Could a professor of college-level physics, or a Ph. D. student for that matter, come up with a functioning, independent design for a thermonuclear device? I presume the answer is no, but that begs the question: what is lacking in their education which would prevent this?
Thanks,
Rob
I seem to recall a project where some government agency hired a handful of “regular” physics? students with only? BS degrees to design a nuclear weapon. And they did a decent job IIRC.
Fancier and bigger hydrogen bomb are probaby a bit harder. I suspect there are some tricks that if you don’t know em will mean failure. Also, I don’t think it is so much that you need a PHD as much as you better also understand how real world engineering works. A bunch of fancy math and physics doesn’t really tell you all you need to know when it comes to designing or building something that works.
My money would be more on someone/some group that designs and builds stuff that can educate themselves enough on the science of this particular project.
Depends on what you mean by “design”. Come up with the basic principles involved with it? Almost certainly. You could probably get things like the amount of fissile material needed, the amount of conventional explosives, etc., too. But if you want to put together actual blueprints, such that technicians working according to those prints could put together something that’d work first try, you need engineers, not just scientists. The devil’s in the details.
The answer to that question is no. Nation states have put their best minds at the task, given them unlimited funds and resources and they still have come up short.
The difficulty is usually in obtaining the fissionable material, though, not in putting it together.
Except for in North Korea, of course, where the main difficulty seems to be just general all-around incompetence.
Step one: get some uranium.
If you assume unlimited resources, and funding; Sure.
The trick is to make one with what little you can actually get your hands on.
They weren’t even trying to make an H-bomb, just an implosion-type A-bomb, which is an order of magnitude easier task.
Once you have a functioning fission bomb, a fusion bomb is comparatively simple.
A competent physics professor could sketch out the design for both the fusion and fission bomb on the back of a cocktail napkin, and probably produce a reasonably correct detailed design after a few weeks of effort. Remember that the first two fission devices (of different, untested designs) worked on the first try in 1945, and the first two fusion devices (also two different, untested designs) also worked on the first try, in 1952.
Most of the money spent during the Manhattan Project and subsequently was not on the theoretical physics, it was on a massive engineering campaign to understand the properties of materials under these extreme conditions, as well as fabrication techniques, etc. Pretty much all of this crucial engineering information, required to actually implement a physicist’s design, is still classified, and can’t be independently derived without a similar expenditure.
I’ll throw this out too. Take a random and well rounded physics PHD. Assume he/she hasn’t had an special education regarding all things nuclear or read much regarding nuclear weapons design.
While I suspect they could get most things mostly right (and computations would be a buttload easier these days) for a nuke, much less a thermonuke/hydrogen bomb you gotta get all things much closer to right to have a good chance it will work.
So, unless that PHD person is allowed to do a bunch of book/internet learning regarding nukes in particular after having been given this task I’d wager there is a good chance some aspect and/or “trick” would elude them and it wouldn’t work/work very well.
And thats assuming the materials are given to them and a nice group of practical engineers are around to build workable stuff based in the details of the design that come from theory and calculations.
An aside. There is a material used in American bombs. It was called “fog”. Apparently our army of nuclear weapons people forgot the secret to making it a few years back. If those people forgot how to make it, what do you think the chances of some non nuke person figuring out how to make it in the first place?
Another factor: If you go up to any reasonably competent physicist, and ask him to do a calculation in some other area of physics, he can probably do it (probably consulting books along the way, but that’s no hardship). The trick, though, isn’t just in answering the questions, but in knowing the right questions to ask. Just because you can solve a problem once it’s been called to your attention, doesn’t mean that you would notice it in the first place. That’s where the specialists come in: They know the questions to ask, and know what problems are likely to crop up.
I suspect that this is true in a great many other walks of life, too, not just physics. There are probably perfectly obvious things that I don’t know about sweeping the floor, that any janitor could tell me.
Good point there Chronos. And I once meet a PHD for whom the physics of sweeping eluded him. Seriously, we had a “clean up the lab/workbay and everyone pitches in” day and he had to be shown/told how to do it 
Two quick observations/recollections. First, the students who designed an implosion a-bomb at, IIRC, Princeton, needed help from a contractor for the exact design of the explosive lenses. AIRI from John Phillips’s story about the project, they tried to derive the design themselves, couldn’t do it, and Phillips ended up having to call someone at a subcontractor with Oak Ridge. Through some social engineering, he got enough help that he and his team figured it out.
The second is that I don’t believe coupling the energy from a primary to a fusion secondary is as easy as just sticking them next to each other and surrounding them with a barrel of Fogbank. From what I’ve read, it’s some version of foamed/pseudo-aerogelled acrylonitrile with some impurities. Recreating the impurities from the original process was what stymied attempts to recreate Fogbank after the original production line was shuttered. Arms Control Wonk goes into more detail and is where I picked up this speculation.
Who even has hydrogen bombs, i.e., devices which derive a great deal of their explosive yield from a fusion reaction or, per billfish in an earlier thread, opportunistic fission of otherwise un-fissionable U-238? I don’t believe that Pakistan, India, or N. Korea are thought to have them. South Africa never made one. The Security Council members have, and Israel probably has too, though I don’t believe they’ve ever tested one. (The Vela 1977 flash in the S. Atlantic, was, I thought, indicative of too small a yield to likely have been a thermonuclear device.) If nation-states like India or Pakistan don’t have them—and I don’t think it’d be through lack of trying, even though most military aims can be achieved through a pure fission weapon (yield <200 kt), given sufficient delivery accuracy—I’m having a hard time believing that a physics prof can conjure one up.
Bah, missed the edit window. Here’s the post at Arms Control Wonk that speculates on the composition of Fogbank. I mis-remembered quite a bit from it. This article at FAS might also be of interest.
I still need to go get that copy of The Curve of Binding Energy and read what Ted Taylor had to say about all of this.
The problem with the resumption of FOGBANK production was not that no-one knew how to make it - once a production facility was set up it did not work. Turns out the original source materials were contaminated by impurities. Modern source materials did not have the impurities, and so the process did not work. The impurities are now added as source feeds.
However, the links provided by Gray Ghost show that FOGBANK production was nasty, risky business involving volatile solvents that are probably toxic and carcinogenic, as well as inflammable. No wonder no one wanted to do the job.
Si
I could interpret your question two different ways:
or
I think everyone here would agree that #1 is outright no.
#2 is what everyone here is debating. My guess would be no. It is way easier now than it was in 1945 because of the advancement of computers and the availability of the open source information on the topic. But in the end, it is just really hard to figure out every single little problem that dozens of teams of engineers and scientist have had to overcome and figure out.
Roughly in order of increasing difficulty.
Uranium fission bomb, big. You got all the uranium you need and the thing can be as big as you need to to make it easier to design and build. Doesn’t have to be particulary efficient either.
Uranium fission bomb, medium. But not a bunch of uranium to use and it needs to be small enough to be pratical to use.
Uranium fission bomb, small. Roughly comparable in size and efficiency to what the miltary eventually developed.
Same sequence for Plutonium fission bomb.
Hydrogen bomb, big and crude. “Fired off” by big Uranium fission bomb. Take the fission bomb, surround it with a bunch of hydrogen, maybe use some tricks to increase the yield, but its very big and not remotely efficient.
Same deal, but using medium Uranium fission bomb.
Again, but now with small Uranium fission bomb.
Repeat Big and Crude Hydrogen bomb but now with big, medium, and small Plutonium fission bombs.
Repeat those sequences again, but now its a half ass designed hydrogen bomb that is maybe transportable by large truck or boat. Not efficient either, but signifcantly increased yield over the fission component.
Well designed hydrogen bomb. Smaller, but still pretty damn big. Big enough bang that it can be respectably called a hydrogen bomb rather than a souped up fission bomb.
Very well designed hydrogen bomb. Small enough to drop from reasonable sized planes. Also, now not some much a hydrogen bomb, but a fission fusion fission where the fusion is causing additional fission of the fissile material making it much more effiecient.
A VERY well designed hydrogen bomb. Very small, very efficient. very reliable, and a predictable yield level.
Also, how long does this prof have? A few years of full time work, or a weekend sitting around the fire at the ski lodge with a pad of paper?
I think your prof, even with a good bit of time, is going to crap out at the medium Uranium fission bomb level and the medium plutonium bomb might be a stretch.
OTOH, I think BS level physics majors might be able to pull off the big crude Uranium fission bomb.
Once the prof has his medium fission bomb, my WAG is the half ass designed hydrogen bomb is where his skill level will crap out. And the result will probably be something like "well the fission yield is gonna be about 50 kilotons. With a little “luck” we might eek out a megaton from the secondary fusion effects. Or we might have bad “luck” or missed a detail or two and just got a 100 kiloton or so extra for all our effort.
I worked for a number of years at a U.S. Department of Energy facility that designed and manufactured components for nuclear bombs. Triggers were our specialty. This was not a small facility; we had over 75 buildings on 300 acres, and close to 2000 employees.
Unless you have actively worked in such a facility on a fulltime basis, you have absolutely no idea the magnitude of effort it takes to design and build a nuclear weapon. (And we didn’t even build the whole weapon - just certain components.)
It would be impossible for one person to possess the breadth and depth of knowledge to completely design & build a modern, reliable nuclear weapon from start to finish.
Of course today, you can just google “how to build an atomic bomb.”
Yes, but the OP’s H-bomb doesn’t have any rigorous requirements for:
Size
Weight
Cost
Safety
Security
Maintainability
Reliability
Sustainability
Producability
Once you remove all those and the only requirement is that it explode with some significant nuclear yield, the design becomes A LOT easier.
However, I still agree with you that it couldn’t be done.