If you think nuclear power and space travel means you don't have backwards opinions about race... well, that's just not true. I mean, the Nazis were pioneers in rocketry, after all, and also worked on nuclear reactors. More to the point, several very smart, "modern" people — William Shockley, James Watson, plenty of others — subscribe to views that are hard to describe as anything other than racist.

Racists have many justifications for racism. Some of them are "scientific" — ideas about innate inferiority, genetics, what have you. Most of them are not, and are based on appeals to criminality, poverty, etc. Some of these claims are "real" in the sense that yes, for a variety of structural reasons minorities can be over-represented in jails, can have far worse poverty conditions, and these sorts of things are associated with worse life outcomes and choices. The "scientific racists" then try to say that this is not about the structure, but about biology, genetics, what have you.

In the USA, "scientific racism" was alive and kicking well into the 1960s and 1970s. By the end of the 1970s it had fallen out of the mainstream fairly definitively. The first concerted pushes against "scientific racism" came in the 1930s (Boas and his students did much with this, esp. in the postwar with their work at UNESCO), but it lingered on. It was not limited to the South — Harvard anthropologist Earnest Hooton, for example, was a scientific racist until his death in 1954.

But anyway. If you are surprised that educated people can hold racist views... Don't be. It still exists today. Racism has proven itself to be extremely seductive even to the intelligent and well-off (as opposed to the idea that it is only something liked by the poor or working class who are looking for scapegoats). "Scientific racism" has its adherents today, though again it is pretty marginalized with regards to mainstream scientific output. The actual science of human differences is, it should be noted, admittedly complex.