I wonder (if/when it's do-able), we fling our trash into the Sun?
I'm thinking beyond rocketry (the pollution of which would undo any good removing trash).
Will we ever have a "space elevator"? Constantly bringing our most unwanted materials to geostationary orbit, then with a relatively minor punt sending it towards the Sun to be captured/recycled there?
Assuming we get that far... I'm assuming throwing the whole Earth into the Sun would not even register from the Sun's perspective. In this, there's no way we could "ruin" the Sun no matter what we put into it? Right/wrong?
The notion of "nanites" reprocessing objects into their elements frightens the bejeesus out of me. The idea of someone retasking them to eat their container, followed by rest of the world... yeah, nah... Thoughts on that anyone? (The Nanites... not my phobias

)
I'm guessing once we harness greater energy (fusion?), recycling of anything will be cost effective enough to do. This leaves us with hopefully very few things that industrial chemistry/applied energy can't recycle.