A measurement set up on photoelectric effect Light is closely integrated with our intellectual, philosophical and scientific discourse. The exact nature of light has remained a mystery since we stepped on earth. Newton postulated the corpuscular theory of light according to which, light comprises of a stream of particles. Around 100 years later, results by Young and Fresnel proved that light is a wave. The idea was further put on a solid theoretical foundation by James Clerk Maxwell who discovered that light comprises of pulsating electric and magnetic fields which propagate in space.

The energy of a wave is associated with its height, which is called its amplitude. However, in photoelectric effect, where light falls on metal and generates current; it is found that the energy of emitted charged particles or electrons is defined by the frequency of light or the number of oscillations per second of the electromagnetic field. These observations, first made by Philipp Lenard in 1902, gave a startling twist to the story! The mystery was finally resolved by Albert Einstein in 1905, while working as a clerk in the Swiss Patent Office in Berne. He presented the revolutionary theory that light can be considered to be comprising of packets of energy or light quanta, with energy proportional to its frequency. This idea forms the central foundation of modern physics, according to which light has a dual nature and can behave like waves or particles, depending on the nature of experiments. Einstein was awarded the 1921 Nobel Prize in Physics.

For over a century, we have been led to believe that Maxwell’s electromagnetic field theory cannot explain the interaction between light and charged particles. In a recent research article, published in the peer reviewed journal, Annals of Physics, from Elsevier, a reputed scientific publication group, Dr. Dhiraj Sinha, a faculty member at Plaksha University, has presented some groundbreaking ideas, which challenge our existing perceptions. He has argued that leading scientists of the time, including Einstein, Lenard and others did not take account of the fact that light has a magnetic field which varies with time and generates an electric voltage. It is an experimental fact that a vibrating magnet near a metallic coil generates an electric voltage. He argues that the magnetic flux of light j, generates a voltage, V=dj/dt over an infinitesimally small change in time t. Thus, an electron of charge e is energised with an energy, W= edj/dt by the magnetic flux of light. Dr. Sinha has used the frequency or phasor domain representation of energy which can be expressed as ejw, where w is the angular frequency of radiation. This magical relationship equals Einstein’s expression of light quanta currently termed the the energy of a photon, ħw, where ħ is the reduced Planck’s constant. Thus, the energy of a photon can be derived starting from one of the basic Maxwell’s equations.

The theoretical discovery resolves a long-standing problem of physics, which considers photons quite detached from Maxwell’s electromagnetic fields, which is rather very silent on quantisation, albeit not completely opposed to it. His theoretical architecture is bolstered by the experimental evidences on magnetic flux quantisation, which are observed in two dimensional electron systems and superconducting loops. Charge quantisation is a standard part of existing formulations of classical physics. By incorporating magnetic flux quantisation, Maxwell's equations spontaneously lead to the idea of a photon.

Modern technology is driven by two key theoretical models of physics. Maxwell's equations govern the operation of electromechanical energy conversion devices like generators and motors along with wired as well as wireless communication. Devices like lasers, solar cells, light emitting diodes etc. operate on the principle of photons of quantum mechanics. Dr. Sinha’s work offers a framework towards a seamless merger of these two parallel technical tracks, while promising immense technological opportunities. For example, it can lead to a radical improvement in enhancing the efficiency of solar cells as we now understand that they rely on the laws of classical electromagnetism.

The work has faced key challenges and faced strong opposition from leading journals in physics. However, a team of faculty members in leading universities vouched strong support for the idea. The lead role was played by Peter Sturrock, Professor at Stanford University, who passed away recently. Other scientists like Jorge Hirsch, Professor Emeritus at University of California, Steven Verrall, former faculty member at University of Wisconsin La Crosse and Lawrence Horwitz, Professor Emeritus at the University of Tel Aviv have expressed strong support for the idea. A leading physicist from Bristol University made an iconic statement, “We learned from Einstein that Maxwell's equations were relativistic forty years before relativity. Now we know that they were already quantum, sixty years before quantum mechanics! I find this amazing.” It can be safely said that this work rewrites the history of light. The argument that light quanta is interwoven into the fabric of Maxwell’s fields through the quantised nature of magnetic flux, eventually leading to the concept of light quant and photons is not just a footnote in physics; it fuses two disconnected theories and worlds. The road to harness light in the years to come, remains wide open.

1. Sinha, D. (2025). Electrodynamic excitation of electrons. Annals of Physics, 473, 169893.(https://www.sciencedirect.com/science/article/abs/pii/S0003491624003002) Dhiraj Sinha is a faculty member at Plaksha University, Mohali, India. He holds a doctorate in electrical engineering from the University of Cambridge, UK. He can be reached at [email protected] (Disclaimer: The above press release comes to you under an arrangement with NRDPL and PTI takes no editorial responsibility for the same.). PTI PWR PWR