WHY
Throughout the large part of the 200,000 years of human history, temperature-wise, human experience was limited to 100 to 1000K range. The ambient temperature of the Earth plus what we could get out of fire was about it. It has been only 150 years since we started exploring the temperatures outside that range. The technical advancement in obtaining both high and low energy allowed us to do some amazing things. As physicists, one of them is of course figuring out the origin of the universe, usually referred to as the high energy physics and cosmology. Currently, we can get to the energy scale that corresponds to 100,000,000,000,000,000K, which is estimated to be the temperature right after the Big Bang. Although, we as human beings are experiencing 100-1000K on the Earth, the average temperature of the outer space is about a few K, constantly cooling down since the Big Bang almost 14 billion years ago. In that sense, temperature captures the history of our universe, and achieving any temperature below a few K is reaching the region the nature itself has never experienced on its own yet. The low temperature physics is our exploration into the future of the universe. As the universe experiences the cold death, everything will likely turn into dilute dusts scattered about in the space. But by some remote chance, should anything interesting remain, they won't be living things of today but the things we are looking into right now with the tools available to the so-called low temperature physics.