When I was a child, I used to visit the Japanese Tea Garden in San
I would spend hours fascinated by the carp, who lived in a very
just inches beneath the lily pads, just beneath my fingers, totally
the universe above them. I would ask myself a question only a child could ask: What would it be like to be a carp?
What a strange world it would be! I imagined that the pond would be an entire universe, one that is two-dimensional in space. The carp would only be able to swim forwards and backwards, and left and right. But I imagined that the concept of “up”—beyond the lily pads—would be totally alien to them. Any carp scientist daring to talk about “hyperspace”—i.e., the third dimension “above” the pond would immediately be labeled a crank.
I wondered what would happen if I could reach down and grab
a carp scientist and lift it up into hyperspace. I thought, What a wondrous
story that scientist would tell the others! The carp would babble on about
unbelievable new laws of physics: beings who could move without fins; beings who
could breathe without gills; beings who could emit sounds without bubbles.
I then wondered: How would a carp scientist know about our
existence? One day it rained, and I saw the rain drops forming gentle ripples on
the surface of the pond. Then I understood. The carp could see rippling shadows
on the surface of the pond. The third dimension would be invisible to them, but
vibrations in the third dimensions would be clearly visible. These ripples might
even be felt by the carp, who would invent a silly concept to describe this,
called “force.” They might even give these “forces” cute names, such as
light and gravity. We would laugh at them, because, of course, we know there is
no “force” at all, just the rippling of the water.
Today, many physicists believe that we are the carp,
swimming in our tiny pond, blissfully unaware of invisible, unseen
universes hovering just above us in hyperspace. We spend our life in three
spatial dimensions, confident that what we can see with our telescopes is all
there is, ignorant of the possibility of 10-dimensional hyperspace. Although
these higher dimensions are invisible, their “ripples” can clearly be seen
and felt. We call these ripples gravity and light.
The theory of
hyperspace, however, languished for many decades for lack of any physical proof
or application. But the theory, once considered the province of eccentrics and
mystics, is being revived for a simple reason: It may hold the key to the
greatest theory of all time, the “theory of everything.”
Einstein spent the last 30 years of his life futilely
chasing after this theory, the Holy Grail of physics. He wanted a theory that
could explain the four fundamental forces that govern the universe: gravity,
electromagnetism, and the two nuclear forces (weak and strong). It was supposed
to be the crowning achievement of the last 2000 years of science, ever since the
Greeks asked what the world was made of. He was searching for an equation,
perhaps no more than one-inch long, that could be placed on a T-shirt, but was
so powerful it could explain everything from the Big Bang, exploding stars, to
atoms and molecules, to the lilies of the field. He wanted to read the mind of
God. Ultimately, Einstein failed in his mission. In fact, he was shunned
by many of his younger compatriots, who would taunt him with the thought,
“What God has torn asunder, no man can put together.”
But perhaps Einstein is now having his revenge. For the
past decade, there has been furious research on merging the four fundamental
forces into a single theory, especially one that can meld general relativity
(which explains gravity) with the quantum theory (which can explain the two
nuclear forces and electromagnetism). The problem is that relativity and the
quantum theory are precise opposites. General relativity is a theory of the very
large: galaxies, quasars, black holes, and even the Big Bang. It is based on
bending the beautiful four-dimensional fabric of space and time. The quantum
theory, by contrast, is a theory of the very small, i.e. the world of sub-atomic
particles. It is based on discrete, tiny packets of energy called quanta.
Over the past 50 years, many attempts have been tried to
unite these polar opposites, and have failed. The road to the Unified
Field Theory, a.k.a. the “Theory of Everything,” is littered with the
corpses of failed attempts. The key to the puzzle may be hyperspace. In 1915,
when Einstein said space-time was four-dimensional and was warped and rippled,
he showed that this bending produced a “force” called gravity. In 1921,
Theodr Kaluza wrote that ripples of the fifth dimension could be viewed as
light. Like the fish seeing the ripples in hyperspace moving in their world,
many physicists believe that light is created by ripples in five-dimensional
space-time. But what about dimensions higher than 5?
if we add more and more dimensions, we can ripple and bend them in different
ways, thereby creating more forces. In 10 dimensions, in fact, we can accomodate
all four fundamental forces! Actually, it’s not that simple. By naively going
to 10 dimensions, we also introduce a host of esoteric mathematical
inconsistencies (e.g., infinities and anomalies) that have killed all previous
theories. The only theory which has survived every challenge posed to it is
called superstring theory, in which this 10-dimensional universe is inhabited by
tiny strings. In fact, in one swoop, this 10-dimensional string theory gives us
a simple, compelling unification of all forces. Like a violin string, these tiny
strings can vibrate and create resonances or “notes.” That explains why
there are so many sub-atomic particles: they are just notes on a superstring.
(This seems so simple, but in the 1950s physicists were drowning in an avalanche
of sub-atomic particles. J.R. Oppenheimer, who helped build the atomic bomb,
even said, out of sheer frustration, that the Nobel Prize should go to the
physicist who does NOT discover a new particle that year!)
Similarly, when the string moves in space and time, it
warps the space around it, just as Einstein predicted. Thus, in a remarkably
simple picture, we can unify gravity (as the bending of space caused by moving
strings) with the other quantum forces (now viewed as vibrations of the string).
Of course, any theory with this power and majesty has a problem. This theory,
because it is a theory of everything, is really a theory of Creation. Thus, to
fully test the theory requires re-creating Creation! At first, this might seem
hopelessly impossible. We can barely leave the Earth’s puny gravity, let alone
create universes in the laboratory. But there is a way out to this seemingly
intractable problem. A theory of everything is also a theory of the everyday.
Thus, this theory, when fully completed, will be able to explain the existence
of protons, atoms, molecules, even DNA. The key is to fully solve the theory and
test the theory against the known properties of the universe.
At present, no one on Earth is smart enough to complete the theory. The theory is perfectly well-defined, but, you see, superstring theory is 21st-century physics that accidentally fell into the 20th century. It was discovered purely by accident, when two young physicists were thumbing through a mathematics book. The theory is so elegant and powerful, we were never “destined” to see it in the 20th century. The problem is that 21st-century mathematics has not been invented yet. But since physicists are genetically predisposed to be optimists, I am confident that we will solve the theory someday soon. Perhaps a young person reading this article will be so inspired by this story that he or she will finish the theory. I can’t wait!