Quantum paradoxes continue to confuse physicists

Two new experiments have surprised physicists: they show that the Standard Model is not fully understood. Duality in elementary physics is more widespread than is thought, while it is proven that a single particle can cross two parallel paths at the same time.

Two recent experiments have increased the paradoxes of quantum mechanics, showing that this field of physics still hides great surprises.

The first experiment, carried out in the Niels Bohr Institute, he has discovered a surprising new duality in theoretical particle physics. Leadered by Matthias Wilhelmthis research proved that there is something about the intricate details of the Standard Model of particle physics that is not fully understood.

The study is based on Young’s experiment, better known as the double slit experiment, conceived in 1801 by Thomas Young to find out the corpuscular nature of light. This experiment has been basic to demonstrate the wave-particle duality of quantum mechanics.

The wave-particle duality it is a concept of quantum mechanics according to which there are no fundamental differences between elementary particles and waves, since particles can behave like waves and waves like particles.

The mystery of the double slit

What happens in the double slit experiment? Well, a particle encounters a wall that it cannot go through, but it takes advantage of the fact that it has two slits and then it slips through them, changing its corpuscular nature for another of a wave. It then regains its original nature and behaves like a particle, even leaving a measurable footprint.

The new study uncovered a similar duality that it hasn’t been able to explain. It is based on the collisions of protons that are caused in the Large Hadron Collider: these protons contain many smaller elementary particles, gluons and quarks.

When proton collisions occur, two gluons from different protons can interact and create new particles, such as the Higgs boson, resulting in entangled patterns that end up reflected back to the detectors.

In the observation of these processes, the surprisewhich Wilhelm explains thus: “we calculate the scattering process of two interacting gluons to produce four gluons, as well as the scattering process of two interacting gluons to produce one gluon and one Higgs particle”.

classical duality

He adds: “To our surprise, we found that the results of these two calculations are related. A classic case of duality. Somehow, the response to the probability of one dispersal process happening carries with it the response to the probability of the other dispersal process happening.”

He also highlights that “the strange thing about this duality is that we don’t know why there is this relationship between the two different scattering processes. We are mixing two very different physical properties of the two predictions, and we see the relationship, but it is still a mystery where it lies.” the connection,” emphasizes Wilhelm.

here lies a new quantum paradox: According to what is known today, the two dispersion processes should not be connected, but after the discovery of this surprising duality, the only proper way to react is investigate further, conclude the researchers from the Niels Bohr Institute, adding however that the result obtained may help to discover the new physics. The results of this research are published in the journal Physical Review Letters.

The S18 laboratory at the Institut Laue Langevin (ILL) in Grenoble, where the second quantum paradox was discovered. Laurent Thion, ILL

Second new paradox

The second new paradox is just as or more surprising than the first and confirms that quantum physics is once again right: it has verified that a single neutron moves along two paths simultaneously, in clearly quantifiable proportions.

Made by the Technical University of ViennaEast study also part of the double slit experiment, and comes to correct an old defect of this paradox.

It focuses on the track left by the particles as they pass through the double slit: once passed, the back wall reflects the impacts of the particles into which they have become again, but they do not clump together randomly (as might be the case). expected), but following an order that would be determined by its wave behavior. That order is called interference pattern.

This interference pattern is what allows the researchers to measure the particle that has crossed the double slit, but with one caveat: they cannot be measured by a single impact, but by considering a series of impacts from which the individual measurement is statistically extracted.

Variant in the slits

The new research, conducted in the Laue-Langevin Institute of Grenoblewhich has one of the most intense neutron sources in the world, simplifies this task for scientists: it developed a variant of the double slit experiment and got the exact measurement of a single neutroneven though he had simultaneously passed through the two slits without losing his individuality.

The statistical arguments of the classic experiment were not needed to describe not only the passage of the neutron through both slits, but also how it was distributed between both slits to emerge intact after overcoming the obstacle. The results are published in the journal Physical Review Research.

Both experiments ratify what the American theoretical physicist and Nobel Prize winner Richard Feynman he said in 1964, when he surprised the world with this phrase: “I think I can say with complete certainty that nobody understands quantum mechanics”. A reflection that, almost 60 years later, is still a reality.


Folding Amplitudes into Form Factors: An Antipodal Duality. Lance J. Dixon et al. Phys. Rev. Lett. 128, 111602; 15 March 2022. DOI:https://doi.org/10.1103/PhysRevLett.128.111602

Quantifying the presence of a neutron in the paths of an interferometer. Hartmut Lemmel et al. Phys. Rev. Research 4, 023075; 27 April 2022. DOI:https://doi.org/10.1103/PhysRevResearch.4.023075

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Quantum paradoxes continue to confuse physicists