Niven's laws were named after science fiction author Larry Niven, who has periodically published them as "how the Universe works" as far as he can tell. These were most recently rewritten on January 29, 2002 (and published in Analog magazine in the November 2002 issue). Among the rules are: Never fire a laser at a mirror. Giving up freedom for security is beginning to look naïve. (Based on a quote from Benjamin Franklin.) It is easier to destroy than to create. Ethics change with technology. The only universal message in science fiction: There exist minds that think as well as you do, but differently. Others Niven's Law (Time travel) A different law is given this name in Niven's essay "The Theory and Practice of Time Travel": If the universe of discourse permits the possibility of time travel and of changing the past, then no time machine will be invented in that universe. Hans Moravec glosses this version of Niven's Law as follows: There is a spookier possibility: Suppose it is easy to send messages to the past, but that forward causality also holds (i.e. past events determine the future). In one way of reasoning about it, a message sent to the past will "alter" the entire history following its receipt, including the event that sent it, and thus the message itself. Thus altered, the message will change the past in a different way, and so on, until some "equilibrium" is reached – the simplest being the situation where no message at all is sent. Time travel may thus act to erase itself (an idea Larry Niven fans will recognize as "Niven's Law"). Ryan North examines this law in Dinosaur Comics #1818. This proposition is also extensively examined in James P. Hogan's Thrice Upon a Time. Niven's Law (re: Clarke's Third Law) Niven's Law is also a term given to the converse of Clarke's third law, so Niven's Law reads: "Any sufficiently advanced magic is indistinguishable from technology." However, it has also been credited as being from Terry Pratchett. Keystone Folklore identifies it as a "fan-composed corollary slogan" of Arthur C. Clarke fans. Gregory Benford in his January 30, 2013 "Variations on Clarke's Third Law" identifies it as a corollary to Clarke’s third law, Both Clarke's Third Law and Niven's Law are referenced in part 2 of the serial Battlefield from season 26 of Doctor Who, first aired September 13, 1989.