Arrow of Time
in [Physics]
|
From: BURT on 20 Jun 2010 15:50 On Jun 20, 12:59 am, oen <ynes9...(a)techemail.com> wrote: > On Jun 19, 5:58 pm, "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" > > > 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 ? > > causality do not need an arrow, > > it is just that, causal, without which you > get chaos, which we dont like > > > > > 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? > > > RLOwww.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 > > wrong, all of them are 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. > > yes, i just said that, you are contradicting yourself > > > > > -------------------------------------------------- > > > (1) We are not absolutely required to accept unconditionally the > > statement that "Microscopically, the laws of physics are time- > > reversible,..." > > no, it is a matter of limitation of detection > > the causality still exist at quantum level !!! > > > > > 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]. > > i just said that > > > > > (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. > > agreed > > > > > RLOwww.amherst.edu/~rloldershaw > > good bye, learn physics from a book- Hide quoted text - > > - Show quoted text - The nature time is to float ahead. Mitch Raemsch
From: Yousuf Khan on 21 Jun 2010 06:44 On 6/20/2010 9:14 AM, Sam wrote: > On Jun 19, 1:58 pm, bert<herbertglazie...(a)msn.com> wrote: >> >> Sam Time has 5 arrows TreBert > > 3.1 The thermodynamic arrow of time > 3.2 The cosmological arrow of time > 3.3 The radiative arrow of time > 3.4 The causal arrow of time > 3.5 The particle physics (weak) arrow of time > 3.6 The quantum arrow of time > 3.7 The psychological/perceptual arrow of time As far as I'm concerned, the thermodynamic, cosmological, radiative, causal and psychological/perceptual arrows of time are all the same thing: basically the causal arrow of time. It's the quantum and particle physics arrows that are slightly different. The quantum arrow probably represents what the universe was like before the Big Bang. Particles would come together, and fall apart, and back again without any structures being built or accumulating. The Big Bang imparted a momentum in a specific direction of space, which we now call "causal" time, where particles travel in the same direction and eventually collide to form bonds, which form structures, which accumulate as they travel through time. The particle physics arrow of time is the weird half-way point between the quantum arrow and the causal arrow. The particle physics arrow describes the lowest level of particles at which we see a causal arrow emerge, i.e. within the kaons. If the direction of time were reversed, then we'd have a universe dominated by anti-matter, because 1% more kaons would decay into anti-matter over matter, rather than the other way around. But we'd still see causality progress the same way. Also we'd likely have renamed anti-matter into matter, and vice-versa. Yousuf Khan
From: Don Stockbauer on 21 Jun 2010 09:08 On Jun 21, 5:44 am, Yousuf Khan <bbb...(a)spammenot.yahoo.com> wrote: > On 6/20/2010 9:14 AM, Sam wrote: > > > On Jun 19, 1:58 pm, bert<herbertglazie...(a)msn.com> wrote: > > >> Sam Time has 5 arrows TreBert > > > 3.1 The thermodynamic arrow of time > > 3.2 The cosmological arrow of time > > 3.3 The radiative arrow of time > > 3.4 The causal arrow of time > > 3.5 The particle physics (weak) arrow of time > > 3.6 The quantum arrow of time > > 3.7 The psychological/perceptual arrow of time > > As far as I'm concerned, the thermodynamic, cosmological, radiative, > causal and psychological/perceptual arrows of time are all the same > thing: basically the causal arrow of time. It's the quantum and particle > physics arrows that are slightly different. > > The quantum arrow probably represents what the universe was like before > the Big Bang. Particles would come together, and fall apart, and back > again without any structures being built or accumulating. The Big Bang > imparted a momentum in a specific direction of space, which we now call > "causal" time, where particles travel in the same direction and > eventually collide to form bonds, which form structures, which > accumulate as they travel through time. > > The particle physics arrow of time is the weird half-way point between > the quantum arrow and the causal arrow. The particle physics arrow > describes the lowest level of particles at which we see a causal arrow > emerge, i.e. within the kaons. If the direction of time were reversed, > then we'd have a universe dominated by anti-matter, because 1% more > kaons would decay into anti-matter over matter, rather than the other > way around. But we'd still see causality progress the same way. Also > we'd likely have renamed anti-matter into matter, and vice-versa. > > Yousuf Khan Little arrows in your clothing, little arrows in your hair. When you're in love you'll find those little arrows everywhere.
From: Robert L. Oldershaw on 23 Jun 2010 23:01 On Jun 21, 4:26 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > If you don't believe me, just try to resolve the issue I brought > up earlier using any of those theories: what is the "cause" of > the fire on this match? ---------------------------------------------------------------- Well, for starters how about: motion, then friction, then heat, then chemical reactions, then fire? Are you saying that going from an unlit match to a flaming match is an ACAUSAL process? What exactly is your point? Can you specify any physical system undergoing any specific physical interaction that violates causality. Please skip the Platonic obfuscation and deal with real systems doing real testable things. RLO www.amherst.edu/~rloldershaw
From: bert on 24 Jun 2010 20:11
On Jun 21, 6:44 am, Yousuf Khan <bbb...(a)spammenot.yahoo.com> wrote: > On 6/20/2010 9:14 AM, Sam wrote: > > > On Jun 19, 1:58 pm, bert<herbertglazie...(a)msn.com> wrote: > > >> Sam Time has 5 arrows TreBert > > > 3.1 The thermodynamic arrow of time > > 3.2 The cosmological arrow of time > > 3.3 The radiative arrow of time > > 3.4 The causal arrow of time > > 3.5 The particle physics (weak) arrow of time > > 3.6 The quantum arrow of time > > 3.7 The psychological/perceptual arrow of time > > As far as I'm concerned, the thermodynamic, cosmological, radiative, > causal and psychological/perceptual arrows of time are all the same > thing: basically the causal arrow of time. It's the quantum and particle > physics arrows that are slightly different. > > The quantum arrow probably represents what the universe was like before > the Big Bang. Particles would come together, and fall apart, and back > again without any structures being built or accumulating. The Big Bang > imparted a momentum in a specific direction of space, which we now call > "causal" time, where particles travel in the same direction and > eventually collide to form bonds, which form structures, which > accumulate as they travel through time. > > The particle physics arrow of time is the weird half-way point between > the quantum arrow and the causal arrow. The particle physics arrow > describes the lowest level of particles at which we see a causal arrow > emerge, i.e. within the kaons. If the direction of time were reversed, > then we'd have a universe dominated by anti-matter, because 1% more > kaons would decay into anti-matter over matter, rather than the other > way around. But we'd still see causality progress the same way. Also > we'd likely have renamed anti-matter into matter, and vice-versa. > > Yousuf Khan Observers can have different perspectives of time. That has been confirmed. Best to keep in mind the effects of SR depends upon how fast one moves. We must always have "time dilation" and Lorentz contraction in our thinking Stuff is not "absolute" iF eINSTEIN DID not merge space and time I know I would have. They are two sides to the same coin. Always got a kick out of this fact. No matter how fast you chase after a light beam it still retreats from you at c Photons never change speed nor do they bounce. My "Spin is in theory" covers this. TreBert |