Are there science fiction ideas of inventions that seemed ridiculous at the time of conception but are now being made in real life?

Large thin flat screen TVs/screens.

Until the early 1980s, there was no practical approach to how to make a flat panel display with the resolution, pixel quality and speed of a cathode ray tube. LCD screens were still more of a curiosity back then and getting their pixel size down to a millimeter or less was quite a challenge.

Plasma displays (such as the earlier IBM 3290 released in 1983) were the most promising 40 years ago, but it seemed they could only be produced as monochrome displays, they didn’t have fast enough refresh rates for video, and early units were also used. . Plenty of power to be practical at home. They weren’t too skinny either.

TV shows like “Star Trek” and movies like Chaplin’s “Modern Times”, which featured flat screens, were definitely seen as “science fiction” by their viewers.