Archive of March 2015

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?


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