With regards to being 'alone' in the cosmos, it seems unlikely because life can exist in conditions that would kill us, such as the bacteria that can live in the sub oceanic vents and in other places in sulphurous volcanic streams. On other planets these conditions may be quite the norm, and if life can exist on them in a simple form it is odds on that there will be cases where that life has developed and is self aware but to whom a visit to an oxygenated, relatively cool world could be dangerous for them. The problem with the human mind is that it cannot contemplate nothing or eternal, it has to have limits or horizons. If they are not apparent it puts them in for you. In effect if you, say, started with a figure of 1,000,000, that is years of age, then added noughts to it until you eventually reached the centre of our galaxy, you would still be nowhere near what the meaning of what 'endless looks like', in fact you could go on adding on naughts for the rest of your life and still not have the answer nor will you ever be able to because the figure is no longer mathematical, endless cannot be described in numbers. IIt cannot even be described as 'N' Thus, it would be foolish to think that, in the concept of endless, that sentient life has never arisen. In our limited universe, of what we can see, may not last for ever, but in other places it will and our universe will eventually come back either in the same format, or in and entirely different format, for the next cycle and certainly in several billion universes down the line it will come back with the same laws of physics as our universe