[Off-topic] Requests author discusses MentalHealthError exception

[Marko Rauhamaa]

Gregory Ewing <greg.ewing at canterbury.ac.nz>:

> Mass on its own is not a conserved quantity. The thing that's
> conserved is total energy.

Similarly, momentum is conserved.

Whether mass is conserved or not depends on the chosen terminology.

> As far as I know, there are no negative masses anywhere in any of our
> current theories of physics, nor have we observed anything that would
> suggest the need for such a thing.

What is not known is how antimatter is affected by gravity: <URL:
http://news.berkeley.edu/2013/04/30/is-antimatter-anti-gravity/>.


Marko