Hatches of Rocky Mountain locusts (Melanoplus spretus) in 1874 and 1875 brought swarms up to 1,800 miles long and 110 miles wide across the Great Plains. Numbers were estimated in the trillions. Farmers risked starvation. The swarm is believed to have been the largest mass of living insects ever witnessed by modern man—but within thirty years the species disappeared. “I can’t believe M. spretus is extinct,” said ecologist Dan Otte in 2014. “But where to look for it?”

The opening of a particle accelerator at Brookhaven National Laboratory in 2000 inspired fears that high-speed collisions might launch a chain reaction that could turn the earth into a hyperdense sphere about one hundred meters across. A risk calculation determined this to be unlikely; if the collider were to run for ten years, the chance was no greater than 1 in 50 million. “The word unlikely, however many times it is repeated,” wrote concerned scientists, “just isn’t enough to assuage our fears of this total disaster.”

“Thank the good God we have all got through and the only family that did not eat human flesh,” wrote fourteen-year-old Virginia Reed, a surviving Donner Party member, in an 1847 letter. “Don’t let this letter dishearten anybody and never take no cutoffs and hurry along as fast as you can.” Reed reported being “pleased with California, particularly with the climate.” 

A 1959 Chicago Daily Tribune article about Robert Frost, who had recently proclaimed his confidence in humanity’s resilience in the face of missile threats, ran with the headline human race bomb proof, poet believes.

When Albert Einstein visited Beno Gutenberg, a seismologist at Caltech, in 1933, the two strolled around the Pasadena campus while Gutenberg explained earthquake science. Suddenly their wives arrived to inform them there had been a massive earthquake. “We had become so involved in seismology,” recalled Gutenberg later, “that we hadn’t noticed.”