Vol. 7 No. 1 (2024)
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Open Access
Original Research Articles
Article ID: 648
Mass-energy equivalence and the gravitational redshift: Does energy always have mass?by Germano D’Abramo
Insight - Physics, Vol.7, No.1, 2024; 99 Views, 41 PDF Downloads
One of the most widespread interpretations of mass-energy equivalence establishes that not only can mass be transformed into energy (e.g., through nuclear fission, fusion, or annihilation), but that every type of energy also has mass (via the mass-energy equivalence formula). Here, we show that this is not always the case. With the help of a few thought experiments, we show that, for instance, the electric potential energy of a charged capacitor should not contribute to the capacitor’s gravitational rest mass (while still contributing to its linear momentum). That result is in agreement with the fact that light (ultimately, an electromagnetic phenomenon) has momentum but not rest mass.