Stressing out a solid block can actually create 'anti-particles' you can see.
April 17, 2026
Original Paper
Hydrodynamic Analog of the Klein Paradox: Vacuum Instability and Pair Production in a Linear Elastic Medium
arXiv · 2604.14378
The Takeaway
The Klein Paradox is a mind-bending prediction where particles can pass through impossible barriers by turning into antimatter. Usually, this requires insane energy, but researchers just recreated it using a simple elastic material. By putting 'supercritical' stress on the material, they generated mechanical versions of antiparticles. It is like pushing on a wall so hard that it doesn't break, but instead spawns a 'ghost' version of itself to move through you. This makes one of the most abstract theories in physics something we can actually touch and observe in a lab.
From the abstract
The Klein Paradox -- the anomalous scattering of relativistic fermions off a high potential step -- signals the limit of the single-particle interpretation of the Dirac equation. While Quantum Field Theory (QFT) resolves this via pair production, the microscopic mechanism is often obscured by abstract formalism. In this work, we investigate this phenomenon through the framework of Analog Gravity and Condensed Matter Physics. We utilize a hydrodynamic model wherein a relativistic particle is trea