Fear of a Black Universe

by Stephon Alexander

  One of Salvador’s concerns was understanding what it took for bacteria to become pathogenic—capable of causing disease in a host like us. According to him, various combinations of genes, like a slot machine, can hit the jackpot in giving the bacteria the ability to become harmful. Salvador made a brilliant analogy between the coupling constants in my cosmological model and the various forms of a gene, known as alleles of the gene. He likened the bacterium’s population cycles and environmental factors to a cyclic universe as a mechanism to change the different combination of genes. The different replicating populations represented the many cycles in the model, each with its own alleles or variations. This led him to propose the theory of virulence adaptive polymorphisms (VAPs).2 The work was published in the top journal in microbiology. The idea worked and has made a big mark on his field.

  Now it was time for my friend to return the favor and inspire some ideas for cosmology. Over the years we had mischievously developed a conviction and intuition that there is a hidden interdependence between living systems and cosmology. I came at the question from cosmology. Salvador came at it from a biological direction. And to our delight this question led us to a few issues that the big bang and living systems (such as ecosystems) have in common.

  A major concern for both of us has to do with the flow of entropy in the universe, whether at biological or cosmological scales. In the epoch in the early universe before there were stars and planets, the universe was mostly filled with an equal amount of radiation and matter, where the photons and electrons were in thermal equilibrium. If a collection of gas molecules occupy a closed system, say a room, they are going to tend to thermal equilibrium—the temperature, essentially, will become the same throughout the room. As they approach equilibrium, their entropy will increase. Entropy is a measure of disorder, and so of ignorance about what the gas molecules are doing. The entropy will increase when there are more particles and more space for the particles to potentially occupy—it becomes increasingly difficult to specify what they are all doing. Entropy also negatively affects the ability of any system to do work. Physics, biology, and chemistry rely on an important concept called free energy, which is a measure of how much energy in a system (such as a living cell) is able to be used for work. Mathematically we can express free energy as ΔF=ΔE−TΔS. The equation states that a system can do work with a positive change in free energy (ΔF), where a positive contribution comes from a change in energy (ΔE) and a negative contribution from the change in entropy (ΔS). The entropy contribution to free energy reduces the amount of energy that can be used to do work. For example, sunlight shining on Earth generates free energy, which we calculate by adding the contribution of the potential energy stored in the wavelength of the photons and subtracting the entropy from the array of photons.

  But there are some important caveats having to do with gravity. The gravitational expansion of the universe keeps the matter and photons in the cosmic microwave background homogeneously distributed. Situations of extremely high gravitational entropy are contained when matter collapses into localized objects like black holes, which did not exist in the era when the CMB formed. So, when the universe expands, gravity acts to distribute matter in a homogenous, ordered fashion, and this lowers the entropy of the universe. When gravity acts to coalesce matter into supermassive black holes, entropy goes up: the heavier the black holes the larger the entropy.3

  And there is an important problem. The photons and matter in our universe were in equilibrium during the CMB epoch, so the entropy then was high. But as the universe continued to evolve, the entropy would continue to increase. This implies that the entropy of the very early universe, before the CMB epoch, must have been very low.

  At the largest observable distances, we see a connected pattern of large-scale structure of galaxies distributed across the universe. As the universe continued to expand and cool, out-of-equilibrium structures with varying complexity like stars, clusters of galaxies, and life formed. The structures will contain lower entropy than the rest of the universe. By starting off with low entropy, the universe is able to arrest the growth of entropy against the trend of the second law, by concentrating regions of lower entropy within cosmic structures. These cosmic structures, such as stars, store potential energy; in the case of stars, it’s from the rest mass of hydrogen, which will release highly energetic photons from nuclear fusion. This entropy-lowering network of structures becomes the main currency for the biosphere and life on planets. Even the father of thermodynamics, Ludwig Boltzmann, said, “The general struggle for existence of animate beings is therefore not a struggle for raw materials… nor for energy which exists in plenty in any body in the form of heat, but a struggle for entropy, which becomes available through the transition of energy from the hot sun to the cold earth.”4 Nevertheless, even as the universe deviated from homogeneity, by seeding and forming lower entropy structure, entropy elsewhere in the universe continued to grow. And entropy also has a tendency to grow within those structures. This makes entropy, or its absence, a key player in sustaining cosmic structure, such as stars and life; therefore, an early lifeless universe with low entropy is necessary for life here on Earth. Stars like our sun radiate free energy to the earth. This free energy is absorbed by electrons in plants and used for the necessary chemical work for its living function. The plant will release this energy in the form of heat and give off to the universe more entropy than it took in.

  Unfortunately, it is difficult to explain with our current understanding of physics why the entropy was so low in the early universe. In fact, this problem of the low entropy we demand of the big bang is one of the major problems with the theory. It was first identified by Roger Penrose. Its solution remains a mystery.5 I remember discussing this problem with Penrose on a nice summer walk, and we both agreed that if we wanted to understand how gravity could have helped set up this unlikely scenario, we were going to need the real connection between entropy and gravity, which is currently lacking, to reveal its nature. One hint is that at the earliest moments of the universe, close to the big bang, the curvature of space-time approached infinity. Whatever new physics tamed this infinity should tell us why the entropy of the universe was so low. We will get to this.

  The biology side of the story stems from Salvador Almagro-Moreno’s research into the genetic and ecological drivers that lead populations of harmless bacteria to evolve and emerge as pathogens. Crucial to the story is that it isn’t just a question of the genetic code of the bacteria. One of Salvador’s mantras is that life is an adaptive phenomena responding to constant and unexpected changes in pressures from the environment. If life can have more channels and resources for being adaptative, it will find a way to use them. Central to his research is understanding evolution from the genetic code in a population of organisms, and the epigenetic influences from the ecosystem. Epigenetic factors are called that because they sit on top of genetic factors, and they are one of those other channels for adapting beyond changes to the genetic code. For example, an environmental factor, such as a pattern of electrical current hitting the cell membrane during replication, can enhance or suppress certain genetic factors, leading to completely different features in the phenotype of the offspring.

  FIGURE 25: A simulation of the large-scale structure of the universe. Each dot represents a galactic system.

  This makes an organism an emergent phenomenon, where the final shape of it is not contained in the individual pieces and influences that make it up. Recall that in emergent phenomenon in general, it is the interactions of the building blocks that collectively exhibit the emergence. This also implies that a population is emergent, too. Living things comprise a network of interactions that is mediated through the environment. A living system is able to regulate billions of cells to maintain its overall functioning. Beyond that, collections of organisms belong to a network called an ecosystem, which also maintains a dynamical equilibrium.

  This extends all the way to networks at life’s larges
t scales. The idea of the earth being a self-regulating ecosystem was codiscovered by James Lovelock and Lynn Margulis in the 1970s, and it became known as the Gaia theory. The name Gaia came from the goddess who personified Earth in Greek mythology. In response to the name, Lovelock, a chemist, observed that “biologists scorned it… it gradually became known as Earth Systems Science, but it is the same thing.” Whatever you call it, the takeaway for me is that the flow of negative entropy exists not only for individual living things but for the entire earth. The sun sends free energy to the earth, and through a chain of complex interactions, the energy gets distributed through a network of interactions to living things, each relying on it to maintain its complexity in the face of increasing disorder. But there’s no free lunch: when living things release this energy back into the environment, they mostly do so in a form that has higher entropy than what they received. Salvador and I noticed the uncanny parallels between living systems and the evolution of the universe through the lens of entropy.

  This could seem like a coincidence in the behavior of the universe and of life, but we decided to treat the parallel as though it were not. Instead, we proposed that Schrödinger’s idea of negentropy is one of the central organizing principles of the evolution of the cosmos and the existence of life. Salvador elected to call this the entropocentric principle, a wink at the anthropic principle that first emerged from string theory and caused such a controversy when I was first working on the vacuum-energy problem. The anthropic principle, in its strong form, states that the universe is fine-tuned for life. The laws of nature and values of coupling constants of their interactions have the values that are consistent with life on Earth. For example, if the strength of the nuclear interactions differed by a few percent then stars would not be able to produce carbon and there would be no carbon-based life. The fine-tuning problem may not be as severe as it seems. In research I conducted with my colleagues Fred Adams, Evan Grohs, and Laura Mersini-Houghton, we showed that the universe can be fit for life even when we let the constants of nature like gravity, vacuum, and electromagnetism vary, so long as they vary simultaneously.6 Maybe we don’t need the anthropic principle after all. The entropocentric principle, on the other hand, is harder to shake. If the universe was unable to provide pathways that enabled it to transfer regions of lower entropy, then life as we know it would not exist. We call this biological dependence on the entropic relationship of the cosmic structure the entropocentric universe. Living systems situate themselves to reduce their entropy by expelling it out into the environment, while consuming energy from their environment. Did the universe play the same game near the big bang?

  13

  DARK IDEAS ON ALIEN LIFE

  Salvador Almagro-Moreno isn’t the only person with whom I went exploring in new territory of the mind. When I lived in the Bay Area, I used to get together with my friend Jaron Lanier to explore the implications of spectacularly weird thought experiments. Occasionally, one of these conversations would lead to an interesting outcome. This chapter explores one of them. Outlandish thought experiments have been essential in the intellectual history of science, but the point isn’t the weirdness itself. The payoff of thinking about strange things like Schrödinger’s cat, the infamous cat that is alive and dead at the same time, is not necessarily that we should then “believe” in the existence of such a cat. Instead, we can hope that uncommon ideas will shed light on the murky margins of our thoughts; in the case of Schrödinger’s cat, in dealing with the question of superposition. The point is not to confuse or bamboozle people, but to eventually find a way to think that makes more sense and is a little less murky.

  The bizarre notion I want to consider here came from a discussion of the search for alien life forms. There are a variety of ways to look for signs of alien life in the universe, usually involving a large array of telescopes. One approach is founded on the hope that perhaps astronomers will get lucky and chance upon an alien radio broadcast. But in the thought experiment Lanier and I explored, we considered a different and far more dramatic possibility. Suppose that there are lots of alien civilizations running hugely capacious quantum computers of the sort that Google and others are just beginning to build here on Earth. This leads to a question of high weirdness: Would an extreme amount of very distant quantum computation result in any astronomically observable effect? Could we humans see evidence of a universe teeming with quantum computers by carefully examining the night sky?

  We thought about various ways this might be possible, but in the end we focused on one wonderful possibility. So here it is: First, alien quantum computers could explain the mystery of dark energy, because computation by multitudes of alien creatures across the universe bends (or rather unbends) the universe as a whole. Because we can observe the effect of dark energy, accelerating the expansion of the universe, this implies that we have already seen evidence that our universe is alive beyond us—we just haven’t recognized it as such! And we found, fortunately, that contemplating this almost imponderable notion has a human-scale practical payoff: it helps us clarify how we think about plausible relationships between gravity and quantum information. (If you think this is strange, you should read some of the competing ideas. One recent paper suggests that dark energy is actually a sign that time is about to cease to be time and turn into space instead. We’d then be frozen out of time, but be four dimensional. Compared to that, our proposal, aliens and all, is practically tame.)

  Let’s go through the argument step by step: What is a quantum computer and why would aliens be using them? Let’s assume that, just like us, plenty of alien civilizations will want the best possible computers for some purpose or other. For the sake of argument, we’ll assume the aliens want to enjoy high-quality virtual reality, and so they build computers to make that happen.

  If the computers that run alien VR are of the classical kind we use these days (based on the mathematical framework laid down in the mid-twentieth century by computer science pioneers John von Neumann and Alan Turing), then aliens would generally endure an inferior sort of virtual-world experience. You might think that classical computers should be up to the task—after all, the special effects in movies are getting fairly realistic, and classical computers are able to calculate those effects—but they are not. Remember that movies are prepared in advance. Virtual reality, however, must create sensations for the human body on the fly and as quickly as reality does. Classical computers can’t work that fast. Furthermore, there are cases where the human body is able to respond to reality at the highest possible level of sensitivity. For example, the retina can, in certain cases, generate a neural response to a single photon. In a case like that, the human body has become as discriminating as physics can possibly allow. Just as classical computers can’t be as fast as the universe, they can’t be that discerning, either. If we assume that aliens elsewhere also evolved to be as sensitive to this ultimate, quantum level of reality in some special cases as we are to light, then when they try to design a nonquantum supercomputer and VR apparatus that could simulate reality at the ultimate level of detail, they would have run into problems. That’s one reason we guess that discerning aliens would seek the power of quantum computers to run their virtual worlds.

  Quantum computers are not yet adequately developed for practical uses on Earth, but they have the theoretical potential to pulverize regular computers in a wide range of calculation contests. A quantum computer can work as if there were copies of it in many parallel universes at once, simultaneously exploring variations of the computational task at hand.

  Suppose the computer is calculating what a virtual rose petal should feel like to your fingertip. The rose petal is pliant, so every part you touch changes all the other parts you touch. You have to calculate all the parts at once, and there’s only a single solution that consistently reconciles all the tiny events in different locations of the petal so that it feels realistic. A quantum computer can be calculating a huge variety of different versions of the petal simul
taneously, even though only one variation is the correct version. That correct version can then be instantly presented to your fingertip, perhaps by the “octopus butler robot” that Lanier has imagined in his book Dawn of the New Everything, as if the computer had somehow known which variation would be correct from the start.

  One big engineering problem for quantum computer designers is heat. Heat is an almost universal problem for any computer designer. Every time you change a bit inside a computer, you’re doing at least a little bit of work, whether that bit is implemented as a bead in an abacus or as a charge in a semiconductor in a silicon chip. Work always gives off heat.

  Let’s consider the example of the abacus. When you move a bead up and down you generate some heat from friction on the wire the bead is sliding on. If you do this only a few times a second, you won’t even notice that heat, but if you move the bead millions of times a second you will melt the wire. Now consider a quantum abacus. This would be a little like having a bunch of copies of the abacus in different parallel realities, each with the beads in different positions, each exploring a different variation of a problem. You can think of each individual bead as being like Schrödinger’s cat: you can either think of a bead as being both up and down at the same time, or that in each particular universe it is either up or down. We call this kind of bead a qbit (quantum bit) instead of a bit. If the quantum abacus gets hot, the beads start jiggling, in just the way that oil in a hot frying pan will start sizzling. If the beads jiggle too much, it becomes impossible to say which universe has a bead that is up or down, which means that the differences between the states of the beads in the parallel universes disappear. When that happens, the quantum advantage also disappears.