Fear of a Black Universe

by Stephon Alexander

  The BV mechanism elegantly paves a way to solving another big problem in string theory that I discussed in a previous chapter on quantum gravity. Recall that the information about the extra dimensions in string theory show up in our four-dimensional world as a large number of fields that could have disastrous effects in our world, called moduli. If string theory is correct, it must provide a way to freeze, or stabilize, these moduli so that they do not disrupt the observations of the CMB and large-scale structure formation.

  My colleague Subodh Patil and his collaborators elegantly discovered an intrinsically stringy mechanism such that the string modes generate a force to stabilize all the moduli in string theory, which made use of new symmetries that are unique to string theory. Patil is a bassist, and I am curious if he imagined the moduli stabilization mechanism as analogous to how a bass line can serve as an anchor for a melodic line. The mechanism also addresses a worry that I always had about the BV mechanism, one that I remained silent about for years. Superstring theory relies on supersymmetry; a symmetry puts fermions and bosons on the same footing, for its consistency. However, our world is not supersymmetric since matter is distinct from its force carriers. In particular, a time-dependent space-time such as our expanding universe is not consistent with supersymmetry. So, trusting the validity of these intrinsically supersymmetric string modes within a cosmological background seems a bit ad hoc. However, Patil and collaborators showed that it was exactly the breaking of supersymmetry that provided the forces for the stabilization of moduli.

  The BV mechanism provides a compelling framework that successfully goes beyond the standard big bang theory. Some unresolved issues persist because the BV model assumes the string universe will exist in the Hagedorn phase for an indeterminate amount of time, then at some point in time the winding modes annihilate, and the universe begins to expand from a nonsingular state. How long does the universe remain in the high-energy stringy state? What placed the pre-expansion universe in such a state? The question of initial conditions persists in this version of the BV mechanism. One possible way out is to invoke a cyclic cosmology.5 In this framework the universe undergoes a series of expansions and contractions long enough for the winding modes in three spatial dimensions to annihilate, and our three-dimensional universe expands and gets macroscopically larger than the other six.

  Current technical and conceptual details are being researched that also touch on other profound questions about the early universe. One big issue that goes beyond BV and other approaches to the early universe concerns the emergence of space itself. In fact this subject is currently the state of the art in quantum gravity research. There are a handful of promising approaches to emergent space-time but I will restrict our discussion to an avenue that extends the BV approach naturally, while also illustrating how to improve a theoretical model. There currently exists no complete theory from which we can obtain an expanding cosmology from a pregeometric state, so I will argue that a promising direction comes from the general framework of noncommutative geometry. But what would we learn about cosmology from a space-time that emerges from such a pregeometric phase?

  In 1989 my friend the late renowned theoretical physicist Joe Polchinski realized that strings were not the only fundamental objects in string theory. He did this by solving a long-standing problem about how to apply T-duality to a version of strings that have no windings. These are called open strings. Polchinski discovered new extended objects that are membrane-like, which he crowned Dirichlet-branes (or D-branes), that open strings can collectively end on.6 These D-branes come in many dimensions; for example, a 2-brane is a two-dimensional hypersurface otherwise called a membrane. For part of my PhD dissertation work, I, along with Damien Easson and Robert Brandenberger, showed that the BV mechanism works even when we include a spectrum of D-brane states in string theory.7 When I gave my thesis defense, one of my examiners was David Lowe. Lowe is a string theorist, and he asked why we did not include D0-branes. This is a zero-dimensional object that strings attach to. I did not have a good answer, except that D0-branes do not have winding modes, like their higher-dimensional cousins. But I’ve reconsidered my response. It turns out that going down that path, incorporating D0-branes to reimagine the early universe, reveals an interesting new possibility—that the universe could have existed without reference to space itself.

  The theory that describes D0-branes falls into a class of quantum geometric theories called noncommutative geometry. What is intriguing is that a handful of approaches to quantum gravity all have some semblance to a pre-space, where geometry itself is fuzzy, or noncommutative.

  FIGURE 28: A membrane is classically unstable because it is more energetically favorable for infinite spikes to form on the surface than to keep the membrane surface smooth. This instability posed problems in quantizing the membrane as a fundamental object in quantum gravity.

  In ordinary quantum mechanics the spin of the electron in the x and y direction cannot be known simultaneously. For example, the more certain you are about spin x the less certain you are about spin y. Suppose the determination of different directions in space were noncommuting. Then the usual notion of a smooth, continuous space-time is no longer valid. Imagine a noncommutative space where a location is restricted to be at a unique point in the x direction, then a definite location in the y direction will be uncertain. In general, a location in space becomes fuzzy in a noncommutative space. There are a handful of proposals in formulating noncommutative space-times. The theory of D0-branes is known as matrix quantum mechanics.

  In matrix quantum mechanics, there are nine matrices, each representing the dynamics of the D0-branes. The D0-branes have a potential energy made up of these interacting matrices that do not commute with each other, which encodes the uncertainty in the spatial dimensions. What I find most interesting about matrix theory is that many formulations of quantum gravity point to the same theory. This coincidence of a quantum theory with no a priori spatial dimensions is a fertile ground to investigate a pre–big bang phase where our smooth, classical, and expanding universe may have emerged from a reality in which space itself did not exist. At this impasse, I leave this speculation of a working emergent cosmological framework as a future project perhaps successfully pursued by a brilliant young cosmologist.

  15

  THE COSMIC MIND AND QUANTUM COSMOLOGY

  Several years ago, a handful of scientists and I received an invitation to have a discourse with Dr. Deepak Chopra at the Carnegie Institution. The other physicist attending was Nobel laureate Frank Wilczek, so I couldn’t resist the chance to be in great company. However, I approached the interview with the fear of being further sequestered from the community of scientists—many who held Chopra to mix mysticism with physics. Chopra and his colleagues have been proponents of the idea that consciousness creates the physical universe.1 It is well known that certain scientists have debated with Chopra and even criticized his ideas as “out there.”

  Chopra is a brilliant medical doctor and effective communicator of science to the masses, and I was silently impressed and inspired by his willingness to debate unconventional ideas with renowned scientists. But he was clearly an outsider to the enterprise of research scientists. I was sympathetic to the resistance he received because he was not a member of the club, made claims that could not—yet—be experimentally supported, and was considered to be a charlatan by a handful of vocal, skeptical voices. And I always enjoyed watching Chopra work the crowd and effectively debate with other scientists. Walking into my interview, I knew that he would certainly ask me about consciousness, quantum physics, and a topic that he has even published on recently with others, called cosmic consciousness.

  In the middle of my interview, Chopra dropped the “C-bomb” on me. With his resonant baritone voice he asked, “So, Stephon, do you think the big bang came from consciousness?”

  Like a skilled coward, I dodged his question. I said, “I’ll take off my scientist hat and put on my Stephon-as-a-person hat
and say that…” What I wanted to say was: “Deepak, I got into physics because I wanted to understand how this basic, direct experience of consciousness was connected to the fabric of the universe.” Instead, I gave a weak response and said, “I think that a future generation of brilliant physicists should be brave enough to tackle the question.” I chickened out and Chopra knew it.

  I wasn’t alone. At that time I was unaware that a handful of the architects of quantum mechanics, including Bohr, Heisenberg, Schrödinger, Wigner, and von Neumann, had been influenced by the question of consciousness in the physical world. Schrödinger was especially influenced by the work of German philosopher Arthur Schopenhauer and the Vedas, which posited the existence of a universal mind that contains all individual minds and the physical universe. Combining those with his own work, Schrödinger imagined the quantum wave function to be part of an undivided cosmic whole.

  We have explored the consequences for our universe of the quantum, invariance, and emergence principles. The laws that follow from these principles, general relativity and quantum field theory, precisely predict a universe that expands from the big bang into a seemingly structureless early universe that vibrates with sound waves of energy and ultimately grows into the web of stars, planets, and galaxies. We don’t have a complete understanding of the bang, the cause of the waves, and the emergence of space-time itself. And as we’ve seen, if we want to transcend the big bang singularity, we may very well need ideas that go beyond our current principles.

  And those might not even be the biggest issues we face. The expansion of the early universe linked with the flow of entropy necessary for biological life is a hint at a deeper interdependence between life and the quantum universe. Did life emerge in the cosmos through a series of accidental historical events? Is there a deeper principle beyond natural selection at work that is encoded in the structure of physical law? And on top of that, the question that bothered Schrödinger and that got me into science in the first place: What is the relationship between consciousness and the fabric of the universe?

  I am fully aware that I risk being written off as an oddball crank by the positivists in the room, because answering these questions might call into question the idea that the world out there is independent of us being there. But I must eat my own words to Deepak Chopra and embrace the stigma of weaving together theoretical ideas to entertain that question. In this final chapter, I am going to engage in an exercise of theoretical dreaming—into the principle of blackness. I am now going to pursue a speculation that intimately relates the big bang to the most complex entities that emerged from the universe: human beings endowed with conscious awareness.

  This begins with the elephant in the room, the measurement problem in quantum mechanics. Quantum systems exist in a superposition of states until a measurement collapses the wave function into one unique state. In his book Mathematical Foundations of Quantum Mechanics, John von Neumann, the father of the modern computer, proved that when a quantum system exists in a superposition of states, a chain of measurements ultimately leading to the consciousness of an observer is what collapses the wave function into one definite state. He argued that this collapse by consciousness cannot be consistent with the mathematical framework of quantum mechanics, especially the linearity of quantum mechanics. This interaction between consciousness and quantum mechanics has to happen outside the constructs of quantum theory itself—unless consciousness is part of quantum physics from the start. We’ll get back to this.

  As we have discussed, in his book What Is Life? Schrödinger makes three key observations about what differentiates living from nonliving matter subject to the laws of physics including quantum mechanics. First, he predicted the basic helical structure for DNA using ideas from quantum mechanics that describe the periodic lattices found in metals. Second, he argued that living things fight against entropy, otherwise known as negentropy. Both predictions inspired the next generation of biochemists and biophysicists and continue to be foundational. And third, Schrödinger speculates about what it means that some (if not all) biological life has consciousness. He asks what is at first glance a strange question: Why are there many minds, each having their unique conscious experiences?

  When Schrödinger was writing this work eighty years ago, he recognized that his era lacked a scientific account of consciousness, and so he resorted to philosophical and metaphysical ideas from Arthur Schopenhauer and Vedic philosophy. Both sources believe that the universe and all that occupies it carries varying forms of awareness. This view is often known as panpsychism. Panpsychism posits that consciousness is an intrinsic property of matter, the same way that mass, charge, and spin are intrinsic to an electron. So according to panpsychism, the electron and all substance come equipped with their own internal protoexperience of being an electron. This might sound crazy. Definitely there’s a question about how an entity, say an electron, can have its own internal experience without resorting to an electron brain. The answer requires new physics or a fresh perspective on known physics. And we find a clue from African philosophy.

  While there was an absence of African philosophy in my formal education, my musical colleague, legendary bassist Melvin Gibbs, introduced me to a view of the creation of the universe presented by the Bantu-Kongo people of West Africa that predates our modern big bang theory—but it has more, including an extra conceptual key to help us understand how to relate the quantum, cosmos, and consciousness with one another. In the Bantu cosmology the universe started in a state of nothingness called mbungi. Here nothingness includes the absence of space and time. Physical objects, such as particles and fields, usually exist in space-time. So mbungi is a prephysical state that is divided into what manifests as the physical, spatiotemporal world and a universal consciousness.2 In the state of mbungi both the physical and conscious awareness are complementary, and have close semblance to the yin and yang in Taoism. Therefore, mbungi finds a natural home in quantum complementary in the context of the entire universe. Translating this into the language of cosmological physics, we can define a pregeometric universe as a quantum state that contains the potentiality of space-time and a fundamental form of consciousness as complementary pairs. To make a cosmological complementarity concrete we will need to actually have a formalism for quantum cosmology—a wave function of the universe.

  In 1985 Stephen Hawking and James Hartle published a paper entitled “Wave Function of the Universe,” which implemented the Schrödinger equation associated with quantum gravity known as the Wheeler-DeWitt equation. Unlike the original Schrödinger equation, which gives the time evolution of the wave function, the Wheeler-DeWitt equation is timeless.3 Hartle and Hawking found a wave function of the universe, which is now famously called the Hartle-Hawking state.

  The wave function of the universe is not some theoretical playground; it actually corresponds to the quantum state that underlies cosmic inflation that we discussed in an earlier chapter. In fact it was shown by cosmologist Alexander Vilenkin that the wave function of the universe can undergo a process of quantum tunneling from a state of nothingness—where space vanishes—to an inflating space-time.4 Recall that a quantum system can go through barriers that are forbidden by classical physics. In this case the quantum universe can tunnel from a state of no-space, which is inaccessible to classical physics, into an inflating space-time. Because the Hartle-Hawking-Vilenkin state is connected to inflation, it is taken quite seriously by the cosmology community as a benchmark for doing calculations that correspond to satellite observations. Despite its pragmatic importance, the Hartle-Hawking-Vilenkin wave function presents a deep conceptual problem about the nature of time and the emergence of space at the big bang. Near the end of his life Hawking stated, “Asking what came before the Big Bang is meaningless… because there is no notion of time available to refer to.… It would be like asking what lies south of the South Pole.”

  Renowned Stanford University quantum cosmologist and co-inventor of inflation Andrei Linde gives us a hi
nt of how to resolve the problem of understanding how the universe emerged from a state of no-space. Linde focuses on the fact that the Wheeler-DeWitt equation of quantum cosmology is timeless, which implies that the universe is “dead.” Linde proposes the way out of this conundrum is to link consciousness with space-time. In a remarkable article Linde asks, “We cannot rule out the possibility a priori that carefully avoiding the concept of consciousness in quantum cosmology constitutes an artificial narrowing of one’s outlook.… Is it not possible that consciousness, like space-time, has its own intrinsic degrees of freedom, and that neglecting these will lead to a description of the universe that is fundamentally incomplete?”5

  But given this hint, how does the universe as we know it get realized at the big bang? This question is still up for debate, and I will argue that the wave function of the universe undergoes self-observation, a form of cosmic protoconsciousness, in the spirit of how the physical world emerges from mbungi.

  The question, then, is how is it that this cosmic protoconsciousness can be timeless and spaceless? Explaining it seems difficult: neuroscience doesn’t even have a complete explanation for where human consciousness comes from. My colleague David Chalmers is a leading researcher in the study of consciousness and pioneered a concept that he called the “hard problem of consciousness.” In a nutshell, while neuronal activities of the brain can correlate with various perceptions and conscious experiences, it cannot explain our private, subjective, internal experiences of perception, self-awareness, emotions, and other experiential states of consciousness. The point the panpsychists make is that maybe neuroscience has set its sights too low. The Vedic system posits that the universe comes with its own singular consciousness, known as Brahman. With this concept, Schrödinger was able to answer his question about the multiplicity of individual minds if there was one universal mind by imagining that the multiplicity of individual minds are actually a hall of mirrors reflecting the one universal mind. For years, I was fascinated by this claim but didn’t understand how many minds could be equivalent to one. And Schrödinger resisted making any further physical connections to his conviction about minds in the universe. What he failed to realize is that the fundamental principle of quantum mechanics, superposition, can hold the key to putting physical meat on the bone of his conviction. At the end of the day, fourteen billion years of cosmic evolution results in beings like you and me, endowed with the faculties of perception and consciousness. Is the question of consciousness solely a matter of emergence of the happenings of the brain? Or did the early universe encode the inevitability of conscious experience for specific cosmic functions?