Science and Ultimate Reality: Quantum Theory, Cosmology, and Complexity

by John D. Barrow (Editor), Paul C. W. Davies (Editor), Charles L. Harper Jr (Editor)

This preview of the future of physics comprises contributions from recognized authorities inspired by the pioneering work of John Wheeler. Quantum theory represents a unifying theme within the book, as it relates to the topics of the nature of physical reality, cosmic inflation, the arrow of time, models of the universe, superstrings, quantum gravity and cosmology. Attempts to formulate a final unification theory of physics are also considered, along with the existence of hidden dimensions of space, hidden cosmic matter, and the strange world of quantum technology. John Archibald Wheeler is one of the most influential scientists of the twentieth century. His extraordinary career has spanned momentous advances in physics, from the birth of the nuclear age to the conception of the quantum computer. Famous for coining the term "black hole," Professor Wheeler helped lay the foundations for the rebirth of gravitation as a mainstream branch of science, triggering the explosive growth in astrophysics and cosmology that followed. His early contributions to physics include the S matrix, the theory of nuclear rotation (with Edward Teller), the theory of nuclear fission (with Niels Bohr), action-at-a-distance electrodynamics (with Richard Feynman), positrons as backward-in-time electrons, the universal Fermi interaction (with Jayme Tiomno), muonic atoms, and the collective model of the nucleus. His inimitable style of thinking, quirky wit, and love of the bizarre have inspired generations of physicists.

Genres: Science, Physics

742 pages, Hardcover

First published June 7, 2004

About the author

John D. Barrow was a professor of mathematical sciences and director of the Millennium Mathematics Project at Cambridge University and a Fellow of the Royal Society.

He was awarded the 2006 Templeton Prize for "Progress Toward Research or Discoveries about Spiritual Realities" for his "writings about the relationship between life and the universe, and the nature of human understanding [which] have created new perspectives on questions of ultimate concern to science and religion".

He was a member of a United Reformed Church, which he described as teaching "a traditional deistic picture of the universe".

Reviews

[Steven H · Rating 5 out of 5]

A CHALLENGING COLLECTION OF ESSAYS ON ‘FRONTIERS’ OF SCIENCE

The Editor’s Preface to this 2004 book explains, “This book project … brought together a carefully selected group of outstanding contemporary research leaders in the physics community to explore the frontiers of knowledge … and to map out … possibilities for far-reaching future exploration… Authors were invited to be bold and creative by developing themes that are perhaps more speculative than is usual in a volume of this sort.” (Pg. xiii-xiv)

David Deutsch suggests, “There is every reason to believe that the brain is a universal classical computer… this strong form of universality of quantum computation assures us that such a technology, and artificial intelligence in general, must be possible, and tractable, regardless of how the brain works. Provided, that is, that universal quantum computers can be built in practice…” (Pg. 98)

Bryce S. DeWitt observes, “the idea that the world may ‘split’ … into many worlds, is hard to reconcile with the testimony of our senses, namely that we simply do not split… the laws of quantum mechanics do not allow us to feel ourselves split… According to [some physicists] it is preposterous to assert the ‘reality’ of worlds of which one cannot be aware. A consistent application of this logic would require one to deny the existence of planets in distant galaxies… Other physicists object to the superfluousness of the ‘other worlds’ and to the prodigality of a universe that includes them all, forgetting the prodigal scale of the universe we actually see.” (Pg. 176-177)

Andreas Albrecht argues, “An arrow of time is critical to quantum mechanics as we experience it. Once a quantum measurement is made there is no undoing it, and one says the wave function has ‘collapsed.’ There are different attitudes about this collapse… [In the] point of view (which I prefer) the quantum mechanical arrow of time is none other than the thermodynamic arrow of time. Others want to establish a quantum arrow of time that is separate from the thermodynamic arrow, but no well-established theory of this type exists so far.” (Pg. 371)

John Barrow notes, “If our expanding universe of stars and galaxies did not appear spontaneously out of nothing at all, then from what might it have arisen? One option… is to … propose that it had no beginning. It always existed. A persistently compelling picture of this sort is one in which the universe undergoes a cyclic history, periodically disappearing in a great conflagration before reappearing phoenix-like from the ashes… This stoic scenario has a counterpart in modern cosmological models of the expanding universe… there is the tantalizing possibility that this episode of cosmic history might continue to repeat itself into the future…. It could be that repulsive gravity stops the universe just short of the point of infinite density, causing it to bounce back into expansion… but this is pure speculation at present.” (Pg. 402-403)

Andrei Linde explains, “in order for life as we know it to exist, it is necessary that the universe be sufficiently large, flat, homogeneous, and isotropic. These facts… lie at the foundation of the so-called anthropic principle… According to this principle, we observe the universe to be as it is because only in such a universe could observers like ourselves exist. Until very recently, many scientists were ashamed of using the anthropic principle in their research… This critical attitude is quite healthy… There is always the risk that the anthropic principle does not cure the problem, but acts like a painkiller… There are two main versions of this principle… The weak anthropic principle simply says that if the universe consists of different parts with different properties, we will live only in those parts where our life is possible… The strong anthropic principle says that the universe must be created in such a way as to make our existence possible… Fortunately, most of the problems associated with the anthropic principle were resolved… soon after the invention of inflationary cosmology…” (Pg.426-427)

Later, Linde adds, “one can consider different universes with different laws of physics in each of them. This does not necessarily require introduction of quantum cosmology, many-world interpretation of quantum mechanics, and baby universe theory. It is sufficient to consider extended action represented by a sum of all possible actions of all possible theories in all possible universes. One may call this structure a ‘multiverse.’… the main reason why we are introducing this structure… [is because] we need to know what emerged first at the moment of the universe formation: the universe, or the law describing the universe. It is equally hard to understand how any law could exist prior to the universe formation, or how the universe could exist without a law… Given the choice among different universes in this multiverse structure, we can proceed by eliminating the universes where our life would be impossible. This simple step is sufficient for understanding of many features of our universe that otherwise seem miraculous.” (Pg. 440-441)

He goes on, “the anthropic principle can be extremely useful in resolving some of the most profound problems of modern physics. However… one should find a proper way to calculate the probability to live in a universe of a given type… An investigation of creation of the universe ‘from nothing’… can be very useful, but I believe that it should be considered only as a part of the more general approach based on the stochastic approach to inflation.” (Pg. 447-448) He continues, “Fortunately, among all possible domains of the universe… there are some domains where inflation is possible…. Our life is possible only in those exponentially large domains (or universes) where the laws of physics allow formation of stable long-living structures… Among all possible universes, we can live only in those where mathematics is efficient.” (Pg. 453)

Max Tegmark asks, “Is there another copy of you reading this article, deciding to put it aside without finishing this sentence while you are reading on? A person living on a planet called Earth, with misty mountains, fertile fields, and sprawling cities, in a solar system with eight other planets. The life of this person has been identical to yours in every respect---until now, that is, when your decision to read on signals that your two lives are diverging. You probably find this idea strange and implausible, and I must confess that this is my gut reaction too. Yet it looks like we will just have to live with it, since the simplest and most popular cosmological model today predicts that this person actually exists in a galaxy [very far] from here. This [assumes] … merely that space is infinite and rather uniformly filled with matter as indicated by recent astronomical observations. Your ‘alter ego’ is simply a prediction of the so-called concordance model of cosmology… If space is infinite and the distribution of matter is sufficiently uniform on large scales, then even the most unlikely events must take place somewhere. In particular, there are infinitely many other inhabited planets, including not just one but infinitely many people with the same appearance, name, and memories as you.” (Pg. 459-461)

He goes on, “the epistemological borderline between physics and metaphysics is defined by whether a theory is experimentally testable, not by whether it is weird or involves unobservable events… Containing unobservable entities does clearly NOT per se make a theory untestable. For instance, a theory stating that there are 666 parallel universes, all of which are devoid of oxygen, makes the testable prediction that we should observe no oxygen here, and is therefore ruled out by observation… The lesson to learn … is that multiverse theories CAN be tested and falsified, but only if they predict what the ensemble of parallel universes is and specify a probability distribution…” (Pg. 460-465)

He argues, “The principal arguments against parallel universes are that they are wasteful and weird, so let us consider these two objections in turn… When we feel that Nature is wasteful, what precisely are we disturbed about her wasting? Certainly not ‘space’… Certainly not ‘mass’ or ‘atoms’… once you have an infinite amount of something, who cares if you waste some more… The second … complaint … is aesthetic rather than scientific…of all four multiverse levels… the simplest and arguably most elegant theory involves parallel universes by default, and that one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates…to explain away the parallel universes. Our aesthetic judgment therefore comes down to what we find more wasteful and inelegant: many worlds or many words. Perhaps we will gradually get more used to the weird ways of our cosmos, and perhaps even find its strangeness to be part of its charm.” (Pg. 488-490)

Philip Clayton states, “Emergence, some say, is merely a philosophical concept, unfit for scientific consumption… Perhaps science can study emergences… but not emergence as such. It’s too soon to tell. But certainly there is a place for those… who attempt to look ahead… the bold question that gives rise to the emergentist research program [is]: Does nature, in its matter and its laws, manifest an inbuilt tendency to bring about increasing complexity... that runs from the periodic table … through the explosive variations of evolutionary history to the unpredictable progress of human cultural history, and perhaps even beyond?” (Pg. 577)

He notes, “Consciousness, many feel, is the most important instance of a clearly strong form of emergence… Unfortunately, consciousness, however intimately familiar we may be with it on a personal level, remains an almost total mystery from a scientific perspective… there is virtually no way to talk about the ‘C’ word without sliding into the domain of philosophy… How far can neuroscience go… in explaining consciousness? Science’s most powerful ally … is emergence… emergence allows one to acknowledge the undeniable differences between mental properties and physical properties, while still insisting on the dependence of the entire mental life on the brain states that produce it.” (Pg. 598-599)

Marcelo Gleiser observes, “To many scientists, it is indeed quite difficult to look beyond reductionism… There is, however, a confusion in associating the reductionist approach to simplicity and everything else to unnecessary complication; it is simply not correct to assume that less is always better. Sometimes, less is just not enough…” (Pg. 651)

This book will be of great interest to those studying some ‘outer areas’ of science.