Los Alamos, 1949: the men who built the bomb spent a day arguing about green fireballs

Los Alamos, New Mexico was where the Manhattan Project built the first atomic bombs, and by early 1949 it had spent the better part of a year fielding reports of unexplained aerial phenomena over the laboratory: fast-moving fireballs, most commonly described as green, that resisted easy explanation. On March 22, 1949, the laboratory convened a conference to work through what was going on. PURSUE Release 04 publishes the verbatim transcript.

DOE-UAP-D004 is not a summary or an after-action report — it is the conference transcript itself, recording the back-and-forth of physicists, many of them Manhattan Project veterans, as they tried to converge on an explanation. The leading hypothesis on the table was a shallow-angle, high-altitude meteor stream, bright and low enough to be mistaken for something closer and stranger. Edward Teller, already at work on the thermonuclear research that would later earn him recognition as a father of the hydrogen bomb, offered a different angle: he floated an 'electron phenomenon' as a possible mechanism, distinct from a physical meteoric body.

The room's dissent came from its meteor expert. Lincoln LaPaz, the University of New Mexico meteoriticist brought in specifically because of his expertise, told the conference: 'Nothing like this, to my knowledge, has ever been observed in the case of meteorite drops.' LaPaz's objection carried particular weight because he was arguing against the leading theory in his own field of specialty, not defending it.

The conference adjourned without a consensus — the transcript ends with disagreement intact, not a resolved finding. Release 04 pairs the Los Alamos file with a second Department of Energy document from a related but separate New Mexico nuclear site: Sandia Base, roughly sixty miles to the south, where a 116-page Air Force / Armed Forces Special Weapons Program compilation — released in PURSUE Release 02 — documented 209 sightings of 'green orbs, discs, and fireballs' between 1948 and 1950. The two files describe the same phenomenon, the same state, and overlapping years, at two of the facilities most responsible for the U.S. nuclear-weapons program in that period.

Seventy-seven years later, the transcript stands as a primary-source record of how seriously the country's physicists treated the green-fireball reports at the time: not as a public-relations problem to be managed, but as an open scientific question, argued out loud, that nobody in the room could close.