“There were tremendous blast effects,” wrote Groves two days later in a memo to the Pentagon. “For a brief period there was a lighting effect within a radius of 20 miles equal to several suns in midday; a huge ball of fire was formed which lasted for several seconds. This ball mushroomed and rose to a height of over ten thousand feet before it dimmed. The light from the explosion was seen clearly at Albuquerque, Santa Fe, Silver City, El Paso, and other points generally to about 180 miles away.”
The Nuclear Legacy: Honoring the WWII Generation of Scientists and Engineers
In total, the Manhattan Project mobilized more than 130,000 scientists, engineers, and skilled workers across a nationwide network of facilities. Among the most prominent were Los Alamos, Oak Ridge, Hanford, Chicago, and Ames—locations that became the bedrock of today’s National Laboratory system and continue to lead in nuclear science, energy innovation, and security.
The Manhattan Project’s origins trace back to an urgent August 1939 letter from Leo Szilárd, signed by Albert Einstein, warning President Franklin Roosevelt that Nazi Germany might develop “extremely powerful bombs” using uranium physics. Just months earlier, nuclear fission had been discovered and verified.
The critical breakthrough for the Manhattan Project came on December 2, 1942, when Enrico Fermi and his team achieved the first self-sustaining nuclear chain reaction beneath the stands of Stagg Field at the University of Chicago. This successful demonstration of controlled nuclear fission in the world’s first artificial reactor, known as Chicago Pile-1, proved that nuclear energy could be harnessed.
As we mark the 80th anniversary of the Trinity Test, we honor the scientific and industrial achievements that ushered in the nuclear age. We salute the World War II generation of nuclear pioneers who, under the existential threat of global war, laid the foundations for a sustainable, technologically advanced civilization—as President Dwight Eisenhower envisioned in his 1953 Atoms for Peace speech to the United Nations.
As Eisenhower declared, “Experts would be mobilized to apply atomic energy to the needs of agriculture, medicine, and other peaceful activities. A special purpose would be to provide abundant electrical energy in the power-starved areas of the world.”
“The United States knows that peaceful power from atomic energy is no dream of the future. The capability, already proved, is here today.”
The Human Cost: Remembering the Downwinders, Hiroshima, and Nagasaki
Yet any commemoration of the Trinity Test must be accompanied by a sober acknowledgement of its human and environmental costs. We recognize the Trinity Test “downwinders”—families, farmers, communities, and even a nearby girls’ summer camp—who received no warning, were lied to, and suffered lasting health effects and premature deaths from Trinity’s fallout. Their experiences remain an inseparable part of the Manhattan Project’s legacy.
In the weeks ahead, we will also mark the 80th anniversaries of the bombings of Hiroshima and Nagasaki, Japan, on August 6 and August 9, 1945. We will commemorate the more than 200,000 lives cut short in those cities and the generations forever changed by the swift, final chapter of the deadliest conflict in human history. We must stand by the solemn inscription on the Hiroshima Peace Memorial: “Let all the souls here rest in peace; for we shall not repeat the evil.”
No nuclear weapon has been used in conflict since the end of WWII. Today, the Cold War’s legacy of deterrence shapes our world, but geopolitical tensions test our global nonproliferation commitments and safeguards. The mission of the International Atomic Energy Agency, along with global adherence to the Treaty on the Non-Proliferation of Nuclear Weapons, remains more crucial than ever.
Nuclear Technology Today: Powering and Healing Lives
Despite its military-driven beginnings, nuclear technology has delivered on its postwar promises of powering cities and treating disease. From clean electricity and lifesaving medical therapies to food safety, manufacturing, naval propulsion, and space exploration, nuclear technology continues to improve—and save—lives at scale.
Radiation therapy alone contributes to the long-term survival of millions of cancer patients around the world, contributing to the care of 50 to 60 percent of all diagnosed cases. If every cancer patient who needs radiation therapy had access to it, more than 1 million additional lives would be saved every year, according to a study published in Radiotherapy & Oncology.
And according to a study by Pushker Kharecha and James Hansen, nuclear power prevented more than 1.8 million premature deaths between 1971 and 2009 by displacing air pollution from fossil fuel combustion.
These lifesaving applications are the reasons the American Nuclear Society exists.
Since its founding in 1954 by veterans of the Manhattan Project, including most prominently Alvin Weinberg, the American Nuclear Society has remained committed to advancing nuclear science and technology for the betterment of humanity. For the succeeding 70 years, our members have worked tirelessly to ensure that, in Eisenhower’s words, “the miraculous inventiveness of man shall not be dedicated to his death but consecrated to his life.”
*5:29:45 a.m. Mountain War Time (MWT). MWT was the World War II–era equivalent of daylight saving time, used from 1942 to 1945. The detonation occurred at 7:29:45 a.m. Eastern Daylight Time and 11:29:45 a.m. Greenwich Mean Time (UTC).
