27
any laws of nature to imagine living beings lasting for millions or even bil-
28
lions of years, so I have no objection there. But eventually all of the stars
29
will have exhausted their nuclear fuel, their cold remnants will fall into
30
black holes, and those black holes will gradually evaporate into a thin gruel
31
of elementary particles in a dark and empty universe. We won’t really live
32
forever, no matter how clever biologists get to be.
33
Everybody dies. Life is not a substance, like water or rock; it’s a process,
34
like fire or a wave crashing on the shore. It’s a process that begins, lasts for
35S
a while, and ultimately ends. Long or short, our moments are brief against
36N
the expanse of eternity.
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PR O l O g u E
•
01
02
We have two goals in front of us. One is to explain the story of our universe
03
and why we think it’s true, the big picture as we currently understand it. It’s
04
a fantastic conception. We humans are blobs of organized mud, which
05
through the impersonal workings of nature’s patterns have developed the
06
capacity to contemplate and cherish and engage with the intimidating com-
07
plexity of the world around us. To understand ourselves, we have to under-
08
stand the stuff out of which we are made, which means we have to dig deeply
09
into the realm of particles and forces and quantum phenomena, not to men-
10
tion the spectacular variety of ways that those microscopic pieces can come
11
together to form organized systems capable of feeling and thought.
12
The other goal is to offer a bit of existential therapy. I want to argue that,
13
though we are part of a universe that runs according to impersonal underly-
14
ing laws, we nevertheless matter. This isn’t a scientific question— there isn’t 15
data we can collect by doing experiments that could possibly measure the
16
extent to which a life matters. It’s at heart a philosophical problem, one that
17
demands that we discard the way that we’ve been thinking about our lives
18
and their meaning for thousands of years. By the old way of thinking, hu-
19
man life couldn’t possibly be meaningful if we are “just” collections of at-
20
oms moving around in accordance with the laws of physics. That’s exactly
21
what we are, but it’s not the only way of thinking about what we are. We are
22
collections of atoms, operating independently of any immaterial spirits or
23
influences, and we are thinking and feeling people who bring meaning into
24
existence by the way we live our lives.
25
We are small; the universe is big. It doesn’t come with an instruction
26
manual. We have nevertheless figured out an amazing amount about how
27
things actually work. It’s a different kind of challenge to accept the world
28
for what it is, to face reality with a smile, and to make our lives into some-
29
thing valuable.
30
31
•
32
In the first section of the book, “Cosmos,” we examine some important
33
aspects of the wider universe of which we are a small part. There are many
34
ways to talk about the world, which leads us to the framework called poetic
S35
naturalism. “Naturalism” claims that there is just one world, the natural
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01
world; we’ll explore some of the indications that point us in that direction,
02
including how the universe moves and evolves. “Poetic” reminds us that
03
there is more than one way of talking about the world. We find it natural
04
to use a vocabulary of “causes” and “reasons why” things happen, but those
05
06
phenomena, part of how we describe our everyday world. The difference
07
between the everyday and deeper descriptions arises from the arrow of
08
time, the distinction between past and future that can ultimately be traced
09
to the special state in which our universe began near the Big Bang.
10
In the second section, “Understanding,” we consider how we should go
11
about trying to understand the world. Or, at least, move closer and closer to
12
the truth; we have to be willing to accept uncertainty and incomplete knowl-
13
edge, and always be ready to update our beliefs as new evidence comes in. We
14
will see how our best approach to describing the universe is not a single,
15
unified story but an interconnected series of models appropriate at different
16
levels. Each model has a domain in which it is applicable, and the ideas that
17
appear as essential parts of each story have every right to be thought of as
18
“real.” Our task is to assemble an interlocking set of descriptions, based on
19
some fundamental ideas, that fit together to form a stable planet of belief.
20
We then turn to “Essence,” where we think about the world as it actu-
21
ally is: the fundamental laws of nature. We’ll discuss quantum field theory,
22
the basic language in which modern physics is written. We will appreciate
23
the triumph of the Core Theory, the enormously successful model of the
24
particles and forces that make up you, me, the sun, the moon, the stars, and
25
everything you have ever seen, touched, or tasted in all your life. There is
26
much we don’t know about how the world works, but we have extremely
27
good reason to think that the Core Theory is the correct description of
28
nature in its domain of applicability. That domain is wide enough to im-
29
mediately exclude a number of provocative phenomena: from telekinesis
30
and astrology to survival of the soul after death.
31
With some laws of physics in hand, there is still much work to be done
32
in connecting these deeper principles to the richness of the world around
33
us. In the fourth section, “Complexity,” we begin to see how those connec-
34
tions come about. The emergence of complex structures isn’t a strange phe-
35S
nomenon in tension with the general tendency of the universe toward
36N
greater disorder; it is a natural consequence of that tendency. In the right
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PR O l O g u E
circumstances, matter self- organizes into intricate configurations, capable
01
of capturing and using information from their environments. The culmina-
02
tion of this process is life itself. The more we learn about the basic workings
03
of life, the more we appreciate how they are in harmony with the funda-
04
mental physical principles governing the universe as a whole. Life is a pro-
05
cess, not a substance, and it is necessarily temporary. We are not the reason
06
for the existence of the universe, but our ability for self- awareness and re-
07
flection makes us special within it.
08
This brings us to one of the knottier problems faced by naturalism, the
09
puzzle of consciousness. We confront this issue in “Thinking,” where we go
10
beyond “naturalism” all the way to “physicalism.” Modern neuroscience has
11
made tremendous strides in understanding how thought actually works
12
inside our brains, and there is little question that our personal experiences
13
have definite correlates in physical processes therein. We can even begin to
14
see how this remarkable ability evolved over time, and what kinds of abili-
15
ties are crucial to achieving consciousness. The most difficult problem is a
16
philosophical one: how is it even possible that inner experience, the
17
uniquely experiential aboutness of our lives inside our heads, can be reduced
18
to mere matter in motion? Poetic naturalism suggests that we should think
19
of “inner experiences” as part of a way of talking about what is happening
20
in our brains. But ways of talking can be very real, even when it comes to
21
our ability to make free choices as rational beings.
22
Finally, in “Caring” we confront the hardest problem of all, that of how
23
to construct meaning and values in a cosmos without transcendent pur-
24
pose. A common charge against naturalism is that such a task is simply
25
impossible: without something beyond the physical world to guide us, there
26
is no reason to live at all, and certainly no reason to live one way rather than
27
another. Some naturalists respond by agreeing, and getting on with their
28
lives; others react strongly the other way, by arguing that values can be de-
29
termined scientifically just as much as the age of the universe can be. Poetic
30
naturalism strikes a middle ground, accepting that values are human con-
31
structs, but denying that they are therefore illusory or meaningless. All of
32
us have cares and desires, whether given to us by evolution, our upbringing,
33
or our environment. The task before us is to reconcile those cares and de-
34
sires within ourselves, and amongst one another. The meaning we find in
S35
life is not transcendent, but it’s no less meaningful for that.
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01
02
03
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07
08
09
10
P A R t O n E
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COSMOS
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01
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1
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The Fundamental Nature of Reality
05
06
07
08
09
10
11
12
I
13
n the old Road Runner cartoons, Wile E. Coyote would frequently
14
find himself running off the edge of a cliff. But he wouldn’t, as our
15
experience with gravity might lead us to expect, start falling to the
16
ground below, at least not right away. Instead, he would hover motionless,
17
in puzzlement; it was only when he realized there was no longer any ground
18
beneath him that he would suddenly crash downward.
19
We are all Wile E. Coyote. Since human beings began thinking about
20
things, we have contemplated our place in the universe, the reason why we
21
are all here. Many possible answers have been put forward, and partisans of
22
one view or another have occasionally disagreed with each other. But for a
23
long time, there has been a shared view that there is some meaning, out
24
there somewhere, waiting to be discovered and acknowledged. There is a
25
point to all this; things happen for a reason. This conviction has served as
26
the ground beneath our feet, as the foundation on which we’ve constructed
27
all the principles by which we live our lives.
28
Gradually, our confidence in this view has begun to erode. As we under-
29
stand the world better, the idea that it has a transcendent purpose seems
30
increasingly untenable. The old picture has been replaced by a wondrous
31
new one— one that is breathtaking and exhilarating in many ways, chal-
32
lenging and vexing in others. It is a view in which the world stubbornly
33
refuses to give us any direct answers about the bigger questions of purpose
34
and meaning.
S35
The problem is that we haven’t quite admitted to ourselves that this
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01
transition has taken place, nor fully accepted its far- reaching implications.
02
The issues are well-known. Over the course of the last two centuries, Dar-
03
win has upended our view of life, Nietzsche’s madman bemoaned the death
04
of God, existentialists have searched for authenticity in the face of absur-
05
dity, and modern atheists have been granted a seat at society’s table. And
06
yet, many continue on as if nothing has changed; others revel in the new
07
order, but placidly believe that adjusting our perspective is just a matter of
08
replacing a few old homilies with a few new ones.
09
The truth is that the ground has disappeared beneath us, and we are just
10
beginning to work up the courage to look down. Fortunately, not every-
11
thing in the air immediately plummets to its death. Wile E. Coyote would
12
have been fine if he had been equipped with one of those ACME- brand jet
13
packs, so that he could fly around under his own volition. It’s time to get to
14
work building our conceptual jet packs.
15
What is the fundamental nature of reality? Philosophers call this the
16
question of ontology— the study of the basic structure of the world, the in-
17
gredients and relationships of which the universe is ultimately composed.
18
It can be contrasted with epistemology, which is how we obtain knowledge
19
about the world. Ontology is the branch of philosophy concerned with the
20
nature of reality; we also talk about “an” ontology, referring to a specific
21
idea about what that nature actually is.
22
The number of approaches to ontology alive in the world today is some-
23
what overwhelming. There is the basic question of whether reality exists at
24
all. A realist says, “Of course it does”; but there are also idealists, who think 25
that capital- M Mind is all that truly exists, and the so-called real world is
26
just a series of thoughts inside that Mind. Among realists, we have monists,
27
who think that the world is a single thing, and dualists, who believe in two
28
distinct realms (such as “matter” and “spirit”). Even people who agree that
29
there is only one type of thing might disagree about whether there are fun-
30
damentally different kinds of properties (such as mental properties and
31
physical properties) that those things can have. And even people who agree
32
that there is only one kind of thing, and that the world is purely physical,
33
might diverge when it comes to asking which aspects of that world are