According to the Many Worlds Interpretation of quantum physics, we live in an infinite web of alternate timelines. It's a serious claim that carries some rather serious scientific, philosophical, and existential baggage. And here are the nine weirdest possible implications.
In his book The Fabric of Reality, physicist David Deutsch presents four key concepts which define the universe: quantum theory, computation, evolution by natural selection and Popperian epistemology. Deutsch calls these four concepts the strands of the fabric of reality.