NASA's Voyager Found a 30k-50k Kelvin "Wall" at the Edge of Solar System

I remember being in school in 2006 and being told that outside of our solar system is a "wall of fire" that we would never be able to cross.

I don't know if any of this info was speculated at that point in time, but it turns out that teacher was at least partially correct!

Probably true, in that if you try to travel interstellar distances you'll going to have to deal with very hot particles hitting your ship on occasion. If you travel slowly the more time you're going to be spend getting hit by high energy particles. If you try to travel quickly you're going to have to deal with more relatively high energy particles. It's potentially enough to make interstellar travel impossible.

Systems we built in the 1970s were able to easily pass through this though. Which doesn't seem to indicate that it would make interstellar travel impossible.

Systems from the 1970s travel at, by interstellar standards, agonizingly slow speeds. The voyagers will be exposed to hard radiation for thousands of years before they get anywhere interesting. They will not survive.