Yes. This is not the point. The point being that we cannot prove non-existence. Perhaps there is a cave in Borneo which has never been explored which contains populations of tiny unicorns. Perhaps unicorns exist in a dimension as yet unknown and imperceptible to the majority of humans. Perhaps unicorns live inside the Moon. The POINT is that what humans assume they know with great conceit and over-confidence in their own current levels of knowledge – regardless of this – humans really do NOT know with 100% certainty. In fact science and experiment does not ever PROVE reality in some universally ultimate way – it can confirm a hypothesis only.