Oppenheimer's Apocalypse Math

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

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.

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."

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.

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.

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.

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

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.

“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

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

"Ferb, I know what we're gonna do today!"

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.

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.

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.

The movie itself left so many of us questioning Nolan's decision to leave out such vital pieces to the remarkable work. The innerworld-building aspects, the highlights of the science itself. The math, the problems, the solutions, the designs, the inner structures of work at Los Alamos. No montage, no groundbreaking research, no frame of view. It's an absolute must in biopics/historical filmmaking. Take a scene in Scorcese's Casino: "The dealers watch the players, the floormen watch the dealers, the pit bosses watch the floormen, and..." while seamlessly keying the audience in to the systems in place. From the beginning to end, the big picture is answered by the little things with balanced structure, screenplay, and dialogue. This is done in Goodfellas and Wolf of Wall Street flawlessly as well. For these specifically, they simplify and engage us with timeline, complexity, shock, and gratification. Nolan crushed this aspect in Inception, The Prestige, The Dark Knight, and parts of so many others. Some less than others, and some more. Some like Catch Me if You Can by Spielberg, surround the entire plot in this notion: of world-building, a microscopic lens into the logic, steps, structure, and overall theme. While I'm not asking he remove the first third, and last third chapter of the film, by just giving us a decent 10-15 mins in each third, or a few montages per chapter; like the contributions of each bright scientist, the timeline of advance, the problems to overcome, the math itself, etc. – this would have done the trick and satisfied us all so much more. The communism and relationship stuff was far overdone. We could have gotten all of the themes and implications of each, from about 60% of that whole combined hour, fully replaced by scenes and clips surrounding better above decisions. These guys were the greatest scientists in the world, the brightest minds in history, among a revolutionary project of high level problem solving, mathematics, physics, chemistry, design, engineering, and fabrication. Let us in on that stuff— their determination, pursuit, and brilliance, but not in a bland, underwhelming general way (like with a single 2 second shot of the bomb construction)... All the impacts of the emotional struggle, success and turmoil, and mental struggle; the plot and theme itself, is enhanced so much further when we can grasp a better idea around: the back-end, the grit, the aptitude, the raw talent, structure and precision, etc. Let us in on THAT, not on sending me out of the theater, right to youtube, to find out how the bomb was assembled and engineered, or what brilliant math allowed that assembly to come to fruition. Even a taste of it! There was just warm alcohol for so much of the behind-the-scenes. So much of the film would have satisified us all so much better, had he highlighted these aspects with a purposeful zoomed in lens, then back and forth out into the big picture stuff.

2:57 the temperature unit of Kelvin is just Kelvin [K] not degree Kelvin [°K]

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.

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

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

I love your new set of videos. Great presentation and explanations! Keep up the good work!