Hiroshima denial theory collides with 6.2 kg of plutonium

Hiroshima, Nagasaki and the 16% of plutonium that doesn't add up

What if the two cities destroyed in 1945 did not fall to a nuclear device? The theory denying the atomic bomb resurfaces with the same repertoire: 60,000 dead in each city, a figure compared without hesitation to Dresden, four photographs marked as "verified" on Wikipedia, tests mistaken for trucks loaded with 2,000 kilos of explosive, and the suspicion that no one has ever seen the device except in propaganda videos. The alternative hypothesis even has a catalogue: massive conventional bombing, ammunition depots detonating in a chain, or ships full of uranium docked in two ports.

What is striking is not that the claim is made. What is striking is that it is presented as the most coherent option. That is where a contest begins between two ways of looking at the evidence: the one demanding to see the bomb with one's own eyes, and the one content with the physics adding up.

What does the theory denying the atomic bomb claim?

The hard version asserts that Hiroshima and Nagasaki were destroyed with conventional explosives, just like Dresden or Tokyo — the latter with phosphorus bombs dropped on a city of wood and wind, a massacre that did not intimidate the Japanese command in the slightest. The mushroom cloud images would be controlled tests and the rest, set dressing. As a comparison of destructive power, the more than 35,000 civilian deaths recorded in Gaza with conventional weaponry are cited.

There is a more elaborate variant: the Japanese leadership itself would have blown up both cities to have a pretext for surrendering to Washington without losing face and, above all, without ending up carved up with Moscow. Hiroshima and Nagasaki, the argument goes, were ports with a mostly Christian population, treated as second-class. Another branch points to bomb ships: two ports, plenty of ammunition, and a blast of similar consequences.

All of them share a framework: the bombs were a good deal for the elites of both countries. Japan gained an alibi, the United States emerged as the sole victor, and the history books would not have to record that the USSR had advanced through Manchuria in two weeks what took others years. None of these hypotheses has, to this day, any documentary or physical evidence to support it.

Little Boy's 1.4% and Fat Man's 16%

Here the matter stops being narrative and becomes arithmetic. Of Little Boy, it is estimated that only 1.4% of the uranium actually fissioned. Of Fat Man, 16% of the plutonium. The bombs were, forgive the expression, an enormous waste of material. That fits a real, crude device, not a laboratory fantasy.

Fat Man's parameters are on the table: 6.2 kilos of plutonium, 90% enrichment of plutonium-239, and a density of 19,800 kilos per cubic meter. With the radius of the nucleus (7×10⁻¹⁵ meters), the cross-sectional area is calculated and, from there, how many fissions are needed to sustain a chain reaction before the core disassembles itself. The step-by-step derivation, with each term and its result, leads to a figure that unsettles anyone expecting total yield.

The most repeated counterargument goes in another direction: if uranium from a power plant, enriched to around 3%, powers cities, submarines and aircraft carriers, a fuel with purity close to 97% should behave differently. The technical answer — a power plant releases energy slowly, a bomb releases it all at once — does not convince those who have already decided it is all a scam. No data will do there.

Einstein's letter turned into proof of bomb ships

The star document of this current is the warning about the possibility of a chain reaction in a large mass of uranium. It describes a bomb transported by ship and detonated in a port, capable of destroying the port and part of the surrounding territory, and warns that such devices might prove too heavy for air transport. From there to claiming that Hiroshima was bomb ships is a considerable leap: a theoretical prediction is not a damage report.

It is worth separating two things the theory deliberately mixes up. Einstein never took part in the Manhattan Project, and in 1940 US military intelligence denied him the security clearance to work on it. His equation explains the energy released; it does not explain how to build a device. That a physicist was not in the workshop does not prove the workshop did not exist.

Why are tests conducted underground, and what does a seismograph measure?

The question of direct evidence has an uncomfortable answer for both sides: for decades, tests have been underground, among other reasons because surface detonations leave climatic and contamination effects no one wants to repeat. That turns the available evidence into indirect evidence. A seismograph records the event, and its signature differs from that of a conventional charge; anyone can consult the records of a seismic network and compare. How exactly does it differ from a TNT explosion? That is the question the conspiracy version leaves unanswered and the one the technical version dismisses too quickly.

If it wasn't the bomb, why did Japan surrender?

The war was lost long before. The Japanese command had designed an exit: inflicting enough casualties on the United States and positioning the USSR as an intermediary to negotiate an honorable surrender. The plan collapsed when Moscow communicated through several channels that it was breaking the non-aggression pact, and the Japanese saw the Soviet mobilization toward Manchuria. Surrendering to Washington became the second option; the first was not to end up with half the country under Soviet rule and the imperial aristocracy swept away along the way.

From there comes the list used as damning evidence: nuclear powers that lose wars. Korea. Vietnam in 1973. Israel against Egypt and Syria in 1973 and against Lebanon in 2006. China in Vietnam in 1979. The USSR in Afghanistan in 1989. The United States in Afghanistan in 2021. And Ukraine, with Kyiv, Kharkiv and Kherson on Russia's debit side and 600,000 Russian dead and wounded on the table. If the button exists, why does no one press it? The obvious answer — pressing it does not fix the battle and does guarantee retaliation — is not discussed because it is inconvenient.

Seventy-nine years later, the proof that textbook skepticism would accept remains seeing another Hiroshima live. Until that live broadcast arrives, the iodine tablets stay in the drawer, and Fat Man keeps making use of a 16% that, for some, is pure coincidence.