Julia: If I ran as fast as the speed of light, do you think that I could stop time?

　　Sergio: No.

　　Julia: Why not?

　　Sergio: Because, according to Einstein, time is not universal. It is personal.

　　Julia: What does that mean?

　　Sergio: It means that if two people move then time changes. If two people stand still, then time is the same, relative to each other.

　　Julia: Science is difficult to understand.

　　Sergio: Science is not for everyone. Most people know about E=mc2 or the four dimensions.

　　Julia: Or the theory of relativity.

　　Sergio: Science and math is everywhere. Galileo said that mathematics is the language of the universe.

　　Julia: Is there a dictionary on it?

　　Sergio: It's as simple as 123.