How were the Manhattan Project scientists able to predict the possibility of the atmosphere igniting after using an atomic bomb, and how did they come to the conclusion that the atmosphere wouldn’t ignite?

Question

Did the non-zero risk of the atmosphere igniting increase as nuclear weapon yields got larger and larger?

Obviously a result of watching Oppenheimer.

In: 789

Answer 1

Earth-like atmospheres don’t ignite, or wildfires would wreak havoc on a global scale every time they happened.

And on a nuclear-level, any nuclear explosion that could cause a chain reaction in Earth-like atmospheres would be so powerful you wouldn’t be able to use it even on your enemy on the other side of the world without direct damage to yourself (and the atmosphere would be quite a minor issue at that point).

They invented the thing using maths/physics, and to work out the possibilities they used maths/physics, like people do every single day somewhere in the world. They also tested small-scale dozens of times to confirm their numbers were correct and any major difference would have sent them back to their chalkboards.

These people were designing never-before-seen weapons. They weren’t idiots. Quite the opposite. Whether you agree with their purpose or not, they were geniuses to even work out it was possible in the first place, so running some fanciful numbers on a par with “if you move on a train over 30mph, you’ll suffocate because the oxygen will be stripped away” (another “belief” held by many people until someone did the maths/physics/engineering and then laughed at the entire principle and built a machine capable of that speed to prove it) was basically a doodle in the margin in comparison.