This entry was published at least two years ago (originally posted on April 2, 2019). Since that time the information may have become outdated or my beliefs may have changed (in general, assume a more open and liberal current viewpoint). A fuller disclaimer is available.
A thought I’ve had on occasion, and has resurfaced thanks to India’s anti-satellite test threatening the ISS: What if the reason we’ve never heard from an alien race is that they all ended up with so much orbital junk that they can’t safely leave their planet anymore?