Exactly. In a certain way, you could call jQuery UI effects a very limited physics engine. I don't think the author is saying everyone should use a physics eng

Exactly. In a certain way, you could call jQuery UI effects a very limited physics engine. I don't think the author is saying everyone should use a physics engine now. I think he means that we should use real-world physics as a guide to making more realistic animations, be it with a simple effects library or a full-fledged physics engine.