Friday, March 04, 2016

Sepia Saturday #322: A Brief look at Nuclear Bomb Design


Quickly, I had to look up the differences between a lamb and a kid. In short, I learned a lamb's tail hangs down and a kid's tail turns up. The tiny lamb's tail is out of view in the prompt photo with the little kids, but I think the creature has a tell-tale wooly coat, another giveaway it's a baaaa baaaa. Even though it's getting a free drink, I bet that lamb would scurry away in a flash if the kids let it go. Have I jumped to a conclusion based on only a fleeting glance at the photo? I'm in such a hurry this week. 

In my hastily chosen photo below of an unknown young girl, the animal's tail is up, and it's coat is obviously goat hair. Speed was of the essence and I just had to go with the goat. As it's a fairly large animal, I'm surprised the little girl's mother(?) in the background let her handle it in this manner. She could get a sharp kick in the bare knee, uncovered as it is with that skimpy skirt. All danger aside, she looks as if she's telling the goat a short story or whispering sweet nano-nothings into her ear. 

As we're leaving for India tomorrow, my contribution this week is skimpy and brief. I could devote only a bit of time to it, perhaps 10 nanoseconds - a time short as two shakes of a lamb's tail, in fact.

From Wikipedia: A shake[1] is an informal unit of time equal to 10 nanoseconds, or 10−8 seconds. It has applications in nuclear physics, helping to conveniently express the timing of various events in a nuclear explosion. The typical time required for one step in the chain reaction (i.e. the typical time for each neutron to cause a fission event which releases more neutrons) is of order 1 shake, and the chain reaction is typically complete by 50 to 100 shakes.[2]
This is also applicable to circuits. Since signal progression in IC chips is very rapid, on the order of nanoseconds, a shake is good measure of how quickly a signal can progress through an IC.
Like many nuclear units, it is derived from Top Secret operations of the Manhattan Project during World War II. The word comes from the expression "two shakes of a lamb's tail," which indicates a very short time interval. For nuclear-bomb designers, 10 nanoseconds was a convenient specific interval to connect to this term.
It has been discussed at length that the oldest documented usage of the phrase "two shakes of a lamb's tail" can be found within the compiled works of Richard Harris Barham calledThe Ingoldsby Legends.


Unknown girl holding goat. Photo marked 1934 on the reverse.

Don't stand on ceremony. You're invited to butt in over at Sepia Saturday for more interesting tails tales. 

14 comments:

  1. Great take on the theme. I never knew that scientists utilized the term to indicate time. That goat doesn't seem terribly comfortable in her arms.

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    1. I'd never heard of this either. Oh, the things you learn while working on Sepia posts!

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  2. The goat looks pretty small. Either a kid or a bush goat. I'm sure her knees were safe. The goat though, not sure about it!

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  3. Have a great time in India! So glad to know about the unit of time called a shake. I certainly need a few million shakes to do things.

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  4. I know that expression as 'two shakes of a dead lamb's tail', but that doesn't sound so nice. Enjoy your trip - watch out for any goats that may be wandering about!

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    1. I've never heard it that way. Does that mean slow or fast?

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  5. What a juxtaposition - lambs and bombs. Only you, Helen!

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  6. A kid with a kid, probably they knew each other well, so no kicking, just hugging; my guess. Happy and safe holidays.

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  7. Well Done! Good on you for even taking the time to post when you are about to go on holiday! Hoping that you have a wonderful time in India!

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  8. Wow, I was wondering how will she bring bombs and little sweet lambs together? Bravo!

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  9. Wow. Like Wendy, I knew of the expression "Two shakes of a lamb's tail" but had no idea it could be applied in a scientific way to the making of bombs. Interesting to say the least! Hope you have a wonderful time in India!

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  10. Cute photo. I hope you have a grand time in India!
    --Nancy. (ndmessier @ aol.com, nancysfamilyhistoryblog.blogspot.com)

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  11. It's a wonderful photo that has the same quality of innocence as the theme photo. There is an urban farm in my neighborhood that raises goats. Baby kids are the cutest animals and quite jumpy things.

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  12. If she had a kick, it wouldn’t be the first, I’m sure. Slippery little things - goats.

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