A Critique of Seth Lloyd's Theory of the Universe as Quantum Computer

Seth Lloyd is an MIT professor of mechanical engineering who wrote a book called Programming the Cosmos. Some of the ideas in this book have been stated in a recent scientific paper he wrote entitled The Universe as Quantum Computer. In this paper Lloyd deals with some fascinating ideas, and flirts with some promising lines of thought. But does he come up with a workable conclusion?

I will skip over the first seven sections of this paper, which mainly deal with a discussion of exotic issues in computer science such as universal Turing machines and cellular automata. In section 8 “The Universe as Quantum Computer,” Lloyd leaps to the conclusion that the universe is “observationally indistinguishable from a giant quantum computer,” but does not justify this assertion. For one thing, no one has built a giant quantum computer. For another thing, if we were to build a giant quantum computer, there is no reason to think that it would look anything like our universe of galaxies, stars, and planets. 

Lloyd then asserts, “The ordinary laws of physics tell us nothing about why the universe is so complex.” This is a very serious misstatement which is easy to disprove. In fact, the ordinary laws of physics tell us a great deal about why the universe is so complex. We have large complex objects such as galaxies, stars, and planets largely because of the law of gravitation. We have 100 different types of atoms (and many complex molecules) largely because of the laws of electromagnetism, and the laws of nuclear physics involving the strong nuclear force. We have a stable planet partially because of conservation laws that maintain various types of balances such as the balance between positive charges and negative charges. We have complex life partially because of various complicated laws that allow stable sun-like stars to produce thermonuclear fusion at a slow, steady pace. I could list numerous other examples of laws of physics that help to assure that we have a universe as complicated as ours rather than merely an unordered lifeless soup of particles.

Lloyd then asserts that the known laws of physics can be written on the back of a tee shirt, something that will come as quite the surprise to anyone studying physics in graduate school, who has to lug around 600-page books filled with the complex mathematics and equations of general relatively, nuclear physics, electromagnetism, and quantum mechanics. This page lists or gives links to more than a hundred laws of physics, a much larger list than can be written on the back of a tee shirt.

Lloyd then wonders how the universe got so complicated after the simplicity of the Big Bang, when everything was presumably packed into a simple incredibly hot and incredibly tiny superdense ball. To explain the rise of complexity in the universe (things such as galaxies, planets, and life), Lloyd offers his “quantum computational model of the universe,” which he attempts to explain in terms of typing monkeys.

The story of the typing monkeys is well-known to anyone who has read books on the origin of order in the universe. The idea is that if you have a sufficient number of monkeys typing for a sufficient length of time, they will eventually produce any imaginable literary work. Lloyd imagines monkeys typing text that will be fed into a computer. Purely by chance, Lloyd infers, some of this output would produce a working computer program. Lloyd suggests such a randomly produced program might somehow be responsible for order in our universe.

But where is this computer, and where are the monkeys? Lloyd gives this answer: “In addition, quantum fluctuations – e.g., primordial fluctuations in energy density – automatically provide the random bits that are necessary to seed the quantum computer with a random program. That is, quantum fluctuations are the 14 monkeys that program the quantum computer that is the universe. Such a quantum computing universe necessarily generates complex, ordered structures with high probability.”

Taken literally, this thesis is quite nonsensical.

First, let's look at the primordial quantum density fluctuations mentioned by Lloyd – not his speculations about them, but the basic concept of primordial quantum density fluctuations. Scientists imagine these as incredibly tiny random variations in density that occurred in the early universe. Cosmologists say that such fluctuations would have occurred in the early universe because of Heisenberg's Uncertainty Principle. But that law of nature (and its associated physical constant, Planck's constant) set a very specific limit on these fluctuations. According to Heisenberg's Uncertainty Principle, a quantum fluctuation cannot be greater than about a billionth of a trillionth of a trillionth of a joule during any second. A joule is about the energy needed to slide a brick a distance of one meter. So the maximum allowed quantum fluctuation in a second is an amount of energy billions of times smaller than the energy used in a single one-second flash of a firefly.

Given that limit, it is quite nonsensical to imagine quantum fluctuations literally being the source of some randomly produced program that might help to produce order in the universe. Even with random fluctuations occurring all over the universe, nowhere in the universe would we have for even one second some program that might be used later in producing order in the universe. If such a program were to somehow permanently pop into existence (contrary to the limitations of Heisenberg's Uncertainty Principle), there is no reason to think that it would then somehow be applied generally as the universe's computer program. Since quantum fluctuations would be occurring all over the universe, any random process producing one computer program would also produce trillions of other computer programs. If those programs were then somehow used by the universe, what we would see is not the universe we see (one in which there are physical laws the same everywhere), but some totally different hodgepodge smorgasboard patchwork-quilt universe in which every little patch of space had its own laws of nature. Our universe is totally different, and scientists have done observations tending to confirm that laws of nature behave the same at opposite ends of the universe, indicating a great uniformity of law throughout the observable universe.

I may also note that there is absolutely no reason for thinking that a particular part of space would start to use a random program that happened to pop into existence due to a quantum fluctuation. Just because a computer program pops into existence doesn't mean that a nearby computer will start using that program as its operating system. Also, if we are to explain the order needed for life by postulating something like a computer program, we need not a random computer program created by quantum fluctuations, but a highly optimized, fine-tuned program (given the huge number of anthropic requirements for observers like us, discussed here).

But perhaps Lloyd is just speaking in metaphorical terms (despite making such statements in a scientific paper). Given his completely incorrect statement that “the ordinary laws of physics tell us nothing about why the universe is so complex,” perhaps Lloyd thinks that most of the universe's order is because of some lucky quantum density fluctuations in the early universe, and perhaps he is poetically or metaphorically referring to these as a computer program. In reality, only a small fraction of the universe's order (less than 10%) is due to such quantum density fluctuations, with most of it (much more than 50%) being due to the universe's seemingly optimized laws of nature and physical constants.

To his credit, Lloyd seems to have some general idea or suspicion that programming and computation play an important part in the universe. But he's taken this promising idea, and failed to create a workable thesis from it. The truth is that the universe's order is mainly caused by a series of highly favorable laws and fine-tuned physical constants that seem to have existed from the very beginning, a seemingly goal-oriented set of laws and constants that can only be described as programmatic and conceptual. Our universe seems to have been programmed for success from the very beginning, as I discuss here and here. We understand only a small part of this programming (that part which we call the known laws of nature), Far from being some simple thing that can be written on the back of a tee shirt, there is every reason to suspect that the programming that allows a life-containing universe to evolve from the super-dense state of the Big Bang is some programming vastly more complicated and proficient than any software man has ever created. We cannot plausibly explain that cosmic programming either through a theory of typing monkeys or through a theory of quantum fluctuations occurring after the origin of the universe.
 

Astonishing Anomalies That May Support an Alternate Theory of Consciousness

In a previous blog post The Receptacle Hypothesis: Could Your Mind Have Come From an External Source? I suggested the hypothesis that human consciousness might come not from the brain, but from some unknown external source. It could be, I speculated, that our brains are mainly a kind of receptacle for our consciousness, rather than the sole producer of that consciousness. This may at first sound like some wild idea that cannot be supported, but in a later blog post 9 Strange Mental Phenomena That May Support an Alternate Theory of Consciousness I listed quite a few phenomena (real or alleged) that may tend to support this hypothesis. Since writing that post I have learned about other anomalies that may lend credence to this hypothesis: additional strange phenomena that lead one to question the conventional thinking that your brain is the sole source of your consciousness. I will discuss these anomalies now.

One such anomaly is the amazing fact that when a certain type of rare brain surgery is done, half of a child's brain is removed. Under the theory that your brain is the sole source of your mind, we would expect that removing half of a child's brain would either cause the death of a child, or cause the child to be doomed to a vegetative state. Instead, amazingly, children who have this surgery done suffer relatively little mental impairment.

The type of surgery in question is called a hemispherectomy, and is sometimes performed on children experiencing severe seizures. The operation is described in a Scientific American article entitled Strange but True: When Half a Brain Is Better than a Whole One. The article states: “Unbelievably, the surgery has no apparent effect on personality or memory.”

According to this link, 70% of the children who had half of their brains removed were able to speak well, and 42% older than 6 were able to read well. Given that only about 60% of the American population can read well, this 42% figure is amazingly high.

These facts seem to stand in stark opposition to the theory that your consciousness is being produced entirely by your brain. Under that theory, we should expect that removing half of the brain would have a crippling effect on someone's mental abilities. That is not at all what we observe. We observe a relatively small effect, at least in children. I may point out that when half of a child's brain is removed in a hemispherectomy, the other half does not grow back.

Now for another similar anomaly that is even more amazing. This is a case in which a human managed to function well in society as a French civil servant, even though he had almost no functional brain.
 

The case is discussed here. Inside a normal brain are tiny structures called lateral ventricles that hold brain fluid. In this man's case, the ventricles had swollen up like balloons, until they filled almost all of the man's brain. When the 44-year-old man was a child, doctor's had noticed the swelling, and had tried to treat it. Apparently the swelling had progressed since childhood. The man was left with what the Reuters story calls “little more than a sheet of actual brain tissue.”

But this same man, with almost no functioning brain, had been working as a French civil servant, and had his IQ tested to be 75, higher than that of a mentally retarded person. The Reuters story says: “A man with an unusually tiny brain managed to live an entirely normal life despite his condition, caused by a fluid buildup in his skull.” The case was written up in the British medical journal The Lancet (link).

In 1980 John Lorber, a British neurologist, recounted a similar case of a brain filled with fluid. “There's a young student at this university,” said Lorber, “who has an IQ of 126, has obtained a first-class honors degree in mathematics, and is socially completely normal. And yet the boy has virtually no brain.” According to Lorber, “We saw that instead of the normal 4-5 centimeter thickness of brain tissue...there was just a thin layer of mantle measuring a millimeter or so. His cranium is filled mainly with cerebrospinal fluid.” Lorber found other similar cases. Here is a link discussing his work.

These accounts seem to stand in stark opposition to the conventional theory that your consciousness is entirely produced by your brain. Under that theory, someone with the conditions described here should have been dead, in a vegetative state, or at best persisting with the intelligence of a squirrel – not working successfully as a French civil servant, or being an honors student with an IQ of 126. But these cases are perfectly compatible with the receptacle theory of consciousness I have suggested. If the brain is mainly just a receptacle for consciousness (consciousness which comes from some unknown external source), then it might not matter all that much if the receptacle is much smaller.

I am not saying that these cases show the likelihood of the receptacle hypothesis I have suggested, but they do make you wonder about whether such a hypothesis may be true, along with the other items I have listed in this post. 

 Montage of mysteries

Loeb's Theory of Early Life Evolution Is Implausible and Sterile

On yesterday's www.slate.com website we have an article about the “early habitability epoch” theory of Harvard professor Abraham Loeb. We normally think of life as something that can only appear on planets revolving around stars, and only planets that have an orbit not too close and not too far from a star. Planets that have such an orbit are said to exist in the habitable zone, also called the Goldilocks zone (because planets in such a zone are neither too hot nor too cold). Loeb's theory is that a few million years after the Big Bang, there was a warm background temperature of space which may have allowed life to appear fairly soon in the early universe, only about 10 to 17 million years after the universe began. For a relatively brief slice of cosmic history (less than a thousandth of the universe's history), this warmth would have existed throughout the universe, in theory allowing life to arise on suitable planets, even planets beyond the normal habitable zone. The visual below is a highly schematic diagram illustrating the idea:

But this brief period of pleasant warmth did not exist for long. The universe rapidly cooled after the Big Bang, and there was only a relatively short period during which the background temperature would have been suitable to support life's evolution on a planet far away from a star. Loeb's scientific paper estimates that this period of warmth (which he calls an epoch of habitability) lasted only six million years. Any life that evolved (outside of the habitable zone) because of this brief period of warmth would have been killed as soon as this relatively short period ended, when the background temperature of space would have plummeted.

Six million years is, in reality, far too short a time to allow for the evolution of a visible organism. Loeb admits this. When asked when whether intelligent life could have evolved in this period, Loeb says, “No. I'm talking about very simple organisms like algae.”

However, it is most improbable that even one-celled organisms like algae or diatoms could have evolved within a six million time frame. Our planet is 4.6 billion years old, but the oldest traces of life are 3.5 billion years old. So we have about one billion years of something going on before there was even evidence of life. Life seems to require hundreds of millions of years of evolution before you get to something like algae or one-celled organisms.

This is one reason why Loeb's theory is not credible. Six million years is too short a time frame for any visible life to appear. We must also consider that the early universe was a place of high radiation, when any young planet would be bombarded by intense radiation causing the sterilization of any freshly evolved life. It is actually very unlikely that any planets would have formed by the beginning of the supposed habitability epoch Loeb imagines (between 10 and 17 million years after the Big Bang). Loeb's paper says that the possibility of such planets is “not ruled out” by the existing data, but he uses some special pleading to get to such a conclusion. We must also consider the fact that between 10 and 17 million years after the Big Bang, any newly formed small planet would be a kind of lava world still cooling from its initial formation, and would also be constantly bombarded by asteroids hanging around from the early formation of its solar system. A negative trifecta of high background radiation, the hellish inferno of a recent planet formation, and constant asteroid bombardment should have been sufficient to prevent life from appearing anywhere during the time frame imagined by Loeb. 

The hellish environment of a newly formed planet

We need a proper theory for explaining how life (and the semantically rich genetic code) could have got started on Earth even given billions of years, something which is actually quite difficult to do, given reasons discussed here. In this light a new theory trying to squeeze an origin of life into a six million year time frame (less than one percent of the time it took on Earth) is rather laughable. But I understand the appeal to certain minds, the attraction of trying to minimize the difficulty of explaining the origin of life by suddenly imagining it occurring 200 times faster. It's kind of like a man saying to his skeptical girlfriend: “You don't think I'll become a millionaire in 30 years? I'll become a millionaire in 3 months!”

I don't particularly object to Loeb advancing a very farfetched theory. When it comes to theories, I say: let a hundred flowers bloom; the more, the merrier. I am bemused, however, by Loeb's grandiose pretensions in which he suggests that his theory is some big intellectual breakthrough. “It’s almost like a Copernican  revolution in our thinking about life,” Loeb says. Fancy that: Abraham Loeb, the new Copernicus!

But far from being some great intellectual breakthrough, Loeb's theory is of little significance. One reason is that it is neither falsifiable nor verifiable. We could never possibly falsify the idea that life arose somewhere in the billions of galaxies between 10 and 17 million years after the Big Bang. We could also never verify such a theory.

For such a theory to be verified, we would need to find fossil traces that life had arisen shortly after the Big Bang. We couldn't find that in our solar system, since our solar system is less than 5 billion years old. We also could not find such fossil traces if we visited any other solar system. As there is absolutely no fossil evidence of life during the first billion years of earthly history, we can conclude that any life that appeared a few million years after the Big Bang (and disappeared a few million years later, when the background temperature became colder) would not have left behind any traces that someone could detect billions of years later. Any such life would at best be pre-cellular life such as self-reproducing molecules, something too primitive to leave behind fossil remains.

Loeb's theory doesn't explain anything, doesn't predict anything, and it also has no important implications. Since his theory imagines a relatively short “epoch of habitability” lasting only six million years near the beginning of the universe (which is merely a “one-night stand” from the standpoint of a 13-billion year cosmic history), the theory does not have any implications for the overall likelihood of life's current existence in the universe.

Loeb's theory is therefore a kind of insignificant curiosity, an idea without any deeper meaning, a sterile idea that we will never be able to confirm or disprove. Far from being the start of a new Copernican revolution, his theory seems to be a dead end.

If You Had Been Born in an Alternate Universe

We live in a universe consisting of galaxies which consist of stars which have planets revolving around them. But one can imagine totally different universes with completely different physical layouts. We can also imagine other universes with laws completely different from the laws of our universe. Let us imagine what it might be like if you had been born in such a universe, one very, very different from ours. 

 

A Simple Oceanic Universe

One interesting possibility is a universe that is one huge ocean. In this universe there are no stars or planets, and no empty space. This universe consists entirely of warm water, and objects and life floating around in the warm water. There might be absolutely no gravity in this universe.

If you had been born in such a universe, you would have no concepts such as the idea of a day or the idea of a year. You probably also would have no home. You would not need one, since you would have no need to protect yourself from bad weather. You would pretty much be like a fish floating around in the water, although you might have arms allowing you to grab things. You would have no idea at all of up or down, and no concept of the surface of the ocean or the bottom of the ocean. It would simply be that no matter how far you traveled in one direction, there would always still be more ocean for you to swim in. If the water in such a universe moved around slowly, you might grow up with your family of oceanic creatures. But if the water moved quickly, you might be separated from your parents very soon after birth, and forced to fend for yourself from a very early age.

Living in such a universe, it is rather doubtful that you would be part of any very complicated society. But if you were part of some society, and the society had villages or cities, such centers would probably be sphere-shaped rather than the almost flat cities we see on our planet.

Such a universe might be totally dark, requiring evolution to produce alternate senses such as sonar for the various species that evolved. Or perhaps such a universe might be dimly lit by phosphorescent plants and phosphorescent rocks.

An Oceanic Universe of Bubble Habitats

Now let us imagine an oceanic universe similar to the one just imagined, except for one big difference: rather than consisting only of living things and objects floating around in water, this universe would be only about 90% water, with one tenth of it being air. The air portions would consist of big bubbles of air existing within the ocean stretching endlessly onward in all directions. In such a case there might evolve creatures designed to live within such bubbles. Imagine yourself as one of those creatures.

You might live in a small ten-meter wide bubble, where there lived only you or your family. Or you might live in a much larger bubble, along with your family and many other families. Your entire city might be in a bubble.

Living in such a bubble, you might be able to jump or fly to any part of the bubble (assuming this universe had little or no gravity). To gather food, you would probably have to dive into the water that surrounded the bubble. Venturing out into the water that surrounded the bubble, you would have to be careful to remember how to get back to your bubble, or you might never see your family again.

This type of universe would be very different from anything in human experience, but humans might actually one day be able to experience such an environment. Space visionaries have imagined a space hotel with a zero gravity center consisting of a spherical pool with a big air bubble inside it. Space tourists would swim halfway through the sphere to get to the waterless center.

A Universe With Countless Inhabited Micro-Planets

In our universe planets (having diameters of thousands of kilometers) revolve around stars, and stars are separated by huge distances (trillions of kilometers). But it is easy to imagine a very different type of universe in which beings live on tiny little micro-planets, spheres that are only a few dozen meters or a few hundred meters or a few thousand meters in size. Such a universe might have millions of such micro-planets in every unit of space the size of our solar system.

Someone might argue that such a universe couldn't exist, because spheres of that size would not have enough gravity to hold an atmosphere. But that objection is not sound, for two reasons. First, we can imagine a universe in which the space between planets and stars is filled with air like the air on our planet. We can also imagine a universe with an entirely different gravitational constant, and in such a universe small spheres might generate enough gravity to hold an atmosphere, and prevent inhabitants from floating off into space. Such planets might get their heat either from regular sunlike stars, or from very small mini-stars, or perhaps just from the background temperature of space (which could be between 60 and 80 degrees in an alternate universe). 

 

A Strange Alternate Universe of Micro-Planets

Now imagine living in such an alternate universe. Your micro-planet might be only 50 meters in diameter. Living on it might be only your family and a few other families. Looking up at the sky, you would not see a vast expanse of empty blue. You would see many other micro-planets. You could probably also see many other people living on those micro-planets. But you might have no way of getting to any of those micro-planets, even though they were only a few hundred meters away. However, if the space between micro-planets was not a vacuum but was instead filled with air, you could probably travel to other micro-planets by using some kind of device resembling wings or a plane.

On the other hand, if the space between micro-planets was a vacuum, you might have no way of ever visiting any of the nearby micro-planets. You would see lots of other people in the sky, but would never be able to touch them. It would be most tragic if you fell in love with someone on a nearby micro-planet, because you would never be able to kiss that person or touch that person. But even if you could not visit anyone on a nearby micro-planet, you would probably have some way of communicating with them, possibly by flashing hand-signals, or using lights or fire as signals.

A Universe With Densely Packed Stars

In our universe stars are very far away, but it is easy to imagine a universe in which the distance between stars is a thousand times smaller. What would it be like living in such a universe?

For one thing, the night sky would be far more interesting, with starlight providing as much illumination as the sun. There would be no darkness at night, and the sky at night would look rather like a huge collection of jewels resting on a background of black velvet. If you lived in such a universe, alien visitations would probably be ridiculously common. You might hardly pay any attention when you read in your morning newspaper that another alien spaceship had arrived in orbit around your planet. Your planet would probably already be packed with visitors from other planets, and when you went to a bar it might well resemble the bar in the first Star Wars movie, with a huge variety of alien creatures.

A Universe With a Compact Spherical Geometry

In our universe, space is flat or almost flat. But another possible spatial geometry is for a universe to be spatially spherical. If you lived in a spatially spherical universe which was relatively compact, you might experience something incredibly strange as an astronaut. You might set off in a spaceship to explore the deepest reaches of space. After traveling for a long time, you might see ahead of you a planet that looked rather like your own planet. You would be very excited, and say to yourself: what a discovery – another planet like my own planet! As you approached nearer and nearer the planet, you would notice more and more resemblances between this planet and your own planet. Finally, as your ship drew closer, you would at last realize the truth: the planet ahead was actually your own planet, not some distant planet. Because of the spherical geometry of your universe, you would have traveled exactly to where you had started out from.

A Universe With Lots of Antimatter

In our universe there seems to be virtually no antimatter, but it is easy to imagine a universe in which there is a great deal of antimatter scattered around. When the tiniest bit of antimatter touches the tiniest bit of matter, both are converted to an enormous amount of energy.

Therefore, in an alternate universe containing lots of antimatter, you would not worry much about your career, your bank account, your love life, war, or the next election. What you would worry about above all is something in the sky blowing up and killing you. You would know that every year there would be a significant chance of an explosion in the sky that showered your planet with deadly radiation. So you would probably spend most of your life deep underground, waiting for the end of the radiation shower from the latest matter and antimatter explosion out in space.

A Universe With Very High Radioactivity

The previous hypothetical universes are very different from our own. But let us imagine a universe exactly like ours, with one difference: the strong nuclear force is significantly weaker, and the weak nuclear force is stronger. As a result, there is much more radioactivity. All this radioactivity causes everyone to be exposed to high radiation throughout their lives. As a result, almost everyone dies of cancer by the time they get to be sixteen.

If you lived in such a universe, you would probably not remember your mother and father, as they both would have died of cancer a few years after you were born. You probably would have been raised by one of your older brothers or sisters. In your society people would encourage marriage between people who just recently reached puberty. It would be the only way to keep your species alive, with almost everyone dying of cancer while they are still teenagers. 

 

You would probably only go to school for a few years, and start working at around age 8. If you announced to your boss as a 12-year old that you were pregnant, your boss (who would probably be only one or two years older than you) would congratulate you for following the norms of your society. But you would know that a few years after giving birth, you would also be dead of cancer, along with all of your friends. You, like all mothers on your planet, would weep about the fact that you would never be able to see your child grow up even halfway. Be thankful you do not live in such a universe.