When something is nothing

Active feedback systems can also have the frustrating property of revealing change that evaporates again as if it had never been there.

So, competent reliable observers may first measure something to be there, and they are correct, but then it goes away again and future measurements show it was "never there."

There are fewer examples here that most people recognize, although the phenomenon is fairly wide spread, because it is subtle.

Still, in the suburbs, anyone can easily see that the process of putting garbage cans out next to the curb causes garbage trucks to arrive. What's up with that?

The cleanest and least ambiguous example, physically, is the middle-range field of a radiating antenna. As discussed in a prior post, very near teh antenna one set of laws appear to apply, where the stable radiation pattern falls off as the inverse of distance. At long distances, the stable pattern can be measured to be falling off as the inverse cube of distance. And, in between, in the really annoying and complicated mid-range field, the pattern is unstable and appears, if measured, to fall off as the inverse square of distance. Worse, in the mid-range, some fields build up that behave as if they are about to be radiated into space, but then sort of change their mind and get basically sucked back into the antenna.

An analogy from the database world is a transaction in some system such as Oracle that is started, figures out it can't complete, and, rather than leave things in a mess, is rolled back out again. This "rollback" is a standard, required operation in database systems - that something can get started, then the application decides midcourse this isn't working, and the world is restored to a state as if the transaction had never started in the first place. In the local world, all trace that this even began is erased. This turns out to be a necessary process for retaining coherence in a database world. There are even more fascinating "two-phase commits" in distributed database worlds. This is a design feature that adds great value, and if evolution was making databases, it would preserve this if it ever found it.

And, another physical example from the realm of tiny-scale physics, and the behavior of light packets known as photons. When a photon approaches a barrier that has a "double slit" in it, the photon has to decide what to do. If it were a particle, it would either bounce off the barrier, or go through one slit or the other. But, waves behave differently. In a very real sense, the photon looks ahead to the future, sees that there are two slits, sees that if it went a certain way it would result in conflict and interference, so it never goes that way in the first place. The exact same interference pattern is generated as if the slit, acting as a wave, went through BOTH slits, except that, if you measure it, no, photons only are measured going through one slit OR the other.

Yet another example from stage magic is the behavior of perception in a crowd. It is well known among stage magicians that observations are reversible. That is, a few people in a crowd may actually see something happen they weren't supposed to see, but if no one around them sees or responds to it, the initial perception "goes away" again, and, if asked later, the people will claim they never saw anything. But video of the audience shows them registering surprise, looking around, and then dismissing the observation.

On an internal scale, I think human vision and perception play many such tricks on people where pre-perceptual processes form an impression, sort of try it on for size, decide it doesn't fit, and then discard it. The behavior can be seen in functional MRI clinical images of the brain, but the person involved claims nothing ever happened in the first place.

The photon example runs into another phenomenon of look-ahead, or feed-forward (instead of feed-back.) When intelligent, observing, thinking agents are involved, to look at the mathematics, systems respond not only to the past but to the future. We all know that people respond to expectations of the future, which really, really messes up measuring the direction of causality. The scientific tools and statistics we use assumes causality goes forward in time, and causality that appears to go the other direction jams the equipment.

A simple example mentioned above would me observational measurements of the suburbs, where anyone can easily see that the process of putting garbage cans out next to the curb causes garbage trucks to arrive.

(photo by abbamouse on flickr )

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