What makes outer space super cold?
Outer space is, on the average, 2 to 3 kelvin super cold. What makes it super cold?
It just happen that vacuum outer space is INHERENTLY SUPER-COLD. Only extremely sparse atoms in plasma state inhibit outer space. The abundant presence of air molecules at surface of earth makes it warm. The higher up, like in Mount Everest, where air is sparse, is very cold. In refrigerator and air con, the principle is the same, compress freon to outlet, to reduce freon on inlet to ref and air con, thus creating vacuum that creates cold.
Thus, it appears outer space which is vacuum is inherently cold in the first place. This has further implication: it shows that cold outer space came into being before Big Bang.