4 ms·

Ice-nine? Update: I originally wrote ice-9, which it turns out is ambiguous. I meant the one from Cat's Cradle. https://en.wikipedia.org/wiki/Cat%27s_Cradle

Ice-nine? Update: I originally wrote ice-9, which it turns out is ambiguous. I meant the one from Cat's Cradle. https://en.wikipedia.org/wiki/Cat%27s_Cradle https://en.wikipedia.org/wiki/Cat%27s_Cradle

robbedpeter 5y ago
Ice 18 - ice 9 irl is boring, unfortunately.
mint2 5y ago
It’s funny that scientists actually thought an ice nine type situation had a minuscule but non-zero chance of occurring when they set off the first nuclear bomb: the entire atmosphere would ignite.
- pfdietz 5y ago
  No, they didn't. They did calculations showing it was impossible, even with very generous assumptions of cross sections and physical processes (like cooling of the plasma by radiation). They would not have done the test if there was any chance that could have happened.
  - aYsY4dDQ2NrcNzA 5y ago
    I was with you until that last sentence.
    - mint2 5y ago
      Here’s a bbc article that inspired my comment. That other response comment was wrong from the start. https://www.bbc.com/future/article/20210217-the-moments-that-we-could-have-destroyed-humanity https://www.bbc.com/future/article/20210217-the-moments-that...
  - throwdecro 5y ago
    NOTE: I am not a physicist. > They did calculations showing it was impossible Doesn't mean they couldn't have been surprised by something their calculations didn't take into account. The yield for the Castle Bravo test in the 1950s was 2.5 times what was predicted [0], because some things they didn't take into account turned out to be important (namely that some of the material in the construction of the device would serve as additional fuel to the explosion). For the first nuclear explosion in 1945, they were initiating an incredibly powerful chain reaction for the first time on Earth. To some extent you just gotta cross your fingers and hope that the chain reaction stops according to your predictions, because you don't know what the "unknown unknowns" are until you try it. The combination of "chain reaction" and "unknown unknowns" is frightening. [0] https://en.wikipedia.org/wiki/Castle_Bravo https://en.wikipedia.org/wiki/Castle_Bravo
  - mint2 5y ago
    Yes they did. See the linked article below. Note I said minuscule chance. That would be at the moment of detonating the bomb. If the assessment was earlier, the fact that they had to run calculations proves they considered it as a possibility. It’s a strong claim to say they proved it couldn’t happen when they didn’t even know the bomb would work for sure. I’m sure the bbc is hamming it up a bit, but the account of the scientist who freaked out when the bomb worked seems credible. https://www.bbc.com/future/article/20210217-the-moments-that-we-could-have-destroyed-humanity https://www.bbc.com/future/article/20210217-the-moments-that... There, a source to back up the original statement. Got one that disproves it? Some scientists believed it was a minuscule possibility at the time of the test, others didn’t believe it would happen. What was wrong about that statement?
    - eesmith 5y ago
      Your source disproves it. That is, the BBC article links to https://sgp.fas.org/othergov/doe/lanl/docs1/00329010.pdf https://sgp.fas.org/othergov/doe/lanl/docs1/00329010.pdf which says: > It is shown that, whatever the temperature to which a section of the atmosphere may be heated, no self-propogating chain of nuclear reactions is likely to be started. The energy losses to radiation always overcompensate the gains due to the reactions. It then goes on to point out that if considerably more powerful bombs (over 1,000 cubic meters in size) were exploded, then the energy losses to radiation isn't enough .. but that's okay because: > energy transfer from electrons to light quanta by Compton scattering will provide a further safety factor and will make a chain reaction in air impossible. That's about as definite as you can be that there would not be a possibility. Note also the comment "the policy should be adopted of exaggerating the dangers at any point which appears at all questionable." In the BBC article, "the scientist who freaked out" is the President of Harvard, right? From https://en.wikipedia.org/wiki/James_B._Conant https://en.wikipedia.org/wiki/James_B._Conant he was a noted PhD chemist who was the chair of the National Defense Research Committee and present as a dignitary. He does not appear to be someone who understood the physics involved. Additional, the BBC article quotes philosopher Toby Ord as saying "we were creating temperatures unprecedented in Earth's entire history". This is bunk. Meteor Crater in Arizona had an impact energy of ~10 megatons - https://en.wikipedia.org/wiki/Meteor_Crater https://en.wikipedia.org/wiki/Meteor_Crater . The Chicxulub meteor was about a billion times greater - https://en.wikipedia.org/wiki/Chicxulub_crater#Impact_specifics https://en.wikipedia.org/wiki/Chicxulub_crater#Impact_specif... . Now, this is total heat, and the quote says "temperature". (Earthquakes release a lot of energy but over a large area, so the temperature isn't hot.) Cosmic rays regularly hit the earth with much higher temperatures, like https://en.wikipedia.org/wiki/Oh-My-God_particle https://en.wikipedia.org/wiki/Oh-My-God_particle . > there also was no evidence that any elected representative was told about the risk Conant clearly had heard about this risk consideration. Why didn't he tell Roosevelt? Perhaps because no one thought it had even a minuscule chance of being possible?

robbedpeter 5y ago

Ice 18 - ice 9 irl is boring, unfortunately.

mint2 5y ago

It’s funny that scientists actually thought an ice nine type situation had a minuscule but non-zero chance of occurring when they set off the first nuclear bomb: the entire atmosphere would ignite.

pfdietz 5y ago
No, they didn't. They did calculations showing it was impossible, even with very generous assumptions of cross sections and physical processes (like cooling of the plasma by radiation). They would not have done the test if there was any chance that could have happened.
- aYsY4dDQ2NrcNzA 5y ago
  I was with you until that last sentence.
  - mint2 5y ago
    Here’s a bbc article that inspired my comment. That other response comment was wrong from the start. https://www.bbc.com/future/article/20210217-the-moments-that-we-could-have-destroyed-humanity https://www.bbc.com/future/article/20210217-the-moments-that...
- throwdecro 5y ago
  NOTE: I am not a physicist. > They did calculations showing it was impossible Doesn't mean they couldn't have been surprised by something their calculations didn't take into account. The yield for the Castle Bravo test in the 1950s was 2.5 times what was predicted [0], because some things they didn't take into account turned out to be important (namely that some of the material in the construction of the device would serve as additional fuel to the explosion). For the first nuclear explosion in 1945, they were initiating an incredibly powerful chain reaction for the first time on Earth. To some extent you just gotta cross your fingers and hope that the chain reaction stops according to your predictions, because you don't know what the "unknown unknowns" are until you try it. The combination of "chain reaction" and "unknown unknowns" is frightening. [0] https://en.wikipedia.org/wiki/Castle_Bravo https://en.wikipedia.org/wiki/Castle_Bravo
- mint2 5y ago
  Yes they did. See the linked article below. Note I said minuscule chance. That would be at the moment of detonating the bomb. If the assessment was earlier, the fact that they had to run calculations proves they considered it as a possibility. It’s a strong claim to say they proved it couldn’t happen when they didn’t even know the bomb would work for sure. I’m sure the bbc is hamming it up a bit, but the account of the scientist who freaked out when the bomb worked seems credible. https://www.bbc.com/future/article/20210217-the-moments-that-we-could-have-destroyed-humanity https://www.bbc.com/future/article/20210217-the-moments-that... There, a source to back up the original statement. Got one that disproves it? Some scientists believed it was a minuscule possibility at the time of the test, others didn’t believe it would happen. What was wrong about that statement?
  - eesmith 5y ago
    Your source disproves it. That is, the BBC article links to https://sgp.fas.org/othergov/doe/lanl/docs1/00329010.pdf https://sgp.fas.org/othergov/doe/lanl/docs1/00329010.pdf which says: > It is shown that, whatever the temperature to which a section of the atmosphere may be heated, no self-propogating chain of nuclear reactions is likely to be started. The energy losses to radiation always overcompensate the gains due to the reactions. It then goes on to point out that if considerably more powerful bombs (over 1,000 cubic meters in size) were exploded, then the energy losses to radiation isn't enough .. but that's okay because: > energy transfer from electrons to light quanta by Compton scattering will provide a further safety factor and will make a chain reaction in air impossible. That's about as definite as you can be that there would not be a possibility. Note also the comment "the policy should be adopted of exaggerating the dangers at any point which appears at all questionable." In the BBC article, "the scientist who freaked out" is the President of Harvard, right? From https://en.wikipedia.org/wiki/James_B._Conant https://en.wikipedia.org/wiki/James_B._Conant he was a noted PhD chemist who was the chair of the National Defense Research Committee and present as a dignitary. He does not appear to be someone who understood the physics involved. Additional, the BBC article quotes philosopher Toby Ord as saying "we were creating temperatures unprecedented in Earth's entire history". This is bunk. Meteor Crater in Arizona had an impact energy of ~10 megatons - https://en.wikipedia.org/wiki/Meteor_Crater https://en.wikipedia.org/wiki/Meteor_Crater . The Chicxulub meteor was about a billion times greater - https://en.wikipedia.org/wiki/Chicxulub_crater#Impact_specifics https://en.wikipedia.org/wiki/Chicxulub_crater#Impact_specif... . Now, this is total heat, and the quote says "temperature". (Earthquakes release a lot of energy but over a large area, so the temperature isn't hot.) Cosmic rays regularly hit the earth with much higher temperatures, like https://en.wikipedia.org/wiki/Oh-My-God_particle https://en.wikipedia.org/wiki/Oh-My-God_particle . > there also was no evidence that any elected representative was told about the risk Conant clearly had heard about this risk consideration. Why didn't he tell Roosevelt? Perhaps because no one thought it had even a minuscule chance of being possible?