there is a theory that if you go back in time and kill your great-grand father then in one time you would cease to exsist but the timeline would split creating a "knot" in the the timeline where you would keep repeating that same event of you killing your grand pappy over and over and over but you wouldnt know it since you ceased to exsist after you did it. if youve ever seen the movie "groundhogs day" that is a time paradox except he wouldnt remember it. their is a cat, the cat is in a sealed solid non-see through box. In the box with the cat is a vile or capsule containing just enough cyanide gas to kill the cat. the vile has a 50/50 chance of breaking or staying unbroken. you wont know if the cat is dead or not untill you open the box and see. so the cat is purely theoretical a "figment of your imagination" if you will... if you open the box and the cat is alivePlease Register or Log in to view the hidden image! then you have "created" one timeline but it would also create an alternate timeline where you opened the box and cat was deadPlease Register or Log in to view the hidden image! this "locked-room" paradox was divised by an Austrian physisist, Erwin Schrodinger.