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PHVSICS OF THE IMPOSSIBLE
chanics course on Earth, depends on an "observer" making an observation and collapsing the wave function. The observation process is
absolutely essential in defining the macroscopic world. But how can
one be "outside" the universe while observing the entire universe? If a
wave function describes the universe, then how can an "outside" observer collapse the wave function of the universe? In fact, some see the
inability to observe the universe from "outside" the universe as a fatal
flaw of the Copenhagen interpretation.
In the "many worlds" approach the solution to this problem is simple: the universe simply exists in many parallel states, all defined by a
master wave function, called the "wave function of the universe." In
quantum cosmology the universe started out as a quantum fluctuation
of the vacuum, that is, as a tiny bubble in the space-time foam. Most
baby universes in the space-time foam have a big bang and then immediately have a Big Crunch afterward. That is why we never see
them, because they are extremely small and short-lived, dancing in
and out of the vacuum. This means that even "nothing" is boiling with
baby universes popping in and out of existence, but on a scale that is
too small to detect with our instruments. But for some reason, one of
the bubbles in the space-time foam did not recollapse into a Big
Crunch, but kept on expanding. This is our universe. According to
Alan Guth, this means that the entire universe is a free lunch.
In quantum cosmology, physicists start with an analogue of the
Schrôdinger equation, which governs the wave function of electrons
and atoms. They use the DeWitt-Wheeler equation, which acts on the
"wave function of the universe." Usually the Schrôdinger wave function
is defined at every point in space and time, and hence you can calculate the chances of finding an electron at that point in space and time.
But the "wave function of the universe" is defined over all possible universes. If the wave function of the universe happens to be large when
defined for a specific universe, it means that there is a good chance
that the universe will be in that particular state.
Hawking has been pushing this point of view. Our universe, he
claims, is special among other universes. The wave function of the uni-
PHVSICS OF THE IMPOSSIBLE
chanics course on Earth, depends on an "observer" making an observation and collapsing the wave function. The observation process is
absolutely essential in defining the macroscopic world. But how can
one be "outside" the universe while observing the entire universe? If a
wave function describes the universe, then how can an "outside" observer collapse the wave function of the universe? In fact, some see the
inability to observe the universe from "outside" the universe as a fatal
flaw of the Copenhagen interpretation.
In the "many worlds" approach the solution to this problem is simple: the universe simply exists in many parallel states, all defined by a
master wave function, called the "wave function of the universe." In
quantum cosmology the universe started out as a quantum fluctuation
of the vacuum, that is, as a tiny bubble in the space-time foam. Most
baby universes in the space-time foam have a big bang and then immediately have a Big Crunch afterward. That is why we never see
them, because they are extremely small and short-lived, dancing in
and out of the vacuum. This means that even "nothing" is boiling with
baby universes popping in and out of existence, but on a scale that is
too small to detect with our instruments. But for some reason, one of
the bubbles in the space-time foam did not recollapse into a Big
Crunch, but kept on expanding. This is our universe. According to
Alan Guth, this means that the entire universe is a free lunch.
In quantum cosmology, physicists start with an analogue of the
Schrôdinger equation, which governs the wave function of electrons
and atoms. They use the DeWitt-Wheeler equation, which acts on the
"wave function of the universe." Usually the Schrôdinger wave function
is defined at every point in space and time, and hence you can calculate the chances of finding an electron at that point in space and time.
But the "wave function of the universe" is defined over all possible universes. If the wave function of the universe happens to be large when
defined for a specific universe, it means that there is a good chance
that the universe will be in that particular state.
Hawking has been pushing this point of view. Our universe, he
claims, is special among other universes. The wave function of the uni-