Why We Might Be Alone

First of course is the overt discussion: what is the likelihood of intelligent life elsewhere in the Universe, and are humans alone or not.

The second strikes me as potentially more interesting: What are the bounds of knowledge and understanding in the face of little direct empirical evidence?

I've spent the past few years listening to several podcasts on philosophy, most notably Stephen West's "Philosophize This" and Peter Adamson's "The History of Philosophy (Without Any Gaps)". The many failings of argument, and in particular appeals to emotion and optimism (not unknown in other domains here on HN) is a large part of that.

Much of both is consumed with epistemology, logic, truth, knowledge, and many (many (many (many (many)))) religious debates. Those too, read at face value offer one level of understanding, but taken at a deeper level concern what do we know, what CAN we know, and how should we best act under circumstances of partial or zero knowledge?

There's a third level which occurs as I write this: much of the interesting work over the past 50--75 years or so in physics has revolved less around new elements, particles, and forces (the major component of physics through the first half of the 20th century), and far more on sensing and detection methods, both direct and indirect. These have allowed us to extract a phenomenal amount of signal and information from immensely distant, faint, and subtle phenomena.