San Francisco, Jan 19 (TIWN) Tesla and SpaceX CEO Elon Musk has slammed the United Nations (UN) once again, saying that there are "not enough people" in the world and one should be more worried about population collapse.

In a latest tweet, Musk posted, "UN projections are utter nonsense. Just multiply last year's births by life expectancy. Given downward trend in birth rate, that is best case unless reversed."  "We should be much more worried about population collapse," Musk wrote.