It’s one of the most fundamental principles of chemistry and physics. It was discovered by Antoine Lavoisier in the late 18th century, and you can only meaningfully break it during nuclear reactions (fusion/fission). If any container is gaining mass, it is either a dying star or there is more mass entering the container than leaving it. This also applies to the human body: If you are gaining mass, it is because there is more going in than out, otherwise you’ve broken pretty much all known physics (or you’re about to go supernova).
It’s one of the most fundamental principles of chemistry and physics. It was discovered by Antoine Lavoisier in the late 18th century, and you can only meaningfully break it during nuclear reactions (fusion/fission). If any container is gaining mass, it is either a dying star or there is more mass entering the container than leaving it. This also applies to the human body: If you are gaining mass, it is because there is more going in than out, otherwise you’ve broken pretty much all known physics (or you’re about to go supernova).