I apologize, I know this all has to be answered in other threads, but when reading through I'm still missing "it"... The whole concept of Dark Energy not conserving energy is of course bothersome. My simple mind has only considered ~3 mechanisms that would give rise to this. Would someone be kind enough to clear up the thought-direction/problems with the lines of thinking. 1) Dark energy comes from the vacuum. Problem is that this approach is essentially creating energy out of nothing, I don't see how an argument like this doesn't break conservation of energy. But it would be uniform in time/space. Of course there is the additional problem that calculations never comes close to matching the expected DE value, but ignore that to start. 2) Dark energy comes from heavier particles that decay, giving off "new" energy. This would require that the energy is stored as mass (which should be noticeable for GR), and would be time dependent like radioactive decay, so 2 strikes right there. So although energy no longer comes out of nothing, I'd assume this is out of the question from the get go. 3) Dark energy comes from our universe expanding into a void. Like a bubble rising through the water. I never really hear this argument made as a possibility, if anything people say that our models don't favor an "outer" void. But this seems to avoid some of the problems of (1) and (2). So its not clear to me why this thought direction is disliked. This is off hand the argument I'd favor, so some clarity on this one would be really appreciated. Best Regards.