The Origin of the Universe

Prologue: 

Condensing the History of the Universe

When we learn that the age of the Universe is 13,800,000,000 years, it is difficult for us to wrap our minds around such a figure. Most of us are used to thinking of time in units that we can relate to our own lives. We tend to think of a decade as a long time. In the advanced nations, 75-80 years constitutes a normal lifespan. A century represents a very long time (or an extremely long life), and a millennium stretches our imaginations. To hear that the life of the Universe is, so far, 138,000,000 times longer than the life of a centenarian challenges our conceptual limits to the breaking point. Why does this matter? Because when we can no longer conceive of something, it becomes, in a sense, invisible to us, and hence meaningless. In order for us to make our place in reality mentally visible and meaningful we have to come up with a way of thinking about the unfolding events of the Universe that uses time frames with which we are intimately familiar. So how can this be done?

In his classic work, The Dragons of Eden: Speculations on the Evolution of Human Intelligence, the great Carl Sagan used an ingenious method to make the vast age of the Universe comprehensible. This method is known as “The Cosmic Calendar” and it is based on conceiving of the Universe’s history, from the Big Bang to this very moment, as having taken place in the span of just one Earth year. The first moment of the Universe’s existence, therefore, would be midnight, 1 January. The current moment would be midnight exactly one year later, right at the start of a new year. So, to measure the progress of the Universe from the earliest moment of its existence to the emergence of human consciousness, we would convert the real times of the most significant developments to our one year framework, always keeping these events in the correct proportional relationship to each other on our calendar.

Since some people think in a more linear way, I will also use the timeline concept I introduced in the chapter entitled A Species Lost in Both Space and Time. This involves, as I said, imagining there is a timeline stretching out 1,000,000 meters (1000 kilometers or 621.3 miles) before us, almost the exact distance between Darjeeling and Agra, India or between Cardiff in the United Kingdom and Magdeburg, Germany, or a little shorter than the distance between Chicago and Harrisburg, Pennsylvania. If the Big Bang is at the very beginning of the timeline and our lives at the very end, where do the great events that mark the progress of the Universe from the unconscious to the conscious fall?

The answers to these questions, as I indicated previously, are not flattering to human vanity. It is startling, as well, to see how near in time to us the age of the dinosaurs actually was, or how downright recent the evolution of the first primates was, perhaps a mere 65,000,000 years ago. On our chronology we will examine all the “firsts” in the prehistory of the world, explain something about the major events surrounding and proceeding from them, and try to elucidate how the physical, chemical, and biological realms produced an utterly unexpected offshoot—us.

BEGINNING

1 JANUARY, 12:00 AM; THE START OF THE LINE

Why is there something rather than nothing? One could argue, I suppose, that true nothingness is impossible, since what we think of as nothingness—the absence of space-time and energy-matter—would still constitute a state of being, and therefore technically be something. But obviously the absence of space-time and energy-matter is not the issue here. We seemingly find ourselves immersed in and part of both of them. In our perception, therefore, the something that exists appears to be physical reality. What accounts for it? If it had a beginning, how did it begin? If it had no beginning, what does that say about our place in it?

The physical reality we know is encompassed in the Universe, an entity, as we have seen, of inconceivable enormity, the sum total of all objects, events, processes, histories, and futures. Our entire being as a genus and species has been, and will be, lived in it. Its creation has been the subject of stories and myths from almost every culture, but it has fallen to the modern sciences, particularly cosmology, to attempt to explain its true inception. And while philosophical and theological arguments often pop up in discussions of our ultimate origins, most cosmologists seek an explanation of the Universe’s provenance that is grounded completely in naturalistic conceptions and empirically-demonstrable explanations.

Questions and Hypotheses Concerning the Universe’s Nature and Origin

The conception of the Universe’s beginning that dominates the thinking of the Earth’s physics community is the Big Bang, the rapid expansion of space-time and the increasing elaboration of energy-matter that began 13,800,000,000 years ago. (Of course, the phrase Big Bang can be misleading; most scientists don’t literally see it as an explosion, but rather a phenomenon characterized by extremely high temperatures and very turbulent energies which began at a definable time in the past.) In the 1920s, the work of Alexander Friedmann and Georges Lemaître pointed to the distinct possibility that the Universe was expanding, and evidence gathered since that time has confirmed this expansion.¹ The equations that describe the density, temperature, and expansion of the Universe, when extrapolated backward in time, seemed to converge on the presence of a singularity at what is called time zero, wherein not only all of space but all of time itself was confined in the beginning to a point of incredible smallness in which all the basic forces that dominate the physical world—gravity, electromagnetic force, the strong nuclear force, and the weak force—had not yet become differentiated, a point of infinite temperature and density. The calculations that pointed to a singularity were worked out most completely by Stephen Hawking and Roger Penrose in the 1960s, and for a number of years this view held the high ground in cosmology.

But the concept of a singularity ran into major difficulties. Many cosmologists now argue that we cannot support the idea of a singularity because it appears that Einstein’s relativity equations break down in the conditions of the extremely early Universe. (An infinity of pressure and an infinitely curved space-time appear to be precluded in relativity theory.) They point out that without a definitive theory of quantum gravity, we simply do not know what happened at the very first moment of the Universe’s existence, and we simply do not know—yet—from whence the Universe sprang. ² Hawking himself has changed his mind about the singularity, and he has proposed a different explanation for the Universe’s beginning. (See below.)

So although the search for a scientific explanation of the Universe’s origins has been underway for many decades, and a great deal has been elucidated about them, there are still unresolved issues and areas of contention among those most deeply involved in the search. In their most basic form, these questions are as follows:

—Is the Universe a one-time, distinct phenomenon, or is it the current incarnation of a physical reality that has existed, and will exist, forever?

—Is the Universe the whole of physical reality, or is there a Multiverse, perhaps infinite, of other Universes which have their own distinct physical rules and constants?

—Does it make any sense to use the phrase “before the Big Bang”? If there was no time or space that existed before the Universe began, then how and from whence did the Universe arise?

—Is it possible for something to emerge out of nothing? Can being emerge out of non-being, or is being the absolute fundamental precondition of reality?

—If the concept of a singularity is no longer tenable, with what can we replace it?

The Universe, in some pictures of its creation, is said to have simply bubbled out of the fabric of reality itself. Perhaps it was here that pure mathematical randomness asserted itself. The Universe was possible; therefore, in an expression of probability, it became. Maybe it was just as likely as it was not that all the features out of which physical reality is composed came into being through what Peter Atkins calls a fluctuation. This was caused, in his view, by an extreme simplicity that gave rise to a set of points, a geometry, a pattern brought forth by sheer chance, in our case a pattern that contained both time and three spatial dimensions, an arrangement which was conducive to expansion and an increasing elaboration.³

Atkins is describing being emerging from non-being—something emerging from nothing. But how can this occur? It seems impossible, and yet physicist Paul Davies has answered in this way:

The lesson of quantum physics is this: Something that "just happens" need not actually violate the laws of physics. The abrupt and uncaused appearance of something can occur within the scope of scientific law, once quantum laws have been taken into account. Nature apparently has the capacity for genuine spontaneity.

It is, of course, a big step from the spontaneous and uncaused appearance of a subatomic particle-something that is routinely observed in particle accelerators-to the spontaneous and uncaused appearance of the universe. But the loophole is there. If, as astronomers believe, the primeval universe was compressed to a very small size, then quantum effects must have once been important on a cosmic scale. Even if we don't have a precise idea of exactly what took place at the beginning, we can at least see that the origin of the universe from nothing need not be unlawful or unnatural or unscientific. In short, it need not have been a supernatural event.⁴

As Davies notes, particles (and, we should add, antiparticles) spontaneously pop into existence all the time, even in a perfect vacuum. It is the nature of the vacuum, many scientists believe, that gave rise to the current Universe. This is related to the phenomenon known as Zero Point Energy. In order to grasp Zero Point Energy, we need to remember Heisenberg’s Uncertainty Principle, wherein we cannot simultaneously know the exact location and momentum of a particle. A particle has both motion energy and positional energy. ZPE is the smallest amount of energy that motion and positional energy can add up to according to quantum principles. Since it is impossible for a particle to be completely motionless (for in that case both its location and momentum would be known at the same time), we must assume that it retains a minimal but still real ZPE. The fluctuations that cause particles to spontaneously (if only briefly) emerge will therefore, by necessity, imply the creation of energy. In other words, if the Universe began as an example of Heisenberg’s Uncertainty Principle, the creation of energy in this instance would have been unavoidable.⁵

Matter is created out of energy, since they are aspects of the same thing. In 1988, Hawking maintained that the energy to create matter has been “borrowed” from the Universe’s gravitational energy, a process which was particularly intense during the rapid inflationary period of space-time. Hawking said this debt will not have to be “paid back” until the very end of the Universe itself. This would imply, mind-bogglingly enough, that the net energy of the entire Universe is zero.

Cosmologist John Barrow challenges all notions of creation out of nothing. Barrow argues that since the concept of an infinitely dense, infinitely hot point from which the Universe sprang is no longer tenable, that it is completely possible that our Universe is part of an eternal sequence of Universes. He points out that a number of scenarios are possible in this regard, from a Universe that was static (before the time we perceive as the Big Bang) and which began the expansion we now observe to a Universe in eternal expansion, to a Universe that “bounced” into being from the decay of another Universe.  Moreover, Barrow contends that gravitation does not behave as we once thought it did. A Universe in which gravitation is always universally attractive does not square with our observations of the Universe’s expansion. Something is overcoming the force of gravitation, and driving the Universe to entropy. (As we saw earlier in this book, that something may be dark energy.) ⁶

The consensus that seems to be emerging, therefore, is that we do not yet know what happened at the very moment of the Universe’s origin (or the origin of its most recent incarnation). There appears to be no inherent contradiction or logical fallacy in asserting that the Universe we inhabit is part of a larger, perhaps eternal space-time reality, but as yet nothing along this line can be demonstrated. There also appears to be no inherent contradiction or logical fallacy in asserting that the Universe is the result of random quantum fluctuation in the vacuum of nothingness. German theoretical physicist Henning Genz puts it this way:

If there was time before the Big Bang, time in which the world originated, we will never know within our model [the standard model of the hot Big Bang]; the first frame of our motion picture is independent of anything that might have preceded it. Increase of temperature eliminates information…no information whatever can be passed on at infinite temperature. To repeat: We have no way of telling whether anything preceded the Big Bang, whether time had its origin together with our universe. ⁷

If there was indeed an “explosion” (so to speak) of energy-matter at the beginning of the Universe, there should be detectable traces of it today, and indeed there are. The traces are in the form of what is known as the cosmic microwave background radiation. This remnant of the Big Bang was first detected in 1965 by two American radio astronomers, and it was measured and “seen” in effect by the COBE satellite in 1992, a monumental discovery. The density and distribution of this radiation confirms many of our conjectures about the Big Bang and the early Universe. The Universe in which we live is both largely homogenous and isotropic—in other words, one which appears to be structurally uniform throughout and one in which all directions seem to yield a similar view. The irregularities within the cosmic microwave background radiation, the level of its anisotropy, constitute about one one-hundredth thousandth of its content, or one one-thousandth of one percent.⁸

In 1983 Stephen Hawking and fellow physicist Jim Hartle proposed what they believe to be a plausible picture of physical reality, one known as the No Boundary Universe. In its original form, it defined a Universe that was both finite and unbounded (in the same sense that the surface of a sphere is unbounded, although Hawking and Hartle do not see the Universe as a spherical object). Such a Universe would not have begun with a singularity. In a 1988 public lecture, Hawking explained his view in this manner:

The proposal that Hartle and I made, can be paraphrased as: The boundary condition of the universe is, that it has no boundary. It is only if the universe is in this ``no boundary'' state, that the laws of science, on their own, determine the probabilities of each possible history. Thus, it is only in this case that the known laws would determine how the universe should behave. If the universe is in any other state, the class of curved spaces, in the ``Sum over Histories'', will include spaces with singularities. In order to determine the probabilities of such singular histories, one would have to invoke some principle other than the known laws of science. This principle would be something external to our universe. We could not deduce it from within the universe. On the other hand, if the universe is in the ``no boundary'' state, we could, in principle, determine completely how the universe should behave, up to the limits set by the Uncertainty Principle.⁹

The term “Sum over Histories” was taken from the work of Richard Feynman. You may recall in the chapter entitled The Rules of the Game: The New Rulebook that Feynman demonstrated, through quantum electrodynamics, that a beam of light explores every possible path between Point A and Point B, and the sum of the probabilities it explores appears to be a straight line. Hawking is arguing that the Universe itself represents the sum of all possible Universes, and that its appearance was basically an act of quantum spontaneity. Hawking spoke again about this theme in a 2007 lecture that recapitulated many of his earlier points. But he elaborated on his previous remarks by saying that the picture he and Hartle had developed of the spontaneous quantum creation of the Universe could be likened to the bubbles that form in heated water. The various bubbles that appear and then disappear again would represent microscopic Universes that spontaneously appear and disappear again after undergoing a very limited expansion. Hawking then added that a few of these bubble-like Universes would attain sufficient size to escape the possibility of collapse, and would continue to expand at increasing rates. It was these Universes, Hawking said, that had the potential to last long enough to produce stars, galaxies, and life.¹⁰

In 2008, New Scientist reported that Hawking, Hartle, and physicist Thomas Hertog proposed that the early Universe was describable as a wave function, meaning that all possible Universes initially came into being but the one that prevailed was the most probable one, the one that we inhabit, the Universe that now appears to act in accordance with the rules of classical physics. Moreover, according to their calculations, this most probable Universe allows for a rapid inflation, inflation consistent with the evidence we have gathered from measuring the cosmic microwave background radiation. In short, according to this view, there was no singularity. Rather, from a dense thicket of possibilities, the most probable one grew into the Universe we inhabit. Hawking also pointed out that in this model there would be small fluctuations in the expansion of the Universe, and it was these localized fluctuations that permitted the emergence of stars, galaxies, and all the other structures of which we know in the Universe. ¹¹

The Very Early Universe After the First Moment

The ground of physical being itself may still be a matter of controversy, but what happened in the immediate aftermath of the Big Bang—whatever its ultimate causes—is much better known. The earliest era of the Universe after the initial events of the Big Bang is known as the Planck Era, and it ended at 10^-43 seconds. Nothing is known with any certainty about it. At the end of this vanishingly brief time gravity began to separate itself from the other fundamental forces, the start of a monumental career in constructing, probably through dark matter’s gravitational fields, the basic structures of the Universe. Between 10^-43 and 10^-34  seconds there was, according to most cosmologists, an enormous inflation of the Universe, perhaps at a greater rate than at any other time in the 13.8 billion years since. (The inflationary hypothesis was first proposed by cosmologist Alan Guth in 1980 and has been developed by Guth, Andrei Linde, Paul Steinhardt, and Andy Albrecht.) According to some physicists, this inflation expanded the Universe in its first moments by a figure of 10⁵⁰. Inflation would account for the fact that parts of the Universe separated by enormous distances show strongly similar background temperatures, indicating that they must have been in close proximity at one time. It was at the end of this period of inflation that the strong force separated itself from what was left of the single primordial unified force.¹²

At around 10^-12 seconds, it appears that the electromagnetic and weak forces separated. In other words, when the Universe was a trillionth of a second old, its fundamental forces and features had already been set.¹³ For a few millionths of a second after the Big Bang, the primordial Universe was dominated by what is known as quark-gluon plasma. Many scientists now think that it was the interaction of quarks and gluons in this state that gave rise to protons and neutrons. It would appear the QGP behaved as a liquid, and although it is not yet fully understood, it has been successfully created in the Large Hadron Collider in Switzerland, and elsewhere.¹⁴ Quarks, of course, are among the Universe’s fundamental building blocks, and gluons are the carriers of the strong force. At around 10^-6 seconds, it appears that all quarks, which had been running free, were now confined into larger structures and began to form the protons and neutrons that were essential to the eventual construction of atoms. By around 10^-4 seconds after the Big Bang’s eruption, all of the kinds of subatomic particles which are part of the Universe were now in existence. All of the necessary building blocks were present. They now were to start aggregating themselves in increasingly complex and diverse ways.

Now hadrons, particles held together by the strong nuclear force, briefly dominated. Some of them were composed solely of quarks and are considered to be matter particles and some of them were composed of quarks and anti-quarks and are considered to be force carriers. Neutrinos decoupled and began to fly freely in space. After a single second, most hadrons had annihilated each other and the extraordinarily fundamental particles known as leptons, a group which includes, as we have seen, the electrons, dominated for the next three minutes. And it is of supreme importance, as I emphasized earlier, that there was an asymmetry between matter and antimatter in the early Universe. Had matter not gained the upper hand, there would be no physical Universe here now at all.

At one second after the Big Bang, it is now thought that the temperature of the early Universe was 10,000,000,000 degrees Kelvin, and the pressures approximately one ton per cubic centimeter.¹⁵ Such temperatures, although not as great as the inconceivable levels that existed prior to that time, were still far too hot to allow for the formation of nuclei.

As we have already noted, it has taken an extraordinary effort on our part to pry open the secrets of the early Universe and the tiniest of all units of energy-matter. The energies required to construct them were so overwhelming that they no longer exist in the current Universe, except when we create them in controlled, experimental conditions. When we peel away the layers of this ultimate physical level of being, we are, in a sense, going back in time, back to the era when quarks were being created in the maelstrom of the earliest Universe.¹⁶

Primordial Nucleosynthesis and the First Elements

At around 180 seconds after the Big Bang, the nuclei of what were to be the first elements formed. The initial extremely high temperatures of the early Universe had cooled sufficiently to allow this process to occur. But the temperature of the early Universe was still so high that it was impossible for the entire atomic structure of these elements to emerge. That would occur much later. These nuclei were extremely light in the sense that their atomic weights were minimal. The nuclei that formed were deuterium, helium, and lithium, in a process known as primordial nucleosynthesis. (Nucleosynthesis: the creation of nuclei.)

According to most cosmologists, the beginning of the period of primordial nucleosynthesis was dominated by the existence of free neutrons, protons, electrons, neutrinos, and photons. The free neutrons were unstable; they had been undergoing radioactive decay since one second after the Big Bang. At three minutes, protons began to capture neutrons, and deuterons—the nuclei of what would eventually be ²H—formed. Once this had occurred, other light nuclei could be formed, as deuterons linked both with each other and with products of their original linkages to produce different isotopes of the lightest nuclei. In this process ³He, ⁴He, ⁶Li, and ⁷Li were ultimately created.¹⁷ The amount of helium in the Universe was ultimately determined by the fact that neutrons were relatively rare compared to protons, and single protons turned out to be the most abundant nuclei. Single protons would eventually be paired with single electrons and become the simplest form of hydrogen, ¹H, (or protium) and this was to be the most abundant element in the Universe.¹⁸

The period of primordial nucleosynthesis ended at around 20 minutes. Following this, there was a period of dominance by radiation, lasting approximately 41,000 years, until the density of radiation and the density of matter became equal. All the while the Universe kept expanding, and as it expanded its temperature was cooling. By 41,000 years after the Big Bang the temperature of the cosmic microwave background radiation had fallen to about 9,300 degrees Kelvin. Because of the rapidity of the expansion of space itself, the Universe’s diameter is thought to have been 24.4 million light years.¹⁹ In the process of cooling it became possible for new structures of energy-matter to emerge. At about 379,000 years after the Big Bang, the temperature of the Universe had cooled sufficiently (to about 3,000 degrees K) to allow the formation of hydrogen, helium, and lithium atoms, as electrons were harnessed to the existing nuclei of these elements. This process is known as recombination.  (Hydrogen and helium isotopes comprise the lion’s share of the visible matter of the Universe, something on the order of  98%.) It is at this point that there were few enough unattached electrons that photons could travel in an unobstructed manner, making the Universe (for a time) transparent. It is this transparency that allows us to detect the cosmic microwave background radiation from that era.

We do not yet know when dark matter and dark energy came into existence in the early Universe. But they certainly must have existed by the time atoms were created, and perhaps well before that. When the first atoms came into existence, it became possible for gravity to begin to organize the structures of the Universe which eventually came to be, again, quite probably with dark matter’s gravitational fields playing an indispensable role in this construction.

Other Considerations

It is understood that the observable Universe in which we exist is finite. The equations by which the expansion of the Universe is measured tell us this. And a more down-to-Earth reason tells us as well: The Night Sky Paradox, which was first noted in the 17^th century. Why is the night sky dark? Because its observable age is limited. If the Universe were of infinite age, and stars randomly distributed throughout it, light would thoroughly saturate the sky at all times, even after sundown. Since it doesn’t we must assume that our Universe is not ageless.

But if the Universe is finite, can it also be part of a process which is eternal? Paul Steinhardt and Neil Turok argue in Endless Universe (2007) that there is significant evidence that the current universe is simply the latest in a series of trillion-year long expansions and contractions (although they point out that the existence of such a cycle does not preclude a beginning of time), and that the Universe may be going through evolutionary changes during each trillion year cycle. Steinhardt and Turok predicate their argument on the existence of branes (short for membranes), the extra dimensions the existence of which is predicted by string theory. In their view, these branes can move through space and exert gravitational influences on each other. As the Universe is driven to entropy by the expansionary action of dark energy (which itself will decay), these branes stretch and extend, and then collide with each other. It is the collision of branes, at the end of the Universe and its attendant entropic state, that will create, according to this hypothesis, new matter and new radiation, and hence a new Universe.²⁰ So is it possible that the Big Bang (or something like it) has happened again and again, recreating space-time in an endless procession?

As we saw in the chapter entitled, The Rules of the Game: The New Rulebook, it is entirely possible (if not yet proven) that there is a multiverse, an inconceivably huge, possibly even infinite collection of universes, that exists, caused perhaps by the collapse  of innumerable waves of probability into alternate histories of the physical world. It is possible also that the basic underlying reality has allowed uncounted Universes to spontaneously erupt, as did ours. There is nothing that would necessarily preclude this possibility. If our own Universe bubbled into existence as a quantum fluctuation, there is nothing to prevent other Universes from having done so as well. Some theorists have maintained that such Universes are spatially in very close proximity to our own, and are in fact parallel to our own Universe. There is no way of testing such ideas empirically; if they are ever demonstrated, it will be through purely deductive means. No one can say what such Universes would be like, whether people such as ourselves exist within them, or even if they have physical constants exactly like our own. It is conceivable, for example, to have a Universe where electrically-charged particles are attracted to particles of a similar charge rather than repelled by them. But it is worth noting that even such a seemingly minor change from our own Universe would mean that everything would be different in this hypothetical Universe, and it would have properties that cannot be fully predicted.

It was this first period in our condensed history’s chronology, from early in the day on 1 January to about 5 January, that the Universe was in its dark ages—the age before stars. Only the microwave residue of the Big Bang itself now reminds us of this era. The Universe expanded and cooled in an uneven fashion. Certain regions of higher gravitation began to collapse. It would take 100-200,000,000 years before there were in these regions of  collapse gas temperatures hot enough to trigger nuclear fusion, and thus to ignite the first stars that existed.

At every stage in its unfolding, the physical universe brought forth levels of organization that made possible, in order, the emergence of distinct physical forces, fundamental particles, composite particles, elements, atoms, molecules, gases, stars, dust, mini-galaxies, true galaxies, clusters of galaxies, solar systems within galaxies, planets within solar systems, satellites around planets, and the whole array of lesser objects that bend themselves to the will of gravitational fields established by stars, both thriving and dying. The evolution of life on some of these planets and lesser bodies was a variation on the physical laws completely consistent with this unfolding process. Our very bodies are composed of the same substances as the celestial objects, and their physiology rests on the laws of physics that underlie all of physical reality.

In short, the nature of the Universe lives within us, and we are the descendants of those first eventful years of its being.

1.   Silk, Joseph,  Cosmic Enigmas pp. 13-14 

2.   Coles, Peter, and Lucchin, Francesco. Cosmology: The Origin and Evolution of Cosmic Structure, pp. 119-122;   

3.   Atkins, Peter, . Creation Revisited , p. 149;

4.   The statement by Paul Davies may be found here:

http://www.fortunecity.com/emachines/e11/86/big-bang.html

5    Genz, Henning, Nothingness: The Science of Empty Space, pp. 199-202

6.   Barrow, John D. The Book of Nothing: Vacuums, Voids, and the Latest Ideas About the Origins of the Universe, pp. 287-297;

7.   Genz, p. 262;

8.   Levin, Frank, Calibrating the Cosmos: How Cosmology Explains Our Big Bang Universe, p. 3

9.   Hawking’s 1988 statement may be found here:

http://www.ralentz.com/old/astro/hawking-1.html

10. Hawking’s 2007 statement may be found here:

http://berkeley.edu/news/media/releases/2007/03/16_hawking_text.shtml

11. New Scientist, 28 June 2008

12. Kaku, Michio, Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos p. 105; 

13. Tyson, Neil De Grasse, and Donald Goldsmith, Origins: Fourteen Billion Years of Cosmic Evolution, p. 39

14. PhysOrg, January 17, 2012,  “The perfect liquid -- now even more perfect” http://www.physorg.com/tags/quark+gluon+plasma/

15. Vilenkin, Alex, Many Worlds in One: The Search for Other Universes, p. 34

16. Ferris, Timothy, Coming of Age in the Milky Way, pp. 340-346

17. Levin, pp. 229-235;

18. Hawley, John F., Holcomb, Katherine A., Foundations of Modern Cosmology, p. 370 

19. Levin, p. 187 

20. Steinhardt, Paul J. and Turok, Neil, Endless Universe: Beyond the Big Bang—Rewriting Cosmic History, pp. 164-166; pp. 188-193

A useful discussion of Zero Point Energy may be found here:

http://www.calphysics.org/zpe.html