Classical Physics and Quantum Physics Can't Come to Terms on Hardy's Paradox

Physicists have provided more validity to Hardy’s paradox, suggesting that the disagreement between Classical Physics and Quantum Physics is even larger than previously thought.

Lucien Hardy is a professor at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

In 1993, Hardy proposed a thought experiment to prove the non-locality principle in quantum physics.

This experiment was first known as Hardy’s paradox. Some argue that it’s not a paradox per se, like say the Einstein-Podolsky-Rosen paradox. In many ways, it’s more of a theorem.

In the Universe, when matter and antimatter meet, particles and antiparticles annihilate one another through a flow of energy in the form of gamma radiation.

Hardy, however, showed that it’s theoretically possible that sometimes (in 6 to 9 percent of cases) when there’s no observer, matter and antimatter can interact and survive the encounter – classical physics cannot allow this.

Toward a Generalized Hardy’s Paradox

Physicists have experimentally demonstrated Hardy’s paradox with two particles. They also believe that it’s also valid with more than two particles, though they couldn’t demonstrate it fully.

Now, an international team of researchers was able to demonstrate Hardy’s paradox with three particles in an experiment that they say could be extended to include “any number of particles”.

With three particles, the odds of researchers observing paradoxical cases increased to an estimated 25 percent.

This experiment suggests that the Hardy paradox could be generalized, which means the schism between classical and quantum theories of physics could be even deeper.

Jing-Ling Chen, coauthor of the study, told Phys.org:

“In this paper, we show a family of generalized Hardy’s paradox to the most degree, in that by adjusting certain parameters they not only include previously known extensions as special cases, but also give sharper conflicts between quantum and classical theories in general. What’s more, based on the paradoxes, we are able to write down novel Bell’s inequalities, which enable us to detect more quantum entangled states.”

Simply put, the goal of Bell’s theorem is to find correlations between two separated particles that are quantumly entangled.

Building on the Einstein-Podolsky-Rosen paradox, Bell showed that the quantum mechanics phenomena can’t be interpreted within a Realistic Local frame.

“Put simply,” Chen explains, “Hardy’s paradox states that a classically impossible sequence of events from end to end—just imagine a snake devouring its tail—as it were, are nonvanishingly possible in the quantum region. This is really surprising.”

The team is planning to further investigate the relationship between Bell’s theorem and Hardy’s paradox.

The results of the experiment are available in arXiv.org.