“Here are the most common reasons for calling quantum mechanics weird. We’re told it says that: • Quantum objects can be both waves and particles. This is wave-particle duality. • Quantum objects can be in more than one state at once: they can be both here and there, say. This is called superposition. • You can’t simultaneously know exactly two properties of a quantum object. This is Heisenberg’s uncertainty principle. • Quantum objects can affect one another instantly over huge distances: so-called ‘spooky action at a distance’. This arises from the phenomenon called entanglement. • You can’t measure anything without disturbing it, so the human observer can’t be excluded from the theory: it becomes unavoidably subjective. • Everything that can possibly happen does happen. There are two separate reasons for this claim. One is rooted in the (uncontroversial) theory called quantum electrodynamics that Feynman and others formulated. The other comes from the (extremely controversial) ‘Many Worlds Interpretation’ of quantum mechanics. Yet quantum mechanics says none of these things. In fact, quantum mechanics doesn’t say anything about ‘how things are’. It tells us what to expect when we conduct particular experiments. All of the claims above are nothing but interpretations laid on top of the theory.”