Thread: Hubble's Law conundrum View Single Post

 Quote by Chronos Bear in mind that expansion increases with cosmological distance. Relative to the star, the planets are receeding at different 'speeds'. Let's say planet A is twice as distant from the star as planet B. This means the recession component of planet A's velocity is twice that of planet B. Now imagine the star is a quarterback, the planets are receivers, and the photons are footballs. The quarterback throws a football to both receivers at the same time at the same velocity. Receiver A is receeding more quickly from the quarterback than receiver B. Which receiver feels more 'sting' upon catching the football?
Here is my conundrum in regards to redshift: I heard energy cannot be destroyed, only converted. But when the universe expands, it's as if someone is poking new universe space in between the old ones and therefore light goes to a longer wavelength. That says the light now has less energy. Where did the energy it used to have before the expansion expanded 5 billion years ago, where did that energy go?