Adapted from a sketch produced during a conversation with a physicist, Andrea Galvani’s neon sculpture is a graphic representation of the relativity of time. It questions the meaning of “now”—illustrating concepts at the heart of Albert Einstein’s theory of special relativity.

Einstein realized that any statement about time is simply a question about what’s simultaneous. This graphic shows a light-source A equidistant from points B and C. Because light travels at a constant speed, observers at both B and C will see the signal at the same time. Observers in a different frame of reference, however, would not perceive the signal simultaneously because the light has to travel a farther distance. Through a thought experiment, Einstein realized that the flow of time is not the same for everyone. It is different depending on how you’re moving through space. If there’s no such thing as simultaneity, time is not absolute.