Over 800 scientists, politicians, entrepreneurs, artists, and celebrities have signed a declaration calling for a halt to the development of artificial superintelligence, a yet-to-be-reached stage of AI that could pose a threat to humanity.     The declaration proposes a ban on the development of superintelligence "until there is scientific consensus that it can be achieved in a controlled and safe way and until there is public support." The initiative, launched by the Future of Life Institute,