No life. Anywhere. Not even a fungus. Or lichen. Just DIRT.

There is certain to be life elsewhere in the universe, after all there are millions of species on Earth. But I guess only one planet per solar system can support life -- considering how sensitive photosynthesis is to temperature (10 - 45 deg C), and how many planets can fit inside the habitable zone of a star.

So what's the meaning of it all. Life may arise anywhere in the universe where the temperature is 10-45 deg.C, and where some water is available and sunlight, and some organic materials. But if only one such planet per solar system will form, how can they ever interact? Natural selection doesn't indicate an uplift universe scenario. So our obligation to other species doesn't extend to engineering intelligence in them. At least not yet anyway, although some selective breeding and genetic "frankentampering" might be justified for our own needs.

In a few hundred million years Earth's climate might gradually shift outside the temperature range that supports photosynthesis. When Earth no longer supports a biosphere, we'll have to adapt to something else. Once we adapt, why would we care about other planets out there that still have life evolving in a biosphere?

What would life be like after living a billion years without a biosphere. Would they remember where they came from? Would they lose context? Would they expect life like us elsewhere in the universe? Or would they expect life like themselves elsewhere in the universe, evolving without a biosphere? Would they know what a biosphere even is?

Ponderous. Maybe that's why the habitable zone is so small. We only need it for a relatively short period in cosmic time, then we move on. I think that a universe that gives rise to life, ought to support it's development. So there must be a general direction for life to evolve, and everything we see out there, will eventually come into play somehow, even if it isn't obvious now.