Barbara Pratt rode inside a reefer container to stop cargo rot

By the 1970s the shipping industry had built refrigerated containers, 'reefers,' to carry perishable produce the way dry cargo already moved — but the reefers weren't working. Food arrived at destination rotten or moldy and no one understood why. As Barbara Pratt, then a new physics graduate hired onto the research team, put it: 'the whole industry was blind to what was happening in transit. ' If only half the load survived, that half got sold and the rest was thrown away, with no way to trace which part of the journey had killed it.

The standard response to a black-box failure like this was to inspect the wreckage at the receiving end and guess backward at a cause — adjust the refrigeration setpoint, try new packaging, blame the grower or the port. Pratt and her research team concluded that guessing from outside the box couldn't work: the failure happened somewhere across weeks of farm, truck, train and ocean transit, and the only way to see it was to be present for all of it, not just its aftermath.

Rode inside the container with 150 sensors to watch spoilage unfold in real time, revealing the condensation cycle that end-of-voyage inspections could never reconstruct.

End-of-voyage inspection sees only the wreckage, not the causal sequence.

Live sensors inside the container captured the day-night condensation cycle.

Seeing the mechanism directly pointed to the airflow fix, not guesswork.

When failure only shows at the end of a black-box process, instrument and ride along with the process itself instead of auditing the outcome.

Their first project traced cocoa beans arriving moldy from the Dominican Republic to a day-night temperature cycle inside the container: daytime heat turned the box into 'a mini oven' that drew moisture out of the beans, and the moisture condensed back onto them as water droplets when night air cooled the container, breeding mold.