The Handheld Analog Computer That Made the Atomic Bomb 45
szczys writes: When the physicists and mathematicians of the Manhattan Project began their work they needed to establish which substance was most likely to sustain vigorous fission. This is not trivial math, and the solution of course is to use an advanced computer. If only they had one available. The best computer of the time was a targeting calculation machine that was out of service while being moved from one installation to another. The unlikely fill-in was a simple yet ingenious analog computer called the FERMIAC. When rolled along a piece of paper it calculated neutron collisions with simple markings — doing its small part to forever change the world without a battery, transistor, or tube.
That "Made" the Atomic Bomb (Score:3)
>> That "Made" the Atomic Bomb
Should be "that simulated the atomic bomb" instead.
Re:That "Made" the Atomic Bomb (Score:5, Informative)
Actually it should be neither. From TFA:
UPDATE: Commentor [lwatchdr] pointed out that the use of the FERMIAC began after the Manhattan Project had officially ended in 1946. Although many of the same people were involved, this analog computer wasn’t put into use until about a year later.
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>> Actually it should be neither.
Well, it DID simulate it. As the community is pointing out, it did its work AFTER the bomb was made, but my correction would make the headline true whether the simulation was before or after.
Now, as for fixing the submission's harebrained summary, well I'd charge triple for that. :)
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I wish people on this site would notice how misleading the headlines are whenever there's a topic about patents. "Microsoft patents page turning on a tablet!" "OH noES!! You won't be able to turn pages on digital devices! Let's babble endlessly about prior art that has nothing to do with the specific bit that was actually patented!"
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Long ago, I had a nice wooden slide rule. I still have a cheap white plastic one, but it's just not the same. Oh, well. I also have an aluminum E6B flight calculator, which is actually a circular slide rule.
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I still miss my old Pickett aluminum rule. Came with a hard leather case. Magnificent.
Re: Wooden calculators (Score:2)
N200-ES.
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The ones I am aware of (and owned) are all either bamboo or aluminum. Bamboo is actually a grass, not a wood.
Want to Know More? (Score:2)
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Oddly enough we're moving back to analog methods, in a fashion.
Modern memory systems, processors, and communication links handle so much data that there is an unavoidable error rate (often dictated by the laws of physics!) that you must factor in to your programs and designs. People are turning back to old analog style methods to deal with noise.
One of the hallmarks of an analog system is having the accuracy of your result tied to the quality of your parts. Instead of part quality you can substitute in comp
Really editors? (Score:5, Informative)
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(KatchooNJ posting Anon because of mod points) True, but the FERMIAC is still interesting tech and I am glad to have now read about it.
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Honestly, are you expecting some form of "journalism" in which the "editors" are actively involved in proof reading and fact checking?
Because that has never been part of the job of editors on Slashdot.
Not even a little.
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Editor: We have the code.
Commander: Can you authenticate?
Editor: Yes, the story is authentic.
Commander: Can you verify?
Editor: Turning key.
Commander: WTF? The procedure is authenticate and ver--BOOM!
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I posted the same thing on HAD. This all happened in 1946. While really interesting it is not accurate and I would have loved more details on the FERMIAC.
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Indeed. In August 1945 the Americans bombed the Japanese. The ENIAC was dismantled in 1947 to move to it's new home, and it was during this outage 2 years after the bombings that the FERMIAC was built.
It contributed to nuclear research, but it definitely did not make the atomic bomb.
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The ENIAC was built in 1946. So if the FERMIAC came after the first bomb, then what did they use for calculations on the first? The GUESSIAC? PAPERIAC?
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The ENIAC was built in 1946. So if the FERMIAC came after the first bomb, then what did they use for calculations on the first? The GUESSIAC? PAPERIAC?
Probably a slide-rule which when used correctly is highly accurate to quite a few decimal places, fast, and easy to use. And everyone involved in the Manhattan Project would have known how to use them.
Re:Really editors? (Score:4, Interesting)
Bunk. A customary 25 cm slide rule is accurate to 2-3 decimal places - and that is plenty for a great many engineering tasks, such as building bridges and locomotives; hell, even B-29s. There are actually markings for 2 places, and the figure for the 3rd place is interpolated by eye. In 18th century Germany, somebody made a slide rule 2 meters long with a microscope attached to it, which could give 6 places. About the only real physical problems at the time which could even make use of that kind of precision were certain subtle astronomical calculations.
Circular slide rules are a way to get about three (pi) times the precision for the same linear dimension by winding the scales in a circle. Mostly all they do for "normal" sizes is make the interpolation of the 3rd place a little more precise. A tradeoff is error due to the slop in the axial pivot.
It should be well known to any high school grad, but I better mention that 3 times the precision is only about half on one decimal place. It's like the way "orders of magnitude" are frequently misspoken. I was reading some bunk about "many" orders of magnitude, where the writer was only talking about a factor of a thousand. A thousand is a large factor, but it's only three orders of magnitude. Ten orders of magnitude encompasses the difference between a large nuclear weapon and a hand grenade.
Slide rules only give you the mantissa. Everything is normalized to 0-999. You still have to keep track of the 10s exponent in your head or on paper. It was damn good mental exercise. Yeah, I know a thing or two about slide rules since I enrolled in engineering college in 1965.
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One of the interesting things about a slide rule is that you get appear to get fractionally more significant digits at the 1-end than you do at the 9-end. That is, it's much easier to read off 3 digits at the 1-end than it is at the 9-end. But that doesn't really represent any increase in accuracy at the 1-end, it's just (afaik) an artifact of the way base-10 works. The ratio 1.11/1.10 (3 significant digits), say, is 1.0090909..., while the ratio 0.99/0.98 (2 significant digits) is 1.010204...; the ratio
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Monte Carlo methods can be applied without a computer. They are just painfully slow to do. So yes, PAPERIAC :-)
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Then MONTIAC. And if you use pencil, it's PONTIAC.
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The artcle described the use of the device in a clever "Monte Carlo" physical modeling scheme for complex geometries of multiple materials. That's how you design reactors, and multistage nuclear bombs (like the Super, or H-bomb, or 'thermonuclear weapon'). Yeah, the first three explo
Nice article but... (Score:2)
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It's been optimized to appeal to a like audience and stuff.
Banks of women sitting at adding machines (Score:3, Informative)
I thought they used banks of women sitting at adding machines, carrying out algorithms handed to them by Feynman...Fermi would do simple back of the envelope calculations, and Von Neumann would solve the differential equations in his head...
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carrying out algorithms handed to them by Feynman
Feynman was there, he even supervised the team running the ENIAC for a while. But he was a pretty junior contributor at that point. He does mention seeing the room full of women doing calculations in his autobiography.
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Well, he mentions the room full of women, and he also talks about being in charge of a group that ran problems through some kind of IBM machines:
Square Brackets (Score:1)
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I wonder why all the names had square brackets around them: [Fermi], etc. I began to wonder if there was an alternate version of the article that had a different set of names. It was like I image it would be like to read a textbook in North Korea: "Then [Glorious Leader] invented the nuclear bomb." "Later [Glorious Leader] was the first person to walk on the moon".
Cut and pasted from a wiki?
Misread... (Score:3)
doing its small part to forever change the world without a battery, transistor, or tube.
Because of the font, I did a double-take cause I initially misread "tube" for "lube". That certainly forever changed my perceptions of nuclear physics research. :)
Slide rule (Score:2)