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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.
While I've grown up with CRTs (90's kid) I've never seen the actual static in real life, only simulations.
I don't think channels ever went out, and if the TV was listening to a connection that didn't give anything it just shone bright blue.