In the late 1970s, legendary physicist John Wheeler proposed a radical question: Exactly when does the universe notice that we're paying attention to a quantum experiment? And does it really matter?

In quantum world, particles like photons can behave like particles (localized points) or waves (spreading out, showing interference patterns). The classic double-slit experiment is a good ...

The theoretical physicist John Wheeler once used the phrase “great smoky dragon” to describe a particle of light going from a source to a photon counter. “The mouth of the dragon is sharp, where it ...