This would have been SO MUCH MORE useful, thought provoking, and enjoyable if, perhaps, English subtitles were provided for Tibetan speech. The English is translated for them, for the most part, but those of us who do not speak Tibetan are completely excluded from their conversations that occur in Tibetan (as Anton points out at one point).
The answer is the density of space is constant but the molecular density is not constant; therefore there is a difference in measurement that is atomically random. In other words think of above the water line and under the water line; or atmospherically different sub-structures. Imagine moving through the air and then in the water to understand the difference. Photons will behave the same way as any material moving through different densities. Put that in your pipe and smoke it...LOL
Este fenómeno é tão simples de explicar. Estes cientistas atrasadinhos só sabem lançar confusão e meias palavras para o ar sem saber explicar claramente uma coisa tão simples. Que conversa mais ignóbil. Uma hora para explicar uma coisa tão fácil. Espero que não sejam professores.
