(December 3, 2015 at 6:21 am)Quantum Wrote:(December 2, 2015 at 5:35 pm)mh.brewer Wrote: Can you expand upon this please? I don't understand the "removes" part. Removed to where?
The idea is that the universe expands, and you send a photon on its way. Once it reaches the destination, it will be redder, i.e. will have lost energy because the wave was stretched. This way, we seem to lose energy as the universe expands. For example, the photons in the cosmic microwave background which we observe now, had 1100 times the juice when they went on their voyage 13.7 billion years ago. For the question where this energy goes see my post above (note that when we ask the question: "where does the energy go", we implicitely assume that it is conserved, because otherwise it can just vanish or appear without having to "go anywhere").
Thanks. Not sure I totally grasp the concept but believe I have a better understanding.
Being told you're delusional does not necessarily mean you're mental.
