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.

It's impossible for many reasons unless there are physics we haven't discovered yet. To me that's the simple answer for the Fermi paradox.

The Fermi paradox doesn't require travel, though. The lack of any sign of life at all is still surprising (no radio signals, etc), even if we knew it couldn't physically come here.

It would take a lot of power to send even a radio signal that could be picked out from the noise at a few light years. Add a requirement for that signal to be more or less continuous over geologic timescales - we’ve only been able to emit and detect these for ~100 years - and my personal surprise diminishes rapidly. Huge distances in time and space with human-level technology make detection highly unlikely.

Radio signals aren't the only sign. I'd really love to see some sign of megastructure engineering, but even detecting O2 in an extraterrestrial atmosphere would be huge.