Sure, dry Venus. I’ve seen the idea, but IIRC a geologist I discussed it with was skeptical. And rightly the dryness can be an effect of the lack of plates, and the atmosphere that gave.

But I see your point about the lack of answers (or even correct questions) all around. Thanks for the answer!

http://en.wikipedia.org/wiki/Zipf%27s_law

This is nothing but a power law distribution which frequently occurs in nature in a variety of settings. Not sure how it applies to extraterrestrial life or how it helps us find it.

http://www.alienreviews.com/b/life-on-other-planets.htm

Also, heard that there are religions that believe in life outside of earth – mormons?? Scientollogy???

They need to go into a snowball mode at some point to nudge evolution away from the remarkably stable state of producing nothing but stromatolites forever.

They need to come out of snowball mode some time later, in order to give all those new species a chance to develop into a Cambrian explosion.”

These are arguments straight out of Ward and Brownlee’s book “Rare Earth” so I’m assuming you’ve read that book. Of course, the thesis of the book is controversial and it’s still being debated. I’m not sure where I stand on the issue. I guess I would be more on the skeptical side of these claims that plate tectonics is essential, a large satellite is essential, a large Jupiter in the right place is essential, etc., etc. If taken to the extreme such arguments would suggest that Homo sapiens is the only intelligent organism in the entire universe, which seems patently ludicrous to me.

[[God told me. (seriously)
Not the God of the Bible — but the Supreme Being who created the Universe.]]

They’re the same God, ken.

Approximately 25% of all those stars have one or more planets circling them.

Approximately 1% of all those planets have some form of biological life.

God told me. (seriously)
Not the God of the Bible — but the Supreme Being who created the Universe.

Think about it: we may live in a universe where 99% of the life-friendly bodies are gas giant moons, rather than rocky planets.

How old are Vega, Fomalhaut and Beta Pictoris? Were they included in this? All three are nearby A-type main-sequence stars -hardly ‘sun-like’ but famed for their dust disks discovrered back in 1983 (?) by IRAS.

How “sun-like” counts as being sun-like?

Are these planets or asteroids belts or – as noted by someone else – is this dust and any proto-exo-planets being swept aside or into Hot Jupiter’s migrating inwards?

Its interesting, its suggestive – but there are still an awful lot of questions and investigations that need to be made.

& while there may be a few other planets similar to Earth, there’ll only ever be one Earth -and we’re standing on it ..

In the super-Earth regime the studies come out conflicting – one recent one suggests that even dry super-Earths would have plate tectonics, another suggesting that the high gravity would compress the rocks to an extent that plate tectonics couldn’t function. Neither of the papers in question seemed to explicitly mention water content.

So Venus may not be the best comparison for determining the lower limit of planetary mass needed for plate tectonics – we need a comparison where the planet’s crust is in contact with liquid water. Therefore it would be very interesting to find out what’s happening on the ocean floor of Europa…

So, BA, sir – what do the odds look like locally?

The ulimate irony of course would be if we found a whole bunch of those planets but they ended up being like Venus!

Which is why we wouldn’t want to look for Earth-sized analogues. AFAIK Earth is marginal for life – a little smaller and it would have been without plate tectonics and have a Venus-like atmosphere instead. Another benefit of plate tectonics apart from extending the habitable zone is that it gives more diverse climates and geography – more speciation possibilities.

The good news is that simulations seems to give plenty of larger rocky bodies.

They need to have been hit at just the right time in their early history by a big enough rock. This gave us the moon (which I already knew) and our oceans (which I didn’t.).

Why would life need a large moon – for spin stabilization? But it could be a toss of the coin if a more stable climate is beneficial or harmful for evolutionary processes.

I’m not sure what you refer to with the oceans. Water will be plentiful, perhaps excessively so. Plate thicknesses, and possibly the likelihood for thinner oceanic plates, will AFAIU not only depend on remaining material proportions after large impactors, but planet and atmosphere sizes as well. (See above.)

do we yet know why Venus recycles its surface so rapidly?

Good question. My earlier readings couldn’t give a consistent answer, but Wikipedia has an account of a more reasonable hypothesis. (Cyclical plate tectonics would explain both recent recycling and the hothouse atmosphere.)

What is the current understanding?

Well of course there are. Slartibartfast and his associates on Magrathea churn them out regularly. Seems those hyper-intelligent, pan-dimensional beings really want that question about life, the universe, and everything answered.

They need to have been hit at just the right time in their early history by a big enough rock. This gave us the moon (which I already knew) and our oceans (which I didn’t.). The odds against this one event alone seem staggering.

They need (reasonable) plate tectonics. It’s easy to see why Mars doesn’t have any at all (too cold) but do we yet know why Venus recycles its surface so rapidly? Without plate tectonics and reasonably stable continents, life will never leave the oceans and therefore won’t ever invent radio.

They need to go into a snowball mode at some point to nudge evolution away from the remarkably stable state of producing nothing but stromatolites forever.

They need to come out of snowball mode some time later, in order to give all those new species a chance to develop into a Cambrian explosion.

And so on…..