Dear All, My quest for an answer began a few days ago when I was at my mates house and we were watching a documentary on time travel and such. My friend voiced a gripe with Theoretical Physicists because them "seem to accept crazy, far fetch ideas as a basis to theorise further, even crazier ideas" (such as worm holes, time travel, quantum mechanics (specifically that something can exist and not exist at the same time). While I consider this view acceptable for a person who knows nothing of the topic, my argument was that it is difficult to believe that scientists are out there just making things up for the fun of it with no real evidence to support their theories. So, the challenge was set out. My friend stated that if something cannot be explained to him in a way that he can understand then it does not exist (to him). His example is of time. My friend does not believe that time exists (watches and clocks exist) but time does not exist, time is something we have invented to explain change, change exists because he can see it, but he cannot see time. Does this make sense? Is there anyway to prove to my friend that time is real? What I am hoping is that you will all share with me your knowledge on time or any topic you feel relevant that would easily explain some of these concepts. Specifically, what we know, how we know it and what we don't know. As I assume most members of this community are qualified to discuss such matters I am hoping that the information you provide is accurate, well presented and you have a sound understanding of the topic. If you can only explain how time works without explaining what it is then you are as good as I am at getting shut down by my friend. He will not accept "time" into the conversation until someone can prove to him that it exists in the first place. .... this is getting a bit long now but I hope some of you will find this an opportunity to defend your science to people who do not understand it and therefore deny it's credibility (I mean that in the nicest possible way) as opposed to some homework to help someone win a silly argument. I am extremely interested in hearing your responses and truly appreciate any time (no pun intended) you devote to helping me. Best Regards, Jack.