I have some strongly-stated, loosely-held hunches about the probability of life elsewhere in the universe. My certainty about these beliefs is quite low, but it is much higher than my belief in the alternatives.

1) Life is rampant and common throughout the universe.

2) This ubiquitous life is single-celled and elemental, and remains at this level for very long periods. Most planets with life never advance beyond the single cell.

3) While life on some planets is seeded from outside sources, most life spawns independently. The conditions to hatch elemental life are relatively common.

4) Most life is DNA-ish, that is a double helix-based on DNA or DNA-like molecules. DNA is the most remarkable molecule in the universe. There may be other life-supporting molecules that can be designed, but none (or few) other than can self-assemble and self-create.

5) Any natural non-DNA-ish life follows the same patterns of distribution as DNA life.

6) Multicellular life is relatively rare. The evolution of higher organisms requires goldilocks conditions to be maintained for billions of years. The mild variability and persistence of favorable planetary conditions is relatively rare — compared to single cell life. But even “relatively rare” events in a vast universe will yield hundred of billions of examples.

7) Advanced civilizations are relatively rare compared to multicellular life (and to life), but are countless in number.

8) Since most life begins with DNA, the evolution of life on a planet converges onto a limited set of shared development sequences until it reaches the threshold of self-direction. Once evolution begins self-direction, including migrating to new material substrates, its evolutionary path diverges widely. Naturally evolved life tends to be similar across galaxies; consciously designed life tends to be unique.

9) Sufficiently advanced civilizations can synthesize, manufacture, or create any resources found naturally anywhere else in the universe. There is no material, or energy source that cannot be synthesized at home if you have the know-how.

10) The only reason for an advanced civilization to visit another planet is to see if there is another civilization which has invented things it has not, and perhaps could not invent. Invented resources are thus unlimited in scale and scope, and can be discovered only in unique places in the cosmos. Interstellar travel is essentially not travel through cosmic space but travel through possibility space. You visit another planet to visit other possible minds to see if they have thought of fabulous technologies your collective minds cannot reach.

11) Every day a few probes of these billions of interstellar civilizations visit our planet scoping out our technological state. These technological probes appear briefly in order to see us, and disappear once they have inspected our inventory. So far we have little to offer; nothing that can’t be found on millions of other planets.

12) Most life capable of meaningful interstellar travel is indistinguishable from technology.