DRAFT 5/29/2007
Emergence Explained: Entities
Nature’s memes
Russ Abbott
Department of Computer Science, California State University, Los Angeles
and
The Aerospace Corporation
The Aerospace Corporation
El Segundo, California
Abstract. We apply the notions developed in the preceding paper ([1]) to discuss such issues the nature of entities, the fundamental importance of interactions between entities and their environment (functionality vs. mechanism), the central and often ignored role (especially in computer science) of energy, entities as nature’s way of remembering, the aggregation of complexity, the reductionist blind spot, the similarities between biology and economics.
Emergence Explained 4/41
DRAFT 5/29/2007
1 Introduction
In [1] we characterized emergent phenomena as phenomena that may be described independently of their implementations. We credited [Anderson] with being one of the first prominent physicists to argue that new laws of nature, i.e., laws not derivable from physics, exist at various levels of complexity. While re-reading [Schrodinger] we found the following relevant passage.
[L]iving matter, while not eluding the 'laws of physics' … is likely to involve 'other laws of physics,' hitherto unknown, which … will form just as integral a part of [the] science [of living matter] as the former.
As we pointed out in the earlier paper, there are indeed new laws, which, while consistent with the laws of physics are not reducible to them. A significant part of this paper is devoted to elaborating this perspective.
In the earlier paper we distinguished between static emergence (emergence that is implemented by energy wells) and dynamic emergence (emergence that is implemented by energy flows). We argued that emergence (of both forms) produces objectively real phenomena (because they are distinguishable by their entropy and mass characteristics) but that interaction among emergent phenomena is epiphenomenal and can always be reduced to the fundamental forces of physics.
Our focus in that paper was on the phenomenon of emergence itself. In this paper we explore the entities that arise as a consequence of the two types of emergence, focusing especially on dynamically emergent entities and their interactions with their environment.
Reductionism is an attempt to eliminate magic from our understanding of nature. Without reductionism, what else could there by besides magic? Software (and engineering in general) is neither reductionist nor magic.
2 Emergent Entities
As human beings we seem naturally to think in terms of entities—things or objects. Yet the question of how one might characterize what should and should not be considered an entity remains philosophically unresolved. (See, for example, [Boyd], [Laylock], [Miller], [Rosen], [Varzi Fall ‘04].) We propose to define an emergent entity as any instance of emergence that produces a physically bounded result.[1] What is fundamental to a emergent entity is that one can identify the force or forces of nature that binds it together and that causes it to persist in a form that allows one to distinguish it from its environment—on grounds of its distinguishing entropy and mass.
Some emergent entities (such as an atom, a molecule, a pencil, a table, a solar system, a galaxy) are instances of static emergence. These entities persist because they exist in energy wells. Biological entities (such as you and I) and social entities (such as a social club, a corporation, or a country) are instances of dynamic emergence. These entities persist as a result of energy flows.
On the other hand, what might be considered conceptual (or Platonic) entities—such as numbers, mathematical sets (and other mathematical constructs), properties, relations, propositions, categories such as those named by common nouns (such as the category of cats, but not individual cats), and ideas in general—are not (as far as we know) instances of emergence.[2] Nor are intellectual products such as poems and novels, scientific papers, or computer programs (when considered as texts). Time instances (e.g., midnight December 31, 1999), durations (e.g., a minute), and segments (e.g., the 20th century) are also not instances of emergence. Neither are the comparable constructs with respect to space and distance.
Since by definition every emergent entity is an instance of emergence, all emergent entities consist of matter and energy arranged to implement some independently describable abstraction. Since conceptual entities don’t involve matter or energy and since, at least to date, conceptual entities don’t have implementations (at least they don’t have implementations that we understand), none of them satisfy our definition of an emergent entity.
2.1 Static emergent entities
Statically emergent entities (static entities for short) are created when the fundamental forces of nature bind matter together. The nucleus of any atom (other than simple Hydrogen, whose nucleus consist of a single proton) is a static entity. It results from the application of the strong nuclear force, which binds the nucleons together in the nucleus. Similarly any atom (the nucleus along with the atom’s electrons) is also a static entity. An atom is a consequence of the electromagnetic force, which binds the atom’s electrons to its nucleus. Molecules are also bound together by the electromagnetic force. On a much larger scale, astronomical bodies, e.g., the earth, are bound together by gravity, as are solar systems and galaxies.
Static entities, like all instances of emergence, have properties which may be described independently of how they are constructed. As Weinberg [W] points out, “a diamond [may be described in terms of its hardness even though] it doesn't make sense to talk about the hardness … of individual ‘elementary’ particles.” The hardness of a diamond may be characterized and measured independently of how diamonds achieve that property—which, as Weinberg also points out, is a consequence of how diamonds are implemented, namely, their “carbon atoms … fit together neatly.”
A distinguishing feature of static entities (as with static emergence in general) is that the mass of any static entity is strictly smaller than the sum of the masses of its components. This may be seen most clearly in nuclear fission and fusion, in which one starts and ends with the same number of atomic components—electrons, protons, and neutrons—but which nevertheless converts mass into energy. This raises the obvious question: which mass was converted to energy? The answer has to do with the strong nuclear force, which implements what is called the “binding energy” of nucleons within a nucleus. For example, a helium nucleus (also known as an alpha particle, two protons and two neutrons bound together), which is one of the products of hydrogen fusion, has less mass than the sum of the masses of the protons and neutrons that make it up when considered separately.[3] The missing mass is released as energy.
The same entity-mass relationship holds for all static entities. An atom or molecule has less mass (by a negligible but real amount) than the sum of the masses of its components taken separately. The solar system has less mass (by a negligible but real amount) than the mass of the sun and the planets taken separately. Thus the entropy of these entities is lower than the entropy of the components as an unorganized collection. In other words, a static entity is distinguishable by the fact that it has lower mass and lower entropy than its components taken separately. Every static entity exists in what is often called an energy well; it requires energy to pull the static entity’s components apart. Static entities are also at an energy equilibrium.
Manufactured or constructed artifacts also exhibit static emergence. The binding force that holds manufactured static entities together is typically the electromagnetic force, which we exploit when we use nails, glue, screws, etc. to bind static entities together into new static entities. As a diamond implements the property of being hard, a house, a more heterogeneous static entity, but one which is bound together by many of the same preceding means, has the statically emergent property number-of-bedrooms. As an entity, a house implements the property of having a certain number of bedrooms by the way in which it is constructed from its components.
A static entity consists of a fixed collection of components over which it supervenes. By specifying the states and conditions of its components, one fixes the properties of the entity. But static entities such as houses that undergo repair and maintenance no longer consist of a fixed collection of component elements thereby raising the question of whether such entities really do supervene over their components. We resolve this issue when we discuss Theseus’ ship.
2.2 Dynamic entities
Dynamic entities are instances of dynamic emergence. As in the case with all emergence, dynamic emergence results in the organization of matter in a way that differs from how it would be organized without the energy flowing through it. That is, dynamic entities have properties as entities that may be described independently of how those properties are implemented. Dynamic entities include biological and social entities—and, as we discuss below, hurricanes.
For dynamic entities, their very existence—or at least their persistence as a dynamic entity—depends on a flow of energy. Many dynamic entities are built upon a skeleton of one or more static entities. The bodies of most biological organisms, for example, continue to exist as static entities even after the organism ceases to exist as a dynamic entity, i.e., after the organism dies. When those bodies are part of a dynamic entity, however, the dynamic entity includes processes to repair them. We discuss this phenomenon also when we examine the puzzle of Theseus’ ship.
Choreographed events like games are also entities.
3 Capital and savings
are used for two purposes.
- To create artificial entities. In capitalism one hopes that they will be self-sustaining.
- For growth. In both biology and economics one needs resources to pay for growth.
4 Petty reductionism fails for dynamic entities—for all practical purposes
Weinberg’s petty reductionism is another way of saying that an entity supervenes over the matter of which it is composed: fixing the properties of the matter of which an entity is composed fixes the properties of the entity.[4] Hurricanes illustrate a difficulty with supervenience and petty reductionism for dynamic entities.
The problem for petty reductionism and supervenience is that from moment to moment new matter is incorporated into a hurricane and matter then in a hurricane leaves it. Let’s define what one might call a hurricane’s supervenience base as the smallest collection of matter over which a hurricane supervenes. Since matter cycles continually through a hurricane, a hurricane’s supervenience base consists of the entire collection of matter that is or has been part of a hurricane over its lifetime. Consequently a hurricane’s supervenience base must be significantly larger than the amount of matter that constitutes a hurricane at any moment. Because a hurricane’s supervenience base is so much larger than the matter that makes it up at any moment the fact that a hurricane supervene over its supervenience base is not very useful. Other than tracking all the matter in a hurricane’s supervenience base, there is no easy reducibility equation that maps the properties of a hurricane’s supervenience base to properties of the hurricane itself.
Furthermore, the longer a hurricane persists, the larger its supervenience base—even if the hurricane itself maintains an approximate constant size during its lifetime. Much of the matter in a hurricane’s supervenience base is likely also to be included in the supervenience bases of other hurricanes. Like Weinberg’s example of quarks being composed (at least momentarily) of protons, hurricanes are at least partially composed of each other. Thus just as Weinberg gave up on the usefulness of petty reductionism in particle physics, we must also give up on the usefulness of petty reductionism and supervenience for dynamic entities.
5 Entities and functionality
When one eliminates the entities as a result of reductionism one loses information. Shalizi’s definition of emergence. Throwing away the entity is the reductionism blind spot.
The question Shalizi raises is do his higher level variables refer to anything real or are they just definitional consequences of lower level variables. Our definitions of entities says they are real.
As we discussed in (1) Weinberg distinguished between what he called petty and grand reductionism. Grand reductionism is the claim that all scientific laws can be derived from the laws of physics. In the first paper, we argued that grand reductionism doesn’t hold. Our example was the implementation of a Turing Machine on a Game of Life platform. A reductive analysis of a Game-of-Life Turing Machine can explain how a Turning Machine may be implemented, but it doesn’t help us understand the laws governing the functionality that the Turing Machine provides.
Weinberg’s characterization of petty reductionism was the “doctrine that things behave the way they do because of the properties of their constituents.” Recall that Weinberg said that petty reductionism has “run its course” because when it comes to primitive particles it isn’t always clear what is a constituent of what.
In most other realms of science, however, petty reductionism still holds sway. To understand something, take it apart and see how it works. Thus the traditional scientific agenda can be described as follows. (a)Observe nature. (b)Identify likely categories of entities. (c)Explain the observed functionality/phenomenology of entities in those categories by understanding their structure and internal operation.[5]
Once this explanatory task is accomplished, the reductionist tradition has been to put aside an entity’s functional/phenomenological description and replace it with (i.e., to reduce it to) the explanation of how that functionality/phenomenology is brought about. The functional/phenomenological description is considered simply a shorthand for what we now understand at a deeper level. Of course one then has the task of explaining the lower-level mechanisms in terms of still lower-level mechanisms, etc. But that’s what science is about, peeling nature’s onion until her fundamental mechanisms are revealed. In this section we argue that that this approach has severe limitations. In particular we discuss what we refer to as the reductionist blind spot.
5.1 Hurricanes as dynamic entities
Most dynamic entities are biological or social, but there are some naturally occurring dynamic entities that are neither. Probably the best known are hurricanes. A hurricane operates as a heat engine in which condensation—which replaces combustion as the source of energy—occurs in the upper atmosphere. A hurricane involves a greater than normal pressure differential between the ocean surface and the upper atmosphere. That pressure differential causes warm moist surface air to rise. When the moisture-laden air reaches the upper atmosphere, which is cooler, it condenses, releasing heat. The heat warms the air, which expands and reduces the pressure, thereby maintaining the pressure differential.[6] Since the heated air also dissipates, the upper atmosphere remains cooler. (See Figure 3.)