Re: GR translation: what hep humorists here are already calling “Critical Mass”

[Monte Davis]

It's a pun: "Mass" DOES refer to the religious ceremony as well as to the
physicists' term for enough fissionable U-235 or Pu-239 to maintain net
energy output in a reactor, or deliver it in an exponential burst as a
weapon.

(Science-nerd sidebar: what is really critical is the RATE at which
neutrons from fissioning atomic nuclei strike other nuclei and cause them
to fission, releasing more neutrons...etc. etc. It's like disease
transmission: on average, how many others does one person with flu transmit
it to? If the rate is less than 1, the outbreak subsides; if it's much more
than 1, it becomes an epidemiic.

That rate depends not only on nuclear physics itself but on the geometry --
the spatial distribution of the atoms, and thus the likelihood of a flying
neutron hitting another nucleus before it exits the material. A sphere is
ideal; better than the same mass in a flat slab. Very early in the
Manhattan Project, they realized that the nascent explosion would melt,
vaporize, and blow the whole mass apart before more than a few percent of
the atoms split. That was acceptable for U-235: the "Little Boy" uranium
bomb fired a slug of U-235 down a short "gun  barrel" into a cavity in a
larger chunk, adding up to more-than-critical mass even though it started
melting as the slug hit. Faster-fissioning plutonium was worse; but if you
could *compress* a sub-critical mass -- literally force the atoms of metal
closer together -- there would be more hits, more fission, doubling and
redoubling in microseconds, before the explosion gathered force. Hence the
much more complex and challenging "Fat Man" Pu-239 bomb, with a spherical
shell of explosives squeezing a ball of solid metal -- very briefly -- to
lesser volume, higher density, and a chain reaction that wouldn't have
happened without the squeeze. You can get a critical RATE -- which is what
matters for the explosive yield -- from a mass that wouldn't be even close
to critical sitting on a workbench.

So the usually unstated subtext to all discussions of how much fissionable
U-235 or Pu-239 Iran or North Korea has, and how many nuclear weapons that
could produce, is "how good is their 'squeeze' design?" That matters more
than the mass -- but the 1940-vintage (for scientists) or 1945-vintage (for
the public) term survives.)

On Wed, Jul 19, 2017 at 9:21 AM, Mike Jing <gravitys.rainbow.cn at gmail.com>
wrote:

> Ah, I missed it completely then. Somehow I thought "Mass" was referring to
> the religious ceremony, and people are celebrating it while listening to
> Father Rapier's "passionate demonstrations".
>
> On Tue, Jul 18, 2017 at 10:13 PM, David Morris <fqmorris at gmail.com> wrote:
>
>> Umm,  my take on the term in this context means the instant that
>> ejaculation becomes inevitable.
>>
>> David Morris
>>
>>
>> On Tue, Jul 18, 2017 at 7:38 PM Mike Jing <gravitys.rainbow.cn at gmail.com>
>> wrote:
>>
>>> V539.10-24, P548.12-26   DEVIL’S ADVOCATE’S what the shingle sez, yes
>>> inside is a Jesuit here to act in that capacity, here to preach, like his
>>> colleague Teilhard de Chardin, against return. Here to say that critical
>>> mass cannot be ignored. Once the technical means of control have reached a
>>> certain size, a certain degree of being connected one to another, the
>>> chances for freedom are over for good. The word has ceased to have meaning.
>>> It’s a potent case Father Rapier makes here, not without great moments of
>>> eloquence, moments when he himself is clearly moved . . . no need even to
>>> be there, at the office, for visitors may tune in from anywhere in the
>>> Convention to his passionate demonstrations, which often come in the midst
>>> of celebrating what hep humorists here are already calling “Critical Mass”
>>> (get it? not too many did in 1945, the Cosmic Bomb was still trembling in
>>> its earliness, not yet revealed to the People, so you heard the term only
>>> in the very superhepcat-to-hepcat exchanges).
>>>
>>> Does the word "critical" here refer to the nature of Father Rapier's
>>> sermon, as in "given to adverse or unfavourable criticism"?
>>> I'm aware of the pun, of course.
>>>
>>
>
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