#### marcus

Science Advisor

Gold Member

Dearly Missed

- 24,713

- 783

Over in "Theoretical" forum a new poster kikuchiyo put up two animated pictures of time.

A. http://homepage.mac.com/aglaser/time.swf [Broken]

B. http://homepage.mac.com/aglaser/time2.swf [Broken]

one is the time-line picture and the other is the falling-leaves picture

I think one's focus should not be "Which picture is right?" but

"How do I understand the falling leaves picture?"

In mathematical terms the difference is between a "linear ordering" and a "partial ordering" relation

if two leaves overlap you can tell which precedes which

and presumably its a transitive relation (yes, kikuchiyo?) which

means that if A precedes B precedes C then A precedes C

the partial ordering idea has interested mathematicians and they have learned some things about partial orderings

there is also the idea of a "directed set" which is a little stronger than a partial ordering but still not a linear ordering----a directed set allows taking limits and some interesting collections of things turn out to be partial-ordered and in some cases directed.

It seems like not a bad idea to see if time can be understood in these terms

A. http://homepage.mac.com/aglaser/time.swf [Broken]

B. http://homepage.mac.com/aglaser/time2.swf [Broken]

one is the time-line picture and the other is the falling-leaves picture

I think one's focus should not be "Which picture is right?" but

"How do I understand the falling leaves picture?"

In mathematical terms the difference is between a "linear ordering" and a "partial ordering" relation

if two leaves overlap you can tell which precedes which

and presumably its a transitive relation (yes, kikuchiyo?) which

means that if A precedes B precedes C then A precedes C

the partial ordering idea has interested mathematicians and they have learned some things about partial orderings

there is also the idea of a "directed set" which is a little stronger than a partial ordering but still not a linear ordering----a directed set allows taking limits and some interesting collections of things turn out to be partial-ordered and in some cases directed.

It seems like not a bad idea to see if time can be understood in these terms

Last edited by a moderator: