How a time cloak could change the past

How a time cloak could change the past: The demo shows how manipulating the laser beam creates an opportune time gap. Laser pulses, shown in red, break the signal beam, denoted in green, into a rainbow of different wavelengths that travel at different speeds. This change creates an opening in the beam where the ball can pass. The effect is then reversed with another pulse of light to make the change undetectable.