We all know what black holes are. The places where matter goes, but from whence it can hardly return. To the extent that it does come back, it does so due to Hawking radiation. Very, very, very slowly.
Because of this, black holes are actually grey holes – a very dark shade of grey.
What about some other examples of grey holes in different contexts? There are plenty of them, in various contexts. Western Germany was once a grey hole for Eastern Germans. Once across the border, they hardly ever came back to the East, not vice versa. Until the whole country was swallowed, in a span of 45 years from 1945 to 1989, this was a clear case of a figurative grey hole, swallowing not only the Eastern Germans, but also the Turks and the people from the Balkans, as well as many others.
The USA is another, even bigger example of a demographic grey hole. For centuries it has attracted and kept many of those who travelled there. Some Americans escape to Sweden or to the UK, but not that many, by far.
A bathroom sink-hole is a grey hole for your hair. They tend to go there, but they hardly ever come back. There are lots of gruesome grey holes everywhere we live. We must exhort special effort to make those clean again.
Whenever the probability of an object O, travelling from A to B is greater than the probability of the same object travelling from B back to A — B is a grey hole for O kind of objects.
Then, we have a build-up of such a grey hole, until the directional probabilities change. The water molecule in the kitchen air has a small chance of colliding with the ice already built up in your freezer. There is a much lower chance of it ever coming back spontaneously. Therefore ice is growing in all older models of deep freezers. There is no energy for those molecules to come back once they land on ice.
Antarctica is the same kind of a grey hole. When a water molecule from the Pacific lands there, it simply lacks the energy to return to the sea – at least when the temperature is, on average, 40 degrees bellow zero. Which it is now, and has been thus for a long time already.
Understanding this rather trivial fact, prevents you from being baffled, like certain scientists allegedly are as to why the Antarctic ice is growing.
A lake in the European Alps, is a grey hole for water molecules from the glacier above. The probability of them travelling to the lake and then to the sea is greater than vice versa. At least until it becomes much colder than it has been for centuries now.
There is no science more powerful than simple maths. If the simple maths/physics doesn’t agree, then no fancy science is even feasible.