Book Review:
Paul Davies continues provocative
writing in latest offering

What's Eating the Universe? and Other Cosmic Questions

Paul Davies, 2021

What's Eating the Universe?; and Other Cosmic Questions, by Paul Davies, is a concise update regarding current cosmological thinking written in a conversational style by one of the most interesting cosmologists alive today. Davies is a physicist at Arizona State University who has written many fascinating and provocative books on cosmology and other subjects, including a great book on the origins of life, The Fifth Miracle. There is no question too deep or philosophical for Davies who has an extraordinary ability to synthesize and simplify large bodies of research for non-scientists. Davies has had personal contact over many decades with famous physicists (including Fred Hoyle at the time the CMB was discovered) who have written about the origins of the universe and its evolution, and he is fully acquainted with the differing views of cosmologists regarding mysteries such as dark matter, dark energy, the brief period of inflation following the big bang and the broken symmetry between matter and anti-matter on which the cosmos depends. Davies touches on all of these subjects (and more) in 165 pages through brief chapters that read like lectures he may have given to students, or Ted talks. This is a book that will leave many curious readers wanting more, which is possibly Davies' goal. 


I have been interested in cosmology since the 1960's when there was still a lively debate between proponents of the big bang such as George Gamow and proponents of the steady state infinite universe, the most famous of whom was Fred Hoyle. Big bang theorists prevailed in this debate, primarily because of the discovery of the Cosmic Microwave Background (CMB) by scientists at Bell Laboratories in 1964. Gamow had predicted that the Big Bang would produce the CMB, while "there was no credible explanation (for it) within the steady state model, and support for it rapidly dwindled," Davies states.  During our lifetimes, there have been enormous advances in the understanding of the origins of the universe, some of which beggars belief it is so fantastic. For example, most cosmologists believe they have a detailed understanding of the conditions in the early universe one trillionth to a billionth of a second after the big bang and extending throughout the first few minutes of the universe's existence. However, as Davies admits, this understanding of the initial split second of the universe, post big bang, is entirely theoretical. The capacity to observe the conditions of the early universe depend on the mapping of the CMB. 


Davies writes: 


 ''The light from the nascent universe imaged there (in the COBE map) has travelled to us for over 13.7 billion years, during which time it has remained largely undisturbed. That means the CMB is a type of fossil: fossilized light;  to be sure, that light has been stretched in wavelength a thousand times, but it's still distinctive... Contrast the pristine CMB with the corrupted fossil remains collected by paleontologists from which they try to reconstruct a plausible narrative. .. . Admittedly, the CMB isn't a relic of the very instant of creation; it's what left of the glow at about 380,000 years after the big bang, an epoch about 0.003 percent of the present age of the universe." (p. 104)  However, this is not all. In a later chapter Davies writes: 


  "In the original version (of the big bang) there is a bang, then a stupendous antigravity force seizes the new born universe and enormously inflates it, ironing out any preceding messiness. After that, inflation stops and the standard big bang theory     unfolds. But inflation erases all record of the cosmic past, how do we know there was any beginning at all? What we have been calling the big bang could simply be what came after inflation." (p. 117)


It is paragraphs like this that make Davies consistently worth reading. He has too much intellectual integrity and curiosity to fudge or ignore doubts, gaps in knowledge or inconsistencies in widely accepted theories. He obviously believes the big bang is the most plausible account of cosmic creation, but he's a scientist, not a believer in a scientific dogma.  


Some of the most interesting parts of What's Eating the Universe is mind boggling information based either on theory or observation:    


  • "At one second after the beginning, it was ten billion degrees, at one microsecond ten trillion degrees, at a picosecond, ten thousand trillion degrees." (p. 30) 

  •  "Just in the last decade or so, the Hubble Space Telescope has actually been been to penetrate almost as far as the dark zone, beyond which there are no stars. It's over 13 billion light years away and encloses a volume of space around Earth that encompasses about a trillion trillion stars." ( p.13)  

  • Recent measurement of the Hubble constant (H), the rate of expansion of the universe, using the CMB  data "yield a value of only 67, implying an age for the universe of well over 14 billion years," ( p. 18) compared to the 13.7 billion year estimate resulting from the measurement of H (73) by the Hubble telescope.  Davies asks, "Does this suggest something seriously amiss with our understanding of basic cosmology? Time will tell."  ( p. 18) 

  • The temperature of the CMB is remarkably similar even in regions which have never been in contact or had the ability to influence each other. "There was nowhere near enough time for heat to flow between these regions to even out the temperature.... to achieve such an exquisite degree of orchestration, the initial conditions at the big bang would have to be arranged with nuanced perfection by the Great Cosmic Marksman. It looks like a fix. " (pp. 46-47) However, inflation soon after the big bang would smooth out the irregularities; "no mixing would be necessary." ... "Inflation soon became the party line among professional cosmologists,  a status it retain to this day."  ( p.47)     

  • "Many black holes are the collapsed remnants of stellar cores .. but there are also supermassive black holes at the centers of galaxies; no one is sure how these formed."  ( p.76)

  • "The Milky Way ...  contains  a black hole with the equivalent to about 2 million solar masses, while the galaxy M 87 has a monster equivalent to 6.4 billion (yes, b as in billion) suns." ( p. 76) 

  • "In March 2020,  the largest such explosion ever recorded was detected coming from a cluster of galaxies about 390 million light years away in the constellation of Ophiuchus. The energy of a single momentary burst was equivalent to a hundred billion times the energy output of the sun over its entire lifetime."  ( p. 76)   


The most interesting theoretical speculation in What's Eating the Universe is that dark energy contributing to cosmic expansion may be a type of antigravity, "the fudge factor in general relativity (which ) has swung in and out of fashion over the decades." (p.54) During the 1990s "astronomers discovered that the expansion of the universe is in fact speeding up," ( p. 54) rather than gradually slowing due to gravity as previously assumed.  According to Davies, '"the dark energy antigravity that is gripping the universe today is a faint remnant of inflation - that brief super-fast burst of expansion at the birth of the universe .. "  (p. 54) Davies and other cosmologists speculate that the source of an antigravity dark energy is 'empty' space which contains "particles that flit in and out of existence for the briefest duration, bubbling up from the void into half reality only to dissolve again almost immediately. ... Experiments confirm that the quantum vacuum really does seethe with energy and where goes energy, there goes mass  ( i.e.,  E = mc2) ... " ( p. 54) Davies explains that "for a few hundred thousand years after the big bang, when heat was so intense, it was radiation that dominated the gravitational pull on the universe, that is the breaking effect on the rate of expansion, outweighing everything else."( pp. 56-57) However, "no one knows how to calculate the actual quantity of quantum energy that is surging through space ... In reality, you can cook up any answer you like  (p. 57) leaving dark energy "high on the list of cosmic mysteries to be solved."  ( p. 57) 


What's Eating the Universe takes its title from speculation that "If, as most scientists believe, dark energy has a quantum origin ... then like atoms, there might by many possible values or levels of vacuum energy. Our universe happens to be in one of these vacuum energy levels, but it may not be the lowest. The worry is, an excited, or elevated state of the quantum vacuum would not be completely stable. There would always be a risk it would transition to a lower energy state-- the vacuum could decay, thereby releasing a stupendous amount of energy .If this happened anywhere in the universe, the consequences would be apocalyptic. A tiny bubble would spread out at nearly the speed of light, with the released energy concentrated into the bubble wall. As this boundary expanded it would destroy everything in its path... There may be no warning ... "   ( p.129) In case you become tired of imagining dystopian futures resulting from global warming, here is another apocalyptic scenario to worry about, though Davies does not seem too concerned. "Of all the things to worry about,  the possibility that our universe might be eaten by another (universe) should be low down on your list." ( p. 130)  Ditto for the possibility that the universe could self destruct "faster than the speed of thought." (p. 129)


Cosmological speculation 


There is something unhinged about Davies' cosmological speculations, which says less about Davies than about the current state of cosmology. The large number of propitious circumstances, i.e., "fine tuning," of the fundamental forces and the ratios of these forces required for star formation, and therefore for life, has made many physicists "uneasy."  Davies asserts that "Like in the story of Goldilocks, our universe seems to be 'just right' for life. It looks too much like Divine Providence, another Big Fix." This idea is anathema to many cosmologists who have found another possible explanation, the multiverse. "Among the countless universes churned out by the multiverse's creative mechanism, surely some fraction will have life encouraging laws replete with happy consequences, purely by chance?"  (p. 125) However, not all cosmologists like the multiverse,  and to others such as Fred Hoyle it's obvious that our universe is a "put up job," though Hoyle added ( I paraphrase) "to what end, no one knows." A belief that the cosmos is designed for life is not necessarily a religious view. For some cosmologists, it is just far more believable than a possible infinity of universes. 


Davies states: "I haven't conducted a straw poll, but there is a list of very distinguished physicists and cosmologists who are totally persuaded that we do indeed live in a universe delicately poised in the Goldilocks zone, and that - theological explanation being anathema -- there must be a multiverse."  ( p 126)  Davies adds: "my own feeling is that, even if a multiverse exists, it still doesn't explain everything." ( p.126)  For example, the origins of cosmic laws remains unexplained. One can ask, "'why this multiverse?" There may be no end to the ontological paper trail." ( p. 126) 


Once cosmologists seriously entertain the idea of a potentially infinite multiverse, just about any speculation is grist for the mill. Davies in this book and others discusses (at length) the possibility that our universe is a computer simulation, per the movie "The Matrix." Davies spells out the meaning of infinity; everything that can happen does happen in some universe, so there may be infinite versions of you and "near you." A few years ago I read the speculation of an author of a book about cosmology suggesting that the increase in the Hubble constant at about 5 billion light years from our solar system might be the pesky manipulation of graduate students in a college of cosmic developers! So much time, so little patience that these aspiring cosmic creators were monkeying around with the laws of physics, perhaps to impress the Head of the department. This was not a book of science fiction. 


There is a long tradition of speculation that the universe was created through and embodies an esoteric mathematical architecture. The quantum physicist, Paul Dirac, noticed that the age of the universe in atomic units ("the duration it takes for light to cross the nucleus of an atom which is about a ten trillionth of a second" ) is 10 to the fortieth power, "which is one followed by 40 zeroes." Davies writes: "It occurred to Dirac that he had come across this enormous number before. It is about the same as the ratio of the electric to the gravitational attraction in a hydrogen atom, the combined force between the proton and its orbiting electron.  Was this just a coincidence?  Dirac, like many scientists, was suspicious of the coincidence "of huge numbers, arising in totally different contexts, should be even approximately the same." ( pp. 141-2) Dirac suggested that "gravity slowly weakens over time in order to keep the two big numbers in lockstep." Dirac's achievements in subatomic physics and reputation were enough to convince NASA scientists to test Dirac's hypothesis regarding the gradual weakening of gravity in the1976 Mars probe, which had the ability to compute Mars' orbit with great precision. No weakening in the strength of gravity was detected. The physicist, Robert Dicke, then used Dirac's speculation to determine "the habitable epoch of cosmic history, a duration that in turn is determined by the ratio of the electric to gravitational forces," 10 to the fortieth power, the number that caught Dirac's attention. These are abstruse speculations of physicists who believe that the universe embodies a mathematical architecture, as real as matter and anti-matter. I view this theory as at least as plausible as the  infinite multiverse. 


There is a note of disquiet in Davies' speculations. It appears that unexpected findings regarding the CMB have "left cosmologists scratching their head."( p. 129) There is an asymmetry in the power of the afterglow (of the CMB) "that seems to align with the plane of the solar system, a finding so bizarre and heretical it has been labelled the Axis of Evil." (p. 130) The confidence of cosmologists that the mapping of the CMB would fill out a coherent account of the big bang and its aftermath has been shaken. The idea has occurred to some that if indeed the big bang and inflation were a product of design, maybe the Designer or designers screwed up. Some cosmologists are convinced they could have done better if they were at the controls of cosmic creation!  

© Dee Wilson