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

It’s very odd to think of something extremely hot but with almost no density, and therefore very little heat transfer.

Closer to home you can get similar things when you grind metals for instance. The sparks are at extremely high temperatures, but won't typically start fires or cause burns (it depends) because they're just too small to impart much actual energy to anything they touch.

You only get fire risks when the things they touch are themselves tiny (like dust), so they're unable to absorb and spread the heat.

A similar thing happens when you bake with tinfoil. The foil will be at like 350 F, but you can still touch it basically immediately if you're willing to gamble that nothing with thermal mass is stuck to it where you can't see. It just doesn't have enough thermal mass on its own to burn you, but if there's a good-sized glob of cheese or water or something on the other side you can really be in for a nasty surprise.

I think similar of radiant heaters. The heating elements are clearly very hot, glowing even, but you never reach equilibrium with it: your leg will not get that hot. This is because your leg is cooled by conduction and convection (which is basically conduction again) and possibly a little evaporation.

Yeah, radiative cooling/heating is actually super slow compared to any other type. This is why it's so hard to cool anything in space, it's your only option and it kind of sucks at its job.

Wouldn't the other option be ejecting heat "ballast"?

I'm sure that would lead to other issues (sure, ejecting it would move you, but you could just always eject it in the opposite of the direction you want to go, which is how spaceships work in the first place), but what if you had super-cooled ice in a thermos-like enclosure, and as you needed to cool you pulled some out, let it melt, then vaporized it, then superheated the steam, then vented that out the back?