The discussion centers on the behavior of gravitons in different media, particularly in relation to how light behaves in various materials. Participants speculate that while photons slow down due to interactions with material, gravitons may pass through without such interactions, as they have not been detected experimentally. The conversation highlights the analogy between electromagnetic waves and gravitational waves, noting that gravitational waves could also experience changes in propagation speed due to the medium's properties, although this effect is expected to be minimal. There is also mention of theoretical frameworks like string theory, which suggest that gravitons could interact differently compared to photons due to their unique characteristics. Overall, the topic remains speculative, with a consensus that more research is needed to understand these phenomena fully.