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People born after 2000 have never seen the cosmic microwave background on their TV set.
(startrek.website)
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. A showerthought should offer a unique perspective on an ordinary part of life.
I found something about some recent-ish LG TVs having a default mode that shows static, but I couldn't find a clear answer on why, and the way to disable it is to enable "Cable DTV", which seems to suggest that it might actually be trying to get analogue signal by default...?