Physics Stack Exchange Question

I posted a [Physics Stack Exchange]( question about mass being lost in the universe and a possible consequence on the expansion of the universe. The original question was: How confident are we that mass is not being lost in the universe? After reading about the latest super-massive black hole in [Nature 518, 512–515 (26 February 2015)](, I couldn't help but wonder if the accelerating expansion is a result of mass being lost. My reasoning is as follows: 1. If the early universe had a particular (greater) mass than at present, 2. Then "space-time" could have had a "momentum" (determined by that mass) [1], 3. And that post-big-bang expansion was being retarded by existing mass [2], 4. But since then mass has been lost to the universe [3] 5. Which reduces the (retarding) due to gravity (less mass) [2] 6. Resulting in the "space-time" of the universe expanding faster [4] I was never a cosmologist, so please point out which of my assumptions are provably invalid! [1] Does spacetime have a "mass" value? or What is "Spacetime" made out of? [2] I'm struggling to remember my undergrad physics - would two particles each with an initial velocity moving away from each other in a gravitational field (relatively) speed up if the gravitational field is reduced? [3] Major assumption on my part! [4] Maybe! So I guess there are two questions here: A. How confident are we that mass is not being lost in the universe? and B. Would such a mass-loss be able to explain the observed accelerating expansion? --- It's been interesting to see how the question was edited down, and the resulting discussion!
@ 07:46 PM on March 19 | 0 Comments