A truck driver uncovers secrets about the first nuclear bombs
newyorker.com> In the standard historical accounts, the way that the bomb’s gun mechanism worked was by shooting a cylindrical “male” uranium projectile into a concave, stationary uranium target. This act of atomic coitus created a mass sufficient to produce a critical reaction. The mass of the projectile was said to be 38.5 kilograms, and the mass of the target was said to be 25.6 kilograms. But no matter how many times Coster-Mullen did the math the numbers never quite worked out in a way that allowed the projectile and the target to fit inside the gun barrel while remaining subcritical.
> The source of the error, Coster-Mullen recognized, was an assumption that every (male) researcher who studied the subject had made about the relation between projectile and target. These scholars had apparently been unable to conceive of an arrangement other than a “missionary position” bomb, in which a solid male projectile penetrated a vessel-like female target. But Coster-Mullen realized that a female-superior arrangement—in which a hollow projectile slammed down on top of a stationary cylinder of highly enriched uranium—yielded the correct size and mass.
Does anyone understand what point is being made here? I don't understand how which piece is the projectile would make a difference in the overall size/geometry. All else equal, I would think it would be easier if the lighter, simpler piece were the projectile. Accelerating a cone/cylinder without breaking/damaging it seems a lot easier than accelerating the complementary shape.
Then again, I'm male, so I guess I'm just not capable of imagining the "female superior" design...
One of the first "public" descriptions of this process was phrased something like:
"shooting a mass of uranium down a barrel into another mass of uranium to form a supercritical mass."
My guess is that the person who first said that didn't intend for the metaphor/description to be taken quite as literally as everyone ended up taking it. (Or they meant to mislead.)
Hypothetically, if you read "into" as crash/collision and not "in to"/inside of, you start to see how a generic description could be ambiguous. Run this (or a similar story) through a few iterations of the telephone game and draft revisions by journalists/editors (that somehow all seem to graduate without ever taking a single sophomore level technical writing course), and a description becomes a misunderstood metaphor becomes a fact. Somewhere along the way, the word "bullet" gets thrown in, and then no one "un-see" the visual.
That's my take. That and the author of tfa is trying way too hard to make a big a deal out of it being a "gendered" thing, when it's not.
> My guess is that the person who first said that didn't intend for the metaphor/description to be taken quite as literally as everyone ended up taking it. (Or they meant to mislead.)
This is the problem. Why are they trying to shoehorn male or female dominance here? The whole thing is not only unpleasant to read, but also confusing.
They are not "trying to shoehorn male or female dominance here"
They are describing the shapes, and the orientations of the projectiles in terms of coital positions - with which, um, some percentage of the adult population has some familiarity.
Here, "female-superior arrangement" means that the male is supine, and the female straddles atop him
>Does anyone understand what point is being made here?
A cylindrical barrel is being fit over a fixed centre pin, rather than a pin inserted into a barrel.
Makes sense when you realise that the moving component is inside of a similarly cylindrical bomb casing and that no fancy and complicated sabot and/or rail arrangement are required to keep it aligned and centered with the fixed pin.
Most DC charging plugs work the same way for the same reason.
I don't quite buy this reasoning. With a car charger, you indeed need to hold a fairly beefy contact in position so it mates with its counterpart. But in a car charger, there's no functional difference between the cable end and the car end -- sure, one is handheld and one is fixed to the car, but both ends need to secure their respective contacts.
With the gun-type bomb, suppose the final critical assembly has a 2"-diameter "male" part in a 3"-diameter formerly hollow ball. If the 2"-diameter "male" part were in a 3"-diameter barrel then, indeed, some mechanism would be needed to stabilize it. But I see no fundamental reason that the barrel needs to be 3" in diameter -- couldn't the "male" part just as easily be a projectile in a narrower barrel?
(I made up the 2" and 3" numbers.)
The barrel is part of the casing, necessary for a sustained reaction.
True, but does the barrel need to be a cylinder? That is, couldn’t the casing be a sphere with a hole cut out and a cylinder inserted? I suppose this could be much less pleasant to machine and to service.
No, but they wanted the first bomb to be simple enough in principle not to need any debugging.
I think it means the female stationary object being impacted by a thrusting male object was an inferior design to the male stationary version being rapidly sheathed by a female apparatus in terms of consistency of the force of impact. But not sure it explains why.
You have a gun barrel, some of the toughest steel around, which required to contain the supercritical mass long enough to allow for an efficient chain reaction. You stick a cone shaped object down the open end of the gun, and weld, or screw it into place with enough mechanical strength to stop an artillery round and keep it from exiting. More than 1/2 of the critical mass is likely here, with the air gap around it helping to keep the neutron flux low, for the time being. It is likely there is a neutron initiator on the very tip of the conical slug projecting into the barrel. (Think of shoving a ice cream cone into a pipe, narrow end first)
On the breech end, you insert a large "hollow point" slug of the rest of the critical mass. (an empty ice cream cone, open end first) The hole in the middle helps keep the neutron flux low, for now. Following this slug is the cordite explosive which will push the slug down the barrel at great speed.
The charge is set off, the slug rushes down the barrel, and gets wedged against the sides, in the process it breaks the neutron initiator, crushing it, and setting off a rush of neutrons, into the now complete, supercritical mass. The temperatures and pressures in the gun barrel begin to rise exponentially as the chain reaction takes off, within microseconds it is just the inertia of the barrel that helps keep things in place, the melting and even vaporization temperatures have been passed, but the contents have yet to disassemble completely, the chain reaction reaches its peak as the temperature climbs past 50,000,000 degrees, and then everything spreads outwards, 7/10ths of a gram of mass (the weight of about 3 rain drops) has been converted to energy, yielding the explosive yield equivalent of 15,000 tons of TNT.
Perhaps, since the larger piece would have more mass than the smaller, therefore it would impact with more force, and for a more sustained period, allowing it to reach criticality?
I don't buy this at all. There is zero logic to firing the larger (female) piece onto the smaller (male) piece. It makes the bore of the barrel needed to actually do it larger, increasing the weight of the air-dropped weapon in the process. From a physics point of view, there is nothing to be gained either. Neither piece knows which got shot at who, and once piece geometry is set, all that is important is that the two pieces are brought together as fast as possible. That means the smaller (lighter) piece goes in the barrel.
New Yorker, I found, is always obtuse, long-winded prose that fill up 14 pages where the whole thing can be, if it was written like a normal article, summarized in no more than 3 pages. It is prose porn for writers and readers alike.
If I want good prose, I read the the Cabinet Magazine which is far superior in writing, curtness and straightforwardness while not affecting the charming and poetical aspects of writing.
Furthermore, New Yorker has inappropriate political and social undertones that is very offputting - they don't belong here and but its beat into place. Any informed reader would see through it. If you enjoy that sort of a thing, great but it's not my thing even if I agree with the underlying message.
I don't even need to read the article to know this is going to be a long winded piece of popular bullshit.
Just look at the title, manages to demean and belittle an entire industry that is entirely required for a functioning economy and society.
Y'all wonder why blue collar America thinks we're stuck up entitled pricks? Maybe it's because we are.
This article basically boils down to "scientists suck, the government sucks, truck drivers have everything figured out". Pretty much the opposite of what you are suggesting. There's a layer of humility which obfuscates this a little.
yep I thought like that too. I don't know truck drivers, but the way the title is put, it seems to oppose the "genius" of a nuclear bomb to, well, a mere truck driver. I'm not entirely sure the people behind the bomb were smarter than a truck driver. The human qualities needed to decide to work on a bomb or not, which to me is infinitely stronger than what it takes to be a physicist or mathematician, can be found as well in a truck driver...
I got this guy's "book" off Amazon back when he was taking them to Kinko's to be printed up. His is a fairly remarkable story of curiosity which I have always enjoyed. He even signed it for me.
What is not often pointed out is that he managed to reason his way into understanding to various points, and the process of doing so revealed information that is otherwise still classified.
As a teen in Las Vegas in the 70's we could "feel" the underground tests, and I was always fascinated by the test site. I even managed to snag a summer internship there (inadvertently[1]) when I was in college.
I know folks who worked at Sandia and Lawrence Livermore who found the book fairly remarkable.
[1] The job offer was for the contractor facility in Las Vegas but my clearance had not come through so they bused me to an unclassified facility at the test site to do the work.
There is significant amounts of classified information already available publicly in documentaries etc. This is readily acknowledged by people at the labs who Ive chatted with, though I didnt push to probe specifics. Much of the secret sauce at the time (knowing the cross sections for various processes, reflecting neutrons etc) that enabled the design of working weapons is all well understood and publicly known now and unclassified. Other than the artisanship needed to make the high explosives do what you want, the only meaningful barier is enrichment.
The interesting part for me, per the nondisclosure and federal law, is that there can be classified information "out there" but that doesn't declassify it! It isn't like technology NDAs where, if you have signed one, you can talk about the secret sauce if it gets disclosed through no fault of your own. Not so with the US Government!
For example, even if "everyone" knows how fast an SR-71 can fly, that number is still classified. And if you have a clearance you can't talk about it because it is classified and you know its classified. So it is illegal for you to talk about its top speed. This is another good reason to avoid getting a government clearance if it can be avoided.
If you don't like nagging subscription popups, here is a popup-free summary of the truck driver's story:
A fairly lengthy interview transcript here: https://www.manhattanprojectvoices.org/oral-histories/john-c...
Try Reader View in Firefox for reading the text uninterrupted.
I think Chrome is the only browser left without a reader view.
chrome://flags/#enable-reader-mode
A way to enable a reader mode has come and gone over the years, always "in testing." That's not the same as a first class feature, and it's clear they have no intention of making it available by default. Defaults matter.
In case you doubt this, here's an article from 2014 on how to enable the perpetually newly-added hidden reader mode: https://lifehacker.com/enable-the-new-hidden-reader-mode-in-...
The "simplicity of the Bomb" phrase reminded me of the story of the Demon Core:
https://en.wikipedia.org/wiki/Demon_core
For me, it shows how hard it is to internalize dangers of a technology one is working with daily. How hard it is to trade convenience for security.
Direct link to the spiral bound copy on Amazon: https://smile.amazon.com/dp/B0006S2AJ0
He binds and ships them himself as far as I can tell.
>> Fat Man used explosives to squeeze together two hemispheres of plutonium.
I thought the plutonium core was one piece and the explosives compressed it, making the same mass critical due to increased density.
The plutonium cores were machined as hemispheres because they had to put an initiator in the center.
Also to prevent criticality problems when moving them.
And to prevent criticality problems while manufacturing them.
You're machining a perfectly spherical plutonium core out of a LARGER chunk of plutonium.
> I thought the plutonium core was one piece...
While other responses have explained it was not, I thought I should point out that any sphere, even if a single piece, will always have at least two hemispheres, iow, a sphere having two hemispheres does not imply it is more than one piece. When you leaned of the Earth's northern and southern hemispheres, did you wonder if it was more than one piece?
(2008)
Can anyone locate the photo from Gene Smith he mentioned towards the end?
(2008)