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Talk:Phase space

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554:"In a phase space, every degree of freedom or parameter of the system is represented as an axis of a multidimensional space" I think this phrase is misleading. There is a difference between phase space as defined here and parameter space. The phase space is all the possible states of a given system (usually over time for different initial conditions). Changing the parameters of a system (for example the stiffness of a spring) can give a different phase space. If we allow the parameters to be changed then we obtain a family of phase spaces. Usually, if the system has fixed points one can study the evolution of this fixed points when changing the parameters of the system, leading to the 200: 947:. However, the "phase" crosses its own path several times, which it cannot do. Since all information needed to determine the evolution of a system's phase can be determined from the phase itself, the time derivative of the phase must also be completely given completely by the phase itself. Hence, a system's phase cannot cross its own path because that would mean that at the crossing point, the phase has multiple time derivatives, which it cannot have in a single point. Therefore, what is shown in the image cannot be the phase path of any system, for the simple reason that the path crosses itself. 535:. By (1) containing all possible states of a system and (2) being visualized by phase portrait, it is essentially identical to the phase space. You claim that the 'state space' is a configuration space, which represents only particle coordinates. Yet, I see the opposite: Instead of being dedicated to the particle potential coordinates, the abstract dynamic system state space permits any state variables. That is, by representing any system, not only particles, state space is more general than your phase space. -- 95: 371: 85: 64: 31: 295: 274: 305: 190: 169: 22: 969:
I agree; the figure also had me baffled. I think that it should be removed since it confuses more than it helps, and as was pointed out above, the path intersects itself. Hmmm... Thinking about this a bit more leads me to believe that the time-dependent forcing term could cause the paths to cross.
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I agree that there's a problem. The prose is ambiguous -- if the "i.e." comment is taken to be explaining only the preceding term "momentum variables", then maybe it's not incorrect, but that's not the natural reading, and in any case, the comment (and the term "cotangent") is out of place in the
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In the text is written "The phase space of a two-dimensional system is called a phase plane, which occurs in classical mechanics for a single particle moving in one dimension, and where the two variables are position and velocity. In this case, a sketch of the phase portrait may give qualitative
1171:"Once the phase integral is known, it may be related to the classical partition function by multiplication of a normalization constant representing the number of quantum energy states per unit phase space. This normalization constant is simply the inverse of Planck's constant 747:
Really? 6N-dimensional space? So for a system of 10^20 gas particles, we'd have a 6*(10^20)-dimensional phase space? It seems to me that this is a typo and should read 6-dimensional phase space. I'll change it in the next couple of days if nobody objects.
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in which the parameters of the system are the axes of the plot. To summarize, in the phase space you do not represent the parameters as an axis. If the parameter has dynamics then ti can be considered a degree of freedom of the system.
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for a classical system with N particles, each point in the 3N + 3N dimensional phase space is a possible configuration of the system. in statistical mechanics, a "state" is then a probability distribution (in mathematical terms, a
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I've noticed the use of the phrase "phase space" used in the context of ideas. It describes all the possible outcomes of a given scenario. Since this use is not widespread, does it merit mention in this article?
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Since the oscillator is being damped and/or driven by a non-constant force, there doesn't seem to be any reason to expect that the entire dynamics of the system would be captured by position and momentum alone.
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a point in the 6N-dimensional phase space describes the dynamical state of every particle in that system, as each particle is associated with three position variables and three momentum variables
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they are not labeled in the graphic. I fancy myself smart and interested in heady stuff like this, but I think I need to knwo what those axes are to understand the illustration. right?
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Non-intersection of phase curves is a property of autonomous systems. Since the Duffing oscillator is not autonomous, it will not have that property. One can, of course, introduce
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I assume all of those "dynamical" and "thermodynamical" should actually be "dynamic" and "thermodynamic"? Didn't change them in case it's some weird mathematical usage.
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For mechanical systems, the phase space usually consists of all possible values of position and momentum variables (i.e. the cotangent space of configuration space).
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To make Phase Space the main article on the (p, q) space of dynamical systems, and Phase diagram mainly on the physical chemistry uses of that term
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I think this is misleading, because if we have a N-particle System in 3 dimensions with coordinates (p,q) it has 6N Dimsnesions but the power of
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The statement on quantisation needs a tidy - it's the product p.q which has the dimensions of action surely. (so from memory, dp.dq = h) Bob aka
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The images require labels on their axes. The first image has none. The second image's resolution is too poor to decipher the axis labels.
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Speaking of that, it looks like someone erroneously linked the English article on Phase Space with the French article on Phase Diagrams...
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It seems to me the expression "cotangent space" should be replaced with "cotangent bundle". As I am not 100% sure, I open a talk page.
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https://web.archive.org/web/20081011041922/http://clesm.mae.ufl.edu/wiki.pub/index.php/Configuration_integral_(statistical_mechanics)
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Even if the axes were dimensionless (and in this case, they can't be as momentum is expressed in units), they should be labelled.
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is a state; it corresponds to the distribution that is constant everywhere on some constant-enery surface of the phase space.
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information about the dynamics of the system, such as the limit cycle of the Van der Pol oscillator shown in the diagram."
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The animated image showing the evolution of a system's phase claims that what is shown is the phase path of the
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to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
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Now, the statement on quantisation is better: no one will understand, who not already knows! It's a pity!
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If x is position & y is momentum, (commom) then the diagram is flipped - should be clockwise...
491:) on the phase space. so the state space is the family of probability distributions. for example, the 1187: 1014: 990: 798: 697: 648: 620: 565: 652: 461:
Isn't "Phase space" = "State space"? They both are the space of all possible states, aren't they? --
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Done. Howeever, I was sloppy with the links, some may be disambig pages. I have to run ...
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http://clesm.mae.ufl.edu/wiki.pub/index.php/Configuration_integral_(statistical_mechanics)
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lede, so the best approach is just to delete it all, which I will now do...
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raised to a power equal to the number of degrees of freedom for the system
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Number of dimensions of the configuration space and the phase space
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of the prefactor of the Phase Space Integral is still 3N.
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for additional information. I made the following changes:
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are the x & y axes of that first illustration defined?
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I think it might be helpful to contrast phase space with
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Editors 1085: 1038: 598:, or at least link to that article at some point. 519:Another related category: "Dimensional analysis" 1163:-dimensional system is called a phase plane..." 1226:Knowledge level-5 vital articles in Mathematics 475:, which is a related but different concept. -- 866:This message was posted before February 2018. 8: 322:, which collaborates on articles related to 1256:C-Class physics articles of High-importance 1159:I think it should be "The phase space of a 836:I have just modified one external link on 268: 163: 58: 1069: 1068: 1051: 1019: 1018: 1016: 1216:Knowledge vital articles in Mathematics 1046:to have a non-intersecting phase space 270: 165: 60: 19: 639:Use outside of physics and mathematics 1271:Systems articles in dynamical systems 1231:C-Class vital articles in Mathematics 7: 1086:{\displaystyle (\tau ,x,{\dot {x}})} 787:Cotangent space or cotangent bundle? 378:This article is within the field of 316:This article is within the scope of 211:This article is within the scope of 106:This article is within the scope of 471:No, "state space" is a synonym for 49:It is of interest to the following 1241:High-priority mathematics articles 14: 840:. Please take a moment to review 590:Contrast with configuration space 126:Knowledge:WikiProject Mathematics 1251:High-importance physics articles 1211:Knowledge level-5 vital articles 1119:Ah, that's right! I removed the 1039:{\displaystyle {\dot {\tau }}=1} 303: 293: 272: 198: 188: 167: 129:Template:WikiProject Mathematics 93: 83: 62: 29: 20: 1266:Mid-importance Systems articles 767:Decoherence#Phase_space_picture 550:Phase space and Parameter space 506:... and zero everywhere else. 356:This article has been rated as 251:This article has been rated as 146:This article has been rated as 1221:C-Class level-5 vital articles 1080: 1053: 1: 1192:10:49, 18 February 2023 (UTC) 939:Duffing oscillator phase path 779:21:02, 23 November 2010 (UTC) 665:21:23, 10 February 2009 (UTC) 585:10:01, 10 November 2007 (UTC) 570:12:40, 20 February 2008 (UTC) 524:11:30, 29 December 2006 (UTC) 336:Knowledge:WikiProject Systems 231:Knowledge:WikiProject Physics 225:and see a list of open tasks. 120:and see a list of open tasks. 1276:WikiProject Systems articles 1236:C-Class mathematics articles 999:22:08, 3 February 2021 (UTC) 980:18:11, 23 January 2021 (UTC) 950:So, what exactly is it that 934:10:39, 7 December 2017 (UTC) 823:20:18, 24 October 2014 (UTC) 758:18:38, 12 October 2010 (UTC) 710:23:25, 17 October 2010 (UTC) 608:02:20, 14 January 2008 (UTC) 339:Template:WikiProject Systems 234:Template:WikiProject Physics 964:17:05, 3 January 2021 (UTC) 725:00:29, 13 August 2011 (UTC) 690:13:58, 21 August 2010 (UTC) 511:10:29, 25 August 2006 (UTC) 500:04:47, 25 August 2006 (UTC) 480:02:48, 25 August 2006 (UTC) 1292: 1139:12:58, 10 April 2021 (UTC) 1103:08:56, 16 March 2021 (UTC) 897:(last update: 5 June 2024) 833:Hello fellow Wikipedians, 452:07:48, 14 March 2006 (UTC) 442:16:24, 13 March 2006 (UTC) 362:project's importance scale 257:project's importance scale 1167:Phase Space Normalisation 730:Thermodynamic Phase Space 633:14:22, 4 March 2008 (UTC) 545:11:47, 31 July 2010 (UTC) 413:18:56, 26 July 2005 (UTC) 405:23:48, 19 Feb 2005 (UTC) 377: 355: 288: 250: 183: 145: 78: 57: 1261:C-Class Systems articles 1246:C-Class physics articles 807:20:21, 7 July 2014 (UTC) 576:WikiProject class rating 152:project's priority scale 829:External links modified 493:microcanonical ensemble 466:19:48, 3 May 2006 (UTC) 109:WikiProject Mathematics 1206:C-Class vital articles 1087: 1040: 533:State space (controls) 374: 311:Systems science portal 1088: 1041: 954:shown in the image? 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