Soroush Salehian raised both arms and spun in circles as if celebrating a touchdown.
Across the room, perched on a tripod, a small black device monitored this little dance and streamed it to a nearby laptop. Salehian appeared as a collection of tiny coloured dots, some red, some blue, some green. Each dot showed the precise distance to a particular point on his body, while the colours showed the speed of his movements. As his right arm spun forward, it turned blue. His left arm, spinning away, turned red.
“See how the arms are different?” said his business partner, Mina Rezk, pointing