Why Does the World Exist?: An Existential Detective Story (7 page)

One of the more confused attempts to imagine nothingness was made by “S,” a patient of the distinguished Russian psychologist Aleksandr Luria. S had such an extraordinary memory that Luria wrote an entire book about him, titled
The Mind of a Mnemonist
. Oddly though, his memory was almost purely visual. So when S tried to conceive of nothingness, the experiment went disastrously awry:

In order for me
to grasp the meaning of a thing, I have to see it… . Take the word
nothing
… I see this
nothing
and it is something… . So I turned to my wife and asked her what
nothing
meant… . She simply said: “
Nothing
means there is nothing.” I understood it differently. I saw this
nothing
… . If
nothing
can appear to a person, that means it is something. That’s where the trouble comes in.

Perhaps any attempt to summon up an image of nothing is self-defeating. Even so, is
thinkability
a reliable test for
possibility
? Does the fact that we cannot imagine absolute nothingness—except, perhaps, in a state of dreamless sleep—mean that something or other must perforce exist?

One must beware here of falling into what has been called the
philosopher’s fallacy
: a tendency to mistake a failure of the imagination for an insight into the way reality has to be. “I can’t imagine it otherwise,” a thinker prone to this fallacy says to himself; “therefore it must be so.” There are many things that lie beyond the powers of our imagination that are not only possible but real. We can’t visualize colorless objects, for example, yet atoms are colorless. (They are not even gray.) Most of us, with the exception of a few preternaturally gifted mathematicians, cannot imagine curved space. Yet Einstein’s relativity theory tells us that we actually live in a curved four-dimensional spacetime manifold, one that violates Euclidean geometry—something that Immanuel Kant found unimaginable and thus ruled out on philosophical grounds.

Bergson and Bradley thought that absolute nothingness was self-
contradictory, because the very possibility would entail the existence of an observer to think about it. Call this the “observer argument” against nothingness. The observer argument is not only dubious on general grounds, but also has some wild implications. It means that
every
possible world must contain at least one conscious observer. But surely a universe without consciousness is physically possible. If the constants of nature in our own universe—the strength of the weak nuclear force, the mass of the top quark, and so on—were even slightly different from their actual values, there would have been no evolution of life in the universe, just a lot of brute matter. But, by the logic of the observer argument, such a zombie universe would be impossible, since there would be no one to observe it.

Bergson’s version of the observer argument has a still more absurd implication. In his mind’s eye, he could not abolish his own self. On the principle that what is unimaginable is impossible, he ought to have concluded that his
own
nonexistence was impossible: that no matter how reality had turned out—empty, full, whatever—it was metaphysically guaranteed to include Monsieur Bergson; that he himself was a God-like necessary being. To call this solipsism would be charitable.

There is a second argument against nothingness that, though similar in its logic, runs along more objective lines. Like the observer argument, it too says that our effort to imagine absolute nothingness is doomed to be only partial, never complete. But instead of pointing to consciousness as the thing left over, it cites a residuum that is nonmental. Even when all the contents of the cosmos have been imaginatively banished, the argument goes, we are always left with the abstract setting that they inhabited. This setting may be empty, but it is not nothing. A container with no contents is still a container. Let’s call this the “container argument” against nothingness.

One venerable exponent of the container argument is Bede Rundle, a contemporary philosopher at Oxford. “
Our attempt to
think away everything amounts to envisaging a region of space which has been evacuated of its every occupant, an exercise which gives no more substance to the possibility of there being nothing than does envisaging an empty cupboard,” Rundle has written (in a book tellingly titled
Why There Is Something Rather Than Nothing
). And just what is this “empty cupboard”? Rundle appears to be identifying it with space itself. Since one cannot “think away” the presence of space, he suggests, it must be part of any possible reality—a necessary existent, like God, or Henri Bergson’s inner self.

So is space to be our great bulwark against nothingness? Rundle hedges his bets. At one point he considers an alternative argument, to the effect that the very idea of nothingness is incoherent. If there were nothing, then it would have been a
fact
that there was nothing. So at least one thing would exist after all: that fact! (This is a truly terrible argument; the enumeration of its fallacies is left as an exercise for the reader.) But it is space that Rundle keeps coming back to, since he just can’t think it away, try as he might. “
Space is not
nothing
,” he insists, “it is something you can stare into or travel through, something of which there can be volumes.”

Not everyone shares Rundle’s conviction that space is a something. Among philosophers, there are two competing views of what space actually is. (To be scientifically up-to-date, we should be talking about “spacetime” rather than “space,” but no matter.) One of them, the
substantival
view, goes back to Newton. It holds that space is indeed a real thing, with its own intrinsic geometry, and that it would continue to exist even if all its contents vanished. The other view of space, the
relational
view, goes back to Newton’s great rival, Leibniz. It holds that space is not a thing unto itself, but merely a web of relations among things. Space could no more exist apart from the things that it relates, on Leibniz’s view, than the grin of the Cheshire Cat could exist apart from the feline itself.

The ontological debate between the Newtonians and the Leibnizians continues to the present day, and it’s a lively one. Relativity theory, in which spacetime affects the behavior of matter, has tipped the balance somewhat in favor of the substantivalists.

But it’s not necessary to resolve this debate to see whether the container argument is any good. Suppose the relationists are right, and space is just a convenient theoretical fiction. In that case, if the contents of the cosmos were to vanish, space would vanish along with them, leaving absolute nothingness.

Now suppose, contrariwise, that the substantivalists are right. Suppose that space is a genuine cosmic arena, with an existence all its own. Then this arena could survive the disappearance of its material contents. Even with everything gone, there would still be unoccupied positions. But if space has real objective existence, so does its geometrical form. It could be infinite in extent. But it could also be finite, even though it has no boundary. (The surface of a basketball, for example, is a finite two-dimensional space that has no boundary.) Such “closed” spacetimes are consistent with Einstein’s relativity theory. Indeed, Stephen Hawking and other cosmologists have theorized that the spacetime of our own universe is finite and unbounded, like a higher-dimensional analogue to the surface of a basketball. In that case, it is not hard to “think away” spacetime along with everything in it. Just imagine that basketball deflating, or rather shrinking. In your mind’s eye, the finite radius of the basketball-cosmos grows smaller and smaller until, finally, it reaches zero. Now the spacetime arena itself has vanished, leaving absolute nothingness behind.

This thought experiment leads to an elegant scientific definition (originally due to the physicist Alex Vilenkin):

Nothingness = a closed spherical spacetime of zero radius

So the container argument fails, regardless of what the nature of the container might turn out to be. If spacetime is not a genuine entity, but merely a set of relations among things, then it vanishes along with those things and hence is no obstacle to the possibility of nothingness. If spacetime
is
a genuine entity, with its own peculiar structure and quiddity, then it can be “disappeared” by the imagination just like the rest of the furniture of reality.

Voiding reality in the mind’s eye is a purely imaginative achievement. What if one tried to carry it out in the lab? Aristotle thought that this would be impossible. He produced a variety of arguments, both empirical and conceptual, purporting to show that you can’t empty out a region of space. The Aristotelian orthodoxy that “nature abhors a vacuum” held until the middle of the seventeenth century, when it was decisively overthrown by one of Galileo’s pupils, Evangelista Torricelli. An ingenious experimentalist, Torricelli had the happy idea of pouring mercury into a test tube, and then, with his finger over the open end, plunging it into a mercury bath. With the tube standing vertically upside down, a little airless void appeared above the column of mercury. What Torricelli had done was to create the first barometer. He had also demonstrated that nature’s supposed
horror vacui
was really nothing more than the weight of the atmospheric air pressing down on us.

But did Torricelli succeed in producing a bit of true nothingness? Not quite. Today, we know that the sort of airless space he was the first to create is far from being completely empty. The most perfect vacuum, it turns out, still contains something. In physics, the notion of “something” is quantified by energy. (Even matter, as Einstein’s most famous equation shows, is just frozen energy.) Physically speaking, space is as empty as it can be when it is devoid of energy.

Now, suppose you try to remove every bit of energy from a region of space. Suppose, in other words, you try to reduce that region to its state of lowest energy, which is known as its “vacuum state.” At a certain point in this energy-draining process, something very counterintuitive will occur. An entity that physicists call the “Higgs field” will spontaneously emerge. And this Higgs field cannot be got rid of, because its contribution to the total energy of the space you are trying to empty out is actually
negative
. The Higgs field is a “something” that contains less energy than a “nothing.” And it is accompanied by a riot of “virtual particles” that ceaselessly wink in and out of existence. Space in a vacuum state turns out to be very busy indeed, rather like Times Square on New Year’s Eve.

PHILOSOPHERS WHO BELIEVE
in Nothing—they sometimes call themselves “metaphysical nihilists”—try to steer clear of such physical snags. In the late 1990s, several British and American philosophers jointly pioneered what has become known as the “subtraction argument.” Unlike the observer and container arguments, which were anti-nothingness, the subtraction argument is pro-nothingness. It is meant to demonstrate that an absolute void is a genuine metaphysical possibility.

The subtraction argument begins by assuming, plausibly enough, that the world contains a
finite
number of objects—people, tables, chairs, rocks, and so forth. It also assumes that each of these objects is
contingent
: although the object does in fact exist, it might not have existed. This too seems plausible. Think of the movie
It’s a Wonderful Life
, and its protagonist George Bailey (played by Jimmy Stewart). After a series of setbacks in his life, George finds himself contemplating suicide. Thanks to the intervention of an angel named Clarence, George gets to see what the world would have looked like if he had never been born. He is confronted with the contingency of his own existence. The same contingency seems to infect not only individual people, but also the entire inventory of actually existing things, from the Milky Way to the Eiffel Tower to the dog sleeping on your sofa to the speck of dust on the mousepad of your laptop. Each of these things, although it happens to exist, might not have existed if the cosmos had unfolded differently. Finally, the subtraction argument makes an assumption of
independence
: that the nonexistence of one thing does not necessitate the existence of anything else.

With all three of these premises in place—finiteness, contingency, and independence—it is easy to derive the conclusion that there might have been nothing at all. You simply subtract each contingent object from the world, one by one, until you end up with absolute emptiness, a pure void. This “subtraction” is supposed to be metaphorical rather than literal. Each stage of the argument asserts a relationship between possible worlds: if a world with
n
objects is possible, then a world with
n−
1 objects is also possible. At the penultimate stage in the subtraction process, the world might consist of no more than a single grain of sand. If such a sad little world is possible, then so is a world where that grain of sand is deleted—a world of nothingness.

The subtraction argument is generally considered to be the strongest one in the arsenal of the metaphysical nihilists. Indeed, it may be the only positive argument they have. Although I have stated the argument somewhat crudely, its proponents have painstakingly put it into a form where it appears to be logically valid: no mean feat. If the premises are true, the conclusion—that absolute nothingness is possible—must also be true.

But
are
the premises of the subtraction argument true? In other words, is the argument not merely valid, but also (as logicians say)
sound
?

Well, the finiteness and contingency premises seem okay. But the third premise, that of independence, is more dubious. Can we really be sure that the nonexistence of one thing does not entail the existence of something else? Think again of
It’s a Wonderful Life
. In the alternative world where George Bailey never existed, many other possible things did exist as a consequence—like the sleazy bars and pawnshops of “Pottersville,” which the greedy banker Mr. Potter would have created had decent George not been around to stop him. Contingent things are not so independent after all. Each thing, no matter how shaky its own claim to existence, seems implicated in a web of ontic interdependency with many other things, both actual and possible.