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Scientists just rewrote what we thought we knew about light. For nearly 180 years, scientists assumed the magnetic component of light was too weak to matter. That assumption has just been overturned. Researchers at the Hebrew University of Jerusalem have discovered that light’s magnetic field plays a far more influential role than previously believed—particularly in the Faraday Effect, where light’s polarization rotates as it passes through a magnetic field. Until now, this rotation was thought to be driven almost entirely by light’s electric field. But new theoretical models and simulations reveal that the magnetic field can directly torque matter, meaning it doesn’t just pass through—it interacts. In experiments involving Terbium Gallium Garnet, a crystal sensitive to magnetism, the team found that in the infrared spectrum, light’s magnetic field accounts for up to 70% of the polarization rotation, and 17% in the visible range. This fundamentally shifts our understanding of how light behaves and interacts with materials. Not only does it rewrite optical physics first laid down by Michael Faraday in 1845, but it also opens new pathways for technology. From quantum computing to light-sensitive materials and magnetic memory systems, the magnetic side of light may now power the next generation of optical innovations. Source: Mazuz-Harpaz, Y., & Fleurov, V. (2025). Faraday effects emerging from the optical magnetic field. Scientific Reports.