Posts tagged with phase space



















Another interesting space.




The illusion that Nature … adopts the same complexity scale used by people … arises each time we face … configuration [space]…. The second law of Thermodynamics, for example, has been interpreted in many textbooks as though Nature exhibits an incurable tendency to disrupt order.

Nature, of course, could not prefer one state of affairs to any other simply because we found an elegant description to the former, not more than the sequence HHHHHH is preferred to any other sequence in a coin-flipping experiment. The second law implies only that a … system tends to “escape” from any narrow region of phase space toward regions of larger volume.

The illusion of an irreversible trend toward disorder originates with the fact that the volume occupied by states to which people can find concise descriptions … is extremely small compared to the entire space of possibilities. The escape from the [describable] to the [formless] is merely a perceptual distortion of the underlying transition from the narrow to the wider, as people fail to record the much more frequent transitions from the complex to the complex.

Judea Pearl, On the connection between the complexity and credibility of inferred models

via Artemy Kolchinsky







I had judged The Emperor’s New Mind by the negative reviews but never actually picked it up. It has a lot of great stuff, almost like an “early draft” of The Road to Reality.




All I knew about Emperor’s New Mind before was that it invokes quantum mechanics to explain free will, which was perceived as “icky” by people who study the brain. (Despite that, like quantum nonsense, the “greats” of QM—Bohr, Schrödinger—also weighed in with QM/free-will speculations (do you hear me, Conrad&Kochen? Quantum communication folks?) — because, let’s be real here, free will is a millennia-old conundrum and I think we’d all appreciate it if the people who understand compositions of Hilbert spaces weighed in on whether and what the latest “master theory” (bringer of semiconductors = transistors, LCD’s, lasers, MRI/PET and certain polymers/piezoelectrics/other materials) would say about the age-old question)

I got a bit more of the debate whilst reading about pi-1 sentences, which is a computability/knowability/logic dealio. But again, this was the level of “What’s RP’s argument in a nutshell?” rather than “Is here anything worth reading in the 400 pages?”. It’s a lot of good.




Mapping from
discrete domain: length × width →
discrete codomain: {A,B,Q,Q+} = stocking size.
Two things.
First, it’s a scale in the sense of Hadley Wickham’s ggplot: an association between logic and graphics.
Second, it depicts a well-known phase space.Just like certain pressure & temperature combinations make plumbumappear as a solid, liquid, or gas [for instance the point (3180℉, 1 atmosphere)] — so do certain height & weight combinations recommend a stocking of A, B, or Q.

Mapping from

  • discrete domain: length × width →
  • discrete codomain: {A,B,Q,Q+} = stocking size.

Two things.

  1. First, it’s a scale in the sense of Hadley Wickham’s ggplot: an association between logic and graphics.
  2. Second, it depicts a well-known phase space.

    Just like certain pressure & temperature combinations make plumbum

    appear as a solid, liquid, or gas [for instance the point (3180, 1 atmosphere)] — so do certain height & weight combinations recommend a stocking of A, B, or Q.




Harmonic and Circular Oscillation by quantumaniac via dataanxiety

I can’t find enough illustrations explaining phase space. Phase space is a space people make up with their minds. The fact that a real thing bobbing up and down harmonically along 1-D is equivalent to a circle (seems like 2-D? but a topologist would say S¹ and in fact we don’t use the interior of the circle at all) is such a huge mental leap forward, I can’t express how much it amazes me or how much potential I think this metaphor has for everything else.

Think about the space of solutions of Rubik’s cube. Physically the cube is what it looks like:  but paths toward the solution are like a high-dimensional pyramid with “solved” at the top and entropy at the bottom.

Rather than being “just a plain-old (ordered){red,blue,orange,yellow,green,white}⁹ with one particular configuration (starting point / solved) called the “centre”, all of that space is equivalence-classed by ,
since some orientations can only be obtained by switching the stickers and not by legal moves,
and since some members of (ordered){red,blue,orange,yellow,green,white}⁹ are actually just setting the cube down on the table differently rather than twisting it. (and therefore equivalent-in-that-sense) 
Anyway the Rubik’s Cube is a “knot” in phase space but nothing like a knot in right-in-front-of-you vision.

Here’s another example: if you have a Mac, you can invert the system’s colour scheme (presuming colours can be 2-inverted rather than in-in-in-verted or triverted but that’s another story) by pressing Alt + Command + N.

You can also 2-invert the colours of just one window (not the system) by pressing Alt + Comand + M. If you accidentally hit M,N, instead of N, your computer’s colour scheme would be 1-tangled. Or if you hit M on the wrong window, then hit N, then switched to another window and hit M, it would be even more tangled. But you can tell me that doesn’t make any sense! A Mac has a flat 2-D screen, with panes on it. Where do these “tangles” come from? It’s just some electronic signals zipping around and lighting up an LCD. Well, in phase space, in this particular mental representation which we can communicate about, it can be tangled.

Harmonic and Circular Oscillation by quantumaniac via dataanxiety

I can’t find enough illustrations explaining phase space. Phase space is a space people make up with their minds. The fact that a real thing bobbing up and down harmonically along 1-D is equivalent to a circle (seems like 2-D? but a topologist would say S¹ and in fact we don’t use the interior of the circle at all) is such a huge mental leap forward, I can’t express how much it amazes me or how much potential I think this metaphor has for everything else.

Think about the space of solutions of Rubik’s cube. Physically the cube is what it looks like:
  
but paths toward the solution are like a high-dimensional pyramid with “solved” at the top and entropy at the bottom.

Rather than being “just a plain-old (ordered){red,blue,orange,yellow,green,white}⁹ with one particular configuration (starting point / solved) called the “centre”, all of that space is equivalence-classed by ,

  • since some orientations can only be obtained by switching the stickers and not by legal moves,
  • and since some members of (ordered){red,blue,orange,yellow,green,white}⁹ are actually just setting the cube down on the table differently rather than twisting it. (and therefore equivalent-in-that-sense) 

Anyway the Rubik’s Cube is a “knot” in phase space but nothing like a knot in right-in-front-of-you vision.

Here’s another example: if you have a Mac, you can invert the system’s colour scheme (presuming colours can be 2-inverted rather than in-in-in-verted or triverted but that’s another story) by pressing Alt + Command + N.

You can also 2-invert the colours of just one window (not the system) by pressing Alt + Comand + M. If you accidentally hit M,N, instead of N, your computer’s colour scheme would be 1-tangled. Or if you hit M on the wrong window, then hit N, then switched to another window and hit M, it would be even more tangled. But you can tell me that doesn’t make any sense! A Mac has a flat 2-D screen, with panes on it. Where do these “tangles” come from? It’s just some electronic signals zipping around and lighting up an LCD. Well, in phase space, in this particular mental representation which we can communicate about, it can be tangled.




—Charles Marx
Capital
, Vol. 1.

image

(Source: Wikipedia)