knowledge - When was this marvelous thing first invented?

The answer to this puzzle will be a year.

Answer

The image doesn't seem to be much at first glance. However:

there is something hidden in an off-white color. Here, I've turned it red:

In The Sphinx's Lair, we spent ages trying to figure out what this might be, with no success. However, athin pointed out that:

they are actually Wakandan letters, from the recent movie Black Panther. (This is additionally hinted at by "marvelous thing", since Marvel Studios produced the movie.)

The letters spell "SOUND ABSORBING METAL". This is a reference to Vibranium, a fictional metal from the Marvel universe. In the comics, this was a naturally-occurring metal, so we must look out of universe for the answer: it was invented by Stan Lee, the author of the Daredevil comic in which it first appeared, in 1966.