The evidence has been accumulating for billions of years that the only aliens around in the endless universe are us, looking in all directions and distances for other life forms.
It seems that we are extremely privileged to have had intelligent life evolve on planet earth. The price for that evolution could be the realization that we are alone in the universe.
Sunday Express reports:
Expert Aditya Chopra said in a statement: “The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens.
“Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable.
“Early life is fragile, so we believe it rarely evolves quickly enough to survive.
He said the survival of life on other planets would depend on something called the ‘Gaian bottleneck’, in which life changes its environment in order to aid evolution – an extremely rare occurence.
For example, life on Earth thrived when tiny organisms began regulating carbon dioxide and producing oxygen, which allowed larger organisms to develop. Failure to do so results in extinction.
ANU say that, four billion years ago, Earth’s relatively close neighbours Venus and Mars may have been perfectly suited for the development of life.
However, the climates on both planets became extremely hostile, as Venus “turned into a hothouse” and Mars “froze into an icebox.”