The most destructive man-made force in the history of the planet exploded for the first time 75 years ago today:
On July 16, 1945, at 5:29:45 a.m., the Manhattan Project comes to an explosive end as the first atom bomb is successfully tested in Alamogordo, New Mexico.
The scientists and a few dignitaries had removed themselves 10,000 yards away to observe as the first mushroom cloud of searing light stretched 40,000 feet into the air and generated the destructive power of 15,000 to 20,000 tons of TNT. The tower on which the bomb sat when detonated was vaporized.
The Alamogordo blast tested the "Fat Man" implosion design that compressed two hemispheres of Pu-239 around a U-235 trigger through a perfectly-timed set of high explosive detonations around the sphere. This resulted in almost 40% more yield than the gun-type "Little Boy" design that exploded over Hiroshima, Japan, three weeks later. The second "Fat Man" exploded over Nagasaki, Japan, three days after that.
In 1952, the United States demonstrated a fusion bomb that produced 450 times more yield than the Nagasaki explosion, igniting an arms race that ultimately led to the USSR developing a 100 MT "Tsar Bomba" that, were it detonated over O'Hare, would produce a fireball completely vaporising the airport and surrounding villages, would destroy any masonry or wood-framed buildings from Mundelein to Oak Lawn and St Charles to the Loop, and would cause third-degree burns to any exposed flesh in a 74 km radius encompassing Kenosha, Channahon, De Kalb, Gary, and more than halfway across Lake Michigan.
The half-strength (!) Tsar Bomba tested on 30 October 1961 remains the most destructive weapon ever demonstrated on earth.
The United States remains the only country to have prosecuted a nuclear war against another country.
In a side note, the nuclear bombings of Hiroshima and Nagasaki killed an estimated 100,000 people outright and perhaps another 50,000 people over the following year due to secondary effects like radiation sickness and disease. This is only 10,000 more than the number of Americans killed by Covid-19 since March.