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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