Goldilocks planet is no fairytale

Elias wrote:

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There appear to be four strains of thought on ET life;
a) It's going to be simple life forms i.e. microbes
b) It's going to be complex but completely different to earth and full of strange creatures with no resemblance to earth
c) There will be beings and they will be far more advanced than us and look like stick insects
d) all life evolves exactly the same way over time so expect to see humanoids

The ADELAIDEAN wrote:

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It's fun to speculate. Centuries ago writers speculated on other worlds and their supposed inhabitants, and came up with physical features that were arbitrary and frivolous. At least with the accumulation of knowledge since then we can now base our speculation on at least some rational guiding principles.
Of your examples above I believe we can rule out "(d)" straight away. Our own planet has staggered and reeled through a turbulent history of natural upheavals from recurring Ice Ages to meteoric bombardments to a Sun that is by now some 30% hotter and more radiant than it was when life first got started, earth quakes and vastly changing atmospheric composition due to vulcanism etc.
Each of these *chance* events has caused mass extinctions, exogenic mutations, divergent and convergent evolution and speciations. All are due to a sequence palaeo/geological events that is so random that it's certain to be unique.
If we could have recorded our planet's history, wind the tape back and re-run it, the same sequence of events would never come up again and life on Earth as we now know it would instead be different from what it's like now.
Given the random complexity of our own planet's biological fortunes, the likelihood of life on any other world marching in lock-step would be non-existent.
They would instead have their own unique histories influencing their biological evolutions equally uniquely.

Elias wrote:

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Agree with your post. It does seem unlikely that a series of random chance events can lead to exact humanoid copies of sentient beings.
An amusing article that better discusses how we seem to be using anthropomorphism to cariciture our proverbial alien.
http://blogs.discovermagazine.com/sciencenotf...

The ADELAIDEAN wrote:

<quoted text>Abiogenesis is no more alien to Murphy's Law than is anything else .... unless someone has a *Scriptural* vested interest in denying its possibility.