The Big Picture

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The Big Picture Page 50

by Carroll, Sean M.


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  new behaviors, are not incorporated into our genetic information, and are

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  therefore not passed down to subsequent generations. (There are nuances

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  here, as some environmentally influenced ways that genes are expressed may

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  be heritable, even if the genes themselves don’t change.) Option 2 is a more

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  standard Darwinian explanation. It’s not that previous generations of

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  giraffes wanted to reach higher; it’s just that those that did accrued an ad-

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  vantage that was passed on to their descendants.

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  Then there is option 3, known as “sexual selection.” It is a perfectly plau-

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  sible Darwinian explanation, one that relies on a specific mechanism of

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  selection pressure to achieve the empirical result. Some researchers have

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  suggested that a form of sexual selection is a better explanation than the

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  traditional leafy- treetop story that we tell about the length of giraffe necks.

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  This illustrates one of the difficulties in understanding how evolution actu-

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  ally proceeds in the real world: there may be more than one way to explain

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  the emergence of a single trait.

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  The debate is ongoing. For example, under sexual selection it’s likely that

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  male and female giraffe necks would evolve differently, but the data seem to

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  indicate that they are fairly similar. Option 2 is currently more popular, but

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  new data will continue to impact our credences for each of the different

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  hypotheses.

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  So what about option 4, which avoids any particular evolutionary story-

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  telling? It’s a true statement, but not a useful one in this context. From the

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  poetic- naturalism perspective, natural selection provides a successful way

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  of talking about emergent properties of the biological world. We don’t need

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  to use a vocabulary of evolution and adaptation to correctly describe what

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  happens, but doing so gives us important and useful knowledge.

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  The evolution of life provides a rich source of higher- level phenomena

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  emerging from the fundamental description of reality, including phenom-

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  ena that have no direct analogue at the deepest level. Because our specific

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  universe starts in a special state and shows a strong arrow of time, these

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  E M E R g E n t P u R P O S E

  emergent pictures can invoke words like “purpose” and “adaptation,” even

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  though those ideas are nowhere to be found in the underlying mechanistic

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  behavior of reality.

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  A common concern among skeptics of evolution is how it is supposed to

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  lead to the creation of new kinds of things out of the mindless motion of

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  matter. “Purposes” are one obvious example. We say, without apparent em-

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  barrassment, things like “The purpose of the giraffe’s long neck is to help it

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  reach fresh leaves near the treetops.” Another example is “information.”

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  DNA is said to carry genetic information; the optic nerve carries informa-

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  tion from the eye to the brain. Then there is consciousness itself. The con-

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  cern is that these concepts represent a radical break from the mere Laplacian

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  working- out of the laws of physics. How could evolution, which itself is

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  ultimately purely physical, bring these utterly new kinds of things into ex-

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  istence?

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  It’s a natural thing to worry about. The process of evolution is unplanned

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  and unguided. Whether or not genetic information gets passed on to future

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  generations depends only on the conditions of its immediate environment

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  and random chance, not on any future goals. How can an intrinsically pur-

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  poseless process lead to the existence of purposes?

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  But this worry is a little strange, at least in the hands of anyone who ac-

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  cepts that natural selection provides an explanation for more prosaic things

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  like gills and eyeballs. These kinds of organs are “utterly new” in their own

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  way. There is no general principle along the lines of “new kinds of things

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  cannot naturally arise in the course of undirected evolution.” Things like

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  “stars” and “galaxies” come to be in a universe where they formerly didn’t

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  exist. Why not purposes and information?

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  In poetic naturalism, the appearance of “truly new” concepts as one

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  theory emerges from another is the least surprising thing in the world. As

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  time passes and entropy increases, the configuration of matter in the uni-

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  verse takes on different forms, enabling the emergence of different higher-

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  level ways of talking. The appearance of something like “purpose” simply

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  comes down to the question “Is ‘purpose’ a useful concept when developing

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  an effective theory of this part of reality in this particular domain of

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  applicability?” There may be any number of interesting and challenging

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  T H E B IG PIC T U R E

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  technical issues to be addressed, but there is no obstacle to the emergence

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  of all kinds of new concepts along the way.

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  Think about Robby the Robot, cleaning up cans from his grid. In the most

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  successful strategies that were artificially generated through many genera-

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  tions of variation and selection, Robby had evolved a technique of not pick-

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  ing up a can on his current square if there were also cans to the east and

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  west. Rather, he would move in one direction— let’s say west— until he ar-

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  rived on a square with a can, but no can on the square just west of his loca-

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  tion. Only then would he double back, picking up all the cans along the way.

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  Why does Robby act in this way? We could simply say, “Those moves are

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  part of the strategy that survives the genetic algorithm process.” That would

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  be the equivalent of answer 4 in the list of giraffe- neck expl
anations above.

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  It’s not wrong, but it’s not very illuminating either. Or we could say, “Robby

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  doesn’t want to forget that there are cans on either side, so he leaves them

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  in place, knowing he will come back and pick them up later.”

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  Is that a sensible way of talking? Robby the Robot doesn’t really want

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  anything. He’s not even a real robot— just a string of ones and zeroes inside

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  some computer memory. Psychologists sometimes speak of the “anthropo-

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  morphic fallacy,” when we attribute human thoughts or emotions to in-

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  animate objects. (My computer gets grumpy if I don’t reboot it every so

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  often.) It may be fun and harmless to speak about Robby as if he has wants,

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  but it’s not really true. Right?

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  Consider the possibility that we have this backward. When we say that

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  Robby the Robot doesn’t really have wants in the same sense that a person

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  does, we are taking the implicit stance that there are things called “wants”

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  that can be correctly attributed to some things in the universe (like human

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  beings) and not to others (like virtual robots). What are these “wants”

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  anyway?

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  The idea that something wants something else is a way of talking that is

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  potentially useful in the right circumstances— a simple idea that summa-

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  rizes a good amount of complex behavior in a convenient way. If we see a

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  monkey climbing a tree, we could describe what’s happening by providing

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  a list of what the monkey is doing at each moment in time, or for that

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  E M E R g E n t P u R P O S E

  matter we could specify the position and velocity of every atom in the mon-

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  key and the environment at each moment. But it’s immensely easier and

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  more efficient to say, “The monkey wants those bananas that are up in the

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  tree.” The fact that we can say that is a piece of useful knowledge over and

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  above all of those positions and velocities.

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  There is no Platonic idea of a “want” floating out there in the space of

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  ideas that can be properly associated with some kinds of beings and not

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  with others. Rather, there are situations in which it is useful to describe

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  things as somebody wanting something, and other situations in which that

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  is not so useful. These situations can emerge in the natural, undirected evo-

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  lution of matter in the universe. Those wants are as real as things ever get.

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  In the particular case of Robby, it is neither necessary nor especially

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  helpful to characterize his behavior in terms of wants, purposes, or desires.

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  It’s just as easy to simply say what his can- collecting strategy actually is. But

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  the difference between him and a person, as far as the ontological status of

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  “wants” is concerned, is simply a matter of degree. We could imagine a ro-

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  bot with an enormously more complicated programming than little Robby.

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  We might not know much about that specific programming, but perhaps

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  we are able to observe how the robot acts. It may be that the best way of

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  understanding the robot’s behavior is to say, “That robot really wants to

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  pick up those cans.”

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  Under naturalism, there isn’t that much difference between a human

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  being and a robot. We are all just complicated collections of matter moving

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  in patterns, obeying impersonal laws of physics in an environment with an

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  arrow of time. Wants and purposes and desires are the kinds of things that

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  naturally develop along the way.

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  There is a similar story to tell about “information.” It’s worth thinking

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  about, as it will come up again when we start talking about consciousness.

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  If the universe is just a bunch of stuff obeying mechanistic physical rules,

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  how can one thing ever “carry information” about anything else? How can

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  one configuration of atoms be “about” some other configuration?

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  Words like “information” are a useful way of talking about certain

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  things that happen in the universe. We don’t ever need to talk about

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  T H E B IG PIC T U R E

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  information— we can take the “option 4” viewpoint and just talk about the

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  quantum state of the universe inexorably evolving through time. But the

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  fact that information is an effective way of characterizing certain physical

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  realities is a true and nontrivial insight onto the world.

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  Consider the Voynich manuscript. This is a remarkable and unique

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  book, whose likely provenance has been traced to the early fifteenth cen-

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  tury, possibly from Italy. It is a whimsical volume, replete with fanciful il-

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  lustrations of astronomical and biological subjects. For the most part, the

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  many flora depicted in the illustrations cannot be identified with actual

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  plant species. Most remarkably, the text of the book has proven, to date, to

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  be completely indecipherable. Not only the language but even the apparent

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  alphabet is something that has never been seen before. Statistical analyses

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  of the words and symbols in the writing seem to be compatible with those

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  of ordinary languages, but cryptographers have been stymied in their at-

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  tempts to interpret the text as some kind of code. It may be a very good ci-

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  pher; it may be a unique language that was invented by an individual and

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  then forgotten; or it may be a complete hoax.

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  Does the Voynich manuscript contain information?

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  An excerpt of the writing that appears in the Voynich manuscript.

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  E M E R g E n t P u R P O S E

  One is tempted to say that it depends on the origin of the book. If it

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  really is a hoax, and the words are some kind of semirandom nonsense, then

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  perhaps it doesn’t contain much information at all. But if it is merely a

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  clever code that will someday be broken, it might contain a great deal—

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  even if that “information” is purely a work of imagination.

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  What if the Voynich manuscript is a code that will never be broken?

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  What if it was originally written with very specific intent, but its meaning

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  has been so well hidden that nobody will ever be able to reveal it? Does it

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  stil contain information? What if the manuscript is placed in a capsule and

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  launched into space, and then the Earth is destroyed by a cataclysmic aster-

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  oid impact, and the book floats through the void for all of eternity. Does it

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  contain information then?

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  We tend to use the word “information” in multiple, often incompatible,

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  ways. In chapter 4 we talked about conservation of information in the fun-

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  damental physical laws. There, what we might call the “microscopic infor-

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  mation” refers to a complete specification of the exact state of a physical

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  system, and is neither created nor destroyed. But often we think of a higher-

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  level macroscopic concept of information, one that can indeed come and

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  go; if a book is burned, the information contained in it is lost to us, even if

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  not to the universe.

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  The macroscopic information contained in a book is relative to the en-

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  vironment in which it is embedded. When we talk about the information

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  contained in the book you are currently reading, what we mean is that these

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  words are correlated with certain ideas that you get upon reading them. You

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  read the word “giraffe,” and the notion of a certain kind of long- necked

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  African ungulate appears in your mind. The same holds for the informa-

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  tion contained in a strand of DNA: it is correlated with the synthesis of

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  certain proteins in the cell. It is this connection with one configuration of

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  matter (a book or a DNA strand) and something else in the universe (the

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  image of a giraffe, or a useful protein molecule) that lets us talk about the

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  existence of information. Without those correlations— if there isn’t, and

 

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