Does quantum physics defy causality?

When you combine these two radical features, Hardy said, two simultaneous quantum possibilities will stretch the metric in different ways. The light cones of events become indefinite — and thus, so does causality itself. Most work on quantum gravity elides one of these features.

What is causality violation?

A common justification for prohibiting many unusual phenomena such as faster than light travel is that if they were possible, causality would be violated. Let’s define causality as: You cannot change the past. Meaning that at any given moment t1, it is impossible to influence any event which took place at t0

What does the delayed-choice quantum eraser experiment tell us?

The delayed-choice quantum eraser experiment investigates a paradox. If a photon manifests itself as though it had come by a single path to the detector, then “common sense” (which Wheeler and others challenge) says that it must have entered the double-slit device as a particle.

Is there a classical equivalent of the quantum eraser?

Versions of the quantum eraser using entangled photons, however, are intrinsically non-classical. Because of that, in order to avoid any possible ambiguity concerning the quantum versus classical interpretation, most experimenters have opted to use nonclassical entangled-photon light sources to demonstrate quantum erasers with no classical analog.

Why use entangled photons for quantum erasers?

Furthermore, use of entangled photons enables the design and implementation of versions of the quantum eraser that are impossible to achieve with single-photon interference, such as the delayed-choice quantum eraser, which is the topic of this article. Figure 2.

Why did the Heisenberg uncertainty principle fail in the double-slit experiment?

In the double-slit experiment, conventional wisdom held that observing the particles inevitably disturbed them enough to destroy the interference pattern as a result of the Heisenberg uncertainty principle . However, in 1982, Scully and Drühl found a loophole around this interpretation.