甚麼人提出空間必然存在熱能量(不可能存在絕對零度)呢？

The universe is full of background radiation with photons of 2.7 K, i.e. in the microwave range.
In other words, you could treat the lowest temperature of the universe at present is at 2.7 degrees absolute.
If objects are kept at such low temperature, the radiation they emitted certainly would fall outside the far infrared region.

翻譯 physics8801 的回答:
是誰提出並不重要。重點是--宇宙中物質的實際最低溫度是 2.7 K。
而這些物質確實會釋放出某種幅射，不過，這種幅射並不是我們常常提到的紅外線。

這是熱力學第三定律