# Universe question **URL:** \ **Category:** Factual Questions\ **Created:** [December 19, 2002, 4:58pm UTC](https://boards.straightdope.com/t/universe-question/143826 "2002-12-19T16:58:01Z")\ **Posts on this page:** 2\ **Page:** 2
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [December 20, 2002, 8:33pm UTC](https://boards.straightdope.com/t/universe-question/143826/21 "2002-12-20T20:33:08Z")
> [@](#): > > \*Originally posted by MC Master of Cermonies \* > \*\*1. Yes, light has relativistic mass (but must have zero rest mass for quantum physics to work) > > 1. what do you mean by ‘measurable’ universe? mass cannot leave the universe as it has no boundaries. \*\* I understand your first point. 2. By “measurable”, I meant “what we can measure”. Seriously, there must be some general agreement as to how much matter exists/existed in the universe. Don`t computer models of the big bang use such guestimates? How is the mass of light dealt with in such physics? ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [December 20, 2002, 11:36pm UTC](https://boards.straightdope.com/t/universe-question/143826/22 "2002-12-20T23:36:13Z")
Estimates of the universe’s weight vary wildly but there is some general agreement. Slight changes in a big bang model at the early stages will lead to huge changes later in time. I don’t know how the (relativistic) mass of light is dealt with, it represents there knetic energy (E=mc^2) and I honestly can’t say that I know if the combined mass is big enough to take into consideration. [Previous page](https://boards.straightdope.com/t/universe-question/143826.md?page=1)