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?

For more than a century, the double-slit experiment has been the sharpest test of what reality is made of, and of whether Albert Einstein or Niels Bohr had the better grasp of the quantum world. Now a ...

Light has always been the stage on which quantum mechanics performs its strangest tricks, and the double-slit experiment is still the star of that show. A new, ultra-clean version of this classic test ...

Schematic of the MIT experiment: Two single atoms floating in a vacuum chamber are illuminated by a laser beam and act as the two slits. The interference of the scattered light is recorded with a ...

Does quantum mechanics allow the future to retroactively influence the past or not? Does quantum mechanics allow the future to retroactively influence the past, as in the infamous delayed choice ...