The discussion centers on the theoretical possibility of capturing photons within a perfectly spherical, reflective ball using a Faraday isolator. Participants explore whether continuously pumping light into the sphere would increase its mass, noting that while photons have no rest mass, their energy contributes to the system's relativistic mass. The conversation also touches on the implications of reaching a point where the sphere can no longer accept more photons, speculating about potential outcomes like black hole formation. Ultimately, the consensus is that while the sphere could theoretically gain mass from the energy of the photons, practical limitations and the laws of physics impose constraints on this scenario. The complexities of photon behavior and energy conservation are key points of contention in the discussion.