
Don't Worry – It Can't Happen (1940) - apsec112
https://www.dropbox.com/s/hzhilstmj94jvlx/1940-sciam-harrington-nuclearweapons-dontworryitcanthappen.pdf
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Animats
Of course it can't happen. As the Germans discussed at Farm Hall, you'd need
giant factories, maybe the biggest buildings in the world, more than a mile
long. They'd need giant power plants, like big hydroelectric dams, to power
them. You'd need entire cities of scientists just to work out the theory.
Other new cities for the plants. It would take hundreds or thousands of test
explosions to get the chemical explosive components right. You'd need some way
to watch an explosion as it happened, maybe even with an X-ray machine. The
project would cost billions of dollars and take years. Even then, you might
only make a few bombs.

~~~
owenversteeg
Just one of those facilities, the Clinton Engineer Works, employed nearly a
hundred thousand people. The vast majority of those did not realize what they
were a part of. For example, this quote underneath one of the article photos:

"Gladys Owens, the woman seated in the foreground, did not know what she had
been involved with until seeing this photo in a public tour of the facility
fifty years later."

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smacktoward
This is not as silly an article as it may appear to be in hindsight. When it
appeared (in May 1940: [https://www.scientificamerican.com/article/dont-worry-
it-can...](https://www.scientificamerican.com/article/dont-worry-it-cant-
happen/)), most scientific authorities, including such non-idiots as Niels
Bohr, believed that, while an atomic chain reaction was theoretically
possible, the only way an it could be achieved was by bringing together a
quantity of nuclear fuel so large as to make the effort impractical.

The first proof that this was not in fact the case came in the Frisch-Peierls
memorandum
([https://en.wikipedia.org/wiki/Frisch%E2%80%93Peierls_memoran...](https://en.wikipedia.org/wiki/Frisch%E2%80%93Peierls_memorandum)),
which had been written two months before Harrington's article appeared, but
which was highly classified and thus out of reach of pop-science journalists.
Frisch and Peierls' figures indicated that a critical mass could be achieved
with just one kilogram of uranium-235; this turned out to be an underestimate,
but not so much as to invalidate their fundamental point, which was that
criticality could be achieved with a mass of fuel small enough to be delivered
by a 1940s-era airplane.

This came as news to the brightest lights in the world of physics, up to and
including Albert Einstein, so it's probably unfair to expect a contemporary
writer for _Scientific American_ to be further ahead in the science than they
were.

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ChuckMcM
We talked a bit about the state of physics in 1940 in my 'Modern Physics' (aka
Physics 401 aka nuclear/quantum). Looking backwards through time its easy to
imagine they were planting disinformation or trying to throw off people from
the potential there, but that view is mostly bolstered by knowing what is
possible now. Had it come out in 1942 after 'pile 1' was demonstrating fission
then yes, it would be subterfuge.

But perhaps most amazing are these results from physics experiments in 1940
and then the changes in the world by 1945. Such profound changes are also
likely when someone figures out how to tap the energy from fusion as well.

~~~
pvg
There was some experimental evidence (and open publication) by 1939, to boot.
The threat outlined by the Einstein-Szilard letter is that the Germans must be
aware of the idea and might be developing a weapon so planting disinformation
was probably not high on anyone's list of priorities.

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falcor84
Clark's First Law:

"When a distinguished but elderly scientist states that something is possible,
he is almost certainly right. When he states that something is impossible, he
is very probably wrong."

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heisenbit
I wonder whether the author was naive or intended to misdirect. The french
experiment he cited answered the question "With the samples as is could it
explode?" and the answer was "It can't happen.".

The relevant question however was "Can the setup be engineered that it could
be made to happen" and the answer to that with all that was known and
elaborated in the article was: "Maybe if a larger percentage could be made
slower or absorbed by other means".

Answering the wrong question is a common way to misdirect.

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aptwebapps
OP claims that the same other wrote a "worry about it" piece a year before.

[https://mobile.twitter.com/wellerstein/status/84169090329099...](https://mobile.twitter.com/wellerstein/status/841690903290998787)

So basically, clickbait through the ages.

~~~
aptwebapps
Too late to edit, but s/same other/same author/

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nl
Note that the Einstein letter which kicked off the Manhattan Project wasn't
sent until August 1940[1].

[1]
[https://en.wikipedia.org/wiki/Einstein%E2%80%93Szil%C3%A1rd_...](https://en.wikipedia.org/wiki/Einstein%E2%80%93Szil%C3%A1rd_letter)

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ajnin
The letter is dated August 2nd, 1939.

~~~
nl
Apologies, you are entirely correct.

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Jaruzel

      Thus the reaction poohs out as the temperature rises.
    

'poohs out' ? I've looked up the definition of 'pooh', and there's nothing to
indicate what this means in this context, can someone elaborate?

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ConSeannery
It's slang, meaning to lose momentum and stop. Saying "died out" or "fizzled
out" is more common these days (eg: A spark jumped from the fire but quickly
fizzled out on the snowy ground).

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hackcasual
Of course this assumed you didn't enrich the uranium.

~~~
taneq
So what's the equivalent of enriched uranium for AI? Some form of recurrent
neural net?

And what's critical mass? Some form of feedback system (a 'strange loop')?

~~~
GuiA
All analogies are leaky, and I think this one is particularly misguided. Why
would you want to draw parallels between uranium and AI? You can go a long way
speculating about...

What's the equivalent of enriched uranium for healthcare? What's the
equivalent of enriched uranium for calculus? What's the equivalent of enriched
uranium for sweatshirts?

~~~
taneq
It's actually a much better analogy than you think. Machine learning (which is
at least a significant part of AI) requires a certain 'critical mass' of
computing power and learning data before it becomes powerful. We had neuron
models in the 90s that were roughly equivalent to what we have today and they
were deemed largely useless, just like the uranium in the article. All that
changed was the data and compute power available.

As for 'critical mass', a defining characteristic of consciousness is that
it's self-referential, so that seems like a fair guess.

~~~
jes5199
but growth of AI usefulness hasn't been faster than Moore's Law, has it? so it
doesn't seem to have a feedback loop

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FeepingCreature
Well yeah, the feedback loop is assumed to happen once the AI system becomes
powerful enough to understand and optimize its own operation better than
humans can. Basically the premise is that AI development speed is bounded by
the capability of the mind working on the AI, so max(human, AI). AI
intelligence grows faster than human intelligence (which has reached the
limits of easy improvements and is thus arguably capped by population size,
which has _also_ stagnated), so the inflection point is assumed to happen once
the second term outstrips the first.

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finchisko
It can replace all those pythons, javas with super efficient platform tailor-
optimised machine code, gaining remarkable computational benefits. I mean
programmers will also loose jobs one day, AI will replace them too only couple
of years later than taxi drivers. But actually I'm looking forward to it, as
programmers are extremely cocky these days.

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henryw
Funny how they said: "With typical French - and scientific - caution ..."

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breck
More readable: [https://www.dropbox.com/s/hzhilstmj94jvlx/1940-sciam-
harring...](https://www.dropbox.com/s/hzhilstmj94jvlx/1940-sciam-harrington-
nuclearweapons-dontworryitcanthappen.pdf)

~~~
Stratoscope
Thank you! The Twitter version in the OP is useless on a mobile device.

