**4. THE OBSERVER.**

From the time of Isaac Newton to the beginning of the twentieth century
science relegated consciousness to the status of passive viewer: our
thoughts were excluded from the action. The decisive counter move of the
founders of quantum mechanics was to recognize that \"in the drama of
existence we ourselves are both actors and spectators.\" \[Bohr, Essays
1958/1962 on Atomic Physics and Human Knowledge\]. After two hundred
years of neglect, our thoughts were suddenly thrust into the limelight.
This was an astonishing reversal of precedent because the successes of
the prior physics had been deemed due in large measure to the policy of
keeping idea-like qualities out.

What sort of upheaval could have forced scientists to this wholesale
revision of their idea of the role of mind in Nature? The answer in
brief is \"quantum jumps!\'\' These events are sudden shifts in our best
mathematical description of the size, shape, and structure of a physical
system. At one moment the form may extend over miles, but an instant
later be reduced to the size of a speck. How can we understand such
precipitous leaps in our scientific description of the physical world?
The resolution proposed by Heisenberg, Bohr, Pauli, and the other
founders of quantum theory was a bold one: bring our thoughts,
unshackled, into the basic theory of nature.

Einstein described a simple situation that illuminates the puzzling
character of these quantum jumps. Suppose a radioactive atom is placed
in a detecting device that responds to the decay of this atom by sending
an electrical pulse to a graphical recording instrument that draws a
line on a moving scroll. A blip in this line will indicate the time at
which the electrical signal arrives. Next, suppose some scientists are
observing the instrument and reporting to each other where the blip is
located on the scroll. What we know is that these observers will more or
less agree amongst themselves as to the position of the blip. But
quantum theory has stringent laws that govern in principle the behavior
of all physical systems. If one applies these rules to the entire system
under consideration here, which consists of the radioactive atom, the
detecting device, the electrical pulse, the graphical recording
instrument, the bodies and brains of the human observers, and all other
physical systems that interact with them, then one arrives at a
contradiction. What we know is that the blip seen by the observers
occurs at a fairly definite location. But according to the mathematical
laws the full physical system will be a smeared out blur encompassing
equally all of the alternative possible locations of the blip. In
particular, for each one of the infinity of possible locations of the
blip on the scroll there will be an entire world, of the familiar kind,
in which all of the observers report seeing the blip occurring at that
particular location. Thus the quantum law, or rule, that governs the
behavior of matter generates a whole continuum of possible worlds of the
kind that appear in our streams of conscious experiences. The empirical
world of experienced facts is just one tiny slice of the full world
generated by the mathematical equations of quantum theory.

This clash, which lies at the heart of quantum theory, is a discord
between the two distinct parts of science, the theoretical and the
empirical: it is a sharp contradiction between theory and fact. These
two interrelated aspects of science are extremely different in
character. Each *fact* comes as a chunk of somebody\'s experience. But
these individual chunks are related to each other. At one moment you see
a chair, then look away. Upon looking back you see a chair that
resembles the one you saw before. You were alone in the room, hence no
continuous human experience bridges the gap between these experiential
moments. Yet the two experiences are obviously linked together by
something.

To explain the connections between the disconnected perceptual facts we
concoct *theories*. We create ideas about persisting realities that
exist even when no one is watching them, and that bind the disjoint
facts together. Our physical theories are conceptual frameworks that we
create for the purpose not only of organizing our perceptual
experiences, but also of permitting us even to have understandable and
describable experiences. As Niels Bohr succinctly puts it: \"The task of
science is both to extend the range of our experience and reduce it to
order.\'\' \[N. Bohr. Atomic Physics and Human knowledge, p.1 \].

Contemporary science teaches us that the enduring reality that provides
the fabric into which our experiences are woven, is composed of both
moving atomic particles and changing physical fields. Laws governing the
behavior of these physical realities were proposed by Isaac Newton,
James Clerk Maxwell, and Albert Einstein. Those \"classical\" laws work
well in cases where the detailed nature of the elementary components is
unimportant, but fail absolutely in other cases. Specifically, they fail
in cases where the \"quantum of action\" becomes important. This
quantity was discovered and measured by Max Planck in 1900, and its
numerical value is called *Planck\'s constant*. This value is very small
on the scale of normal human activity, but becomes significant when we
come to the behavior of the atomic particles and fields out of which our
bodies and brains, and all other physical objects, are made. Planck\'s
constant enters, in particular, into Heisenberg\'s uncertainty
principle, which says that atomic particles can never reveal themselves
to be the tiny moving objects that they had been imagined to be since
the time of Isaac Newton. Nor is there any reason to believe that such
tiny objects exist at all. Each \"particle\", insofar as we can ever
know it, may be associated with a particular mass (e.g., the mass of an
electron) and a particular charge (e.g., the charge of the electron),
but there is no evidence that it has a particular location. All the
empirical evidence is most parsimoniously represented by taking each
atomic particle to be a cloud-like structure that has a strong
proclivity to spread out over ever-larger regions.

The important and amazing thing is that the older classical laws, built
on the notion of miniscule objects, become automatically converted into
unique new quantum laws when the empirically measured value of Planck\'s
constant is consistently introduced. This \"quantization\" procedure
automatically converts the notion of a particle as a minute entity into
the notion of a \"particle\" as an extended cloud-like structure.
Physicists had, for more than two hundred years, imagined Nature to be
composed, at least in part, out of entities resembling miniature
planets. But Nature, at least as she reveals herself to us through our
observations, and through our mathematics, appears to be made out of a
very different kind of stuff.

The unique quantum laws produced by the quantization procedure make
predictions that are accurate to as much as one part in a hundred
million, and they correctly describe various features of the behavior of
systems of billions of particles. But Einstein\'s example shows that
these quantum laws of motion lead also to smeared out physical states
that are grossly discordant with the more narrowly defined character of
our actual experiences.

You might immediately think that this huge disparity between the
mathematical theory and the empirical facts would render the theory
false and useless. However, the creators of quantum theory found that
*all* of the successes of classical physics and a great deal more could
be explained, without any contradiction ever arising, by adopting the
following dictum: assume that the natural quantum laws do indeed hold,
but if they lead to a physical state that disagrees with your empirical
observation then simply discard the part of that (mathematically
computed) state that disagrees with your observations, and keep the
rest. This sudden resetting of the physical state is the \"quantum
jump.\" By itself it would yield nothing. But it is accompanied by a
statistical law \-\-- to be described later \-\-- that produces all of
the wondrous results.

You, like all of us, are continually creating, on the basis of the best
information and ideas available to you a theoretical image of the
physical world around you: you have an idea about the status of all
sorts of things that you are not currently experiencing. But every time
you gain more information you revise that picture to fit the new facts.

Quantum theory instructs the scientist to do the same. That simple
dictum (revise your theoretical picture of the world to fit the
empirical facts), together with its statistical partner, produces not
only incredibly accurate predictions, but every successful result of the
earlier classical physics, and all of the thousands of successes of
quantum theory where classical physics fails. These impressive results
are achieved by simply allowing the beautiful, internally consistent,
and unique natural generalization of the old classical laws to hold
whenever we are not actually acquiring knowledge about a physical
system, but incorporating promptly any knowledge we acquire. The close
connection maintained in this way between what the mathematical
description represents and what we empirically know underlies
Heisenberg\'s assertion that the quantum mathematics \`\`represents no
longer the behavior of particles but rather our knowledge of this
behavior.\"

The shocker, however, is that Bohr and the other founders have argued
persuasively that *no other description of nature in terms of its atomic
constituents can be more complete than this one,* in the scientific
sense of telling us more about relationships between human experiences.
That is, this theory built on the unique adequate generalization of the
older classical laws seems to tell us everything that a basic physical
theory could ever tell us about relationships between human experiences.

This claim was strongly disputed by Einstein, who tried repeatedly to
devise a counter-example. In the end he admitted that he had failed.
Thus it does indeed seem to be true that this fantastically coherent
quantization of the older laws generates *everything that is knowable
about reality*: any attempt to add something more may please some
philosophers, but carries us outside of science, regarded as a tool for
\"expanding our experience and reducing it to order.\"

This apparent scientific completeness of quantum theory, together with
the fact that the \"quantization\" procedure totally *eliminates* the
classically conceived \"realities,\" and replaces them by cloud-like
forms, make plausible the conclusion that there simply are no
*classical-type or quasi-classical-type* realities lying behind our
thoughts, and that searching for them is a futile endeavor. The
presumption that such realities exist is therefore a gross philosophical
blunder. There is absolutely no empirical evidence that rationally
supports the notion that there is a physical reality out there that is
better defined than what quantum theory provides. Assuming that such a
quasi-classical type reality exists is not justified by the scientific
evidence, and is likely to produce a conception of both nature and human
beings that is fundamentally incorrect.

Let us, however, be clear about one thing. Although quantum theory is
built upon human experience, it does not assert that thought is the only
reality, and matter naught but an invention of mind: the founders did
not espouse the philosophy of idealism. Their position was the more
conservative one that science is about what we can know, and that our
theories must be judged not by concordance with intuition, but rather by
rational coherence and capacity to order the empirical facts. This view
liberates theoretical creativity: it allows science, unfettered by
ancient prejudice and fallible intuition, to build its idea of reality
upon the empirical evidence.

This philosophical retrenching did not satisfy everyone, Einstein and
Schroedinger being the most notable hold-outs. But it did allow the
scientists who accepted it to get on with the business of developing,
testing, and using this practically useful and immensely successful
theory.

Quantum theory brings your consciousness into physics in two distinctly
different ways. The first is as a passive stream of conscious thoughts
that constitutes a growing reservoir of knowledge. Each waking moment
adds something new to what you knew before. The second way is as an
active agent endowed with a free will that can influence both how your
body moves and how your thoughts unfold. It is this second role that
gives you your moral dimension. But to understand yourself as active
participant you must first appreciate yourself as an expanding
collection of knowings.

\"The observer\" as understood in the original \"Copenhagen\"
formulation of quantum theory differs from what one would normally mean
by this term. For one thing, it involves an extension of the human
observer outside his physical body. Bohr mentioned several times the
example of a man with a cane: if he holds the cane loosely he feels
himself to extend only to his hand. But if he holds the cane firmly then
the outer world seems to begin at the tip of his probing cane.

In analogy, the quantum \"observer\" is considered to include not only
the human experimenter himself, but also the measuring devices that he
uses to probe what is outside his extended self. Thus the world is
imagined to be cleaved into two parts, which are described in different
ways. The outer \"observed system\" is described in terms of the quantum
mathematics, whereas the inner \"observing system\'\' is described as a
collection of empirical (i.e., phenomenal or experiential) facts. This
way of dividing the world reflects the point, stressed already above,
that quantum physics \-\-- like all of science \-\-- rests on two
disparate kinds of descriptions, the first being of conscious
experiences that we can record, remember, and communicate to our
colleagues, and which form the empirical database, and the second being
of a theoretical structure that we have invented for the purpose of
comprehending the structure of our experience.

Copenhagen quantum theory regards the measuring instruments as part of
the observer because these devices are described not in terms of their
atomic constituents but rather in terms of our conscious knowings. Bohr
repeatedly points to this key feature of quantum theory, in statements
such as:

\"The decisive point is that the description of the experimental
arrangement and the recording of the observations must be given in plain
language, suitably refined by the usual terminology. This is a simple
logical demand, since by the word \`experiment\' we can only mean a
procedure regarding which we are able to communicate to others what we
have done and what we have learnt.\" (Essays 1958/1962....p.3)

You might think that since the key realities in quantum physics are
descriptions of experiences pertaining to measuring instruments, we
ought to disregard the observer and describe instead these devices
themselves, regarded as objectively existing realities, and thereby
dispense with all the mumbo jumbo about observers. But then the quantum
jumps, which are now neatly placed at the interface between the two
parts of science, which must always be linked by some sort of rule, get
shifted into the physical world, which is supposed to be enduring, and
continuously evolving. Such a move would bring in a host of questions as
to how, when, and why the natural quantum generalization of the
classical laws of physics should fail in the *physical* world. The most
simple, natural, and parsimonious assumption is to retain the physical
laws in the entire physical universe, but rescind the banishment of mind
from the workings of nature.