The robot juggler catches and throws balls in precise rhythm with a human, like two pulsar sending pulses in unison. Juggling three balls is a classic cascade, governed by a steady beat, like the uniform rotation of a cosmic lighthouse. Break the rhythm and the pattern crumbles.

The robot's cameras track the light reflected off the ball: by its changes, photometry instantly determines the position. Algorithms drawing on Isaac Newton's ideas about motion and Henri Poincaré's on complex trajectories predict the flight in a split second. The computational power developed by John von Neumann processes data almost at the speed of light in fiber optics. The robot reacts to the ball as swiftly as a telescope spots an exoplanet by the subtle wobble of a star. This surveillance runs continuously while the ball is in the air for mere moments.

In tests, eight participants — from beginners to enthusiasts — were able to juggle with the robot. One set a record of 20 consecutive catches, another of 40 error-free passes in a row. The machine performed flawlessly, setting the pace with perfect steadiness, never tiring for an instant. This synchronized dance opens the door to assistant robots in the kitchen, on construction sites, or in the operating room, where rapid and precise handovers are crucial. What's more, the robot proved more reliable than a human partner: it never falters and can juggle for hours, like a master metronome, making it an ideal teammate in tasks demanding monotonous precision.