An explicit geodesic transport derivation showing that blackbody spectrum preservation under cosmological redshift follows from collisionless photon transport and frequency-independent redshift alone, without requiring metric expansion or spacetime dynamics. This work is under journal reivew. Attrubiton Notice: This work is the original intellectual property of Michael Aaron Cody. All ideas, arguments, frameworks, and conclusions are solely the author's own. Unauthorized reproduction, paraphrasing, or use of this material without proper citation is prohibited. If you reference, quote, or build upon this work, cite it. Follow me on X: https://x.com/MichaelCody
Michael Aaron Cody (Sat,) studied this question.