A lower bound estimate of the probability of finding extraterrestrial life, and intelligent communicating life in particular, has previously generally followed the Drake equation. This equation assumes that such life is only on other planets. This premise of the Drake equation is wrong. Life is lurking quite nearby in the big black objects like Barnard 68.
The following steps of logic with some reasoned speculation shows why this is so:
1. Unusual life exists under our ocean. This life gets its energy, not from the sun, but from volcanic vents. The conditions for life require only a nutrient ocean and underwater volcanism.
2. The somewhat small moon, Io, orbiting Jupiter would seem to be too small and cold to be generating volcanoes. Yet Io has some of the largest, most active volcanoes seen in the solar system. Io's volcanoes and liquid core are now thought to be generated by tidal friction as it orbits Jupiter. This new mechanism for volcanism is key to these new ideas of where life is. The idea that the interior of massive objects can be heated to molten conditions just by its orbital motion suggests that the interior may also be heated by spinning. Indeed, the interior of the earth has recently been found to be spinning faster than the surface, which may contribute to its heating.
3. Europa is another moon of Jupiter. Its ice-covered surface is thought to cover an ocean about 65 kilometers deep. This is 2 to 3 times as much water as is in all the earth's oceans. Big sections of Europa are observed to have moved, showing that the ice is floating over a fluid. It assuredly has a liquid ocean under the ice. There are large cracks in the ice on Europa with dark areas growing alongside them. The cyclic pattern of those cracks near the south pole matches that of tidal forces modelled for a thin ice covering a liquid ocean. Europa has been found to have a tenuous oxygen atmosphere. Some places on the surface show smooth features where hot water spewed out and flowed before refreezing, indicating that, like Io, Europa has volcanoes. The nightime temperature patterns on Europa are unexpectedly varied. With underwater volcanoes generated by tidal forces and a deep ocean, Europa is a strong candidate for extraterrestrial life to have developed over the 4.5 billion years of our solar system's existence. Deep oceans are a very benign environment for life. The temperature is always above freezing and the water protects life from damaging radiation and meteoroids. Dirk Schulze-Makuch and Louis Irwin have suggested many alternative methods for life to exist on Europa using non-solar energy sources. Other moons are also similar to Europa and may be candidates for life as well. These include moons of Saturn soon to be visited by the Cassini spacecraft. We plan to look for life in the deep waters of ice-covered Lake Vostak in Antartica as a test of how to look for life on these moons. In fact such life has been found inside the ice itself.
4. Pluto has been in the news recently. There was a suggestion that it should not be classified as a planet. Pluto is a member of a recently discovered class of a large number of comet-like objects that cross Neptune's orbit. Pluto may well not even be the largest one of these. Like all comets, these objects contain a large amount of water ice. Pluto has a large moon, Charon. Charon orbits very closely to Pluto, within 8 Pluto diameters. The tidal forces between Charon and Pluto are huge and should cause liquid oceans and underwater volcanoes on Pluto and/or Charon like those volcanoes seen on Io. Thus, despite the fact that these bodies would, at first, seem to be desolate, cold objects far from the sun, they may well be teeming with life.
5. Comets are black masses of dirt and ice. They contain the material for life. Comet Halley was measured to be the blackest object ever observed in the solar system when it was visited by the Giotto spacecraft. Its albedo was measured at 0.03, making it blacker than a chunk of coal. It absorbs 97% of all visible light that hits it. The black objects like Barnard 68 are dust clouds which the STARDUST spacecraft has found to be very complex organic compounds that could be bacterial in origin. These clouds probably contain huge comets or swarms of co-orbiting comets with liquid ocean interiors and underwater volcanoes. Already the Orion Nebula cloud has been found to be rich in water. Comet Hale Bopp may have had a companion that would cause orbital heating. Other comets may also have companions.
6. Carbonaceous chondrites constitute about 3% of all meteorites from cometary debris that hits the earth. They are rich in organic carbon compounds. Some investigators have found microorganisms in them. Others have found other lifeforms that they call nannobacteria. Of particular interest is the carbonaceous chondrite that fell to earth in September 1969 near Murchison, Australia. This meteorite has been studied so extensively that some fondly have nicknamed it "Murchy". Great care has been taken to assure that the interior of Murchy has not been contaminated by earth life. Amino acids are the building blocks of life. Murchy contains 92 amino acids, only 19 of which are found naturally on earth. The earth's petroleum may come from carbonaceous chondrites that were included in the material that formed the earth according to Professor Thomas Gold. Both Gold and Haggerty think diamonds are formed from these carbonaceous chondrites. A near earth object is a spherical, fast-spinning carbonaceous chondrite. There also have been reports that Murchy may also contain microorganisms. A meteorite that landed in Monahans, Texas in 1998 was cut open and water was found in it. A very recent carbonaceous chondrite was found in Canada and is presently being studied.
7. Some astronomers have measured the spectra of the black clouds in our galaxy and other galaxies. It shows organic material! The best match to this spectra is the spectra of Murchy! More detailed spectra have found the methyl radical CH3, which is an important tracer of complex organic compounds, in surprisingly great abundance. Astronomers are now beginning to see that these clouds can contain life in big oceans.
Other astronomers have found free floating planets inside these clouds (as well as sugar molecules). Now even more free floaters have been found these nebulae. The moons of these planets can be like Europa. The probability of finding extraterrestrial life is not according to the premises of the Drake equation after all. Life is right nearby our solar system in the oceans inside the big black objects. We should be listening at very low frequencies like the Navy uses to communicate with underwater submarines if we want to hear from them. But it's also in the black dust lanes in our milky way and other galaxies, too. Here's a great photo of the dust moving from one galaxy to another. Life is travelling intergalactically!