Mass-energy equivalence and the gravitational redshift: Does energy always have mass?

2024-08-23T03:17:45+00:00

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.

Strong-field nondipole approximation in laser-assisted thermal electron scattering

2024-11-20T01:01:49+00:00

This study investigates the differential cross-section (DCS) of electrons scattered by a hydrogen molecule (H₂) under varying conditions, including temperature, momentum, laser intensity, and polarization. The objective was to understand how these parameters affect electron scattering and to compare the effects of linear and circular polarizations. Methodologically, theoretical model was developed using strong-field nondipole approximation with linear and circular polarized laser fields, examining DCS as a function of thermal electron temperature, momentum, and laser intensity. The study utilized a modified Volkov wave function model to account for thermal electron effects and analyzed DCS variations across different orbitals (n = 1, n = 2, and n = 3). Findings reveal that DCS increases with temperature due to enhanced electron oscillations, with higher orbitals (n = 3) showing greater DCS compared to lower orbitals (n = 1). Increased momentum results in decreased DCS, with higher orbitals exhibiting higher DCS values under circular polarization, contrary to linear polarization. Laser intensity decreases DCS for both polarizations, with circular polarization providing a narrower range of DCS values and generally higher DCS compared to linear polarization. This research further exploration of polarization effects on DCS in different atomic systems and extending studies to higher energy regions for a comprehensive understanding of electron scattering dynamics.

Insight - Physics

Mass-energy equivalence and the gravitational redshift: Does energy always have mass?

Strong-field nondipole approximation in laser-assisted thermal electron scattering