Oppenheimer's Apocalypse Math

References

Welch Labs

[jhonbus]

The fact the calculation starts with the assumption that every collision between nitrogen nuclei results in a fusion tells you exactly what you need to know about the actual possibility of this scenario occurring.
This wasn't a serious concern after this calculation was done. It's a kind of "Is this vaguely plausible even given the worst possible case?" and the answer was no.

[MomirViggwilv]

It's kind of reassuring, actually, to know just how much effort scientists put on calculating the potential remifications of their experiments.

[JayKayKay]

The version I like best is during the first test in New Mexico, someone asked, "Are we going to set fire to the Earth's atmosphere?
Enrico Fermi whips out a slide rule, does some quick calculations, puts the slide rule away, turns to the original questioner, and states flatly, "Probably not."

[beehard]

how is this video only 5 minutes long? So much material presented concisely yet beautifully, it feels like I got more than 5 minutes' worth

[Psyopcyclops]

This 5 minute video felt like 15 minutes of information, and was still perfect. I love when a creator tries to make their videos succinct yet engaging enough to not feel short.

[lakshaymd]

Never knew that this was a possibility they were discussing. Wild to think about. Of course, if it is the first bomb of its kind, there might be consequences that no one has thought about. Terrifying.

[gorpand]

Would have been a perfect experiment for Mythbusters - first busting the myth and then creating conditions and seeing what does it take to make it work.

[danielferrell]

“Edward (Teller) brought up the notorious question of igniting the atmosphere. Bethe went off in his usual way, put in the numbers, and showed that it couldn’t happen. It was a question that had to be answered, but it never was anything, it was a question only for a few hours. Oppy made the big mistake of mentioning it on the telephone in a conversation with Arthur Compton. Compton didn’t have enough sense to shut up about it. It somehow got into a document that went to Washington. So every once in a while after that, someone happened to notice it, and then back down the ladder came the question, and the thing never was laid to rest” - Robert Serber

[DanOC]

The y axis is logarithmic; the scale looks close but it's really quite distant

[dwurry]

Please note that the graph in this video is logarithmic. This makes the lines appear to be converging when they actually are diverging. The more extreme the temperature gets, the further they diverge. The appearance of these lines become closer together because logarithmic graphs hide exponential growth by design! If you displayed thins information the bottom line would bearly come off the bottom of the graph and you would see zero (or near zero relationship between them. At 12 MeV (right side of graph) value of the green line at the end of the graph is 1, 500, 000 while the red line is 4, 000, 000. At 6 MeV the values are 700, 000 and 2, 000, 000. So at 6MeV the values are 1, 300, 000 apart while at 12 they are 2, 500, 000 (almost twice as far apart). *Like all good physics my characteristics of values of lines are estimates.

This is a great example of "how to lie with statistics". Want to make two things appear to converge? Use logarithmic charts.

[MrAntiKnowledge]

Holy fuck. The stuff about igniting the atmosphere has been brought up a couple times in sci-fi.
And I always thought it's a bit far fetched since the atmosphere can't "burn" on its own, being mostly nitrogen and oxygen.
It never clicked until now that it meant a fusion chain reaction.

Luckily for us that it isn't that easy to keep a fusion reaction going, I guess.

[icybrain]

I think it's also worth pointing out that your perception of a small margin of safety may be a bit skewed if you don't take into account that you're looking at a logarithmic scale on the y-axis

[Howtheheckarehandleswit]

I think a very important point that is often not made clear, is that the phrase "igniting the atmosphere" does not mean "setting the atmosphere on fire". In the context of nuclear physics, "ignition" refers to starting a self-sustaining fusion reaction. To "ignite the atmosphere" in this context means to cause the entire atmosphere to momentarily behave like the core of a star.

[dannymartial]

I like how in the movie, Einstein said that if they DID conclude that atmospheric ignition was a possibility, then the next step would be to release the information publicly, especially to the Nazis and they’d all agree not to use any nukes. The thinking being no matter how evil the other side of the war is, no one would risk human extinction.

[lidarman]

One of the best lines in the movie was "What do you expect from theory alone?!" -Oppenheimer (Movie version). A running joke in my quantum mechanics class and education was "In theory, there is a small, but very small, chance you could tunnel through the door instead of opening it."

[LeftyScaevola]

Everything after "worst case scenario" for the probability of nitrogen fusion was essentially academic, since that assumption was WAY higher the the actual probability of nitrogen fusion, and with an actual figure there, the energy produce and and lost curves would be very far apart.

[guesswho]

The physics and mathematics of the Manhattan Project are absolutely stunning. It makes for such a crazy juxtaposition with what they were working towards.

[tanchienhao]

Thanks for covering this part of the movie! Your series came out just at the right time for Oppenheimer movie release!

[Ka-zlfi]

This video is everything I wish the rest of YouTube was - your delivery is so succinct and concise - really well made I loved it

[sumthnunreal]

I mean, if the whole atmosphere turned into plasma, I'm pretty sure that would end the war in an instant.