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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.
Amateur radio operators are indeed allowed to transmit analog NTSC television in the UHF band. It's most commonly done on the 70cm (440MHz) band, and a normal everyday 90's television is all you need to receive the signals. You'd tune to what would have been cable channels 57 through 61. The use cases for this have decreased in recent years; for example you used to see hams using amateur television to send video signals from RC aircraft or model rockets, now that's done with compressed digital video over something like Wi-Fi and doesn't require a license. But, it's still legal for hams to do.