On Sunday, Aug. 9, 1945, at 11:02 a.m., a U.S. Air force B-29 named Boxcar opened its bomb-bay doors and dropped its cargo, a plutonium bomb nicknamed “Fat Man,” over the city of Nagasaki, Japan.

The blast, which was 40 percent greater than the bomb dropped on Hiroshima three days earlier, vaporized an estimated 40,000 men, women and children (an additional 60,000 were injured). By January 1946, the number of deaths was estimated to approach 70,000. Many died from burns or leukemia.

In addition, 14,000 homes were destroyed and 5,400 were seriously damaged. The day after the bomb was dropped, the emperor of Japan overruled his military leaders and forced them to surrender (almost) unconditionally and ended World War II.

Sixty-nine years later, almost every day, our newspapers and televisions run stories about nuclear weapons to the point that the unspeakable horror of those weapons has been marginalized. We have become numbed to their demonic character.

As a young ensign in the U.S. Navy, I visited Japan as part of the Navy’s technical mission to Japan, and I visited Nagasaki a few weeks after “Fat Man” had been dropped.

The memory of the horror is seared on my brain — the impression is still vivid. Even after 69 years, I recall that, if a chair could have been found, I could have stood on it and seen the whole city, which was reduced to, well, nothing. Where houses and buildings had stood, the only remains were formless puddles of congealed glass that must have been windows.

The possibility of a nuclear war lay heavily on the conscience of Dr. Bernard Lown of the Harvard School of Public Health. In 1980 he, along with Dr. Yevgeny Chazov of the USSR Cardiological Institute, who shared his concern, founded a group called the International Physicians for the Prevention of Nuclear War (IPPNW), and encouraged their fellow physicians, nurses, and others in the health care industry and private citizens to join the organization and support its goal of ridding the world of nuclear weapons.

When my wife, Bette, and I heard of the organization, we joined and have supported it ever since. We have attended two of its international congresses. In 1985, the IPPNW was awarded the Nobel Peace Prize. When the prize was announced, Mikhail Gorbachev of the Soviet Union immediately invited its founders to the Kremlin to discuss how the world could be freed of nuclear weapons.

As an aside, then-U.S. President Ronald Reagan never even acknowledged the IPPNW for its award.

In 1987, Bette and I attended an IPPNW World Congress in Moscow. Speakers included astronomer Carl Sagan; Pulitzer Prize-winning author E.L. Doctorow; a young congressman from Tennessee named Al Gore, who had traveled at his own expense and political risk; and a host of distinguished scientists, writers, thinkers and religious leaders from around the world.

Our government almost ignored the meeting. Today, the IPPNW is active in working for its goal of ridding the world of nuclear weapons.

Currently, the Nuclear Club (possessors of “the bomb”) has spread to at least six countries, and humanity is faced with the addition of possibly two more.

When notified of the bombing of Hiroshima, J. Robert Oppenheimer, the scientific director of the Manhattan Project, which built the bomb, remorsefully said, “I have become death, destroyer of worlds.”

In his notes, Albert Einstein penned, “I know not what weapons World War III will be fought with, but World War IV will be fought with sticks and stones.”

For information about the International Physicians for the Prevention of Nuclear War, visit IPPNW.org.