Einstein said if you can’t explain it to a six year old, you don’t understand it yourself. And that sums up every person who’s ever talked about any kind of dimensions, string theory, and so on. They talk with contradictions and have explanations
How cold is the coldest place in the Universe, that we know of? What's the lowest man-made temperature ever achieved? And just how many zeroes are needed to express 'absolute hot', after which the fundamentals of conventional physics start to break.