Posted on 04/18/2016 7:17:04 PM PDT by MtnClimber
Most everyone has a pretty good idea of what an atomic explosion looks like. Through images and video, we know the flash, the fireball, the mushroom cloud. Seeing it all in person is quite different, however.
One of the few firsthand accounts immortalized to paper comes courtesy of the inimitable Richard Feynman, who was present for the very first detonation of a nuclear weapon. The test, codenamed "Trinity" was carried out on July 16, 1945 in the Jornada del Muerto desert of New Mexico. The 20-kiloton blast was the culmination of years of work by the scientists of the Manhattan Project. One of those scientists, the 27-year-old Feynman, sought to view his handiwork with his own eyes: They gave out dark glasses that you could watch it with. Dark glasses! Twenty miles away, you couldn't see a damn thing through dark glasses. So I figured the only thing that could really hurt your eyes (bright light can never hurt your eyes) is ultraviolet light. I got behind a truck windshield, because the ultraviolet can't go through glass, so that would be safe, and so I could see the damn thing.
Time comes, and this tremendous flash out there is so bright that I duck, and I see this purple splotch on the floor of the truck. I said, "That's not it. That's an after-image." So I look back up, and I see this white light changing into yellow and then into orange. Clouds form and disappear again--from the compression and expansion of the shock wave.
Finally, a big ball of orange, the center that was so bright, becomes a ball of orange that starts to rise and billow a little bit and get a little black around the edges, and then you see it's a big ball of smoke with flashes on the inside of the fire going out, the heat.
All this took about one minute. It was a series from bright to dark, and I had seen it. I am about the only guy who actually looked at the damn thing--the first Trinity test. Everybody else had dark glasses, and the people at six miles couldn't see it because they were all told to lie on the floor. I'm probably the only guy who saw it with the human eye.
Actually, Feynman wasn't the only person who chose not to don their safety glasses that day. Ralph Carlisle Smith, the future assistant director of Los Alamos Scientific Laboratory, also observed the explosion with the naked eye. Here's what he saw:
Heinz Guderian would have recognized the NVA tactics and operations in the final assault on the RVN.
BTTT!
Because of the two A-bombs, they were not needed then...
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I do know that, when exploring the Japanese back country on my trail bike; I discovered that even the smallest hill was riddled with bunkers and gun emplacements. That invasion would have been Iwo Jima and Okinawa --to the Nth power!
That small crater outside the Trinity fence at 4:30 was made by a huge conventional (ANFO) explosion for instrument calibration...
That last sequence looks like a serious trigger-timing or detonator failure...
The article showed a shot down a long, dark hall with a single 100W light bulb at the far end. The fast layer exposed the hall perfectly, the normal layer exposed the bulb so that you could read the label on the glass -- and the slow layer exposed the filament so that every detail of it was sharp and clear -- all done with a single, short exposure!
My guess is that that sort of film was used to make the images you posted...
Rapatronic camera
From WikipediaNuclear explosion photographed by rapatronic camera less than 1 millisecond after detonation. From the Tumbler-Snapper test series in Nevada, 1952. The fireball is about 20 meters in diameter in this shot. The spikes at the bottom of the fireball are known as the rope trick effect.
The rapatronic camera (a portmanteau of rapid action electronic) is a high-speed camera capable of recording a still image with an exposure time as brief as 10 nanoseconds.
The camera was developed by Harold Edgerton in the 1940s and was first used to photograph the rapidly changing matter in nuclear explosions within milliseconds of ignition, using exposures of several microseconds. To overcome the speed limitation of a conventional camera's mechanical shutter, the rapatronic camera uses two polarizing filters and a Faraday cell (or in some variants a Kerr cell). The two filters are mounted with their polarization angles at 90° to each other, to block all incoming light. The Faraday cell sits between the filters and changes the polarization plane of light passing through it depending on the level of magnetic field applied, acting as a shutter when it is energized at the right time for a very short amount of time, allowing the film to be properly exposed.
In magneto-optical shutters, the active material of the Faraday cell (e.g. dense flint glass, which reacts well to strong magnetic field) is located inside an electromagnet coil, formed by few loops of thick wire. The coil is powered through a pulse forming network, by a discharge of a high-voltage capacitor (e.g. 2 microfarads at 1000 volts), switched into the coil by a trigatron or a thyratron. In electro-optical shutters, the active material is a liquid, typically nitrobenzene, located in a cell between two electrodes. A brief impulse of high voltage is applied to rotate the polarization of the passing light.
For a film-like sequence of high-speed photographs, as used in the photography of nuclear and thermonuclear tests, arrays of up to 12 cameras were deployed, with each camera carefully timed to record sequentially. Each camera was capable of recording only one exposure on a single sheet of film. Therefore, in order to create time-lapse sequences, banks of four to ten cameras were set up to take photos in rapid succession. The average exposure time used was three microseconds.
Funny that they don't mention the film used. The other coincidental thing is that Muybridge used the same technique of a series of multiple cameras firing in sequence to create the first motion picture. I've never heard of the multilayer film you described -- sounds fascinating. It's incredible that they could get exposure times as short as 10 nanoseconds in the 1940s.
It's hard to read anything dealing with the area just west of Area 51, without running across the initials," EG&G". If an effect was detected and measured, they probably made a fortune doing so...
Probably one of the most inventive companies -- ever... (Ever hear of side-scan sonar? Yep -- Doc's baby...)
Probably a fun place to work, too...
I read short bios of Edgerton last night. He was an amazing man. I also found the award winning film he collaborated on, “Quicker n a Wink.”
I remember my Dad brought a strobe light home from his job to show me how it was used on motors. I was about 8 or 9 at the time (1959 or 1960). I didn’t realize or know at the time how new the portable technology was at the time. The unit Dad brought home looked like one of the units used in the film cited above.
Edgerton was a born promoter. After getting married, he and his wife were driving to Nebraska from Massachusetts to visit family. He would stop in towns and call local factory President’s and ask if they had motor problems. The next morning he was often invited in to give a demo. He sold a lot of units to GM. What a great entrepreneurial story.
There are stories that visitors to EG&G's Commonwealth Avenue site in Boston, would frequently feel the floor shake and hear a muted, "thump!", When asked about it, employee would say, "Oh, that's just Doc down in the basement -- playing with his 'thumper'..."
Supposedly, when Edgerton was striving for ever-more powerful electronic flashes, he noticed that, when discharged instantaneously through his flash tubes, the capacitor banks supplying the impulse would emit a loud "THUMP!" When he traced the sound down to loose capacitor plates that were flexing during discharge, he thought, "Hmmm -- wonder what I could do with a capacitor with deliberately-loose plates?" So, he built big, water-filled tanks into the floor of the basement -- and started "playing"...
He soon was creating brief, ultra-powerful sound impulses -- coupled into the water -- and, from that grew both side-scanning sonar and sub-bottom profiling technologies. I remember seeing one of his "thumper" plots of Boston Harbor that showed several shipwrecks -- and the Sumner Tunnel -- beneath its covering of silt...
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IMO, that is invention at its best: "That's weird! Hmmm -- wonder what I could do if I played with with that...?"
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I can't vouch for the source, but, here's an article that hints at some of the "weirdness" that EG&G "got into": "EG&G Profile ...
Great stuff, Tx. Thanks.
I like to read about the history of science, technology and inventors. It is indeed fascinating the number of serendipitous discoveries from profound to silly (cf, Silly Putty).
I like to listen to the BBC podcast “In Our Time.” There is a recent episode about the discovery of chromatography — it’s full of “aha, I wonder...” moments.
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