TL;DR – The speed of light tells us how many different positions can fit in an interval of time. I was having a run with a buddy of mine. “The speed of light is fascinating” he panted. “Could we ever go faster?” “If we go faster, do we travel back in time or something?” I …
TL;DR – The laws of physics are the same for all observers because nature couldn’t care less what coordinate system we use. I recently met someone who had some slight misconceptions about the principle of relativity. “Is it true that time and space are relative concepts?” “That contemporary events for you may not be contemporary …
TL;DR – Time loops don’t really work. Either they degenerate into sources of infinite mass or they violate thermodynamics. My last thought experiment on time travel struck a chord. “Surely, you must know about wormholes!” someone assailed me. “You could go through a black hole and come out in a totally different era!” “There could …
TL;DR – Time travel violates physical laws way before you get to the point where you can kill your own grandfather. A person bumped into me the other day. “Time travel has always fascinated me,” he said. “Is it possible? Could we go back in time and kill Hitler and prevent Nazism? There are so …
TL;DR – We cannot always validate all answers to a scientific question with the same process. For some yes/no questions, only one side can be actually experimentally verified. Some people write me things like “Is it true that absent of evidence is not evidence of absence?” “Is it true that there my be a China …
TL;DR – The laws of physics are not the laws of nature. They can only describe what is experimentally accessible. I am often cautious about sharing my interest in fundamental physics to strangers. “Ah, fundamental physics!” They may get excited and step too close to me. “What can you tell me about the nature of …