Wednesday, April 8, 2009

What do we know of the probability of life in the Universe? First part

Alas, not very much. All we know is OUR biosphere, and we didn't know how exactly it originated. There's however some logical assumptions we can do. Life is compatible with known Nature's Laws, and it began very early on our planet, so we can assume that life's s origin from chemical elements and energy is a natural consequence of natural laws at work.One of the best theories I've heard is- it originated at the bottom of the oceans near hydrothermal vents via energy-aided auto catalysis, and initially it made use of inorganic supports that gradually where replaced with organic ones, till the birth of the first independent living cell with a membrane and RNA. I find it a plausible hypothesis.. Chemical elements components of life have been found to be common in interstellar space, so we can assume that life at the simplest level must be fairly common. There are archaean and bacterial micro-organism that thrive at levels of radiation, extremes of temperature and others, that would kill complex cells. Yeah, and what of complex life?

As you can see, a lot of time, nearly 2,5 billions of years passed betweeen the birth of life and the first multicellular beings.Maybe this gap is due to local conditions, maybe in other biospheres complex life is achieved a lot more sooner.Certainly, a star must live at least a ten billions of years to allow life to evolve. Surely we can't assume life as we know it is the only life that can exist. But complex life seems to need time and a stable environment. It's certainly less common than bacterial level life, we can assume.
(to be continued)

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