This article is very interesting as it proposes the possibility of life on planets that are not orbiting around stars:
Is Our Solar System Missing a Giant Planet?
http://www.time.com/time/health/article/0,8599,2099347,00.html
It suggests that an Earth-sized object could get thrown out of the solar system, yet still have the capacity to have liquid water because of a thick blanket of hydrogen acting as an insulator. If this idea has any merit, then it would seem that any object capable of retaining a thick hydrogen blanket could also harbor life, including the putative 5th giant planet the article talks about (I have read about lots of ideas that suggest life in gas giant’s upper atmosphere).
I remember reading long ago a SciFi book by Frederik Pohl and Jack Williamson called “The Reefs of Space” (part of the “Starchild Trilogy”) that extended Fred Hoyle’s stead state hypothesis (http://en.wikipedia.org/wiki/Steady_State_theory) that posits an universe that is infinite in age as well as space. If you assume the universe is infinite in age as well as extent, then any event that has a non-zero probability not only has happened somewhere, but has happened an infinite number of times. Thus, the authors produced the idea of reefs in space that live off the hydrogen purported to pop into existence in between stars and fused that hydrogen to produce energy and raw materials for life. The stories had other interesting things going on, but I always remember the reefs in space with a lot of fondness. I have often thought that even in a non-infinite universe there is still room for some pretty low probability events to happen with rather pedestrian occurrence (to me, life is not just probable, but inevitable when water, minerals and a heat gradient are present; intelligence is, to me, a bit less likely, but still probable enough it happens all the time), so the idea of reefs in space still seem like a winner to me. Once some life form evolves in space and develops some way to maneuver, feed and reproduce, it has so much area to work with that it seems given the life of the universe I would feel surprised if there wasn’t life between the stars. It might be difficult to recognize, but then again it might not be.
I imagine if you had a very powerful telescope that looked toward a patch of sky that is dense with background stars, perhaps you would be able to see the stars being eclipsed in such a way that shows movement beyond plain orbital mechanics. I wonder how powerful such a telescope would have to be.
Obviously the universe need be neither infinite nor eternal. Very large and very old allows for a very high probability of life being present.
Just as obviously, the larger the universe the MUCH greater the volume (whatever the number of dimensions). As a first approximation I would say that the larger the probability of other life-forms existing, the smaller the probability of detecting them.
Rigid thinkers are also probably restrained enough to look only for carbon-based “life.”
As an aside, I would postulate the the problems with the world today are that not enough people read “Golden Age” science fiction.
An earlier post talks about very early seeding of the universe with heavy metals which would mean that there has been 12+ billion years (or four times the age of our solar system) for life to have evolved independently and for intelligent life to arrive. Given how fast our species has gone from just another animal competing on the African savannas to advanced enough to destroy the entire ecosystem of a planet (less than a couple of million years, depending on how you measure things) it would seem that there must have been and probably are today millions, if not billions of intelligent species. Of course, given the magnitude of the communication problem, we might only be able to contact the tiniest fraction of the tiniest percentage of those extant, which might mean we are de facto alone due to the communication gulf.
I wholeheartedly agree with your sentiment that people should spend more time reading old-style SF!
Quite aside from the current discussion, one of my favorite authors wrote a book predicting that the human race would die off in the 1980s due to population explosion (starvation). Even the huge sideburn guys don’t always get it right.
Didja see my post that described how our planet could sustain a trillion people on just 10% of the land surface?
http://sol-biotech.com/wordpress/2011/10/30/one-trillion-people/
Yeah, I did. Like all spoiled first-headed-for-third worlders, I don’t want to eat that stuff. Unless you can make it taste like pico de gallo and pony up some chips.