4 ms·

Potassium-40 decay is also one of the largest sources of geothermal heat [0]. The cumulative energy released is within two orders of magnitude of the Earth's gr

Potassium-40 decay is also one of the largest sources of geothermal heat [0]. The cumulative energy released is within two orders of magnitude of the Earth's gravitational binding energy. [0] https://en.wikipedia.org/wiki/Earth's_internal_heat_budget#Radiogenic_heat https://en.wikipedia.org/wiki/Earth's_internal_heat_budget#R...

dredmorbius 5y ago
TIL! Though I've got ... questions and concerns about how certain we are that there's no large-scale heavy-element fission occurring within the Earth's core. I'd think that within the nickel-iron core, one might find even heavier elements, that those would have sunk through the primordeal (and one presumes, not-yet solid) inner core, and would tend to have greater radioactivity. How to demonstrate this does seem something of a challenge. Decay products and/or neutrino flux, possibly?
- perihelions 5y ago
  Neutrino observatories have ruled it out (for meaningfully large aggregate power levels). - "...hypothetical georeactor at the center of the Earth having power greater than 2.4 TW at 95% C.L. is excluded" https://arxiv.org/abs/1909.02257 https://arxiv.org/abs/1909.02257 (That physics paper counts more coauthors than neutrinos!)
  - dredmorbius 5y ago
    > That physics paper counts more coauthors than neutrinos. And that's even before enabling Javascript. (Javascript-enabled neutrinos will be a key feature of Web 6.0.) (Oh, and thanks!) Questions: - How'd you find this? I'm suspecting something like "earth's core reactor neutrinos". - I don't even know how to read/interpret the notation used to express neutrino counts. Though if we can divide 112 co-authors (including deceased) by annual detection rates we can come up with a neutrino-seconds equivalent of authors....
    - dredmorbius 5y ago
      From another source --- it looks as if the detector was picking up 2 neutrino events per month. So yes, authors > neutrinos. (That's a ... really low detection rate.)
devoutsalsa 5y ago
How’d they get so many bananas down there?
owenversteeg 5y ago
Interesting, for the curious that's ~10 terawatts of Th-232, ~9 TW of U-238, ~4 TW of K-40 and ~1 TW of U-235. Plus about 5-15 TW of primordial heat left from the earth still cooling down from when everything got real hot about 4.5B years ago. I like the "New York's worth of bananas" unit (3e17 bananas), doing some back of the envelope math apparently if everyone ate one a year for 80 years we could significantly slow climate change [0] [1] [2] [3] [4]. [0] World electricity usage was apparently 23,900 terawatt-hours in 2019, which works to a constant 2.73 TW. If we can eliminate the mantle heat from K-40 that's 4 TW out of the way which would be lovely. [1] ~4.9e17 kg total K-40 in the mantle, so if every human dedicated themselves to eating them in a human lifetime of 80 years would take 4.9e17 kg K-40 * 1 banana/3.9e-9 kg K-40 /7.9 billion people/80 years = 1.9e17 bananas per person per year or 6.1e9 bananas per second, (very) roughly about one New York's worth of bananas per year, what's a couple tens of quadrillions of bananas between friends anyway. [2] If you somehow vaporized the K-40 content of the bananas as you ate them. [3] And managed to concentrate potassium directly from the earth's mantle into bananas. [4] I have no choice but to note that this whole idea would be... Bananas. I'm sorry.
- perihelions 5y ago
  You're confusing technological energy production (~10^13 W) with climate heating, which is two orders of magnitude larger (~10^15 W). The heat released from burning carbon fuels isn't significant. The modulating effect of the CO2 released on radiative heat transfer is far more powerful. Like a weak current driving a high-gain amplifier. https://en.wikipedia.org/wiki/Earth's_energy_budget#Earth's_energy_imbalance https://en.wikipedia.org/wiki/Earth's_energy_budget#Earth's_...
  - owenversteeg 5y ago
    Ah, so I did! A classic mistake. Thanks.

dredmorbius 5y ago

TIL! Though I've got ... questions and concerns about how certain we are that there's no large-scale heavy-element fission occurring within the Earth's core. I'd think that within the nickel-iron core, one might find even heavier elements, that those would have sunk through the primordeal (and one presumes, not-yet solid) inner core, and would tend to have greater radioactivity. How to demonstrate this does seem something of a challenge. Decay products and/or neutrino flux, possibly?

perihelions 5y ago
Neutrino observatories have ruled it out (for meaningfully large aggregate power levels). - "...hypothetical georeactor at the center of the Earth having power greater than 2.4 TW at 95% C.L. is excluded" https://arxiv.org/abs/1909.02257 https://arxiv.org/abs/1909.02257 (That physics paper counts more coauthors than neutrinos!)
- dredmorbius 5y ago
  > That physics paper counts more coauthors than neutrinos. And that's even before enabling Javascript. (Javascript-enabled neutrinos will be a key feature of Web 6.0.) (Oh, and thanks!) Questions: - How'd you find this? I'm suspecting something like "earth's core reactor neutrinos". - I don't even know how to read/interpret the notation used to express neutrino counts. Though if we can divide 112 co-authors (including deceased) by annual detection rates we can come up with a neutrino-seconds equivalent of authors....
  - dredmorbius 5y ago
    From another source --- it looks as if the detector was picking up 2 neutrino events per month. So yes, authors > neutrinos. (That's a ... really low detection rate.)

devoutsalsa 5y ago

How’d they get so many bananas down there?

owenversteeg 5y ago

Interesting, for the curious that's ~10 terawatts of Th-232, ~9 TW of U-238, ~4 TW of K-40 and ~1 TW of U-235. Plus about 5-15 TW of primordial heat left from the earth still cooling down from when everything got real hot about 4.5B years ago. I like the "New York's worth of bananas" unit (3e17 bananas), doing some back of the envelope math apparently if everyone ate one a year for 80 years we could significantly slow climate change [0] [1] [2] [3] [4]. [0] World electricity usage was apparently 23,900 terawatt-hours in 2019, which works to a constant 2.73 TW. If we can eliminate the mantle heat from K-40 that's 4 TW out of the way which would be lovely. [1] ~4.9e17 kg total K-40 in the mantle, so if every human dedicated themselves to eating them in a human lifetime of 80 years would take 4.9e17 kg K-40 * 1 banana/3.9e-9 kg K-40 /7.9 billion people/80 years = 1.9e17 bananas per person per year or 6.1e9 bananas per second, (very) roughly about one New York's worth of bananas per year, what's a couple tens of quadrillions of bananas between friends anyway. [2] If you somehow vaporized the K-40 content of the bananas as you ate them. [3] And managed to concentrate potassium directly from the earth's mantle into bananas. [4] I have no choice but to note that this whole idea would be... Bananas. I'm sorry.

perihelions 5y ago
You're confusing technological energy production (~10^13 W) with climate heating, which is two orders of magnitude larger (~10^15 W). The heat released from burning carbon fuels isn't significant. The modulating effect of the CO2 released on radiative heat transfer is far more powerful. Like a weak current driving a high-gain amplifier. https://en.wikipedia.org/wiki/Earth's_energy_budget#Earth's_energy_imbalance https://en.wikipedia.org/wiki/Earth's_energy_budget#Earth's_...
- owenversteeg 5y ago
  Ah, so I did! A classic mistake. Thanks.