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Not to take anything away from their achievement, but they're cheating kinda. It's not actually a picosecond movie camera.

There is no way to capture enough light to register an image on any current or foreseeable technology in one picosecond. The exposure is so brief that it would appear as a completely black frame. So what they actually do is shoot millions of 100 picosecond pulses of laser light at the water bottle and do a mathematical integration of the data.

A 100 picoseconds pulse of laser light is about three centimeters long. Since a single frame exposed for one picosecond is too dark to register an image, what they do is a carefully choreographed temporal dance, shooting a frame, then waiting for that burst of light to exit the water bottle. Then the laser emits the next 100 picosecond burst. When this next burst reaches the exact spot the previous burst was at when the previous image was captured, they make another picosecond exposure. They repeat this many times, then they digitally add together all the frames into a single frame in the final video. This integration reinforces the very dim three-centimeter burst of light until it registers sufficiently to be seen clearly. Astronomers use a similar technique to image very dim objects in the sky.

Next they advance the clock one femtosecond (the time it takes light to travel a fraction of a millimeter) and repeat the process to arrive at the second frame of the final video. Over and over until they assemble the whole video.

So each individual frame in the final video is not a picture of a 100 picosecond burst of light. It's the integration of hundreds of separate 100 picosecond bursts of light all shot when they reached the exact same spot in the water bottle.

This takes nothing away from their impressive achievement. I'm just clarifying the details because, well, I like clarity.

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