Theoretical physicist here.
"The universe weighs less than we thought" is a misleading section at best. Sure, originally physicists were quite confused and posited dark matter to explain the lack of mass required to hold galaxies together. Since then, we've made tons of progress, and we can (arguably) even "see" dark matter in galaxy collisions using an effect called gravitational lensing. We still don't know what it is exactly, but we're way less in the dark about dark matter than we were even just 10 years ago.
Temperatures below absolute zero have been modelled for at least 50 years, if not longer. Systems with negative temperatures have only been physically built recently, but we've known what they meant for much, much longer. It's not that we don't know what to do with them, it's that they're so exotic they don't really have a practical application.
Cold fusion as claimed doesn't work. The cold fusion that does work is wildly impractical. It's really old news and does not deserve research money, so please stop talking about it in popular media.
I've really become disillusioned with Gizmodo recently. Do they have their authors/staff actually contact anyone doing the research they talk about? Because their articles sure as hell don't look like it.