PARALLEL UNIVERSES 239
The eleventh dimension gave us a new picture. It also meant that
perhaps the universe itself was a membrane, floating in an eleven-dimensional space-time. Moreover, not all these dimensions had to be
small. In fact, some of these dimensions might actually be infinite.
This raises the possibility that our universe exists in a multiverse
of other universes. Think of a vast collection of floating soap bubbles
or membranes. Each soap bubble represents an entire universe floating in a larger arena of eleven-dimensional hyperspace. These bubbles
can join with other bubbles, or split apart, and even pop into existence
and disappear. We might live on the skin of just one of these bubble
universes.
Max Tegmark of MIT believes that in fifty years "the existence of
these 'parallel universes' will be no more controversial than the existence of other galaxies-then called 'island universes'-was 100 years
ago."
How many universes does string theory predict? One embarrassing feature of string theory is that there are trillions upon trillions of
possible universes, each one compatible with relativity and the quantum theory. One estimate claims that there might be a googol of such
universes. (A googol is 1 followed by 100 zeros.)
Normally communication between these universes is impossible.
The atoms of our body are like flies trapped on flypaper. We can move
freely about in three dimensions along our membrane universe, but
we cannot leap off the universe into hyperspace, because we are glued
onto our universe. But gravity, being the warping of space-time, can
freely float into the space between universes.
In fact, there is one theory that states that dark matter, an invisible
form of matter that surrounds the galaxy, might be ordinary matter
floating in a parallel universe. As in H. G. Wells's novel The Invisible
Man,
a person would become invisible if he floated just above us in the
fourth dimension. Imagine two parallel sheets of paper, with someone
floating on one sheet, just above the other.
In the same way there is speculation that dark matter might be an
ordinary galaxy hovering above us in another membrane universe. We
could feel the gravity of this galaxy, since gravity can ooze its way be-
The eleventh dimension gave us a new picture. It also meant that
perhaps the universe itself was a membrane, floating in an eleven-dimensional space-time. Moreover, not all these dimensions had to be
small. In fact, some of these dimensions might actually be infinite.
This raises the possibility that our universe exists in a multiverse
of other universes. Think of a vast collection of floating soap bubbles
or membranes. Each soap bubble represents an entire universe floating in a larger arena of eleven-dimensional hyperspace. These bubbles
can join with other bubbles, or split apart, and even pop into existence
and disappear. We might live on the skin of just one of these bubble
universes.
Max Tegmark of MIT believes that in fifty years "the existence of
these 'parallel universes' will be no more controversial than the existence of other galaxies-then called 'island universes'-was 100 years
ago."
How many universes does string theory predict? One embarrassing feature of string theory is that there are trillions upon trillions of
possible universes, each one compatible with relativity and the quantum theory. One estimate claims that there might be a googol of such
universes. (A googol is 1 followed by 100 zeros.)
Normally communication between these universes is impossible.
The atoms of our body are like flies trapped on flypaper. We can move
freely about in three dimensions along our membrane universe, but
we cannot leap off the universe into hyperspace, because we are glued
onto our universe. But gravity, being the warping of space-time, can
freely float into the space between universes.
In fact, there is one theory that states that dark matter, an invisible
form of matter that surrounds the galaxy, might be ordinary matter
floating in a parallel universe. As in H. G. Wells's novel The Invisible
Man,
a person would become invisible if he floated just above us in the
fourth dimension. Imagine two parallel sheets of paper, with someone
floating on one sheet, just above the other.
In the same way there is speculation that dark matter might be an
ordinary galaxy hovering above us in another membrane universe. We
could feel the gravity of this galaxy, since gravity can ooze its way be-