Decoherence of planetary-sized pure quantum states
https://physics.stackexchange.com/questions/442432/planetary-sized-pure-quantum-statesWhy aren't particles constantly "measured" by the whole universe ?
https://physics.stackexchange.com/questions/460855/why-arent-particles-constantly-measured-by-the-whole-universeApparent wave function collapse caused by scattering - Tegmark