Arrow of Time
in [Physics]
|
From: Robert L. Oldershaw on 19 Jun 2010 11:58 An interesting discussion has started at sci.physics.research concerning the nature of the "arrow of time" Below are the original post and a follow-up. Check it out and contribute! -------------------------------------------------------- I would like to explore an idea one more time. Could we not define the arrow of time as the arrow of causality? Consider a typical Rube Goldberg device. Event 1 triggers event 2, which triggers event 3, and so on. There is no way that the sequence could go backwards, or that the ordering of events could be changed. In any part of the cosmos that we can fully investigate, causality appears to be always obeyed and always moves in one direction from cause to effect. Is there any reliable, fully tested empirical knowledge that prevents us from simply saying: ARROW OF TIME = ARROW OF CAUSALITY ? Thinking of the Rube Goldberg device again, we say the diagram represents a temporal or causal sequence. Perhaps the concept of time is a simple way to describe the ordering of causal sequences, and a simple way to define magnitude relations between the rate at which two sequences proceed? RLO www.amherst.edu/~rloldershaw ---------------------------------------------------- On Jun 19, 3:58 am, hel...(a)astro.multiCLOTHESvax.de (Phillip Helbig--- undress to reply) wrote: > > There are several arrows of time: thermodynamic, cosmological, causal > etc. Everyone agrees they exist. By "defining" one as "the" arrow of > time, we gain nothing. In other words, WHY can we define a causal arrow > of time? Microscopically, the laws of physics are time-reversible, but > on larger scales, we observe various arrows of time. Why? That is the > question. -------------------------------------------------- (1) We are not absolutely required to accept unconditionally the statement that "Microscopically, the laws of physics are time- reversible,..." In fact, I reject this Platonic over-idealization categorically. Can you prove me wrong empirically? The "laws" *you* subscribe to may be reversible, but mine are definitely not. Mine are always causal, deterministic [in the nonlinear dynamical systems sense] and irreversible [although limited periodic behavior is permited]. (2) There may be many "arrows of time", but there is always ONE and the same Arrow of Causality. A subtle, but important distinction, I admit. RLO www.amherst.edu/~rloldershaw
From: Sam on 19 Jun 2010 12:04 On Jun 19, 10:58 am, "Robert L. Oldershaw" <rlolders...(a)amherst.edu> wrote: > An interesting discussion has started at sci.physics.research > concerning the nature of the "arrow of time" > Consider these Arrows http://en.wikipedia.org/wiki/Arrow_of_time#Arrows
From: Thomas Heger on 19 Jun 2010 14:12 Robert L. Oldershaw schrieb: > An interesting discussion has started at sci.physics.research > concerning the nature of the "arrow of time" > > Below are the original post and a follow-up. Check it out and > contribute! > -------------------------------------------------------- > > I would like to explore an idea one more time. > > Could we not define the arrow of time as the arrow of causality? > > Consider a typical Rube Goldberg device. Event 1 triggers event 2, > which triggers event 3, and so on. There is no way that the sequence > could go backwards, or that the ordering of events could be changed. > > In any part of the cosmos that we can fully investigate, causality > appears to be always obeyed and always moves in one direction from > cause to effect. > > Is there any reliable, fully tested empirical knowledge that prevents > us from simply saying: > > ARROW OF TIME = ARROW OF CAUSALITY ? > > Thinking of the Rube Goldberg device again, we say the diagram > represents a temporal or causal sequence. > > Perhaps the concept of time is a simple way to describe the ordering > of causal sequences, and a simple way to define magnitude relations > between the rate at which two sequences proceed? > > RLO > www.amherst.edu/~rloldershaw > ---------------------------------------------------- > > On Jun 19, 3:58 am, hel...(a)astro.multiCLOTHESvax.de (Phillip Helbig--- > undress to reply) wrote: >> There are several arrows of time: thermodynamic, cosmological, causal >> etc. Everyone agrees they exist. By "defining" one as "the" arrow of >> time, we gain nothing. In other words, WHY can we define a causal arrow >> of time? Microscopically, the laws of physics are time-reversible, but >> on larger scales, we observe various arrows of time. Why? That is the >> question. > -------------------------------------------------- > > (1) We are not absolutely required to accept unconditionally the > statement that "Microscopically, the laws of physics are time- > reversible,..." > > In fact, I reject this Platonic over-idealization categorically. Can > you prove me wrong empirically? The "laws" *you* subscribe to may be > reversible, but mine are definitely not. Mine are always causal, > deterministic [in the nonlinear dynamical systems sense] and > irreversible [although limited periodic behavior is permited]. > > (2) There may be many "arrows of time", but there is always ONE and > the same Arrow of Causality. A subtle, but important distinction, I > admit. > Hi I do perfectly agree. But this is a tough topic to tell, because everybody thinks about only one 'arrow'. This is understandable, because everybody has his own arrow and only thinks, that everywhere else have the same. But this is stunning stupid, because things move around, hence all have their own. Only specific surfaces, like that of the earth, allow the same rate of timeflow. There should be no distinction between timeflow and causality, but that should be 'glued' to the objects. So, there is no universal time. (What is kind of tough to tell, too. ) TH
From: BURT on 19 Jun 2010 14:55 On Jun 19, 11:12 am, Thomas Heger <ttt_...(a)web.de> wrote: > Robert L. Oldershaw schrieb: > > > > > An interesting discussion has started at sci.physics.research > > concerning the nature of the "arrow of time" > > > Below are the original post and a follow-up. Check it out and > > contribute! > > -------------------------------------------------------- > > > I would like to explore an idea one more time. > > > Could we not define the arrow of time as the arrow of causality? > > > Consider a typical Rube Goldberg device. Event 1 triggers event 2, > > which triggers event 3, and so on. There is no way that the sequence > > could go backwards, or that the ordering of events could be changed. > > > In any part of the cosmos that we can fully investigate, causality > > appears to be always obeyed and always moves in one direction from > > cause to effect. > > > Is there any reliable, fully tested empirical knowledge that prevents > > us from simply saying: > > > ARROW OF TIME = ARROW OF CAUSALITY ? > > > Thinking of the Rube Goldberg device again, we say the diagram > > represents a temporal or causal sequence. > > > Perhaps the concept of time is a simple way to describe the ordering > > of causal sequences, and a simple way to define magnitude relations > > between the rate at which two sequences proceed? > > > RLO > >www.amherst.edu/~rloldershaw > > ---------------------------------------------------- > > > On Jun 19, 3:58 am, hel...(a)astro.multiCLOTHESvax.de (Phillip Helbig--- > > undress to reply) wrote: > >> There are several arrows of time: thermodynamic, cosmological, causal > >> etc. Everyone agrees they exist. By "defining" one as "the" arrow of > >> time, we gain nothing. In other words, WHY can we define a causal arrow > >> of time? Microscopically, the laws of physics are time-reversible, but > >> on larger scales, we observe various arrows of time. Why? That is the > >> question. > > -------------------------------------------------- > > > (1) We are not absolutely required to accept unconditionally the > > statement that "Microscopically, the laws of physics are time- > > reversible,..." > > > In fact, I reject this Platonic over-idealization categorically. Can > > you prove me wrong empirically? The "laws" *you* subscribe to may be > > reversible, but mine are definitely not. Mine are always causal, > > deterministic [in the nonlinear dynamical systems sense] and > > irreversible [although limited periodic behavior is permited]. > > > (2) There may be many "arrows of time", but there is always ONE and > > the same Arrow of Causality. A subtle, but important distinction, I > > admit. > > Hi > I do perfectly agree. But this is a tough topic to tell, because > everybody thinks about only one 'arrow'. This is understandable, > because everybody has his own arrow and only thinks, that everywhere > else have the same. But this is stunning stupid, because things move > around, hence all have their own. Only specific surfaces, like that of > the earth, allow the same rate of timeflow. > There should be no distinction between timeflow and causality, but that > should be 'glued' to the objects. So, there is no universal time. (What > is kind of tough to tell, too. ) > > TH- Hide quoted text - > > - Show quoted text - Time is always going forward in space for matter and light. There is no other way. Mitch Raemsch
From: bert on 19 Jun 2010 14:58
On Jun 19, 12:04 pm, Sam <sworml...(a)gmail.com> wrote: > On Jun 19, 10:58 am, "Robert L. Oldershaw" <rlolders...(a)amherst.edu> > wrote: > > > An interesting discussion has started at sci.physics.research > > concerning the nature of the "arrow of time" > > Consider these Arrows > http://en.wikipedia.org/wiki/Arrow_of_time#Arrows Sam Time has 5 arrows TreBert |