While the title may seem to overblow it, showing that negative mass exists may be just that big. After all, as I understand, the primary obstacle to the reality of the Alcubierre Drive or Krasnikov Tubes is the negative energy density requirements. This of course violates certain energy conditions and allows for "ill-behaved" spacetimes. Is that what happened? Link to a media article on the WSU finding. I don't have access to the actual paper, but it's here. Does this allow for arbitrarily large negative energy densities over non-quantum volumes, or is there some kind of quantum "catch" to this that wouldn't make this suitable for breaking some of the energy conditions? Is WSU's negative-mass hydrogen that "exotic matter" that's needed, or am I missing something?