nomadreid

Gold Member

- 1,334

- 113

## Main Question or Discussion Point

I am missing something basic here. In https://en.wikipedia.org/wiki/Negative_energy, it is stated that "a universe in which negative energy dominates will either expand indefinitely or...." But gravitational potential energy is negative, so if I make the substitution, I would get "a universe in which gravitational energy dominates will either expand indefinitely or...", but a universe in which gravity dominates would collapse, no? The only way I see out of this is if the original excerpt means "a universe in which

*a negative change of energy*dominates will either expand indefinitely or...", since changing negative energy would be balanced out by increasing kinetic energy (although, given that the conservation of energy does not necessarily apply for the universe as a whole, so one should better say that each local section of the universe would increase in kinetic energy). But increasing kinetic energy is not enough....after all, if (a section of) the universe is contracting, it could also be doing so at an accelerated pace (until the singularity). Please correct me. Thanks.