The Future of the Mind (54 page)

MULTIPLE UNIVERSES

The third way to resolve the paradox is the Everett, or many-worlds, interpretation, which was proposed in 1957 by Hugh Everett. It is the strangest theory of all. It says that the universe is constantly splitting apart into a multiverse of universes. In one universe, we have a dead cat. In another universe, we have a live cat. This approach can be summarized as follows: wave functions never collapse, they just split. The Everett many-worlds theory differs from the Copenhagen interpretation only in that it drops the final assumption: the collapse of the wave function. In some sense, it is the simplest formulation of quantum mechanics, but also the most disturbing.

There are profound consequences to this third approach. It means that all possible universes might exist, even ones that are bizarre and seemingly impossible. (However, the more bizarre the universe, the more unlikely it is.)

This means people who have died in our universe are still alive in another universe. And these dead people insist that their universe is the correct one, and that our universe (in which they are dead) is fake. But if these “ghosts” of dead people are still alive somewhere, then why can’t we meet them? Why can’t we touch these parallel worlds? (As strange as it may seem, in this picture Elvis is still alive in one of these universes.)

What’s more, some of these universes may be dead, without any life, but others may look exactly like ours, except for one key difference. For example, the collision of a single cosmic ray is a tiny quantum event. But what happens if this cosmic ray goes through Adolf Hitler’s mother, and the infant Hitler dies in a miscarriage? Then a tiny quantum event, the collision of a single cosmic ray, causes the universe to split in half. In one universe, World War II never happened, and sixty million people did not have to die. In the other universe, we’ve had the ravages of World War II. These two universes grow to be quite far apart, yet they are initially separated by one tiny quantum event.

This phenomenon was explored by science-fiction writer Philip K. Dick in his novel
The Man in the High Tower
, where a parallel universe opens up because of a single event: a bullet is fired at Franklin Roosevelt, who is killed by an assassin. This pivotal event means that the United States is not prepared for World War II, and the Nazis and Japanese are victorious and eventually partition the United States in half.

But whether the bullet fires or misfires depends, in turn, on whether a microscopic spark is set off in the gunpowder, which itself depends on complex molecular reactions involving the motions of electrons. So perhaps quantum fluctuations in the gunpowder may determine whether the gun fires or misfires, which in turn determines whether the Allies or the Nazis emerge victorious during World War II.

So there is no “wall” separating the quantum world and the macroworld. The bizarre features of the quantum theory can creep into our “commonsense” world. These wave functions never collapse—they keep splitting endlessly into parallel realities. The creation of alternative universes never stops. The paradoxes of the microworld (i.e., being dead and alive simultaneously, being in two places at the same time, disappearing and reappearing somewhere else) now enter into our world as well.

But if the wave function is continually splitting apart, creating entirely new universes in the process, then why can’t we visit them?

Nobel laureate Steven Weinberg compares this to listening to the radio in your living room. There are hundreds of radio waves simultaneously filling up your room from all over the world, but your radio dial is tuned to only one frequency. In other words, your radio has “decohered” from all the other stations. (Coherence is when all waves vibrate in perfect unison, as in a laser beam. Decoherence is when these waves begin to fall out of phase, so they no longer vibrate in unison.) These other frequencies all exist, but your radio cannot pick them up because they are not vibrating at the same frequency that we are anymore. They have decoupled; that is, they have decohered from us.

In the same way, the wave function of the dead and alive cat have decohered as time goes on. The implications are rather staggering. In your living room, you coexist with the waves of dinosaurs, pirates, aliens from space, and monsters. Yet you are blissfully unaware that you are sharing the same space as these strange denizens of quantum space, because your atoms are no longer vibrating in unison with them. These parallel universes do not exist in some distant never-never land. They exist in your living room.

Entering one of these parallel worlds is called “quantum jumping” or “sliding” and is a favorite gimmick of science fiction. To enter a parallel universe, we need to take a quantum jump into it. (There was even a TV series called
Sliders
where people slide back and forth between parallel universes. The series began when a young boy read a book. That book is actually my
book
Hyperspace
, but I take no responsibility for the physics behind that series.)

Actually, it’s not so simple to jump between universes. One problem we sometimes give our Ph.D. students is to calculate the probability that you will jump through a brick wall and wind up on the other side. The result is sobering. You would have to wait longer than the lifetime of the universe to experience jumping or sliding through a brick wall.

LOOKING IN THE MIRROR

When I look at myself in a mirror, I don’t really see myself as I truly am. First, I see myself about a billionth of a second ago, since that is the time that it takes a light beam to leave my face, hit a mirror, and enter my eyes. Second, the image I see is really an average over billions and billions of wave functions. This average certainly does resemble my image, but it is not exact. Surrounding me are multiple images of myself oozing in all directions. I am continually surrounded by alternate universes, forever branching into different worlds, but the probability of sliding between them is so tiny that Newtonian mechanics seems to be correct.

At this point, some people ask this question: Why don’t scientists simply do an experiment to determine which interpretation is valid? If we run an experiment with an electron, all three interpretations will yield the same result. All three are therefore serious, viable interpretations of quantum mechanics, with the same underlying quantum theory. What is different is how we explain the results.

Hundreds of years in the future, physicists and philosophers may still be debating this question, with no resolution, because all three interpretations yield the same physical results. But perhaps there is one way in which this philosophical debate touches on the brain, and that is the question of free will, which in turn affects the moral foundation of human society.

FREE WILL

Our entire civilization is based on the concept of free will, which impacts on the notions of reward, punishment, and personal responsibility. But does free will really exist? Or is it a clever way of keeping society together although
it violates scientific principles? The controversy goes to the very heart of quantum mechanics itself.

It is safe to say that more and more neuroscientists are gradually coming to the conclusion that free will does not exist, at least not in the usual sense. If certain bizarre behaviors can be linked to precise defects in the brain, then a person is not scientifically responsible for the crimes he might commit. He might be too dangerous to be left walking the streets and must be locked up in an institution of some sort, but punishing someone for having a stroke or tumor in the brain is misguided, they say. What that person needs is medical and psychological help. Perhaps the brain damage can be treated (e.g., by removing a tumor), and the person can become a productive member of society.

For example, when I interviewed Dr. Simon Baron-Cohen, a psychologist at Cambridge University, he told me that
many (but not all) pathological killers have a brain anomaly. Their brain scans show that they lack empathy when seeing someone else in pain, and in fact they might even take pleasure in watching this suffering (in these individuals, the amygdala and the nucleus accumbens, the pleasure center, light up when they view videos of people experiencing pain).

The conclusion some might draw from this is that these people are not truly responsible for their heinous acts, although they should still be removed from society. They need help, not punishment, because of a problem with their brain. In a sense, they may not be acting with free will when they commit their crimes.

An experiment done by Dr. Benjamin Libet in 1985 casts doubt on the very existence of free will. Let’s say that you are asking subjects to watch a clock and then to note precisely when they decide to move a finger. Using EEG scans, one can detect exactly when the brain makes this decision. When you compare the two times, you will find a mismatch. The EEG scans show that the brain has actually made the decision about three hundred milliseconds before the person becomes aware of it.

This means that, in some sense, free will is a fake. Decisions are made ahead of time by the brain, without the input of consciousness, and then later the brain tries to cover this up (as it’s wont to do) by claiming that the decision was conscious.
Dr. Michael Sweeney concludes, “Libet’s findings suggested that the brain knows what a person will decide
before
the
person does.… The world must reassess not only the idea of movements divided between voluntary and involuntary, but also the very idea of free will.”

All this seems to indicate that free will, the cornerstone of society, is a fiction, an illusion created by our left brain. So are we masters of our fate, or just pawns in a swindle perpetuated by the brain?

There are several ways to approach this sticky question. Free will goes against a philosophy called determinism, which simply says that all future events are determined by physical laws. According to Newton himself, the universe was some sort of clock, ticking away since the beginning of time, obeying the laws of motion. Hence all events are predictable.

The question is: Are we part of this clock? Are all our actions also determined? These questions have philosophical and theological implications. For example, most religions adhere to some form of determinism and predestination. Since God is omnipotent, omniscient, and omnipresent, He knows the future, and hence the future is determined ahead of time. He knows even before you are born whether you will go to Heaven or Hell.

The Catholic Church split in half on this precise question during the Protestant revolution. According to Catholic doctrine at that time, one could change one’s ultimate fate with an indulgence, usually by making generous financial donations to the Church. In other words, determinism could be altered by the size of your wallet. Martin Luther specifically singled out the corruption of the Church over indulgences when he tacked his 95 Theses on the door of a church in 1517, triggering the Protestant Reformation. This was one of the key reasons why the Church split down the middle, causing casualties in the millions and laying waste to entire regions of Europe.

But after 1925, uncertainty was introduced into physics via quantum mechanics. Suddenly everything became uncertain; all you could calculate was probabilities. In this sense, perhaps free will does exist, and it’s a manifestation of quantum mechanics. So some claim that the quantum theory reestablishes the concept of free will. The determinists have fought back, however, claiming that quantum effects are extremely small (at the level of atoms), too small to account for the free will of large human beings.

The situation today is actually rather muddled. Perhaps the question “Does free will exist?” is like the question “What is life?” The discovery of DNA has rendered that question about life obsolete. We now realize that the
question has many layers and complexities. Perhaps the same applies to free will, and there are many types.

If so, the very definition of “free will” becomes ambiguous. For example, one way to define free will is to ask whether behavior can be predicted. If free will exists, then behavior cannot be determined ahead of time. Let’s say you watch a movie, for example. The plot is completely determined, with no free will whatsoever. So the movie is completely predictable. But our world cannot be like a movie, for two reasons. The first is the quantum theory, as we have seen. The movie represents only one possible timeline. The second reason is chaos theory. Although classical physics says that all of the motions of atoms are completely determined and predictable, in practice it is impossible to predict their motions because there are so many atoms involved. The slightest disturbance of a single atom can have a ripple effect, which can cascade down to create enormous disturbances.

Think of the weather. In principle, if you knew the behavior of every atom in the air, you could predict the weather a century from now if you had a big enough computer. But in practice, this is impossible. After just a few hours, the weather becomes so turbulent and complex that any computer simulation is rendered useless.

This creates what is called the “butterfly effect,” which means that even the beat of butterfly wings can cause tiny ripples in the atmosphere, which grow and in turn can escalate into a thunderstorm. So if even the flapping of butterfly wings can create thunderstorms, the hope of accurately predicting the weather is far-fetched.

Let’s go back to the thought experiment described to me by Stephen Jay Gould. He asked me to imagine Earth 4.5 billion years ago, when it was born. Now imagine you could somehow create an identical copy of Earth, and let it evolve. Would we still be here on this different Earth 4.5 billion years later?

One could easily imagine, due to quantum effects or the chaotic nature of the weather and oceans, that humanity would never evolve into precisely the same creatures on this version of Earth. So ultimately, it seems a combination of uncertainty and chaos makes a perfectly deterministic world impossible.