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.

>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 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.

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.

A fairly lengthy interview transcript here: https://www.manhattanprojectvoices.org/oral-histories/john-c...

Try Reader View in Firefox for reading the text uninterrupted.

The plutonium cores were machined as hemispheres because they had to put an initiator in the center.

> 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?