The effect is as astonishing as it is hypnotic: a chain of metal beads magically arcs above its container as the beads fall to the ground. The beads in the video, made by Steve Mould, who hosts several BBC science shows, are not magnetic, either.

Pretty cool, huh?

Mould gives us an explanation the video below, which offers a super slow-motion view of the effect. In a nutshell, the gravity-defying effect is the result of inertia: the beads moving out of the glass cannot instantaneously change momentum to follow the beads falling down. Instead, they gradually change course and assume a curved path out of the glass. Notice the little standing-wave kink that forms on occasion, too.

You can really get into the physics in this post on the blog Empirical Zeal by Aatish Bhatia. The explanation is also Bora’s Video of the Week.