What is something that's crazier than the wildest dreams of any ~1970s nerd, but exists today? I'll start with an easy one:

The Patch was hypothesized in 1988 and first documented in 1997, by a passing yacht racer. Research on the patch began in earnest in 2009.

Estimates on the size are still nebulous, as it continues to expand and shift. But I doubt anyone in the 1970s was predicting a patch of trash twice the size of Texas would appear in the Pacific Ocean over the next 50 years.