don't think anyone knows for sure what is going on down there. My theory is that it's both critical and quiescent, with a violent dynamic at play. Gravity will concentrate the heaviest and least stable elements as you'd expect. As that happens pockets of dense matter in close neutron proximity will approach critical and heat billions of tons of matter which then convects outwards, dispersing the mixture. Think of a lava lamp.
  - pencilguin 4y ago
    Geochemists say uranium concentrates in the crust, for chemical reasons -- which is, in fact, where we find it.

pas 4y ago

are there estimates for how much heat is produced this way? any other way? (solar magnetic field interaction?) how much is the residual heat dissipation? edit: ah, just read the title of the link posted in the top level comment. apparently it's "half of the heat" :)

yummypaint 4y ago

Yes. Alpha decay in particular is also the source of essentially all helium on earth, and the reason helium is captured from gas wells.