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Lost Images from the 1945 Trinity Nuclear Test Restored

spectrum.ieee.org

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Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#51

Post by jodacola »

Enjoyed this article, but was immediately distracted into another rabbit hole from the editor's note on the time zone, which I hadn't heard before:

> If you’d like to pinpoint the instant when the world entered the nuclear age, 5:29:45 a.m. Mountain War Time on 16 July 1945

So, I went digging because time zones have been a weird fascination for me due to dealing with all their annoyances as an engineer, and found this article from 2019 [0]!

From the article:

> In February 1942, Congress implemented a law instating a national daylight saving time to help conserve fuel and "promote national security and defense," which is why it was nicknamed "war time." The time zones were even known as that: Eastern War Time, Pacific War Time, etc.

[0] https://www.war.gov/News/Feature-Stories/story/Article/17791...

edit: grammar

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#52

Post by libraryofbabel »

SoftTalker wrote: post #49
libraryofbabel wrote: post #36

I used to teach a class on the history of contemporary science (WW2-present) and I started the class with Trinity. There’s no other moment better. We know how it turned out, but the people there waiting for the test did not know how it would turn out. The bomb might not have worked. Or it might have ignited a fusion reaction in the atmosphere and destroyed the world. Hans Bethe had sat down and done the calculations…

Was it a single solid core that was imploded? I thought it was at least two non-critical-mass hemispheres, or more, that were smashed together by the conventional explosives/detonators, to create a critical mass.

You’re thinking of the other bomb, the U-235 one, which they didn’t test at Trinity and which was dropped on Hiroshima. That is two separate pieces of Uranium that are slammed together to create a critical mass. The Pu-239 core was a single sphere of metal. It was subcritical until you compress it down with a spherical implosion from explosive charges all around it (from the size of a grapefruit to the size of a lime), at which point it reaches a high enough density to go critical.

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#54

Post by ronnier »

libraryofbabel wrote: post #50
marc_g wrote: post #44

Earlier quoted context omitted.

It's in the TFA, there a photo of a fellow holding a small box thing that looks like a battery from a car or an old box torch.

That’s the one I meant. It’s the core, but in a box, which makes it look even more innocuous, like he is indeed just lugging a piece of industrial equipment around. There’s lots of photos of the actual (unboxed) cores online if you search.

On flight WiFi so searching was a hard but I did find it. Thanks!

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#55

Post by dvh »

russdill wrote: post #53
dvh wrote: post #45

What a coincidence, just yesterday Adam Savage made replica of demon core enclosure seen at: https://spectrum.ieee.org/media-library/black-and-white-phot...

Was actually almost a year ago https://x.com/DJSnM/status/1947293757612994886

1 day ago: https://www.youtube.com/watch?v=V1Y4UR8xqxA

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#56

Post by wk_end »

omgmajk wrote: post #3

Some stunning images, looks like a sun plopped down in the middle of the desert.

Well that's a fusion reaction, but close enough.

Every time I see a photo or video of a nuclear explosion, it's simultaneously the most incredible thing I've ever seen and the single worst thing I've ever seen. I can't imagine what it must have been like to witness it first-hand, with no prior expectation of how monstrous a nuclear explosion would be until there it is in front of you in an instant.

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#57

Post by dennis_jeeves2 »

butlike wrote: post #46
cassianoleal wrote: post #5

> And physicist George Kistiakowsky found himself certain that “at the end of the world—in the last millisecond of the Earth’s existence—the last human will see what we saw.” I highly doubt it. The last human will likely live many years in agony, fighting disease and starvation.

I doubt it. I've ruminated a little on this and what I think is that as people start dying off, the survivors will find a rather pleasant existence before the end. People start dying off, and all of a sudden housing prices go down. There's more parks open. The air feels fresher gradually. It's a gradual decline as human influence tapers off near the end. I think it will be more "The Last of Us" than "Mad Max"

>People start dying off, and all of a sudden housing prices go down. There's more parks open. The air feels fresher gradually.

Ted Kaczynski had a point...

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#58

Post by wat10000 »

libraryofbabel wrote: post #52
SoftTalker wrote: post #49

Earlier quoted context omitted.

Was it a single solid core that was imploded? I thought it was at least two non-critical-mass hemispheres, or more, that were smashed together by the conventional explosives/detonators, to create a critical mass.

You’re thinking of the other bomb, the U-235 one, which they didn’t test at Trinity and which was dropped on Hiroshima. That is two separate pieces of Uranium that are slammed together to create a critical mass. The Pu-239 core was a single sphere of metal. It was subcritical until you compress it down with a spherical implosion from explosive charges all around it (from the size of a grapefruit to the size of a lime…

The gun-type bomb (where a subcritical mass is shot into another subcritical mass) is very simple to build once you have the materials to do it. They didn't think it needed a test since it was pretty obvious that it would work.

The implosion design is tricky. You need to arrange and detonate the explosives precisely to compress the core evenly from all sides, otherwise it shoots out the side or otherwise doesn't go bang the way you want it to. Hence the test.

That trickiness can be a good thing. Almost all modern weapons use the implosion design, partly because it's much safer. With a gun-type design, an accident could easily cause the two pieces to contact each other, resulting in an unwanted detonation. With an implosion design, accidentally setting off the explosives is very unlikely to set them off with the correct timing, so you'll probably just lose the core.

The implosion design is also a lot more efficient. Little Boy used 64kg of uranium. Fat Man used just 6.2kg of plutonium and even got a bigger bang out of it.

Re: Lost Images from the 1945 Trinity Nuclear Test Restored

#60

Post by dist-epoch »

sandworm101 wrote: post #2

I suspect the actual first frames are still classified as they likely evidence detonator tech/performance. So the real first moments of the nuclear age will never be shown. (The high-speed cameras would have started filming shortly before the blast.)

https://reddit.com/r/interestingasfuck/comments/zl72x5/submi...
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