More than two thousand years ago, Socrates said, “To know thyself is the beginning of wisdom.” We are on a long journey to complete his wishes.
APPENDIX
QUANTUM CONSCIOUSNESS?
In spite of all the miraculous advances in brain scans and high technology, some people claim that we will never understand the secret of consciousness, since consciousness is beyond our puny technology. In fact, in their view consciousness is more fundamental than atoms, molecules, and neurons and determines the nature of reality itself. To them, consciousness is the fundamental entity out of which the material world is created. And to prove their point, they refer to one of the greatest paradoxes in all of science, which challenges our very definition of reality: the Schrödinger’s Cat paradox. Even today, there is no universal consensus on the question, with Nobel laureates taking divergent stances. What is at stake is nothing less than the nature of reality and thought.
The Schrödinger’s Cat paradox cuts to the very foundation of quantum mechanics, a field that makes lasers, MRI scans, radio and TV, modern electronics, the GPS, and telecommunications possible, upon which the world economy depends. Many of quantum theory’s predictions have been tested to an accuracy of one part in one hundred billion.
I have spent my entire professional career working on the quantum theory. Yet I realize that it has feet of clay. It’s an unsettling feeling knowing my life’s work is based on a theory whose very foundation is based on a paradox.
This debate was sparked by Austrian physicist Erwin Schrödinger, who was one of the founding fathers of the quantum theory. He was trying to explain the strange behavior of electrons, which seemed to exhibit both wave and particle properties. How can an electron, a point particle, have two divergent behaviors? Sometimes electrons acted like a particle, creating well-defined tracks in a cloud chamber. Other times, electrons acted like a wave, passing through tiny holes and creating wavelike interference patterns, like those on the surface of a pond.
In 1925, Schrödinger put forward his celebrated wave equation, which bears his name and is one of the most important equations ever written. It was an instant sensation, and won him the Nobel Prize in 1933. The Schrödinger equation accurately described the wavelike behavior of electrons and, when applied to the hydrogen atom, explained its strange properties. Miraculously, it could also be applied to any atom and explain most of the features of the periodic table of elements. It seemed as if all chemistry (and hence all biology) were nothing but solutions of this wave equation. Some physicists even claimed that the entire universe, including all the stars, planets, and even us, was nothing but a solution of this equation.
But then physicists began to ask a problematic question that resonates even today: If the electron is described by a wave equation, then what is waving?
In 1927, Werner Heisenberg proposed a new principle that split the physics community down the middle. Heisenberg’s celebrated uncertainty principle states that you cannot know both the location and the momentum of an electron with certainty. This uncertainty was not a function of how crude your instruments were but was inherent in physics itself. Even God or some celestial being could not know the precise location and momentum of an electron.
So the wave function of Schrödinger actually described the probability of finding the electron. Scientists had spent thousands of years painfully trying to eliminate chance and probabilities in their work, and now Heisenberg was allowing it in through the back door.
The new philosophy can be summed up as follows: the electron is a point particle, but the probability of finding it is given by a wave. And this wave obeys Schrödinger’s equation and gives rise to the uncertainty principle.
The physics community cracked in half. On one side, we had physicists like Niels Bohr, Werner Heisenberg, and most atomic physicists eagerly adopting this new formulation. Almost daily, they were announcing new breakthroughs in understanding the properties of matter. Nobel Prizes were being handed out to quantum physicists like Oscars. Quantum mechanics was becoming a cookbook. You did not need to be a master physicist to make stellar contributions—you just followed the recipes given by quantum mechanics and you would make stunning breakthroughs.
On the other side, we had aging Nobel laureates like Albert Einstein, Erwin Schrödinger, and Louis de Broglie who were raising philosophical objections. Schrödinger, whose work helped start this whole process, grumbled that if he had known that his equation would introduce probability into physics, he would never have created it in the first place.
Physicists embarked on an eighty-year debate that continues even today. On one hand, Einstein would proclaim that “God does not play dice with the world.” Niels Bohr, on the other hand, reportedly replied, “Stop telling God what to do.”
In 1935, to demolish the quantum physicists once and for all, Schrödinger proposed his celebrated cat problem. Place a cat in a sealed box, with a container of poison gas. In the box, there is a lump of uranium. The uranium atom is unstable and emits particles that can be detected by a Geiger counter. The counter triggers a hammer, which falls and breaks the glass, releasing the gas, which can kill the cat.
How do you describe the cat? A quantum physicist would say that the uranium atom is described by a wave, which can either decay or not decay. Therefore you have to add the two waves together. If the uranium fires, then the cat dies, so that is described by one wave. If the uranium does not fire, then the cat lives, and that is also described by a wave. To describe the cat, you therefore have to add the wave of a dead cat to the wave of a live cat.
This means that the cat is neither dead nor alive! The cat is in a netherworld, between life and death, the sum of the wave describing a dead cat with the wave of a live cat.
This is the crux of the problem, which has reverberated in the halls of physics for almost a century. So how do you resolve this paradox? There are at least three ways (and hundreds of variations on these three).
The first is the original Copenhagen interpretation proposed by Bohr and Heisenberg, the one that is quoted in textbooks around the world. (It is the one that I start with when I teach quantum mechanics.) It says that to determine the state of the cat, you must open the box and make a measurement. The cat’s wave (which was the sum of a dead cat and a live cat) now “collapses” into a single wave, so the cat is now known to be alive (or dead). Thus, observation determines the existence and state of the cat. The measurement process is thus responsible for two waves magically dissolving into a single wave.
Einstein hated this. For centuries, scientists have battled something called “solipsism” or “subjective idealism,” which claims that objects cannot exist unless there is someone there to observe them. Only the mind is real—the material world exists only as ideas in the mind. Thus, say the solipsists (such as Bishop George Berkeley), if a tree falls in the forest but no one is there to observe it, perhaps the tree never fell. Einstein, who thought all this was pure nonsense, promoted an opposing theory called “objective reality,” which says simply that the universe exists in a unique, definite state independent of any human observation. It is the commonsense view of most people.
Objective reality goes back to Isaac Newton. In this scenario, the atom and subatomic particles are like tiny steel balls, which exist at definite points in space and time. There is no ambiguity or chance in locating the position of these balls, whose motions can be determined by using the laws of motion. Objective reality was spectacularly successful in describing the motions of planets, stars, and galaxies. Using relativity, this idea can also describe black holes and the expanding universe. But there is one place where it fails miserably, and that is inside the atom.
Classical physicists like Newton and Einstein thought that objective reality finally banished solipsism from physics. Walter Lippmann, the columnist, summed it up when he wrote, “The radical novelty of modern science lies precisely in the rejection of the belief … that the forces which move the stars and atoms are contingent up
on the preferences of the human heart.”
But quantum mechanics allowed a new form of solipsism back into physics. In this picture, before it is observed, a tree can exist in any possible state (e.g., sapling, burned, sawdust, toothpicks, decayed). But when you look at it, the wave suddenly collapses and it looks like a tree. The original solipsists talked about trees that either fell or didn’t. The new quantum solipsists were introducing all possible states of a tree.
This was too much for Einstein. He would ask guests at his house, “Does the moon exist because a mouse looks at it?” To a quantum physicist, in some sense the answer might be yes.
Einstein and his colleagues would challenge Bohr by asking: How can the quantum microworld (with cats being dead and alive simultaneously) coexist with the commonsense world we see around us? The answer was that there is a “wall” that separates our world from the atomic world. On one side of the wall, common sense rules. On the other side of the wall, the quantum theory rules. You can move the wall if you want and the results are still the same.
This interpretation, no matter how strange, has been taught for eighty years by quantum physicists. More recently, there have been some doubts cast on the Copenhagen interpretation. Today we have nanotechnology, with which we can manipulate individual atoms at will. On a scanning tunneling microscope screen, atoms appear to be fuzzy tennis balls. (For BBC-TV, I had a chance to fly out to IBM’s Almaden Lab in San Jose, California, and actually push individual atoms around with a tiny probe. It is now possible to play with atoms, which were once thought to be so small they could never be seen.)
As we’ve discussed, the Age of Silicon is slowly coming to an end, and some believe that molecular transistors will replace silicon transistors. If so, then the paradoxes of the quantum theory may lie at the very heart of every computer of the future. The world economy may eventually rest on these paradoxes.
COSMIC CONSCIOUSNESS AND MULTIPLE UNIVERSES
There are two alternate interpretations of the cat paradox, which take us to the strangest realms in all science: the realm of God and multiple universes.
In 1967, the second resolution to the cat problem was formulated by Nobel laureate Eugene Wigner, whose work was pivotal in laying the foundation of quantum mechanics and also building the atomic bomb. He said that only a conscious person can make an observation that collapses the wave function. But who is to say that this person exists? You cannot separate the observer from the observed, so maybe this person is also dead and alive. In other words, there has to be a new wave function that includes both the cat and the observer. To make sure that the observer is alive, you need a second observer to watch the first observer. This second observer is called “Wigner’s friend,” and is necessary to watch the first observer so that all waves collapse. But how do we know that the second observer is alive? The second observer has to be included in a still-larger wave function to make sure he is alive, but this can be continued indefinitely. Since you need an infinite number of “friends” to collapse the previous wave function to make sure they are alive, you need some form of “cosmic consciousness,” or God.
Wigner concluded: “It was not possible to formulate the laws (of quantum theory) in a fully consistent way without reference to consciousness.” Toward the end of his life, he even became interested in the Vedanta philosophy of Hinduism.
In this approach, God or some eternal consciousness watches over all of us, collapsing our wave functions so that we can say we are alive. This interpretation yields the same physical results as the Copenhagen interpretation, so this theory cannot be disproven. But the implication is that consciousness is the fundamental entity in the universe, more fundamental than atoms. The material world may come and go, but consciousness remains as the defining element, which means that consciousness, in some sense, creates reality. The very existence of the atoms we see around us is based on our ability to see and touch them.
(At this point, it’s important to note that some people think that because consciousness determines existence, then consciousness can therefore control existence, perhaps by meditation. They think that we can create reality according to our wishes. This thinking, as attractive as it might sound, goes against quantum mechanics. In quantum physics, consciousness makes observations and therefore determines the state of reality, but consciousness cannot choose ahead of time which state of reality actually exists. Quantum mechanics allows you only to determine the chance of finding one state, but we cannot bend reality to our wishes. For example, in gambling, it is possible to mathematically calculate the chances of getting a royal flush. However, this does not mean that you can somehow control the cards to get the royal flush. You cannot pick and choose universes, just as we have no control over whether the cat is dead or alive.)
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.)