Trinity site open house

It was a stressful 24 hours, logistically, but I was able to get to the Trinity site open house. Everything I own is with me in the van including a few things the Army doesn’t permit.

I was able to secure these items in a locker before heading to Trinity, though the limited hours of access meant I was about an hour late getting to the site.

the queue

The gate opened at 8am and my preference would be to get there before that. By the time I got there around 9am the line for security was a mile long. It moved reasonably fast and I was through (after a cursory check for vans and RVs) in about 45 minutes.

The parking area is a little ways from ground zero, and the biggest remaining chunk of Jumbo (proposed fizzle containment) sits right outside the gate separating the lot from the walk to GZ. Before being blown up later with conventional materials the object weighed 214 tons (!!)

At the time, it was the heaviest item ever shipped by rail - wiki

ground zero

monument far monument near

The GZ monument is made of igneous rocks from the nearby hills, which explains why it looks so different from the local geology (and different from Trinitite).

The crater and trinitite features have been filled in with sand over the years. There is a Trinitite viewing structure in the area but is closed due to the fill-in.

The Ranch House where the physics package was assembled was not accessible due to recent storms (flooding?). I couldn’t have gone anyhow because dogs aren’t allowed on the bus-access-only trip.

Update: I made a panorama of GZ facing roughly east. The viewing structure is to the left/north. The monument is center/east. Entrance to GZ with people walking in/out is center-right (SE). Parking area is is the distance to the right (south); you can make out the larger vehicles against the darker mountain.



The thing that strikes me about this event is the intellectual brilliance required. They were standing on the shoulders of Fermi and the half-watt Chicago Pile #1 reaction, but the math and timing involved is brain-melting. Reactors can be ramped up over minutes, hours, or days. Bombs are more time-sensitive, needing to complete the necessary reactions in microseconds before the bomb disassembles itself (as they tend to do).

It looks like yield estimates were generally lowballed:

The observers set up a betting pool on the results of the test. Edward Teller was the most optimistic, predicting 45 kilotons of TNT. Ramsey chose zero (a complete dud), Robert Oppenheimer chose 0.3 kt… Kistiakowsky 1.4 kt and Bethe chose 8 kt.. Rabi, the last to arrive, took 18 kilotons of TNT (75 TJ) by default, which would win him the pool.

The official estimate for the total yield of the Trinity gadget… is 21 kilotons… A re-analysis of data published in 2021 put the yield at 24.8 kilotons.

And a bit of dark humor…

Enrico Fermi offered to take wagers among the top physicists and military present on whether the atmosphere would ignite, and if so whether it would destroy just the state, or incinerate the entire planet.


I have a van service appointment on the 6th. I’m staged in the mountains east of Alb at 7200ft until then.

After months of no OTA a scan showed 73 channels (!) and the Pi-based DVR is slurping hungrily.


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