It was a very good week for very cold things. Absolute zero - theoretically, the lowest possible temperature - just became a little less sure of itself, the smug thing. Physicists in Germany believe that they have created an ultracooled gas that goes "beyond absolute zero" into negative Kelvin temperatures.
They found that the atoms in the ultracooled gas attract each other and give rise to a negative pressure. Instead of standing still when they go beyond 0 K, the gas becomes hotter.
"The gas is not colder than zero kelvin, but hotter," says physicist Ulrich Schneider, lead author on the paper that is published in the journal Science.
"It is even hotter than at any positive temperature."
One way of understanding how these "negative temperatures" (so called because they dip below zero degrees Kelvin; not like the negative temperatures we experience on the Celsius or Fahrenheit scales) can warm up is to consider them "hotter than infinity."
As the Universe should be contracting under the force of gravity, rather than expanding as measurements suggest, the authors believe that dark energy could cause the expansion of the Universe by behaving in the opposite way to what is expected from the force of gravity. In the same way that the gas particles attract each other at negative temperatures rather than being repelled, dark energy may cause the expansion of the Universe by acting as a sort of negative gravity.
Capitalizing the word "universe," as if the universe were a close friend going on a long trip, is surely one of scientists' more endearing habits. The discoveries don't end there, either: tomorrow marks the real beginning of The Coldest Journey: British adventurer Ranulph Fiennes' team sets sail from Cape Town for Antarctica in the first-ever attempt to cross the continent in winter.
Up in Norway (and buried under 700 feet of ice), not to be outdone by their German counterparts, researchers are gathering "some of the best glacial data that has ever been compiled" from a laboratory underneath the Svartisen glacier.
The scientists there convinced workers at a nearby hydropower company to dig extra tunnels for the lab to use, and spend their days scuttling through the heart of an icy giant, studying its movements. The glacial laboratory is currently the only of its kind, but don't let that stop you from hoping for more to open up and hire us all in the future.