When Scott was showing the flowchart for the process for making Plutonium in a reactor, it reminded me of your channel, Cody... and here you are! What a coincidence!
My favourite factoid about the Trinity test is that after the war they released photos of the test...which included a time stamp and distance scale. A physicist named G.I. Taylor (who had worked on the manhatten project) used those images, with a spot of dimensional analysis, and published papers wherein he calculated (to a remarkable degree of accuracy) what the explosive yield of the device was. He got in a little bit of trouble for this, as the number he'd worked out was very classified...but when it was discovered that he was able to work this out from information that was in the public domain, he was let off, and an important lesson was learnt about never underestimating what a clever person will do with information.
A scientist (It may have been Fermi) calculated the Trinity yield by throwing bits off paper into the air, and measuring how far they traveled as the shock wave passed. I think this method predicted a yield of 20 kilotons.
In later years, we used a surprisingly simple method to get a first-order approximation of a weapon's actual yield during a test. Remember those smoke trails you always see next to the mushroom cloud? Those were left by rockets, and were at known points perpendicular to the camera's line of sight. By watching high-speed footage of the test frame-by-frame, the visible disruption of those smoke trails from atmospheric lensing would allow them to track the passage of the shock front... and by calculating the speed at which it was going (from distance between trails and number of frames it took to go that distance), they could get a fairly close estimate of how big a boom they actually got.
This lesson was promptly forgotten by President Trump when he tweeted out classified images of an Iranian launch failure taken by a KH-11 satellite. Scott’s video on the subject uses the publicly known information of the KH-11’s imaging sensor to determine the exact orbit of the spacecraft, allowing the tracking number of that specific satellite to be determined.
Nah; this is all "open source" stuff at this point. The only limiting factor in making nuclear weapons is not information; it's acquiring or creating the materials. The "information" cat got out of the bag 60-odd years ago, and there's no putting it back. What he's discussing is stuff that kids learn in college these days, at least those who take nuclear physics courses.
yeah ... think of it what you want but some technology had to be invented from scratch to make the manhattan project a reality and others were advanced by decades.
In the video at the end, you can see a few of these engineers (actually nuclear scientists): Feynman on the left (no shirt, slight belly), Oppenheimer (slim man with the hat) who was the director of the program. The others I didn't recognize. I wonder who the guy with a pen on his ear is.
Really? I don't understand any of them. And I lived with a scientist who did his doctoral thesis on the third way they make these. They use photon energy; he did his thesis on photons. That's all I know. I couldn't even read the first page of his paper, which was over 200 pages long. I didn't understand the first page. Math & Science were my weakest subjects. Language was supposed to be my strength but you'd never guess it now. I've been trying to learn German for 5 months. Not going well at all.
X-ray photons are used to detonate secondary fusion stage in thermonuclear (hydrogen) bombs! Your roommate could have been the hydrogen bomb scientist, really... Of course no lamp can do it, those photons are produced by regular (or boosted) fission nuclear bomb=)
An underappreciated British contribution to the Manhattan Project, quite apart from the Frisch/Peierls Memorandum that kicked the whole thing off. The American experimenters were getting nowhere with implosion until a) Jeff Taylor showed them the way they were going wouldn't work and b) James Tuck told them about his work with shaped charges.
I'll fill in what Scott left out after the 8 min mark. Detonation wave profiles take the form of a leading edge pressure spike followed by a region of rarefaction. The shock reflection that would occur at the Al/U interface would produce a higher pressure behind the shock front, minimising the rarefaction that occurred behind the shock front, thus maintaining pressure for a good distance behind it, and thus allowing for the entirety of the core to be compressed to a higher degree, rather than the material that was just behind the shock front at that period of time.
Taleric1 "Oh, I'll just hold these two halves of a reflector over a plutonium core juuuuust barely apart with a screwdriver.... *screwdriver slips and both halves cover the core* Oh damn... *radiation intensifies* Hm, well, fuck."
There wasn't a standard operating procedure at the time, but safety was an issue (since there were two instances where people screwing around with the Demon Core lead to fatalities.
I worked on submarine nuclear reactors when I was in the US navy and these videos cover most of the material taught pretty well, I’d love to see many more videos like this, I would definitely watch a series about shock dynamics
Early on in the project, Fermi's joke/slight speculation about the bomb possibly igniting the atmosphere was a serious concern. They did a lot of calculations on that and concluded it was PROBABLY not possible. Nobody was 100% certain going in to the Trinity test, just mostly pretty sure, maybe 99% it wasn't going to be a thing.
The entire 20th century is truly a technological golden age. The rate at which we progressed from crude planes that flew a few hundred yards to ubiquitous home computers and thousands of artificial satellites is staggering. Player pianos to 3D accelerated video games.
The two horrific world wars and the tense stand-off between two nations that could have ended life as we knew it likely helped accelerate that, somewhat.
Thanks, chilling stuff. I grew up in the cold war and we were warned about 6 minutes before explosion. Hope those days are gone forever. Thanks for your very professional presentation.
We as a species didn't know about radioactivity until the late 1800's. not even half a century later we figured all this out. Will always boggle my mind. Smart people? Alien tech? Amazing stuff that 99.9% of the population doesn't think about.. Amazing explanation/simplification Mr. Manely!
I've watched/read a lot of stuff about the Manhattan project and nuclear bombs/energy, and so far there have been new info for me in each of your videos. I love how you explain the details instead of just glancing over them.
Have you read the Nuclearsecrecy blog, by the creator of Nukemap? That goes into a lot more detail than anything else I have read. Stuff like how a lot of the energy of an H bomb actually comes from fission.
Reactors make plutonium as a by product the a goal for plutonium is more cheaper easier bombs that is the point of of going ror plutonium. Enriched uranium even at low none weapons grade is a problem because with that you can make reactors and the reactors will make your easy bomb material plutonium the ignition timing for the explosives is tricky but only down to nanosecond tolerances easily within the capability of switching diode available for purchase through digikey not that big a deal to set up if you have a 100 mhz scope and can read the graticule.
I love the way you expect everyone is following along! In this episode I was fascinated to learn about the U238 tamper. It's amazing to think that U238 actually accounted for as much as 20% of the total yield of the Fat Man
After 4 years, a question I've had about why gun type isn't more widespread today is finally answered, and with 2 good reasons instead of 1 half-arsed answer. Thank you very much Scott!
It´s hard to wait till you get to Castle Bravo and fusion. I love this series. Do you already know where you will stop are do you go up to the point where you´ll talk about Tokamaks Stellators and the National Ignition Facility?
I know that I need at least 3 more parts covering 1) Improving implosion devices (hollow cores, fission boosting, etc) 2) Thermonuclear 3) Enriching Uranium & Manufacturing Plutonium.
Sounds cool. maybe if yoou have time and Ask nice the people at the NIF may give you a tour for the Video. but these three Parts are already a good thing to look foward to. But it´s always a problem of time and Space and all that inside a curvey Spacetime. Sometimes I wish we would have Tardisses or what ever the plural of TARDIS is.
and after that there is gen 4 nuclear weapons too : antimatter initiated fusion weapons; which can theoretically be minimized to a *much* smaller scale .
And while we're at it, you can go off a tangent and use 'Plutonium production' as a subject to cover nuclear power reactors, the various types of that, notable incidents, and planned future nuclear power generation?
8:18 Engineering shockwave interference patterns using pencil, paper, and slide-rules (not super-computers or even calculators) deserves it's own video. Damn, those were some geniuses. How did they even measure explosive speeds nearly 5 miles per second to the necessary accuracies needed without computers? As destructive (and controversial) as Hiroshima and Nagasaki were, no one can deny the shear brilliance of the human mind.
The implosion reminds me of neutron star formation. A huge collapse crushing the center down with huge pressure. Of course, implosion only crushes the pit down to about half it size vs neutron stars whose collapse crushes the stars core down ~idk ...10,000 times as the electron degeneracy pressure is overcome and atoms collapse into just the nucleus ...or neutrons. Love your video's Scott !
Shaped Charges are the Coolest Thing I ever Learned About! Especially with the Copper Plate Penetrator. The Explosive Shock Wave propagates from Point of Ignition and when it reaches the Lens, it Focuses into a Point Source. This was used in the Oklahoma City Attack.
Excellent Video! I appreciate you taking the time to educate us on this matter. This also puts into perspective how intelligent the people involved in the Manhattan project were.
If I try to estimate the number of spontaneous fissions, I use this logic: - remaining quantity Q(t) = Q(0) exp(kt) where k = ln(0.5)/t_half - decays per second = -Q(0) k exp (kt) = ln(2)Q(t)/t_half - spontaneous fissions per second = Q(t) * P * ln(2)/t_half Using the table at 2:53, converting the half live periods to seconds, and setting Q(t) to Avogadro's number, I get these figures for the *Number of fissions per mole per second* : For Pu-240: 6.0E23 * 5.0E-6 * ln(2)/5.0E18 = 0.42 For Pu-239: 6.0E23 * 4.4E-10 * ln(2)/1.7E23 = 1.1E-9 Even with a pit of 6 kg (25 moles) consisting of 80% Pu239 and 20% Pu-240 I cannot see how more than about 2 spontaneous fission per second would occur, so from this b-o-t-e-calculation I would say that 1 millisecond would be quick enough in 99.8% of the cases, and from these data I don't see how timescales of microseconds are so crucial to prevent predetonation. Anyone?
Great videos. You're doing an impressive job explaining a lot of these complex technical concepts and making them understandable for most folks. Looking forward to the rest of the series. If you're feeling really confident at explaining difficult to comprehend subjects, how about one on how anyone can think MAD is such a great idea, which is inexplicable to me and a lot of others who think it's simply insane.
Fermi also suspected that the electromagnetic pulse from the Trinity explosion would destroy measuring instruments, so they were shielded. Despite the effort a significant number were destroyed. Someone must have been taking notes because it led to experiments like Starfish Prime, and the Soviet K bomb (EMP) test.
I'm not going to question why my entire recommended list is full of radioactive material. This video was on the recommended list anyways so I might as well watch this.
The Earth I'm no nuclear physicist, but my understanding is that the heat and pressure created by the fission causes the hydrogen nuclei in the plasma to near the speed of light, allowing colisions that produce fusion and a crap-ton of energy.
it's worth noting 'fusion bombs' (technically thermonuclear bombs) produce so much energy by combining the forces of fusion and fission. A great deal of their energy is still fission based.
First time I've seen photo of implosion test result on metal cylinder. Fascinating! After decades of gobbling up data on nuclear weapons, I must say you have demonstrated very fine knowledge of the process in an excellent video. I learned some new things here, like the complexity of the "urchin" neutron initiator. Now, how did they print such a modern looking, stick on label on that first 2.5 micro gram of PU239 sample? Do you have any photos of the inside of the gaseous diffusion plant at Oak Ridge, during its operation? I'm always stunned by what that plant accomplished, and how fast it was built. Thank you.
Oh, cool. One of my favorite novels is The Sum of All Fears by Tom Clancy. There's an entire chapter dedicated to a description of everything that happens inside a hydrogen bomb as it detonates. The one part that I never really understood was the bit about explosive lenses, but now it makes sense.
Really appreciate your intelligent, concise, and engaging videos. Well done Mr Manley! For those who appreciate a good read and are interested in learning more about the history of nuclear weapons: The Manhattan Project by Richard Rhodes Dark Sun, again by Richard Rhodes Stalin And The Bomb by David Holloway US Nuclear Weapons: A secret History by Chuck Hansen (long out of print
Kommander Manley, thank so much for these videos. I have no doubt that these take many hours of research, scripting and editing. -- A fellow Physicist.
Scott: "warning do not stare at nuclear explosions (unless you know what you're doing, like Feynmann did)" me: guess that mean i cant look at the one in back garden
Wow much details in this. I'm first time hear about construction of the neutron generator in this video i was thinking that is classified information :D Great job Scott, fly safe or better fission safe :)
Hi Scott, Longtime KSP watcher here. I want to say you'r HSB t-shirt is great. When I lived in SF I loved that festival. Keep up the great work and hope to see you in GGP some day!
Scott, @11:54 a dark skinned man with cornrows appears with his back to the camera. This is monumental and demonstrates the inclusive nature of the project. Single focus on the mission. This man needs to be identified and brought out of the shadows of history.
What?? Your brainwashed, seeing afro diversity that isn't there. Those Scientists stole idea from Wokanda. Thats a skinny jewish guy, there the diversity.
Great piece. Scott, did you know that the massive pressure, during an atmospheric detonation, centered on the pit is sufficient to create opaque air for a very short period until the explosion expands and releases light. Hence the double flash that satellite sensors look for.
Watching Oppenheimer the other day I thought it was funny how they placed the last section of explosive lens like it was made of styrofoam. They just picked it up and gently fitted it into the opening and let it down slowly with the tips of their fingers.
11:55 "Saturdays are for assembling nuclear weapons with the boys" legitimately, though, this looks a lot like me and my friends working in dropping an engine into their Jeep.
Hi Scott, Thank you for being such a Great Teacher! I only studied naval reactors. Your explanations are easy to follow and my knowledge base was able to follow you. 👍
FYI. Fermi was not joking. His numbers showed there was a scenario that said the bomb could ignite the atmosphere. I have heard this before and I can tell you that why he believes the probability was low, some calculations indicated this could have occurred. Love your series and thanks for not getting overly detailed especially with the timing plugs and other things I won’t get into here. Very good job!
Scott Manley Well, my grandfather worked with Fermi. He claimed he wasn’t joking, at least initially. He was very concerned. However, all that is neither here nor there. The fact is you are doing an excellent job on these videos! Appreciate you keeping these great men’s memory alive.
Story about one of my old climbing partners When [my partner] arrived at Los Alamos, his supervisor handed him a pea-size chunk of dull grayish metal and said, This is the world's supply of plutonium. I m going to lunch; please brief me on its metallurgical properties when I get back. [He] pondered his task, then put the pellet on an anvil and smacked it with a hammer, and later reported to his supervisor that it was malleable. As he recounted later, fortunately it was very impure plutonium; otherwise it would have pulverized and contaminated the entire building. That's just one of his after dinner tales about being on the cutting edge.
This april 1 I went to Trinity site as well as the large radio telescope array in New Mexico. Worth the visit. Only can go to trinity site twice a year so plan accordingly.
It is interesting that pictures of 'thin man' always show a large number of casings as if to anticipate its mass production or at least testing. It shows that initially this was the horse scientists were betting on until they realized the flaw of the design.
The shape charges sound similar to what General Fusion is trying to do, where a bunch of pistons spherically compress a liquid metal tank with plasma in the middle to achieve fusion.. hopefully.
Excellent video with great detail all the way through. I have to say, this is my favorite nerd-fest channel for science related topics. I have been subbed for years now as I remember when your vid popped up on your trek to Oregon for the 2017 eclipse. Funny thing is I invited my wife and friends to accompany me on that "Once in a lifetime chance" to simply drive to where the total eclipse will happen, but no one understood how cool this was going to be. In my case I drove from Victoria, BC, to Madras Oregon and I ended up with my younger brother joining me for that trip as he knew what this really was. I tried to explain to my friends that people travel all around the world to witness this. I was talking about going camping over a long weekend.
My dad turned 19 on his way across the Pacific on 7/16/45, the day the gadget was tested. On 8/9/45, a destroyer sailing next to his was hit by a kamikaze, the day the real thing exploded over Nagasaki.
