Time, 2

Of all the many interpretations I've heard of time, the one I remember the most is the story about a famous graffiti that read "Time is God's answer to prevent all events happening simultaneously." This phrase made me think for some time. But I cannot take much from it. It is kind of obvious, but we must also take into consideration the relativity of simultaneity introduce by Special Relativity.

Other views of time I found were in Stephen Hawking's A Brief History of Time. As I recall, Hawking attempts to give time a vector like behavior (direction). He states three ways to measure the "directionality" of time: psychologically (biological), thermodynamically and cosmologically.

The psychological direction of time is the direction we see time pass by. People are born, grow up and get older; not the other way around.

The laws of thermodynamics say that states evolve to higher entropy states. This is viewed when ice cubes melt into water and not the other way around (you have to put water in a cold place to freeze it). Another example is the traditional breaking of an egg. If you let an egg fall to the floor it will break into pieces. You can wait in front of it and will never see the egg coming back together. This is the sense processes take place, and one can associate time to follow along this direction.

The third view of time's direction has to do cosmological observations. If you follow the trajectories of galaxies, you'll find that all of start their trek through space from a single point. The direction of cosmological evolution is then chosen as the chronological order of events in the universe. This analysis may imply the existence of the "origin" of time, a point where time began ticking.

All of this views just assign an orientation to time according to physical observations.