Friam - Re: Assistance sought: The meaning of constraints

Friam

Re: Assistance sought: The meaning of constraints

Posted by Nick Thompson on
URL: http://friam.383.s1.nabble.com/Assistance-sought-The-meaning-of-constraints-tp6165767p6175281.html

Vladimyr,

Everything you say is interesting and relevant, but some of it makes me feel guilty for drawing Eric out on to thin ice. Remember the idea that motionless object is not doing work, or that an object cannot be being worked on if it’s not being moved is from FEYNMAN, not from Eric or even from me.

In the passage Feynman goes on to talk about the situation in which the bowling ball is being held up by a person and says that in that case work is being done because of the micro movements of the ball as the person struggles to hold it up. He then says that if the person could actually lock his muscles no work would be done.

So blame it on Feynman, first, me second, but not at all on Eric, who was just trying to help me out.

Nick

From: [hidden email] [mailto:[hidden email]] On Behalf Of Vladimyr Burachynsky
Sent: Tuesday, March 15, 2011 5:25 PM
To: 'The Friday Morning Applied Complexity Coffee Group'
Subject: Re: [FRIAM] Assistance sought: The meaning of constraints

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Hello Tori,

As ever those supposedly silly questions are inevitably very nasty when one tries to explain them. Most sensible people steer clear of them. I am not always sensible I am afraid, and will take a chance to give a different perspective of Eric’s Travelling Magic Act.

Gravity is apparently a force and as such it even has a definition which can be used mathematically, g , 9.8 m/sec ^2 But that’s an approximation for earth only and the moon and every other mas has its own specific values. The fact that gravity is ubiquitous and constant allows us to basically ignore it just like we ignore Oxygen or the composition of what we stand upon. In a sense then when we do consider it at all, it is usually as a “constraint” , some kind of limiting factor as are handcuffs. So in our language we begin to use like words to describe entirely different concepts. I looked at the way people use the term briefly and generally a constraint appears to be associated with a limitation on movement ( Call it a distance or perhaps a direction) In psychological language it seems to be a limit on freedom of choice( the distance parameter disappears) This translation from real world to the metaphysical is not perfect, the fact that the units of measurement have been lost also has other consequences. We understand the world through measurable quantities, taking a trip to the metaphysical leaves us without references. I suspect Freedom once meant to be able to wander freely about a valley without bears threatening us. So the distance component seems to linger some how even in the metaphysical spaces. I generally avoid the metaphysical because none of my tools seem to work without dimensions. ( I never previously appreciated the manner in which real world concepts were translated in the Metaphysical but the loss of dimensionality seems typical. This may be a general rule? The stripping away of units of measurement is some sort of attempt to grasp another meaning in terms of the human reality which seems dimensionless. We know that is not absolutely true and even nerve impulses must travel distances through time yet we ignore those completely as well. If we ignore physical reality because we do not perceive it, then we live in a delusion automatically by default. I suspect we make every effort possible in life to impose our reality on other systems, I think this is what we call Controlling the situation.)

In engineering analysis we are often concerned about how Loads( Forces) will deform ( distance displacements) or fail structures. We use constraints to redirect forces to other less critical areas. Force applied to an area is stress. Things fail when the stress value exceeds the limits of material properties.

The Bowling Ball on the table may not appear to be moving but in fact it is working to deform the table top, that work is stored in the table structure as strain energy. Remove the Ball and the table will attempt to return to a rest position. The table top resists deformation by pushing back at the ball which is being pulled down by gravity. The ball also must deform ever so slightly . Under the influence of the gravitational force the Bowling Ball and the Table and even the ground all seem to establish little changes in their strain energy and negotiate a stable position, it looks exactly like “No work has been Done” Should you be able to Remove gravity instantly then the strain energy releases should launch the ball up and alter the table. We treat gravity as a constraint assuming balls do not launch upwards at random moments. Yet it is an elusive force. Psychologically I have no idea what the equivalent to material properties might constitute. Seems there is no psychological equivalent to Hooke’s Law.

The example Eric gave is a cunning Magicians trick, he set the stage to confuse the audience. The scenario as given contains many constraints which are assumed to be in place before the show but left undeclared. No gravity, complete dissipation of all stored strain energy no other external sources of gravity and no other forces to impart motion. The table must be removed precisely so that it never contacts the free floating bowling ball. The excessive grunting and sweating of the magician leads us to believe that work is being done. The other unstated constraint on the scenario is that all observers are still living inside a gravity dependent reality and there are no apparent relative motions. The magician has a small problem not defined, is he inside the gravity zone or is he also in zero gravity.? If he is outside then he may be able to move the table in only specific ways. He also is floating and now all bodies are subject to the same laws. He will have to move unexpectedly if he touches another body( Newtons law). He has no constraints on his motion nor do any of the other objects. Metaphors do not always have the intended results. I worked for a professional magician for some time and have a little understanding about manipulating the reality of Observers. We as human beings are rarely aware of our own prejudicial thinking. As long as the audience feels the pressure on their buttocks they assume gravity is still in place and actually extends to include Eric and all his stage props. The Magician is a master of understanding human being’s limited sensory abilities.

Never disclose to an audience the actual workings of a magic act or they will rise in uproar. Now one is willing to admit they were deceived, many will claim you to be a liar. They fear being labelled stupid. So many will resort to gobbledygook explanations of mysterious magical elements to preserve credibility. Collaborating with a Magician had to be one of the most remarkable experiences of my life. Funny that years later I had a Thesis advisor employ many of the same protocols. One of my students actually became a clown/juggler/magician between professional gigs. He now runs a department of hundreds for a large city. Perhaps magicians are not quite human and learn to exploit our imaginary constraints. Scientists are the natural enemies of Magicians. But even the smartest scientists have the same pathetic sensory systems so they often lose in a first encounter. They too fear looking silly or stupid. Magicians spend long hours in practise and in front of mirrors, they invest heavily in the art of misdirection and they have no fear of criticism they encourage it before the audience arrives..

In the engineering math simulations we are occasionally able to model structures ignoring gravity altogether. We simply assume it is too small to notice (Every magician exploits that weakness). The larger the structures the more important gravity becomes. This is referred to as self weight. Each element of a large bridge must support the traffic loads but also its own weight. Hence strings sag in the middle when stretched between two points. The string is a system of elements, predicting the shape of the sag is an old trick but it requires that you nail the two ends to an immovable structure. That is two constraints .( Magicians exploit this also, if we see a sagging string we assume it has two constraints when a little Hair Gel does the trick) In effect the constraints basically state that the equation for the string sagging must be equal to zero displacement at exactly the beginning and end positions, also that the slope in the middle is also zero and down(that is a rather large number of constraints for a little system now that I reflect upon it). Once the constraints are applied mathematically the equation has a solution. So the nails were physically real constraints but the zero displacement values assigned to the equation were not real nor physical, I guess. They are imaginary representatives of nails and carelessly many engineers will speak of the two kinds of restraints as constraints and as if they were equivalent. Most constraints are attempts to model something physical by another means. The handcuff may be a constraint for a policeman but not for an accomplished lock picker. So the curious part of your question is the peculiar nature of what humans believe to be real. The border fences with Mexico may be real constraints as far as Texans are concerned but many Mexicans simply ignore that belief.

Partly your questions suggest an old philosophical premise that human beings only imagine causality out of habit (Hume). Now perhaps we only imagine constraints as some form of Punishment or Limit or a Zero value or impossibility.

Gravity is a force belonging to all bodies of mass proportional to their mass. EVery body has a gravitational force . That force extends well out into space for planets and stars. The forces overlap and may in effect cancel eachother out at specific points ( Lagrange points if I recall correctly). Each gravity well appears to act normal to the centre of mass in all directions. If the body is in motion so too will be the direction of action of the forces attributed to gravity. The force falls off quickly with the square of distance. But it is probably never zero.

The assumption that something is a constraint seems to exist in our minds in an attempt to mimic reality. The fence electrified to contain prisoners appears as a constraint which is quite subjective an opinion. Certainly grasshoppers ignore the concept. In that sense the constraint was a belief in a concept by the security guards that would alter the reality of the prisoners. That belief was specific to that very smalll portion of reality that contains the prisoners and the guards. The grasshoppers and the Tectonic Plates were not part of the concern. Reality does not abide by our imposition of constraints. The sea walls in Japan certainly point that out clearly.

One has to be very careful with metaphors such as the child and bumper balls. Every engineering simulation I have ever seen excludes more of reality than it attempts to include. There are obvious practical reasons for this but we seem to forget the fact and swear the simulations are valid everywhere. In a strange manner the Gullible human mind believes the constraints to be real. That Gullibility is what the Magician exploits and apparently Eric has some of that talent as well. In some manner Mubaruk was convinced his constraints on citizens were real and they defied him with another version of reality that completely ignored his. In some sense we are attempting to reflect what we think is real from our minds back upon the REAL world. Sometimes it fits and sometimes not. ( That is the nature of Experiment). Surprisingly for such a stupid animal Humanity has managed to work out some ways around previous well established constraints, we do fly heavier than air machines and drive to shopping malls without horses. We can extract freshwater from the sea, and we have been to the moon. Not bad for a monkey that asks silly questions. We delivered a machine to Mars and it talked back to us and sent pictures.

Perhaps my response was more than required and it was my curiosity that pulled me in deeper than needed. I hope it made a little sense. Lately I watch the news casters struggle with technical terms and regularly call in experts to explain the language. The experts do not seem proficient at alleviating fears in the public mind. Regrettably few technocrats ever learned to speak before a general audience. I suspect there is a small fear of speaking in public that hampers everyone and everyone is afraid of appearing silly or stupid which seems to be another imaginary Constraint.

Now the forces that can be measured seem to be real the others we speak about are metaphysical or psychological. If we were to treat the forces as I did the constraints one has to concede that generally Force is something that moves bodies through some distance over time and Constraints are the devices used to control forces. They both seem to be dependent on distance in some manner and mass is not absolutely required in general language. Star Wars Force is very real to some observers and it always struck me as some cosmic Strain Energy that could jump out of the metaphysical reality and manifest itself here in various dimensions and against all laws of physics. It is a little like a sublime God like force that can operate without any constraints of reason or physics oh I forgot to mention that it was controlled by will. This fits with a desire for beings to impose delusions upon reality with no regard to consequences. This Will seems to be the substance of magical powers.

Someday hopefully Eric can discuss the full context of psychological constraints and forces.

Please Keep asking questions and hopefully we can gain some experience in answering them.

Vladimyr Ivan Burachynsky PhD

[hidden email]

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From: [hidden email] [mailto:[hidden email]] On Behalf Of Victoria Hughes
Sent: March-13-11 4:32 PM
To: [hidden email]; The Friday Morning Applied Complexity Coffee Group
Subject: Re: [FRIAM] Assistance sought: The meaning of constraints

Well, I know this is another one of my out-of-left-field questions, but out of curiousity is gravity a constraint or a force? Does it depend on where you measure it? What about at planetary distances?

Really I am just curious and not attempting to poke or provoke.

Thank you-

Victoria

[ ps so is my ignorance a constraint or a force, and what changes that?

On Mar 13, 2011, at 9:45 AM, Russ Abbott wrote:

Eric and Lee have nice discussions. The only thing I would add as something of a generalization is that constraints have to do with the structure of something--in Lee's case, the way the hand is structured and how it's held together at the joints and in Eric's case the structure created by the bumpers on the alley. Forces become important when one discusses the expenditure of energy--in Lee's case the use of energy to move the hand given the constraints and in Eric's case the energy that imparted momentum to the ball.

One thing that makes this more difficult is that many social (and biological) systems expend energy to maintain structure: a police force is an example as is a government more generally. In Lee's and Eric's examples, we imagine the structures being maintained statically (and indefinitely) by whatever holds the pieces in place. In social and biological organizations many of the structures would fall apart were it not for the continual expenditure of energy.

-- Russ Abbott
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Professor, Computer Science
California State University, Los Angeles

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On Sun, Mar 13, 2011 at 7:57 AM, ERIC P. CHARLES <[hidden email]> wrote:

I suspect that outside the context of a specific example, this is not really possible to answer. Throwing your own pet distinction back at you, we need to know what we are trying to explain, so we can avoid slipping levels of analysis. I have not read the author in question, but suspect an example (with slippage) would go something like this:

Imagine a child bowling with bumpers. The child causes the ball to roll down the lane, and to hit the pins. The bumpers constrain the path of the ball to be in the direction of the pins. That is, the overall path of the ball is roughly: /\/\/\/\/\/\/\/\X (our lucky kid rolls a strike), and when asked to explain that macro-movement - the child causes, the bumpers constrain. If that is correct, it is going to be a big problem if we slip our level of analysis to the details of the path of the ball. If, instead of explaining the overall pattern, we ask about a single jag (a single \) then the bumper has a causal roll, in that it applied force to the ball (or redirected force applied to it by the ball). So, what we find from our example is that all "constraints" are "causes" at another level of analysis - which would be terribly confusing if not specified.

For a more flippant example: Does my cable TV subscription constrain what I watch, or cause it? When I am flipping through the channels, it constrains it. When I stay on the same channel, whatever is on, it causes it.

Another thought: This is the same silly distinction made by people who are not willing to commit fully to epigenetic development. They say things like "genes create the constrains that the environment works within." (The most obvious reason it is silly is because one could just as easily reverse the terms.)

Hope something in that helps,

Eric

On Sun, Mar 13, 2011 01:45 AM, "Nicholas Thompson" <[hidden email]> wrote:

Dear anybody,

I am reviewing a book by a psychologist in which the author makes a distinction between constraints and causes. Now perhaps I am over thinking this, but this distinction seems to parallel one made by Feynman in his famous physics text, where he defines a constraint as a force that does no work. If I have it right, the idea goes like this: If you place a bowling ball on a table the ball neither receives work from gravity nor does the table do any work holding the ball up because the ball does not move, and work is just the movement of mass. Indeed, even if you were to slide the table out and, with great effort, were to hold the ball in the same position for an hour, you wouldn’t be doing any work, either. Similarly, in a ball rolling down an inclined plane, the plane itself does no work because even tho it affects the motion of the ball, its effect is always perpendicular to the motion of the ball and there fore affects its motion neither one way or the either …. i.e., does no work!

Now I would leave it at that except that Alicia Juarrero in her book also makes a huge distinction between forces and constraints, one which I think our own Steve Guerin applauds. It is the constraints that make it possible for far-from-equilibrium systems to self organize and do work. Perhaps I can make this work with Feynman’s definition if I think about the dam beside a water wheel, and the water wheel itself, as applying constraints to the water (they do no work themselves) which make it possible for the falling water to do work. Am I still on track, here?

Now Juarrero goes on to make a distinction between between context sensitive and context-free. I have read these passages dozens of times and I just don’t understand this distinction. Can anybody out there explain it to me as to a Very Small Child.

Thanks,

Nick

Nicholas S. Thompson

Emeritus Professor of Psychology and Biology

Clark University

http://home.earthlink.net/~nickthompson/naturaldesigns/

http://www.cusf.org
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Eric Charles

Professional Student and
Assistant Professor of Psychology
Penn State University
Altoona, PA 16601

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