Conclusion of Symmetry in Photon Momentum Changes:

Soumendra Nath Thakur

February 22, 2024

The effective momentum changes of a photon in an external gravitational field can be described as zero (=0), as outlined in the concept of symmetry in photon momentum changes. This symmetry, represented by Δρ = -Δρ, illustrates how changes in photon momentum due to gravitational effects are symmetrically balanced, resulting in an overall equilibrium. As photons traverse through external gravitational fields, such as the gravitational well of a massive object, they experience momentum exchanges that lead to phenomena like blueshift and redshift. These exchanges occur as the photon follows an arc path, with momentum gradually increasing upon entering the influence of the massive object and gradually decreasing upon exiting it. Consequently, the net effect of these momentum exchanges is zero, ensuring conservation of momentum in the interaction between photons and external gravitational fields. 

Reference: [1] (PDF) Exploring Symmetry in Photon Momentum Changes: Insights into Redshift and Blueshift Phenomena in Gravitational Fields, ResearchGate http://dx.doi.org/10.13140/RG.2.2.30699.52002