Terence Tao on Nostr: There are a small number of physical laws that are considered so fundamental and ...

There are a small number of physical laws that are considered so fundamental and universally applicable that they provide much stronger negative results. Famously, the law of conservation of energy prohibits the existence of a perpetual motion machine that produces more energy output than energy input over extended periods of time, while Einstein's theory of special relativity (together with basic axioms of causality) prohibits faster than light travel for any object capable of carrying information. Even in such cases, though, some loopholes remain. For instance, there are mathematically viable (though practically impossible) "warp drives" that exploit the spacetime-distorting effects of extremely massive objects to achieve travel that is faster than light at global scales, despite not exceeding the light speed limit at any local point in the trajectory. (2/7)