Arrow of Time
in [Physics]
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From: BURT on 2 Jul 2010 15:15 On Jul 2, 9:58 am, "Robert L. Oldershaw" <rlolders...(a)amherst.edu> wrote: > On Jul 2, 7:41 am, Yousuf Khan <bbb...(a)spammenot.yahoo.com> wrote: > > > Alright, I'll bite, and give you the time of day to explain yourself. > > What exactly are you saying that is any different than what we call > > "causal time"? > > ---------------------------------------- > > Sean M. Carroll's argument, and that of many other physicists, is > that: > > (1) the "laws of physics in the microcosm are reversible" > > (2) time has an arrow, it only goes one way. > > (3) It's all the fault of the Big Bang, multiverses, Boltzmann Brains, > extra dimensions, etc. > -------------------------------------------- > > RLO's argument is that: > > (a) the "laws" [read artifical human models] are reversible, but > nature's physical systems and their interactions are NOT. Real > physical systems and interactions are irreversible. Always. > > (b) Causality is the first and most fundamental principle of nature. > > (c) It is causality that determines the arrow, not time. Time is a > purely relational concept we use to order causal sequences, and to > measure the relative rates at which two causal sequences occur. > > A bit subtle, I admit. But a thousand times better than Carroll's > untestable postmodern pseudoscience. > > RLOwww.amherst.edu/~rloldershaw There is only one direction of time and that is ahead. It is the same for space. You are always moving ahead in space-time. Mitch Raemsch
From: JT on 2 Jul 2010 15:45 On 2 Juli, 21:15, BURT <macromi...(a)yahoo.com> wrote: > On Jul 2, 9:58 am, "Robert L. Oldershaw" <rlolders...(a)amherst.edu> > wrote: > > > > > > > On Jul 2, 7:41 am, Yousuf Khan <bbb...(a)spammenot.yahoo.com> wrote: > > > > Alright, I'll bite, and give you the time of day to explain yourself. > > > What exactly are you saying that is any different than what we call > > > "causal time"? > > > ---------------------------------------- > > > Sean M. Carroll's argument, and that of many other physicists, is > > that: > > > (1) the "laws of physics in the microcosm are reversible" > > > (2) time has an arrow, it only goes one way. > > > (3) It's all the fault of the Big Bang, multiverses, Boltzmann Brains, > > extra dimensions, etc. > > -------------------------------------------- > > > RLO's argument is that: > > > (a) the "laws" [read artifical human models] are reversible, but > > nature's physical systems and their interactions are NOT. Real > > physical systems and interactions are irreversible. Always. > > > (b) Causality is the first and most fundamental principle of nature. > > > (c) It is causality that determines the arrow, not time. Time is a > > purely relational concept we use to order causal sequences, and to > > measure the relative rates at which two causal sequences occur. > > > A bit subtle, I admit. But a thousand times better than Carroll's > > untestable postmodern pseudoscience. > > > RLOwww.amherst.edu/~rloldershaw > > There is only one direction of time and that is ahead. It is the same > for space. You are always moving ahead in space-time. > > Mitch Raemsch- Dölj citerad text - > > - Visa citerad text - Actually you could consider a prerendered universe where our realtime destinies already settled as they go along. You think that decision just not made yet. JT
From: Sam Wormley on 2 Jul 2010 15:56 On 7/2/10 2:08 PM, JT wrote: > On 19 Juni, 18:04, 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 > Well the spatial dimensions in special relativity is all fucked up. Sounds like a rock song from the 50s. Special relativity, like general relativity uses the three observed spatial dimensions plus a time dimension. Those relativity theories, as well as the modern physics theories, such as QED, enjoy the fact that there has never been an observation that contradicts a prediction of those theories.
From: BURT on 2 Jul 2010 16:30 On Jul 2, 12:45 pm, JT <jonas.thornv...(a)hotmail.com> wrote: > On 2 Juli, 21:15, BURT <macromi...(a)yahoo.com> wrote: > > > > > > > On Jul 2, 9:58 am, "Robert L. Oldershaw" <rlolders...(a)amherst.edu> > > wrote: > > > > On Jul 2, 7:41 am, Yousuf Khan <bbb...(a)spammenot.yahoo.com> wrote: > > > > > Alright, I'll bite, and give you the time of day to explain yourself. > > > > What exactly are you saying that is any different than what we call > > > > "causal time"? > > > > ---------------------------------------- > > > > Sean M. Carroll's argument, and that of many other physicists, is > > > that: > > > > (1) the "laws of physics in the microcosm are reversible" > > > > (2) time has an arrow, it only goes one way. > > > > (3) It's all the fault of the Big Bang, multiverses, Boltzmann Brains, > > > extra dimensions, etc. > > > -------------------------------------------- > > > > RLO's argument is that: > > > > (a) the "laws" [read artifical human models] are reversible, but > > > nature's physical systems and their interactions are NOT. Real > > > physical systems and interactions are irreversible. Always. > > > > (b) Causality is the first and most fundamental principle of nature. > > > > (c) It is causality that determines the arrow, not time. Time is a > > > purely relational concept we use to order causal sequences, and to > > > measure the relative rates at which two causal sequences occur. > > > > A bit subtle, I admit. But a thousand times better than Carroll's > > > untestable postmodern pseudoscience. > > > > RLOwww.amherst.edu/~rloldershaw > > > There is only one direction of time and that is ahead. It is the same > > for space. You are always moving ahead in space-time. > > > Mitch Raemsch- Dölj citerad text - > > > - Visa citerad text - > > Actually you could consider a prerendered universe where our realtime > destinies already settled as they go along. > You think that decision just not made yet. > > JT- Hide quoted text - > > - Show quoted text - Einstein said that everything was predetermined in order. This is God's forever design. Absolute order is predetermined from the atom to the star. Mitch Raemsch
From: Yousuf Khan on 2 Jul 2010 16:51
On 7/2/2010 10:58 PM, Robert L. Oldershaw wrote: > Sean M. Carroll's argument, and that of many other physicists, is > that: > > (1) the "laws of physics in the microcosm are reversible" > > (2) time has an arrow, it only goes one way. > > (3) It's all the fault of the Big Bang, multiverses, Boltzmann Brains, > extra dimensions, etc. > -------------------------------------------- > > RLO's argument is that: > > (a) the "laws" [read artifical human models] are reversible, but > nature's physical systems and their interactions are NOT. Real > physical systems and interactions are irreversible. Always. That's of course not true. There's plenty of things in the universe that are reversible. Earth's orbit around the Sun, for example, is so reversible that you can roll it back in time billions of years, and still be able to tell where it was. You could also roll it forward billions of years, and tell where it will be. As long as the interaction doesn't involve any entropy changes, processes can be perfectly reversible. Of course, at some point the Sun and the Solar system was created, which involved entropy changes, and at some point in the future, the Sun will fade out, which is also entropy changes. Those processes are not reversible. > (b) Causality is the first and most fundamental principle of nature. If you say so. I don't want to belabour this point, but whether it's the *first* most fundamental principle of nature is debatable, but it certainly is highly fundamental. > (c) It is causality that determines the arrow, not time. Time is a > purely relational concept we use to order causal sequences, and to > measure the relative rates at which two causal sequences occur. You see, this is where you're not thinking carefully enough. At the quantum level, causality is still preserved, but you just can't tell which way the film is running. Almost all of the processes that occur in the quantum realm, can be reversed exactly. If A happens, then B occurs is just as likely as if B happens, then A occurs. For example if a photon hits an electron, then the electron gains energy and jumps up an orbital level. But if you run that film backwards, you see exactly the process by which an electron loses energy, emits a photon, and falls back down an orbital level. Causality is preserved completely in both these two cases. > A bit subtle, I admit. But a thousand times better than Carroll's > untestable postmodern pseudoscience. Time does affect causality. At relativistic speeds, time slows down, and therefore causality slows down too. Chemical reactions slow down, biological processes slow down, therefore a person traveling at relativistic speeds will age slower than somebody standing still (i.e. the Einstein twin paradox). Yousuf Khan |