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 flapp
ing 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.
THE QUANTUM BRAIN
This debate also affects the reverse engineering of the brain. If you can successfully reverse engineer a brain made of transistors, this success implies that the brain is deterministic and predictable. Ask it any question and it repeats the exact same answer. Computers are deterministic in this way, since they always give the same answer for any question.
So it seems we have a problem. On one hand, quantum mechanics and chaos theory claim that the universe is not predictable, and therefore, free will seems to exist. But a reverse-engineered brain, made of transistors, would by definition be predictable. Since the reverse-engineered brain is theoretically identical to a living brain, then the human brain is also deterministic and there is no free will. Clearly, this contradicts the first statement.
A minority of scientists claim that you cannot authentically reverse engineer the brain, or ever create a true thinking machine, because of the quantum theory. The brain, they argue, is a quantum device, not just a collection of transistors. Hence this project is doomed to fail. In this camp is Oxford physicist Dr. Roger Penrose, an authority on Einstein’s theory of relativity, who claims that it is quantum processes that may account for the consciousness of the human brain. Penrose starts by saying that mathematician Kurt Gödel has proven that arithmetic is incomplete; that is, that there are true statements in arithmetic that cannot be proven using the axioms of arithmetic. Similarly, not only is mathematics incomplete, but so is physics. He concludes by stating that the brain is basically a quantum mechanical device and there are problems that no machine can solve because of Gödel’s incompleteness theorem. Humans, however, can make sense of these conundrums using intuition.
Similarly, the reverse-engineered brain, no matter how complex, is still a collection of transistors and wires. In such a deterministic system, you can accurately predict its future behavior because the laws of motion are well known. In a quantum system, however, the system is inherently unpredictable. All you can calculate are the chances that something will occur, because of the uncertainty principle.
If it turns out that the reverse-engineered brain cannot reproduce human behavior, then scientists may be forced to admit that there are unpredictable forces at work (i.e., quantum effects inside the brain). Dr. Penrose argues that inside the neuron there are tiny structures, called microtubules, where quantum processes dominate.
At present, there is no consensus on this problem. Judging from the reaction to Penrose’s idea when it was first proposed, it would be safe to say that most of the scientific community is skeptical of his approach. Science, however, is never conducted as a popularity contest, but instead advances through testable, reproducible, and falsifiable theories.
For my own part, I believe transistors cannot truly model all the behaviors of neurons, which carry out both analog and digital calculations. We know that neurons are messy. They can leak, misfire, age, die, and are sensitive to the environment. To me, this suggests that a collection of transistors can only approximately model the behavior of neurons. For example, we saw earlier, in discussing the physics of the brain, that if the axon of the neuron becomes thinner, then it begins to leak and also does not carry out chemical reactions that well. Some of this leakage and these misfires will be due to quantum effects. As you try to imagine neurons that are thinner, denser, and faster, quantum effects become more obvious. This means that even for normal neurons there are problems of leakage and instabilities, and these problems exist both classically and quantum mechanically.
In conclusion, a reverse-engineered robot will give a good but not perfect approximation of the human brain. Unlike Penrose, I think it is possible to create a deterministic robot out of transistors that gives the appearance of consciousness, but without any free will. It will pass the Turing test. But I think there will be differences between such a robot and humans due to these tiny quantum effects.
Ultimately, I think free will probably does exist, but it is not the free will envisioned by rugged individualists who claim they are complete masters of their fate. The brain is influenced by thousands of unconscious factors that predispose us to make certain choices ahead of time, even if we think we made them ourselves. This does not necessarily mean that we are actors in a film that can be rewound anytime. The end of the movie hasn’t been written yet, so strict determinism is destroyed by a subtle combination of quantum effects and chaos theory. In the end, we are still masters of our destiny.
NOTES
INTRODUCTION
1 You may have to travel: To see this, define “complex” in terms of the total amount of information that can be stored. The closest rival to the brain might be the information contained within our DNA. There are three billion base pairs in our DNA, each one containing one of four nucleic acids, labeled A,T,C,G. Therefore the total amount of information we can store in our DNA is four raised to the three-billionth power. But the brain can store much more information among its one hundred billion neurons, which can either fire or not fire. Hence, there are two raised to the one-hundred-billionth power possible initial states of the human brain. But while DNA is static, the states of the brain change every few milliseconds. A simple thought may contain one hundred generations of neural firings. Hence, there are two raised to one hundred billion, all raised to the hundredth power, possible thoughts contained in one hundred generations. But our brains are continually firing, day and night, ceaselessly computing. Therefore the total number of thoughts possible within N generations is two raised to the one-hundred-billionth power, all raised to the Nth power, which is truly astronomical. Therefore the amount of information that we can store in our brains far exceeds the information stored within our DNA by a wide margin. In fact, it is the largest amount of information that we can store in our solar system, and even possibly in our sector of the Milky Way galaxy.
2 “The most valuable insights”: Boleyn-Fitzgerald, p. 89.
3 “All of these questions that philosophers”: Boleyn-Fitzgerald, p. 137.
CHAPTER 1: UNLOCKING THE MIND
1 He was semiconscious for weeks: See Sweeney, pp. 207–8.
2 Dr. John Harlow, the doctor who treated: Carter, p. 24.
3 In the year A.D. 43, records show: Horstman, p. 87.
4 “It was like … standing in the doorway”: Carter, p. 28.
5 The Transparent Brain: New York Times, April 10, 2013, p. 1.
6 “Emotions are not feelings at all”: Carter, p. 83.
7 the mind is more like a “society of minds”: Interview with Dr. Minsky for the BBC-TV series Visions of the Future, February 2007. Also, interview for Science Fantastic national radio broadcast, November 2009.
8 consciousness was like a storm raging: Interview with Dr. Pinker in September 2003 for Exploration national radio broadcast.
9 “the intuitive feeling we have”: Pinker, “The Riddle of Knowing You’re Here,” in Your Brain: A User’s Guide (New York: Time Inc. Specials, 2011).
10 Consciousness turns out to consist of: Boleyn-Fitzgerald, p. 111.
11 “indeed a conscious system in its own right”: Carter, p. 52.
12 I asked him how experiments: Interview with Dr. Michael Gazzaniga in September 2012 for Science Fantastic national radio broadcast.
13 “The possible implications of this”: Carter, p. 53.
r /> 14 “If that person dies, what happens?”: Boleyn-Fitzgerald, p. 119.
15 a young king who inherits: Interview with Dr. David Eagleman in May 2012 for Science Fantastic national radio broadcast.
16 “people named Denise or Dennis”: Eagleman, p. 63.
17 “at least 15% of human females”: Eagleman, p. 43.
CHAPTER 2: CONSCIOUSNESS—A PHYSICIST’S VIEWPOINT
1 “We cannot see ultraviolet light”: Pinker, How the Mind Works, pp. 561–65.
2 “Everybody knows what consciousness is”: Biological Bulletin 215, no. 3 (December 2008): 216.
3 We will do so in the notes: Level II consciousness can be counted by listing the total number of distinct feedback loops when an animal interacts with members of its species. As a rough guess, Level II consciousness can be approximated by multiplying the number of others in an animal’s pack or tribe, multiplied by the total number of distinct emotions or gestures it uses to communicate with others. There are caveats to this ranking, however, since this is just a first guess.
For example, animals like the wildcat are social, but they are also solitary hunters, so it appears as if the number of animals in its pack is one. But that is true only when it is hunting. When it is time to reproduce, wildcats engage in complex mating rituals, so its Level II consciousness must take this into account.
Furthermore, when female wildcats give birth to litters of kittens, which have to be nursed and fed, the number of social interactions increases as a consequence. So even for solitary hunters, the number of members of its species that it interacts with is not one, and the total number of distinct feedback loops can be quite large.