Friday, July 16, 2010

critical states

Do we live in a perpetual or constant world that is in the critical state? Is there any difference between "action at a distance" and microscopic forces influencing macroscopic properties and behavior?
If I have a ferromagnetic material near its Curie temperature and change one electron's spin direction, then it should have an effect on another electron's spin at any range from it. Certainly, the force that the change in spin of the electron I choose first influences to some degree its neighboring electrons, then they influence their neighbors and so on until they find electrons at any distance to influence a complete change in direction. The influential role of the electron I have chosen is merely a fluke of probabilities in my eyes while certain in the eyes of nature.
However, is this any different than if I were to blow a feather off a table. My lungs create a pressure change which causes a chain reaction of colliding air molecules which in the end, and along the direction from my mouth to the feather, is just events that can be described microscopically in order to affect the feather from a distance. To provide another example of microscopic local influences causing global reactions, consider social networks.
My undergraduate research advisor, Dr. Ojakangas, would tell his students about some physical law or theory, then asked, "Do you buy that? Because that's all I'm selling!" Now, when I tell some story or give a lecture, I might ask whomever I am talking to, "You buy that? That's what I'm selling!"...or something to that effect. The point is this: after Ojakangas fed us (his Mechanics II students) that line the first time, he told us that he had heard a professor of his say that (I think at CalTech). He apparently liked it, so he made a similar comment to us. I like it as well, so I make the comment to whomever cares to listen to me on occasion. I imagine that by this point, others either those who have heard Ojakangas' professor at CalTech, Ojakangas, or myself say this line have or will also say this to others. Other people who have no idea where the source of the silly line came from. This is like action at a distance. (I'm not going to claim that the source is even Ojakangas' professor; that's just as far as I know who came up with what!)
An even bigger social network analogy is that of the internet. Before the internet one person with a video of something ridiculous would only be able to show the people they knew and not too many others. Now, that video can go viral and effect millions of people who have absolutely no direct connection to that person. The internet has provided a way to make a correlation distance between people in the world near its maximum possible value, just as in the critical state of electrons in a ferromagnetic material near the Curie temperature.
Does this all mean that we live in a constant state of criticality? Where the butterfly effect really changes everything? If not everything, does it at least make great dents in the previous order that existed? Has there ever been order? I suppose when talking about correlation distances of one object or idea influencing another at a distance, we must consider correlation times. For our brief time on this earth, most of us probably won't cause the global changes in our lifetimes, but our actions now may influence the next generations in ways we would not expect. Stories your parents may have told you about their times in life may influence the way you conduct yourself. Your actions may then influence others which may lead to global implications later, like the leaders of nations deciding between good and evil.

My bet is that we live in a constant state of criticality. I think that every action now influences the current order to be reordered. Whether there is an end to the criticality, I doubt it exists. I cannot think of anything on any scale in which a scale's microscopic forces do not propagate to influence objects at a distance. However, the time scale in which to consider universal objects may need to be characteristically near infinite. Keep in mind that pockets of objects that do not seem to be influenced are part of the property which determines criticality. Nothing is globally special, no matter the amount of detail you consider.

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