Hold your hands up. See that gap between them? That's a space, and you can see itís there, even though you can't see the space itself. Now waggle those hands. That's motion, and you can see thatís there too. But can you see time? No. Can you see time flowing? No. Can you see any travelling through time? No. These phrases are just figures of speech. Thereís no scientific evidence for time flowing or time travel. Time travel is science fiction, and itís going to stay that way forever because travelling back in time is impossible. Itís impossible because we donít even travel forward in time, not really.
To understand this, think about a stasis box. Thatís science fiction too. Itís the ultimate refrigerator. No motion occurs inside the box, so when I put you inside one, electromagnetic phenomena donít propagate. So you canít see, you canít hear, and you canít even think. Hence when I open the door 5 years later, to you itís like I opened the door just as soon as I closed it. And get this: you ďtravelledĒ to the future by not moving at all. Instead everything else did. And that motion wasnít through time, and it wasnít through spacetime, it was through space. Yes, the stasis box is fighting fire with fire, but donít forget, we can freeze embryos now, so ďin the futureĒ maybe weíll be able to freeze an adult. Then you could ďtravelĒ to the future by stepping into a freezer. But you arenít really travelling. You arenít moving. Everything else is.
Thatís the size of it. Time is very simple, once you get it. But ďgetting itĒ is so very difficult. Thatís because for most people, the current concept of time is so deeply ingrained, from childhood in a catch Ďem young way. Theyíre locked into a conviction that days pass, that time flows, and that a journey takes a length of time. It takes some steely rationality to break out of this, but it can be done.( This post is quoted from phbpp physics discussion forum, Iím very interested in this post. I want to explore more of it. Anybodyís comment is welcome.)