Computer-generated image of DNA molecule

Image by Mehmet Pinarci (CC BY 2.0)

Image of an electric street railway car

A preserved street railway car at the Seashore Trolley Museum, Kennebunkport, Maine • Photo by Rene Schwietzke (CC BY 2.0)

Image of a model of a stereotypical "space alien"

Photo by Stephen Leonardi on Unsplash

Image of pair of shoes with untied laces

Photo by Lukas from Pexels

Image of modern bullet train

A Japanese bullet train • Photo by Fikri Rasyid on Unsplash

Image of New England forest

Photo by Ning Shi on Unsplash

Close up image of an old Macintosh computer

Photo by Matt Mech on Unsplash

Image of man in dirty overalls next to pile of graphite bricks

The world's first nuclear reactor was within a pile of graphite bricks • (Public Domain)

Chicago, December 1942

Physi­cist Albert Wat­ten­berg was pok­ing about in the Chica­go branch of the Nation­al Archives recent­ly. He was look­ing for arti­facts used by Enri­co Fer­mi and his team of nuclear physi­cists in achiev­ing the first self-sus­tain­ing nuclear reac­tion in a squash court under the Uni­ver­si­ty of Chicago’s foot­ball sta­di­um in Decem­ber 1942.

Image of bored woman reading books

Photo by Andrea Piacquadio from Pexels

Image of two frogs mating

Atelopus frogs pondering the universal mystery • Photo by Brian Gratwicke (CC BY 2.0)