— Remote Sensing Tutorial 1 documentation (2024)

The BIG BANG; The First Minute of the Universe;¶

The Nature and Origin of Matter; The Early Eras

Introductory Overview

Cosmologists - those who study the origin, structure, composition,space-time relations, and evolution of the astronomical Universe -generally agree that the Universe had a finite beginning between 12and 16 Ga (Ga = 1 billion years [b.y.]) ago; the current best estimatelies close to 14 Ga. This is derived by measuring the time needed forlight to have traveled from the observable outer limit of the Universeto Earth in terms of light years *, whichcan be converted to distances. The physical conditions that guaranteedthe present Universe must have burst into existence almostinstantaneously. During the first minute of the Universe’s history, manyof the fundamental principles of both Quantum Physics (or, as applied tothis situation, Quantum Cosmology) and Relativity - the two greatestscientific discoveries of the 20th Century (see Preface, accessed bylink above) - played key roles in setting up the special conditions ofthis Universe that have been uncovered and defined in the 20th Century.Quantum processes were a vital governing factor during the buildup andmodifications of the particles and subparticles that arose in theearliest stages. Likewise, Relativity influenced the space-time growthof the Cosmos from the very start.

In the most widely accepted current model of the Universe, there is nostarting place or time in the conventional sense of human experience.Space**, as now defined and constrainedby the outer limits of the observable Universe, did not yet exist (seebelow); also, sequential events, embedded in a temporal continuum, hadnot begun. The observable Universe is just the visible or detectablepart extending to the outermost reach of the Universe where objects orsources of radiation have sent signals traveling at the speed of lightover an elapsed time not greater (usually somewhat less) than the time(age) of the start of expansion. Since now most cosmologists feel someconfidence that there is something beyond the observable Universe (be itthe unseen parts of our Universe or some other Universe(s)), thatunobserved part plus the observed part is sometimes spoken of as theCosmos.

The initiating event, referred to as the Big Bang, began at apoint-like singularity (so small that the notion of spatialthree-dimensions [3-D] has no conceptual meaning), some sort of quantumstate of still-being-defined nature that marks the inception ofspace/time (thus, without a preceding “where/when”; philosophically“uncaused”), from which all that was to become the Universe can bementally envisioned to have been concentrated. This singularity is thusdescribed as not quite a point (dimensionless) condition which hasextreme curvature and incredible density and where the laws of physics(including relativity) break down, i.e., do not apply. The singularityalso ties in to the nearly instantaneous moment in time when theUniverse is initiated after which some things can be said about theearliest behaviour of the Universe in terms of known or postulatedconcepts in physics). Just prior to the singularity’s unfolding into thefirst moments of the Universe, space and time were completely joined(not distinguishable) but without any meaningful geometric or temporalvalue.

At the very beginning of this (our) Universe, multidimensional space andtime came into being and began to take on physical characteristics. Butat the cosmic scale, these two fundamental properties must, according toSpecial Relativity, comprise the 4-dimensional spacetime Universe we nowobserve (according to some theories discussed below and on page 20-10,additional dimensions are possible). The exact nature (concept) of timeis still not fully understood and is subject to continuing debate (foran excellent review of time, read About Time: Einstein’s UnfinishedRevolution by Paul Davies, 1995); also consult his Web site on “Whathappened before the Big Bang” at thissite(the host site contains many interesting and provocative articles; clickon Albert Einstein within the page that comes up to get to the parentsite). There is, of course, the conventional time of everyday experienceon Earth (years, days, seconds, etc.), measured fairly precisely byatomic clocks (e.g., the pulsating beat of a cesium atom, used to definethe ‘second’) and less so by mechanical timepieces or crystal watches.There are the redefining ideas of time consequent upon SpecialRelativity, in which the perception of time units proceeds faster orslower depending on frames of reference moving at different relativevelocities. There is the notion of “eternity” in which time just is -has no specific beginning or ending.

But, all these measures and concepts are difficult to extrapolate tothat nebulous temporal state (if real) which was before the singularityof our Universe came into being (conceivably the singularity could haveexisted for some finite “time” before its inevitable instability forcedthe beginning we describe below as the Big Bang). But, time had toseparate at that instant and become measurable in terms we have setforth to use its property of steady progression of a temporal nature. Ifnothing existed prior to the singularity event, then there is no meansto determine and measure the time involved as a prior state. If ours isnot the only Universe (see the discussion of multiverses on page 20-10),and other Universes existed before the one we observe, then time in someway can be pushed backward to their inceptions. One possibility is aninfinite number of Universes in time and space, with no end pointsfor starts and finishes (read Paul Davies’ book for the philosophical aswell as physical implications of time, and the still unresolved dilemmasin specifying the meaning of time). For our purposes in studying theCosmology of the one known Universe, we will assume a start to the timeaccompanying the moment of its existence and its subsequent progressionas being comprehensible in the units we define for Earth living. Thus,the Universe, under this proposition, can be dated as to its age inyears.

At the very beginning, the fundamental energy within the singularity mayhave been (or been related to) gravitational energy that controlledthe nature of the singularity. An alternative now being investigated issome form of repulsive energy (similar to that once proposed byAlbert Einstein) such as quintessence (see page 20-10) which may proveto be related to the “dark energy” (page 20-9) that seemingly dominatesthe present Universe. At the instant of singularity, the initial energy(some of which was about to become matter) was compressed into a stateof extremely high density (density = mass or amount of matter [or itsenergy equivalent] per specific [unit] volume), estimated to be about10⁹⁰ kg/cc (kilograms per cubic centimeter) and extraordinarytemperatures, perhaps in excess of 10³² °K (K = Kelvin = 273 +°C [C = degrees Centigrade]), both without any counterpart in thepresently observed Universe. As you will see below, certain forms ofmatter came from the pure energy released during the first fraction of asecond of the Universe’s history. The famed Einstein equation E =mc² accounts for the fact that under the right conditions,energy can convert to matter, and vice-versa.

At the instant of creation, the singularity (which theory holds to havebeen far less than 10^-33 of a centimeter in diameter), provedexceptionally unstable and proceeded to “come apart” by experiencingsomething akin to an “explosion”, which goes under the popular name ofthe “Big Bang” (B.B); implicit in this is the general idea ofexpansion (see page 20-1a, accessed through the link below on thispage). This was not an explosion in the conventional sense, such asproduces an incandescent gaseous fireball, but rather anextremely-violent release of kinetic energy released from thesingularity that initiated the general expansion and has since (so far)exceeded the countering effect of gravity. The prime effect was tocreate and enlarge space itself. The explosion is described as “not intospace” but “of space”. Expansion is thus continuing to the present inpart because the inertial effects (evident in the observed recessionalmotions of galaxies, etc.) imposed at the initial push still influencehow space grows and, now it is believed, in part due to the continuingaction of the above-mentioned repulsive energy. After the freeing ofgravity from the other fundamental forces (see below), it has since beenacting on all particles, from those grouped collectively into stars andclouds making up the galaxies to individual nucleons, photons, etc. -thus at macro- to micro-scales. Gravity therefore exacts one controllinginfluence on the rate of expansion, serving to slow it down. As we shallelaborate later, recent evidence suggests that anti-gravity forces(enabled by the repulsive energy of presently uncertain nature) haveovercome the restraining effects of gravity seeking to slow theexpansion and perhaps eventually draw matter together in a generalcollapse.

However, as treated on page 20-8, and again in thesecond part of this page, this expansion is actually a dilation (or“dilatation”, a synonym) of space rather than a thrusting apart ofindividual matter through direct outward motion as for a familiarexample the centripetal ejection of debris following a central explosionof, say, dynamite inside an automobile. Thus, the matter does notphysically travel as do particles from a dynamite detonation site; spaceitself “travels” by progressive enlargement over time.

One cannot speak of “there” in reference to the singularity (because thespace that characterizes our Universe did not start to form until themoment of its beginning, it is difficult to think of any “there” sinceno dimensional frame of reference can be specified). At the outset of“creation” the singularity was made up of pure energy of some kind (in a“virtual” state within a “void” called the false vacuum). What mighthave preceded this moment at which the Universe springs into being andhow the singularity came to be (become) remains speculative;theoreticians in the Sciences have proposed inventive, although somewhatabstract, solutions but the alternative and traditional views ofphilosophers (metaphysicians) are still taken seriously by many in thescientific community. This last idea is treated again near the bottom ofPage 20-11 and a link to some of the writer’s speculations.

This is an appropriate point to insert comments about what the writerhas recently learned about the concept of the Instanton. This is analternative version of the notion of the Singularity described inprevious paragraphs. The Instanton is a condition that derives fromYang-Mills Gauge theory which is a part of what is known as QuantumChromodynamics (QCD). We will not further delve into that subject butwill just mention that Cosmologists such as Stephen Hawkings and NeilTurok have adapted Instanton theory to the conceptualizing of what wasbefore and led up to the Big Bang, or any of the competing ideas for theUniverse’s inception. In a nutshell, they envision a process by which aquantum fluctuation in the vacuum or void prior to the initiation of theBig Bang led to the appearance of energy by a quantum tunneling process.Their “Pea Instanton”, which had such high temperatures and pressuresthat it had to “explode” was created in this way. Rather than pursuethis topic further here, we refer you to the Cambridge University linkat the bottom of the Preface and to these two additional Web sites:`(1) <http://stripe.colorado.edu/~yulsman/Instanton1.html>`__ and`(2) <http://web.uvic.ca/~jtwong/>`__.

Many scientists believe that what may have “existed” prior to theUniverse was a quantum state (in a sense, analogous to the condition of“potency” in ancient Greek philosophy) which influenced a true vacuum(no matter whatsoever) that somehow possessed a high level of energy (ofunknown nature but not, however, as photon radiation). Countless quantumfluctuations (which in quantum theory are said not to depend on [obey]metaphysical cause/effect controls and are not subject to timeordering) in this vacuum energy density produced sets of virtualparticles and anti-particles (analogs to positrons, thepositively-charged equivalent of an electron; neutrons andanti-neutrons, etc) that came into existence for very brief moments andthen annihilated. But, rarely, annihilation did not occur, so that aparticle could grow and trigger a ‘phase transition’ that led to thesingularity from whence all that entails the Universe - matter, energy,space, and time - came into being. In this quantum model, it isconceivable that many such singularities could form from time to time,leading to mulitple universes that, as far as we know theoretically,cannot have any direct contact.

This is one example of prohibition by relativistic limits, in whichinformation travelling at the speed of light cannot reach us from beyondthe horizon - outer edge - of our own observable universe. The conceptof the Cosmological Horizon refers to the boundary or outer limits ofthe Universe that we can establish contact with. This is approximated bythe currently observed farthest galaxies that formed in the firstbillion years of cosmic time. This Horizon is also conceptualized as thesurface dividing spacetime (which includes all locatable 4-dimensionalpoints) into what we can see and measure from what is hidden andunobservable. The observable therefore must lie within our Light Cone,an imaginary surface that encloses all possible paths of light reachingus since the beginning of time. (The second illustration below is anexample). Check page 20-10 for further discussionof these ideas.

The controlling factor in this “visual” awareness is just the speed oflight (photons). If the Universe is about 14 billion years old (in termsof our terrestrial perception of time, based on a complete revolution ofEarth around the Sun), then light leaving just formed protogalaxies nearthe observable limit of the Universe departed some 13+ billion years agobut this radiation is only now reaching us, since it had to traverseacross a Universe that was expanding (ever increasing distances) anddrawing the protogalaxies away from us. (We actually have detectedcosmic background radiation [see page 20-9], which pervades the entireUniverse, whose first appearance was only about 300,000 years since thebeginning of the B.B. - this is the present longest-term limit to thelookback time involved, thus peering into the past to find the earliestdiscernible event). A distinction must be made between observed andobservable: as will be discussed in detail on pages 20-8 and 20-9,there is strong reason to believe that the real Universe is (much?)larger, but part lies beyond the present limits of observation. As timemoves through the future, the horizon will move into ever more of theultimate Universe.

A corollary: In the Standard Model for the Big Bang, there have been andare parts of the Universe which cannot directly influence each otherbecause there hasn’t been enough time for light from one part to havereached the other. Thus, the ‘horizon’ relative to Earth as theobserving point (but any other position in the Universe is equally asvalid an observing point) refers to the spatial or time limit thatdemarcates between what we can establish contact with in any part of theUniverse and what lies beyond. This figure illustrates an extremeexample of parts that cannot mutually communicate:

Let astronomers look out towards the apparent limits to the “outer”Universe, say at a distance of 13 billion light years, in two oppositedirections. We, at the center of this diagram, would assume that thegalaxies at the opposing edges are 26 billion light years apart. But fora 14 billion year old Universe, and radiation from each set of galaxiestraveling at the speed of light, a signal from one galaxy group wouldnot have had enough time to penetrate well beyond US into the region ofspace on the other side. Thus, there is no (time for) communicationbetween one part of the Universe and various other parts. This is truethroughout a Universe whose dimensions are equivalent to a 28 billionlight-year diameter sphere (not necessarily the real shape of theUniverse, but an adequate means to visualize the collection of objectsin the observable part of the Universe). Within this sphere, there arepockets of space that are not in touch with other pockets. (A pocket ofthe pervasive Cosmic Background Radiation, for example, that coversabout 2° of the sky hemisphere above us on Earth does not interact withradiation beyond it as the Universe continues to expand.)

This seeming paradox is called the “Horizon problem”. Simply stated: howcan these isolated regions have very similar properties (such as similardensities of dark matter, Cosmic Background Radiation, and numbers ofgalaxies) if they are not in contact. This appears to violate thefundamental principle of universal causality, which holds that duringexpansion all parts of the Universe would need to have been incommunication (by light transfer or other means of exchanging energy) sothat the fundamental principles of physics would have ample causalopportunity to influence each other. This is seemingly necessary if at agross scale the Universe is to maintain uniformity (the essence of theCosmological Principle which postulates broad hom*ogeneity andisotropism). One explanation that accounts for the causality needed toobey this Principle is given below in the subsection dealing withInflation.

Nevertheless the isolation of regions of the Universe from one anotheris a real fact, as evident in the above illustration. And, specificallythere were situations whereby some parts of the Universe were not incausal contact shortly after the Big Bang, and thus not visible to oneanother during early cosmic history, but will eventually as expansionproceeds become known to each other. Consider the diagram below:

From J. Silk, The Big Bang, 2nd Ed., © 1989. Reproduced by permission ofW.H. Freeman Co., New York

Start with hypothetical observers at two points A and B not then incontact in early spacetime. Over expansion time, their light cones wouldeventually intersect, allowing each to see (at time t₁) otherparts of the Universe in common but not yet one another. At a latertime, beyond t₂ (“now”) in the future, the horizons of A and B(boundaries of the two light cones) will finally intersect, allowingeach to peer back into the past history of the other.

Commenting further on the Universe’s geometry: One view holds thepresent Universe to be finite but without boundaries; its temporalcharacter is such that it had a discrete beginning but will keep onexisting and growing into the infinite future (unless there issufficient [as yet undiscovered] mass to provide gravitational forcesthat slow the expansion and eventually cause contraction [collapse]). Amuch different model considers the Universe to be infinite in time andspace - it always was and always will be (philosphically, there areconcepts that equate God as an “intellectual presence” distributedthroughout this naturalistic Universe). These and other important ideas- whether the Universe’s shape is analogous to spherical, hyperbolic, orflat; whether it is open or closed, whether it is presently deceleratingor accelerating, and whether it is infinite or finite in time and space- are treated in detail on pages 20-8, 20-9, and 20-10.

By the end of the second quarter of the 20th Century, most models forthe Universe’s behavior considered expansion of some sort as an outcome.Einstein, in particular, showed that any three-dimensional expansionmust also consider the effects of the fourth dimension - time - toaccount for the behaviour of light traveling great distances in a vast“volume” (without known boundaries) making up what we conceive of as“space”. He also deduced that space must be curved (and light and otherradiation will therefore follow curved paths as the shortest distancebetween widely separated points) and would, in his view, expanddynamically in a 4-dimensional spherical geometry (a spacetimedimensionality). (Einstein, at least in his early thinking, alsoconsidered the Universe to be finite and eternal.)

The next figure is a spacetime diagram that summarizes the history ofthe expanding and evolving Universe in terms of what is popularly knowntoday as the general or Standard Big Bang (B.B.) model for itsinception. (It received its descriptive name as a derisive comment fromthe astronomer Fred Hoyle, then precept of expansion, who advocatedinstead a Universe of constant size as described in his Steady Statemodel; variants of this and other models have been put forth, asdescribed on page 20-9). Simply stated, theStandard Big Bang model holds the Universe to have expanded from ainfinitesimally small point. In essence, the Big Bang is the creationevent that started the Universe and determined its ultimate course ofevolution through the state now observed and into its long term (perhapsinfinite) future.

From J. Silk, The Big Bang, 2nd Ed., © 1989. Reproduced by permission ofW.H. Freeman Co., New York

A variation of this figure which gives a summary of energy levels andtemperatures for the evolutionary history of the Universe is too big forthis page. You can access it by clicking here. Notethat most temperatures are expressed in energy equivalents as eV’s orelectron volts (GeV refers to Giga-electron volts). To return to thepresent page, you will need to hit the X button on the upper right ofthe screen that comes up with your browser.

The Big Bang as an expansion theory traces its roots to ideas proposedby A. Friedmann in 1922 to counter ideas attendant to Albert Einstein’sTheory of General Relativity, from which that titan had derived a modelof a static, non-expanding, eternal universe (he eventually abandonedthis model as evidence for expansion was repeatedly verified and herealized his General Relativity proved very germane to the expansionmodels). The Abbe George Lemaitre (a Belgian priest) in 1927 set forthanother expansion model that started with his proposed “Primeval (orPrimordial) Atom”, a hot, dense, very small object that resembles the“singularity”, a term more widely accepted. The nature of a Big Bang wasrefined and embellished by G. Gamow and others in the 1930s. Confirmingevidence for expansion came from Edwin Hubble in the late 1920s. The BigBang can be mentally related to the above-mentioned singularity byimagining that the expansion is run in reverse (like playing a filmbackwards): all materials that now appear as though moving outward (asspace itself expands) would, if reversed in direction, then appear toultimately converge on a “point of origin” that is represented by thesingularity.

As described later in this Section (page 20-9), theB.B. concept drew its principal support from the observations by EdwinHubble and others on radiation redshifts associated with thedistribution of galaxy velocities. The Universe has been enlarging eversince this first abrupt explosion, with space expanding, and galaxiesdrawing apart, so that the size of the knowable part of this vastcollection of galaxies, stars, gases, and dust is now measured inbillions of light years (representing the distances reached by thefastest moving material [near the speed of light] since the moment ofthe Big Bang [14 to 15 billion years ago]). This age or time sinceinception is determined from the Hubble Constant H (which may change itsvalue) which is derived from the slope of a plot of distance (to stellaror galactic sources of light) versus the velocity of each source (seepage 20-9).

Aside from quantum speculation, nothing is really known about the stateof the Universe-to-be just prior to the initiation of the Big Bang (amoment known as the Planck Epoch). The Laws and the 20 or sofundamental parameters or factors that control the observed behavior ofall that is seeable in the Universe become the prevailing reality atthe instant of the Big Bang, but Science cannot as yet account for the“why” of their particular formulation and values, i.e., what controlstheir specifics and could they have come into existence spontaneouslywithout any external originator, the “Creator” or “Designer”. Amongthese conditions that had to be “fine-tuned” just right is this partial,but very significant list: hom*ogeneity and isotropy of the Universe (theCosmological Principle); relative amount of matter and anti-matter; theH/He and H/deuterium ratios; the neutron/proton ratio; the degree ofchaos at the outset; the balance between nuclear attraction and electricrepulsion; the optimal strength of gravity; the decay history of initialparticles; the total number of neutrinos produced early on; the eventualmass density which affects the Critical Density; the specific (butvarying) rates of expansion after the Big Bang; the delicate balancebetween Temperature and Pressure, both during the first moments, andmuch later during star formation; the ability within stars to producecarbon - essential to life; and much more. (See also another list at thebottom of page 20-11a.) Some of these areinterdependent but the important point is that if the observed values ofthese parameters/factors were to differ by small to moderate degrees,the Universe that we live in could almost certainly not have led toconditions that eventually fostered intelligent life capable of evolvingduring the history of the Universe as we know it. (Also presumablynecessary: beings that can attest to the Universe’s existence andproperties by making observations and deductions that lead to knowledgeof the Universe; this requires the eventual appearance of “consciousreasoning” at least at the level conducted by humans on Earth, andperhaps also human-like creatures existing elsewhere in the Universe, -this concept is one of the tenets in what is referred to as the“Anthropic Principle”).

The First Minute of Universe History

At the moment of the Universe’s conception, gravity, matter, and energyall co-existed in some incredibly concentrated form (but capable ofsupporting fields of action) that cannot be adequately duplicated ordefined by experiment on Earth since it requires energy at levels of ata minimum 10¹⁹ GeV (Giga-electron volts; “Giga” refers to abillion; one electron-volt is the energy acquired by a single electronwhen accelerated through a potential drop of one volt; 1 eV = 1.602 x10^-12 ergs); 10¹⁹ GeV is vastly greater than currentlyobtainable on Earth by any controllable process (presently, the upperlimit obtained experimentally in high energy physics labs (with theirlarge particle accelerators and colliders is ~10³ GeV). Bestpostulates consider the singularity (whatever its origin) at thisinstant to be governed by principles underlying quantum mechanics, havemaximum order (zero entropy [see page 20-8]), andbe multidimensional (i.e., greater than the four dimensions - threespatial and one in time - that emerged at the start of spacetime as theBig Bang got underway). Quantum theory does not rule out discrete“things” (some form of energy or matter) to have existed prior to theinception of the Planck Epoch; on the other hand, this existence is notrequired or necessary. But, as implied above and discussed in detail onpage 20-10, “fluctuations” within possible energyfields in a pre-Universe quantum state (an abstract but potentially realcondition that runs counter to philosophical notions of “being”) mayhave been the triggering factor that started the B.B.

This theory allows cosmologists to begin the Universe at a parametercalled the Planck time , given as 10^-43 seconds (what happenedor existed at even earlier time is not knowable with the principles ofphysics developed to this day). At that instant, the Universe must havebeen at least as small at 10^-35 meters - the Planck length(about the same size as a string in superstring theory [see below]). Atthe initiation of the Big Bang, the four fundamental forces (gravity,and the strong [nuclear], weak [radioactivity], and electromagnetic[radiation] forces, referred to collectively as the Superforce) thatheld the Universe together existed momentarily (until about10^-32 sec) in a special physical state that obeyed theconditions imposed by one meaning of the termSymmetry***. During this fraction of asecond interval, gravity then was as strong as the other forces. Itstendency to hold the singularity together had to be overcome by theforce that activated the Big Bang. The onset of fundamental forceseparation may have been tied to the force driving Inflation (seebelow).

But gravity thereafter rapidly decreased in relative strength so thattoday at the atomic scale it is 2 x 10^-39 weaker than theelectrical force between a proton and an electron (according to onerecent theory, gravity remains strong until about 10^-19seconds). However, since the forces between protons (positive) andelectrons (negative) are neutralized (balanced) in ordinary matter, thenow much weaker gravitational forces are the major residual force thatpersists and acts to hold together collective macro-matter (at scaleslarger than atoms, specifically those bodies at rest or in motionsubject to and described by Newton’s Laws; includes those aspects ofmovements of planets, stars, and galaxies that can be treatednon-relativistically). And gravity has the fortunate property of actingover very long distances (decreasing as the inverse square law).Although we think of gravity as the most pervasive force acting withinthe Universe, there is growing evidence that some form of gravity-likeforce also resides within an atom’s nucleus but extends its effects oververy short (atomic scale) distances.

The non-gravity forces that separated from the gravitational force aredescribed by the still developing Grand Unified Theory or GUT, whichseeks to explain how they co-existed. The GUT itself is a subset of theTheory of Everything (TOE) which, when it is finally worked out,will specify a single force or condition (or, metaphysically, a state ofBeing) that describes the situation at the very inception of theUniverse. Thus, TOE unites the gravity field with the quantum fieldwithin the singularity that emerged as separate entities almostinstantaneously at the start of the Big Bang. The TOE speculates on whatmay have existed or happened prior to the Big Bang, based on bothquantum principles and belief that some other type of [pre-Bang] physicsyet to be developed governed the pre-Universe void. At the Planck time,the four fundamental forces are said to be united (the Unified Epoch).The flow chart below (see also the third figure below) specifies themajor components of each of the forces as they are assumed to existafter the first minute of the Big Bang. When unified at the outset ofthe Big Bang, they are presumed to exist in a state shown by the ?(whose nature and properties are still being explored theoretically; atpresent this condition cannot be produced experimentally because of thehuge energies [way beyond present capabilities in laboratories]involved).

One model, now gaining some favor, based on Superstring theory (see lastparagraph on this page) contends that at the first moment of the BigBang (at the 10^-43 sec mark; before which any singularity orother state of existence cannot yet be described by present physics) theUniverse-to-be consisted of 10 dimensions. As the process of theUniverse’s birth starts, six of those dimensions collapse (but presentlyexist on microscales as small as 10^-32 centimeters) and theremaining four (three spatial; one time) enlarged to the Universe oftoday.

The behavior of these forces in the earliest moments of the Big Bang wascritical to the construction and development of the Universe as weperceive it today. Gravity in particular controls the ultimate fate ofthe Universe’s expansion (see below) and formation of stars and galacticclusters. (According to Einsteinian Relativity, gravity, which weintuitively perceive as attractive forces between masses, is afundamental geometric property of spacetime that depends closely on thecurvature of space, such that concentrations of matter can “bend” spaceitself; Einstein and others have predicted the existence ofgravitational waves that interact with matter; see the Preface foradditional treatment). For all its importance, it is surprising thatgravity is by far the weakest of the four primary forces; its role inkeeping macro-matter together and controlling how celestial bodiesmaintain their orbits is just that it becomes the strong,action-at-a-distance force left whenever the other forces areelectrically neutral and have influence only out to very shortdistances.

Between 10^-36 and 10^-33 sec (a minuscule but vitalinterval of time - about a billionth of a trillionth of a trillionthearth seconds - referred to as the Inflationary Stage) a mechanismto explain certain properties of the Universe was first proposed by AlanGuth, then at Princeton University), to explain some aspects of theUniverse [see below]; that were serious difficulties in the StandardModel. The theory holds that the nascent and still minute Universeunderwent a major phase change (probably thermodynamic) in whichrepulsion forces caused a huge exponential increase in the rate ofexpansion of space. Through this brief moment (approximately atrillionth of a trillion of a trillionth [10:sup:-36] of a second),the micro-Universe grew from an infinitesimal size (but still containingall the matter and energy [extremely dense] that was to become theUniverse as it is now) to that of a grapefruit or perhaps even apumpkin. This is an expansion factor that may have been between10⁵⁰ and 10⁷⁸ (this is the range of uncertainty,although some theoreticians choose 10⁵⁰ as the more likelynumber). Or, using another analogy, this is equivalent to increasing thesize of the proton (~10:sup:-13 cm) to roughly the size of a sphere10,000,000 times the Solar System’s diameter (arbitrarily, taken as thedistance from the Sun to the far orbital position of Pluto, or ~5.9 x10⁹ km). This extreme growth determined the eventual spatialcurvature of the present Universe (in the most “popular” model, tendingtowards “flat”). This next diagram illustrates the extreme growth of theincipient Universe during the Inflationary moment (both horizontal andvertical scales are in powers of ten); in the version shown, the BigBang expansion is shown as decelerating over time but a vitalmodification is discussed on page page 20-10.

From Astronomica.org

Within this inflationary period, temperatures dropped drastically.During this critical moment, the physical conditions that led to thepresent Universe were preordained. The driving force behind this huge“leap” in size (which has happened at this extreme rate only once inUniverse history) is postulated by some as a momentary state of gravityas a repulsive (negative) force (perhaps equivalent to Einstein’sonce-defunct Cosmological Constant but in a new form: forces such as theHiggs boson or the postulated “inflaton”) that forced this tremendousexpansion.

The source of the energy that powered Inflation has not been preciselyidentified but the separation of gravitational force from the remainingthree forces (see third diagram below) may have released a huge amountof energy capable of bringing about the repulsion that marks inflation(see paragraphs on page 20-10 that describeEinstein’s Cosmological Constant which depends on a similar repulsiveenergy related to an as yet undiscovered but apparently real “darkenergy”). During the brief inflationary period, different parts of thestill “empty” void (energy existed but the first particles that wouldform matter had not yet appeared and organized) separated at a rategreater than the speed of light - in effect, it was this initialevolving dimensionality or space that was expanding. (Recentdiscoveries indicate that the Universe is now undergoing a second butrelatively much slower rate of accelerating expansion that has turnedaround the post Big Bang gravitationally-mandated deceleration,beginning at some [still undetermined] stage [probably prior to the last7 billion years] of the Universe’s growth; see page 20-10.)

During inflation, as gravity began to act independently, gravitationalwaves were produced that had a critical bearing on the minute but vitalvariations in distribution of temperatures (and matter) in thesubsequent history of the Universe as we know it. As time proceeded,gravity then reverted to the attractive force that took over control offurther expansion. Specifically, a metastable state called the falsevacuum - devoid of matter per se but containing some kind of energy -underwent a decay or phase change by quantum processes to a momentaryenergy density that produces the negative pressure capable of poweringthe inflation. Inflation continues until the false vacuum potential(which starts out as positive when its associated density field iszero), which initiated the expansion, drops to zero (now with a positivefield that has varied in space and time).

Advantages of the Inflationary model are that it sets the stage for the“creation” of matter, it accounts for the apparent “flatness” of theUniverse’s shape, and helps to explain its large-scale hom*ogeneity andisotropy (smoothness). Before the Inflation began this uniformitycondition existed, with the initial conditions in causal contact, andwas subsequently “frozen in” to the Universe by the rapidity ofinflationary expansion. Theory suggests that during inflation, energymay not have been pefectly uniformly distributed, producing narrow zonesof greater concentration called “cosmic strings”. These, during thefollowing slower expansion, served as the irregularities whicheventually led to concentrations of matter that localized into the earlyUniverse structure around which the first galaxies formed.

Inflation also seems to solve the above-mentioned “horizon problem”(recall that horizon refers to the sections of the Universe that arelimited in their interactions [causal contact] by the distances photonscan travel at light speed during the interval of time in which acosmological phenomenon is being considered). This problem is present inthis diagram:

In this diagram parts of the Universe seem to lie outside these horizonlimits. This simple diagram may help to better visualize this:

Such distant parts are not now in contact with one another (do notexchange light signals) and would seem causally independent. But thisisolation, which appears to defy causality, in the Inflation model getsaround this by 1) assuming these and all parts were in contact in thatminiscule fraction of the Universe’s first second before Inflation, andthus 2) had inherited, or “locked in” the co-ordinating physicsunderlying the Universe’s operations that subsequently preserved generaluniformity as the Universe went through its huge inflationary expansion.

A good summary of the essence and history of Inflation is at a Web siteprepared by JohnGribbin.

Although theoretical calculations and certain experiments seem to beconfirming the essential points in the Inflation model, not everycosmoscientist has come to accept this innovative explanation of theearliest moments of the Universe and the consequences of its subsequenthistory that inflation seems to predict. In the past few years, somehave turned their attention to alternate models. Most striking in itsdeparture is the Varying speed of Light (VSL) model first espoused byDr. Joao Magueijo in 1995, who later joined forces with Dr. AndreasAlbrecht when they collaborated at the Imperial College in London. Theessence of VSL is that during roughly the same time in the first B.B.second that Inflation would have operated, at this earliest moment theintense energy being release would cause the speed of light to begreater than today’s value. That speed, ever decreasing, would thenconverge on the now constant value today, thus meeting Einstein’sfundamental posit that this speed is constant. Magueijo and Albrechthave calculated that this phenomenon of rapidly dropping speed in theseearly instances can produce most of the same outcomes that the spatialexpansion of Inflation leads to. Initially largely rejected by hiscolleagues, recent observations of possible light speed changes in thepost B.B. Universe, if confirmed, have refocused attention on VSL. LikeInflation, VSL remains hard to prove since its essential characteristicsoccur under physical conditions that are still near-impossible toduplicate experimentally. Stay tuned.

Returning to the progression of physical events after Inflation butwithin the first minute of the B.B.: As described above, during thefirst fraction of a second following the Planck moment incredible eventsunfolded in rapid succession that led to release of kinetic energy thatpowered the Universe’s development and created the initial stages ofradiation. From the radiation associated with this energy, matter wasformed (an E = mc² transformation)(in the first minute some ofthe matter decayed back into radiation, releasing neutrinos and otherparticles). These primitive forms of matter rapidly organized into amyriad of elementary particles. They fall into two broad classes:

I) the *FERMIONS*: all particles with quantum spins of 1/2 of oddwhole numbers such as 1, 3, 5 (includes protons, electrons, neutrons);they all obey the Pauli Exclusion Principle which states that no twodifferent particles can have the same values of the four quantumnumbers. Fermions can be divided into subgroups: 1) the heavierHadrons (minute particles, consisting of certain quark combinationsheld together by gluons permitting strong interactions within atomicnuclei), further subdivided into (a) the Baryons (combinations ofthree quarks [see 4th paragraph below on this page] that include thefamiliar protons and neutrons (each about 10^-13 cm in size[compared with diameters on the order of 10^-8 cm for theclassical Bohr atom]) and (b) the Mesons (short-lived heavierparticles) families, and 2) the Leptons, even tinier discreteparticles that are weakly interacting (that are represented byelectrons, tauons, muons, and three types of neutrinos(electron-neutrino; tau-neutrino; muon-neutrino; the discovery of thelatter two imply that the neutrino may have a small mass, and if provedcould account for some of the missing matter in the Universe talkedabout later in this Section), and

II) *BOSONS*, the force carrying messenger particles; these haveunit [1] spins. Best known of the bosons are the 1) photons (whichhave zero rest mass) that are quanta ****of radiant energy responsible for electromagnetic (EM) forces whichtravel at light speed as oscillatory (sinusoidal) waves and 2) thegluons that bind the nucleus by mitigating against the strongrepelling forces therein. A boson that theory says exists, but as yethas not been “found” is 3) the graviton, which transfers the forceof gravity (also, at the speed of light).

Much of the above information is summarized in the chart below. Thisclassification of particles and their interactions is an integral partof the Standard Model for the ways in which matter is put together,which applies to any Big Bang scenario (without the refinements ofInflation) that leads to a broadly hom*ogeneous, isotropic large-scaleUniverse and is an acceptable summary of what is verifiably known nowabout the origin of matter and energy (with the caveat that the model issubject to continual modification or revision).

Illustration produced by AAAS, taken from The Economist, Oct. 7-12,2000, p. 96

In this classification, the major entities are the fermions composed ofquarks (elementary particles with fractional charge that compriseprotons, neutrons, and mesons), the leptons (including the electron),and the bosons, force particles with finite (but very small) mass. Thegray field containing the quarks is the Baryon group. The quarkparticles have generally been discovered and proved to exist from highenergy physics experiments using particle accelerators.

A variant of this classification, which arranges the mass and forceparticles according to measured or estimated mass of each type ofparticle is shown below. The chart emphasizes the growing belief thatmass itself is governed by the relative contribution from the HiggsBoson.

From The Dawn of Physics Beyond the Standard Model, by Gordon Kane,Scientific American, June 2003

Quarks were the first (sub)particles to form during the early moments ofthe first minute. The nomenclature for the 6 quarks (of which there aresix types or “flavors” [up, strange, etc. each subject to variants or“colors” ; various combinations of quarks give rise to the differentnucleons) are descriptive terms for convenience and carry no specialphysical significance. Quarks have a baryon number of +1/3, chargenumbers of +2/3(up) and -1/3(down), and a spin quantum number of 1/2.The two baryons familiar to most are made of three quarks: the protonconsists of two up (each +2/3) and one down quark (-1/3) for a netcharge of 1; the neutron two down and one up quark, for a net chargeof 0 (zero). Mesons contain only two quarks. As a visual aid, this issummarized in this diagram:

|Quark components of protons, neutrons, and mesons. |

Quarks also can have a reverse sign, thus they can organize intoanti-protons and anti-neutrons. Other combinations of quarks lead tomore exotic particles; one group includes mesons, which include memberssuch as the pion Π^-, consisting of an anti-up quark (-u) and a(d) quark and the kaon K⁺ made up of a (u) and an (-s) quark.

The leptons have much smaller masses and are single particles (notcontaining the quark subparticles). They are not influenced by thestrong nuclear force but can interact through the weak nuclear force.Three of the leptons (upper row) are neutrinos which have extraordinarypenetrating power (one can pass through the entire Earth withoutinteracting or changing); once thought to be massless, evidence nowsuggests a very small mass.

The force particles (bosons) are involved with the individualfundamental forces mentioned above. For example, the gluon holds thenucleus of baryons together; z and w bosons control the weak nuclearforce; photons are the force carriers that are associated withelectromagnetic radiation; gravitons transmit the force of gravity. TheHiggs boson has not yet actually been proved to exist (but from theoryis considered almost certainly to be real); recent experiments in aEuropean supercollider may have witnessed a few genuine Higgs particlesbut confirmation will likely await several new supercolliders capable ofmuch higher energies due to come on line before the end of the firstdecade in 2000. The Higgs boson is considered to be the force particlethat accounts for mass in the fundamental particles that have thatproperty.

The Standard Model, when examined rigorously, is now considered only anapproximation to full reality in subatomic physics. It fails, forexample, to explain and integrate gravity. Theoreticians believe thatgravity must have its own boson which they have named the graviton.Although it most likely exists in some form, its actuality has yet to beproved. It has not been found during any of the current particleaccelerator experiments (which are also looking for the Higgs boson).

Now, returning to the events of the first minute: By ~10^-39 secthere was a fundamental symmetry break that brought on a split betweenthe GUT forces and the other fundamental force known as gravity,dependent on the graviton (an infinitesimal particle which has yet tobe “discovered” or verified by physicists). The history (pattern) offorce dissociation during the first second is depicted in thisillustration:

From The Left Hand of Creation, J. Barrow and J. Silk, 1993, OxfordPress

At 10^-35 second there was a further split of non-gravitationalforces into the strong and the electroweak (combination of weak andelectromagnetic) forces; the electroweak pairing then separated intotoday’s EM and weak forces at about 10^-10 sec. From10^-35 to 10^-6 sec, matter consisted of the subatomicparticles known as quarks (Quark Era), and their binding particles,the gluons, present but not yet involved in producing nucleons (protons,neutrons). Temperatures were still too high (10:sup:28 °K) to fosterquark organization into these nucleons. By the start of this interval,at the time when energy levels dropped to about 10^-16 GeV, theGUT state underwent dissociation into the strong nuclear force (bindingnuclei) and the electroweak force (itself an interactive composite ofthe electromagnetic and weak forces). At about 10^-9 sec, bywhich time temperatures had fallen to ~10¹⁵ K, the weak nuclearforce (involved in radioactive decay) and the electromagnetic (EM) force(associated with photon radiation) separated and began to operateindependently. Then, by 10^-6 seconds, the six fundamentalquarks had organized in combinations of 2 or 3 into hadrons during thebrief Hadron Era.. Protons formed by this time remained stable butsome neutrons produced later experienced decay into protons andelectrons. This Era was followed at 10^-4 seconds, lasting up toone second or so, by the emergence of electrons, neutrinos and otherleptons (Lepton Era). Thus, prior to 10^-6 seconds, quarkshad formed almost exclusively, but by the end of the first second oftime they were greatly reduced in number as free (unorganized)particles, even as hadrons, leptons (especially neutrinos) and photons(the particle carriers of electromagnetic energy) were becoming thedominant products despite extensive electron-positron andbaryon-antibaryon annihilation. As electrons emerged, some reacted withprotons to form neutrons, releasing neutrinos. From this point on, theratio of baryons to photons is 1 to a billion (a similar number holdsfor the ratio of baryons to neutrinos).

From the GUT stage onward, both matter and antimatter were being created(baryogenesis). By 10^-4 sec both quark particles andantiparticles (with opposite charges, e.g., at the lepton level ananti-electron or positron would have a + charge) that had earliercoexisted had now interacted by mutual annihilation. Neutrinos andantineutrinos released by proton-electron reactions also experiencedthis destruction. So, at this moment only a residue of elementaryparticles survived - (almost?) all antiparticles apparently werecompletely wiped out leaving only some of the numerically larger amountsof particles. Annihilation is an extremely efficient process forreleasing the maximum amount of energy when positrons and electrons meet- destruction of a pair generates 10⁶ electron volts. Duringthe annihilation phase, a great quantity of high energy gamma rayradiation and other energetic photons produced from the interactionscomes to dominate the particles in the incipient Universe.

By 10^-3 seconds, the temperature had now dropped to10¹⁴ K and the proto-Universe had a diameter roughly the sizeof our present Solar System. In the next few seconds, temperaturesdropped below a level where further antiparticle production took placein abundance. The particles making up the Universe today represent theexcess over the few surviving antiparticles. Most of the latter wouldhave concentrated in near empty space outside any cluster of matter(stars, galaxies, gas clouds, etc.) - if antiparticles still co-exist insignificant amounts with the particles we deal with on Earth or in thedenser cosmic world, the effects of destruction might be detectable; noevidence that this is going on to a noticeable degree has been found.

At the 1 second stage, the Universe had already expanded***** to a diameter of about 1 to 10light years even as its density had decreased to ~10 kg/cc [kilogramsper cubic centimeter], and its temperature had dropped to about10¹⁰ K. By this time all the fundamental particles (essentialmatter) now in the Universe had be created, largely from the vastquantities of photons (energy “fuel”) released during the first second.As of the first minute, about 1 free neutron existed for every sixprotons, although all of these neutrons would eventually combine withprotons in isotopes and heavier elements. The general excess of protonspersisted, making those hydrogen atom nuclei then and still the mostprominent atomic species in the Universe. Neutrinos by now had appearedin abundance as the energy released when protons combined withelectrons. These thereafter were decoupled from other matter.

The search goes on for convincing proof of the full nature of theneutrinos that are often the energy particle released from weak forcenuclear reactions that took place at very high temperatures. They areabundant today (~100 million of them for every atom in the Universe),with most coming from production during the first minute, and some fromstellar reactions. Being without charge (and with an energy of 0.001 eV)and massless or nearly so, these particles do not readily interact withmatter. They pass easily through your body, or even through the entireEarth, because the likelihood of collisions is very small. They are thusvery hard to detect (and thus prove their existence); elaborateexperiments using huge tanks containing water or other hydrogencompounds have so far recorded only a few possible neutrinointeractions. However, they are important in the high temperatureprocesses of the initial minutes of the Big Bang because they arefactors in some of the possible reactions, especially in the formationof helium, and thus helped to determine the relative abundances of H,He, Li, and Be - those elements that mark the initial composition of thematerial Universe.

Much of what is known about events, conditions, and sequences during thefirst minute of the Universe has been surmised from theoreticalhypotheses and calculations. Experimental verification, particularlyduring the earlier moments in this critical minute, has been limitedbecause, as they were taking place, the energies involved were huge -well beyond the capabilities of even the most powerful particleaccelerators and other means of directly observing particle behavior.However, in February, 2000 an announcement from CERN in Geneva claims(as yet unverified by other labs) to have reproduced conditionsequivalent to the first microsecond (10:sup:-6 sec) of the Big Bang.Accelerators hurled lead atoms in a beam that struck lead or goldtargets at tremendous velocities. Momentarily, temperatures at thecollision point reached 100,000 times that of the Sun’s interior (~1.5billion °C), at which the physicists interpreting the experiment believethe plasma emanating from the contact zone was composed, for a verybrief instant, of quarks and gluons. These quickly combined intoprotons, neutrons, and electrons as the heated material dissipated. Newcolliders, generating at least 10 times more energy, will be coming online by 2000 and subsequent years, so that relevant new experiments willlikely confirm the theoretical models that describe the history of thelater part of the first minute. Energies comparable to those extantduring the first moments are so great that no appropriate experimentalsetup is feasible for the foreseeable future, and may never beattainable in physics labs on Earth.

We close this part of the page by commenting on some other topics in BigBang expansion. Newer models treating aspects of the physics andmechanisms of expansion during the first fraction of a second of the BigBang have been proposed (see below) and the theory behind each iscurrently being tested experimentally. We will cite and briefly describethree of the most intriguing at the moment, but will forego any in-depthexplanation:

1) Primordial Chaos: which postulates that in the earliest stages ofthe Big Bang the distribution and behavior of matter and energy in theincipient Universe was notably disordered and inhom*ogeneous, irregular,and turbulent, with variations in temperature and other scalar(non-directional) properties, anisostropic expansion rates, and otherdisturbances in the initial conditions within various parts of therapidly changing microverse (a variant, called the Mixmaster model,considers the expansion to oscillate into a few momentary contractionsat the outset); as the Universe grew both during Inflation andafterwards, these irregularities were smoothed out, leading to the grossisotropy of the present Universe; one version assumes a cold rather thanvery hot initial state;

2) Supersymmetry: a symmetry property which states that for everyfermion (quantum spin of 1/2) there must be a correspondingforce-carrying boson (quantum spin of 1), called a sparticle of theappropriate kind; likewise each boson has a corresponding fermionsparticle; thus, in this model the number of particles is doubled; theconcept predicts that there must be some subatomic particles still to bediscovered if this pairing is valid); it also aids in simplifying thebroken symmetry problems that beset the Standard Model; and

3) Extra Dimensions : such as those associated with Superstringtheory; (last paragraph).

Big Bang Eras after the First Minute¶

The extremely hot, dense “soup” of matter and energy that began in thefirst minute is often described as the “primeval fireball”. It has beenlikened to something akin to a thermonuclear fusion event, yielding adetonation-like release of energy on a grandiose scale that is justhinted at by a hydrogen bomb’s explosion. This is a misnomer becausehydrogen atoms did not exist as such in the early Universe. The energyrelease would not be visible (such radiation is characteristic of muchlower temperature processes) but the fireball “glow” would radiate atvery short wavelengths (gamma rays among them). This so-called invisiblefireball cooled as the Universe expanded. Its existence is equated withthat of the Cosmic Background Radiation, the remnant of the initial (andsmall) ‘fireball’ consisting of the radiation and matter of the firsteras.

Over the next 10 to 100 seconds after the first minute, during the firststage of the Nucleosynthesis Epoch, the predominant process was theproduction of stable nuclei (nucleons) of hydrogen and helium. Some ofthe protons (p:sup:+) and electrons (e:sup:-) that survived initialannihilation combined to produce new neutrons (n) by weak forceinteractions, which added to the supply of remaining hadronic neutrons.During this stage, at first the dominant atomic nucleus was just asingle proton (hydrogen of A=1). The basic fusion processes that formedhydrogen and helium isotopes are shown in this diagram:

As temperatures dropped below 10⁹ °K (at ~ 3 minutes), some ofthe neutrons started combining with available protons (hydrogen nuclei)to form deuterons (heavy hydrogen or H² nuclei) plus gamma (γ)rays (resulting from the conservation of the binding energy released inthe reaction). When a neutron is captured at lower temperatures, theassemblage is a deuterium atom (presently, ~1 such atom per 30000hydrogen atoms is the survival ratio; since deuterium is not produced inmost stars, the deuterium we find on Earth [isolated from heavy watermolecules] is thought to be a remnant from the first seconds of the BigBang); the amount detected provides a good theoretical control on thenuclear processes acting during the early Big Bang. A much smallerfraction of the deuterium can capture a second neutron to form the moreunstable H³ or tritium.

Reaction between a deuteron and and a proton can produce helium(He:sup:3). The much more abundant He⁴ (two protons; twoneutrons) is generated in several ways: by reactions between twodeuterons, between H³ and a proton (rare), between He³and a neutron, or between two He³ nuclei plus a releasedproton. Two other elements are also nucleosynthesized in this earlystage in very small quantities: Lithium (Li; 3 protons; 4 neutrons):He⁴ + H³ –> Li⁷ + γ and Beryllium (Be; 4protons + 3 neutrons): He⁴ + He⁴ –> Be⁸ +e^- (under the still high temperatures during nucleosynthesis,most of this highly unstable Be decays to Li). The general time line forformation of these elements during primary nucleosynthesis appears inthis next diagram which plots mass numbers of the primordial isotopes.In it, the abundance of the hydrogen proton is arbitrarily set at 1 - itis set to remain constant in the ensuing processes in which the othernucleons develop as temperatures drop in the relative abundances shown.

From Astronomica.org

Elements with higher atomic numbers (Z) are not produced at all duringthis initial nucleosynthesis because of energy barriers at Z = 5 (boron)and Z = 8 (oxygen); also the statistical probability of two nucleons ofjust the right kind meeting is quite low. This stability gap is overcomein stars by the fusion of 3 He⁴ nuclei into a singleC¹² nucleus. The higher atomic number elements through iron arecreated in more massive stars as they contract and experience risingtemperatures by a complexity of fusion processes such as helium nucleicapture, proton capture, and reactions between resulting higher N nucleithemselves. Elements with atomic numbers higher than iron are producedlargely by neutron capture processes. (See page 20-7 for more details onthese various processes.)

Thus, this brief era witnessed the synthesis of the primordial nuclearconstituents – ~90% hydrogen/deuterium and 10% helium by numbers ofparticles and 75-25% by mass – that make up the two elementssubsequently dominating the Universe, along with minute amounts oflithium and boron. Most helium was produced at this early time, butyounger helium is also the product of hydrogen burning in stars; theratio of He/H has remained nearly constant because about as much new Heis then created in star fusion as is converted to heavier elementsduring stellar evolution. The hydrogen and helium nuclei generated inthis critical time span of the original nucleosynthesis later became thebasic building materials for stars, which in turn are the sites of theinternal stellar nucleosynthesis (fusion) that eventually spawned theelements with atomic numbers (symbol = Z, whose value is the uniquenumber of protons in the nucleus of a given element) up to 26 (Fe oriron); these account for the dominant elements, in terms of both massand frequency, in the Universe (elements with Z > 26 are produced inother ways that require energy input rather than release [as occurs forelements of Z < 26], as described later). (More about the creation[formation] of the heavier elements is covered on page20-7.)

(An astounding fact, worthy of prominent insertion at this point: Thevast majority of the hydrogen atoms in your body and mine, present ashydrogen-bearing substances, including water and various organiccompounds, throughout the Earth [and extrapolated in scale up to thefull content of the Universe] is primordial, that is, consists of thesame individual protons that formed in the first minute of the Big Bangand then the nucleons of H during nucleosynthesis and the H atoms[single electron] soon thereafter. The additional elements in ourbodies, O, C, N, Ca, Na, Mg, K, Al, Fe and others, were generatedexclusively in stars, as we shall see later. We therefore consist oftruly old matter, billions of years in age, and are in a sense“immortal” or “eternal”. Although seemingly far-fetched, some of anindividual’s atoms can conceivably end up in another human’s body -reincarnation of sorts - as atoms released during decay may migrate intothe food chain [although actual tracing of specific atoms through thetransferrence is next to impossible]; or a more direct path bycannabalism is an alternative means.)

As the fireball subsided with continuing Universe expansion, the matterproduced was dispersed in a still very dense “soup” of predominantlyx-ray photon radiation along with neutrinos plus nucleons and otherelementary particles (this mix of radiation, ionized H and He nuclei,and free electrons is called a plasma). The time that lasted from afterthe first few minutes to about 300,000 years (cosmic time, i.e., sincethe moment of the Big Bang) is known as the Radiation Era (connotingthe dominance of electromagnetic radiation). As expansion proceeded, themass-equivalent radiation density (E = mc² equivalency)decreased as mass density increased (today, mass density significantlyexceeds radiation energy density even though the number of photons ismuch larger [in a ratio of ~1 billion photons to every baryon]). Matterbegan to dominate after ~10000 years but temperatures remained too hotfor electrons to combine with nuclei. The Universe during this stage wasopaque (in the sense that no visible light passes from one point to thenext) because even with decreasing photon density detectable radiationat these wavelengths was prevented from traversing or leaving the stillenlarging fireball’s confines owing to internal scattering by freeelectrons.

This era of first opaqueness ended roughly 300,000 years after the BigBang (some recent estimates put this termination at closer to 500,000years after the B.B.) with the onset of the Decoupling Era, at whichstage cooling had dropped below 4,000° K, allowing protons and heliumnuclei to combine with electrons forming stable hydrogen and heliumatoms - a process known as Recombination). As this era began, theUniverse was about 1/200th its present size. Thereafter for a time, theextreme decrease in numbers of free electrons (today there are about onefree proton and electron for every 100,000 atoms) drastically reducedscattering (not by direct collision as occurs when sunlight hits dustbut by close interaction between the photon and electron or protonfields).

This atomic hydrogen absorbs radiation at various wavelengths. In thevisible, for example, the Universe would appear as though it consistedprimarily of a dark fog. For about 500,000 years more, this hydrogenacted as a kind of atomic “fog” which still kept the Universe opaque(often referred to as a cosmic Dark Age). At this time, any radiationwithin the fog would have extended into the ultraviolet. A glow would beapparent at those wavelengths, since at that time the Cosmic BackgroundRadiation would give off UV light as it continued to redshift (see page20-9) from preceding shorter wavelengths enroute to its present-daymicrowave emission wavelengths brought on by continuing expansion ofspace.

Then, as the first stars and protogalaxies began to develop, theirstrong outputs of electromagnetic radiation caused a Re-ionization(removal of electrons) of the hydrogen that increased to the extent thatthe earlier opaque (at visible wavelengths) Universe now became ratherrapidly transparent to radiation spanning those wavelengths. Thisallowed visible light photons to pass through interstellar space, whichis an almost perfect vacuum, and by itself is black, i.e., does not giveoff luminous self-radiation but does contain very low densities ofphotons and other particles (about 3 atoms per cubic meter). Thistransparency facilitates free passage from external sources of visiblewavelengths within any region of the Universe. (Evidence for thisre-ionization has been found so far not from visible light but by usingUV radiation to “see” quasars that formed in this period). Thus, asstars and galaxies began to form, their thermal and other energy outputswould ionize the interstellar hydrogen, allowing their light to appearas now detectable in the visible range, so that the Universe at thisstage started to show the stars as individuals and clusters. This didnot happen “all at once” but gradually as galaxies formed and made theirregions transparent; thus “holes” appeared intermittently in the opaqueearly Universe letting light from the reionizing process in galacticneighborhoods begin to spread through their surroundings as theopaqueness progressively dissipated.

The Decoupling Era is estimated to have lasted to perhaps as long as thefirst million years, although most of the baryon-lepton recombinationtook place in the beginning years. The end of the Decoupling Era wasthus the end of the Dark Ages in Cosmology. As we will see in the nextpage, during this period conditions turned favorable for the theclustering of matter (slight increases in density) that eventually gaverise to the organization of galaxies.

Let us summarize the above ideas, plus several introduced in the nextpages, with two diagrams. The first is a variant of the above Silkdiagram for the development of the Universe after the Big Bang, as seenhere:

The second has been produced on one of the Websites mentioned in thePreface, the 21st Century Science course developed by Dr. J. Schombert.Labeled on his site “The Birth of the Universe”, it serves to summarizemuch of what has been already introduced on this page, but introducesthe idea that Black Holes may have form at the very moment of inceptionof matter. Black Holes (in this Section often abbreviated “B.H.”) areubiquitous objects found mostly within galaxies (but some may exist inintergalactic space). They are extremely dense, so much so that theirextraordinarily intense gravitational pull prevents radiation fromescaping them (exception: Hawking radiation) but also causes materialaround them to be pulled into them, commonly generating huge amounts ofenergy release that can be detected over the entire spectrum. They rangein size from very small (centimeters) to sizes on planetary scales(these latter are referred to as Supermassive B.H.’s. Black Holescommmonly form from ultimate collapse of very massive stars. Black Holesplay an important - perhaps critical - role in getting galaxies startedand are thought to lie in the central region of most (possibly all)galaxies.

Three additional comments are appropriate here, now that the above ideashave given you a background understanding within which they becomerelevant:

First, The terms “mass density” and “energy density” have appearedseveral times in the above paragraphs. In the initial moments of theUniverse, radiation energy density was dominant. By the timetemperatures had fallen to ~10000 °K, when the Universe was about1/10000 its present size, radiation mass density (remember the E =mc² equivalency) became about equal to matter density. Afterthe first second or so, the mass density has come to exceed radiationdensity, despite the aforementioned preponderance of photons overhadrons and leptons.

Second, some recent hypotheses contained in the concepts of Hyperspaceconsider the Universe at the Planck time to have consisted of 10dimensions [other models begin with as many as 23 dimensions but thesereduce to fewer dimensions owing to symmetry and other factors]; thechief advantage of this multidimensionality lies in its mathematical“elegance” which helps to simplify and unify the relevant equations ofphysics. As the Big Bang then commenced, this general dimensionalitysplit into the 4 dimensions of the extant macro-Universe that underwentexpansion and 6 dimensions that simultaneously collapsed into quantumspace realms having dimensions of around 10^-32 centimeters insize. This rather abstruse concept is explored in depth in the bookHyperspace by Michio Kaku (Anchor Books).

The third comment considers that the physical entities that make up bothmatter and energy may be smaller than quarks and leptons; these areknown as superstrings - one dimensional subparticles that vibrate atdifferent frequencies and combine in various ways (straight to looped;in bundles) to then make up the many different fundamental particles.Each species of particle has its characteristic vibrational frequency orharmonic) that are now known to exist or can be reasonably postulated.Proof of superstrings existence has yet been to be verified but theoryfavors their existence and they are consistent with quantum physics.Superstrings account for the ultimate makeup of particles that areobvious to us as the inhabitants of 3-dimensional space. In addition tothe 4th dimension, time, superstrings are tied to 6 more curleddimensions whose spatial arrangement around a particle is expressed by acurvature of radius R (probably very small but one recent model allows Rto be up to 1 millimeter). Superstrings therefore exist in hyperspace.If superstring theory proves to be valid, it will be one of the greatestachievement ever in physics. It is currently the most promising way toreconcile quantum theory and relativity. A more recent variant accountsfor the graviton and contributes to an explanation of the role ofgravity, the pervasive but weak force that is critical to thedevelopment and maintenance of our Universe. This is the so-calledM-theory (M stands for multidimensional “membranes” (commonly spoken ofas “branes” by superstring theorists). This theory postulates an 11thdimension (the membrane); when added to the dimensional mix, the resultpermits gravitons to fit in the general picture. An outstanding reviewof what is known or surmised about superstrings, in the context of itsimportance to Cosmology, has been summarized in a book (which reachedbest seller status) by Brian Greene, The Elegant Universe, 1999, W.W.Norton & Co.)

Note to reader: These next paragraphs were added to this first page onNovember 1, 2002: Before proceeding to the second page (coveringGalaxies), it seems advantageous to give you a broader framework at theoutset that describes a General Model for the SpaceTime expansion of theUniverse that has continued after the first eras of the Big Bang. Thisand related subjects are considered in more detail on page 20-8, 20-9,and 20-10. Because of the length of this synopsis, you are given theoption of skipping it by going directly to page 20-2 (click on Nextbelow) or if you wish to build up this background now, you can access itat page 20-1a.

:sub:`` <>`__*A measure of cosmic distance to any object beyond ourSun is the light year [l.y.], defined as the distance [~ 9.46 x10<sup>12</sup> or 9,460,000,000,000 km or ~5.9 trillion miles] traveledby a photon moving at the speed of light [2.998.. x 10<sup>8</sup> m/sec,usually rounded off and expressed as 300,000 km/sec] during a journey of1 Earth year; another distance parameter is the parsec, which is thedistance traversed in 3.3 l.y.) The parts of the Universe now visibleare thought to be a region within a (possibly much) larger Universe ofmatter and energy, with light from these portions beyond the detectablelimits having not yet arrived at Earth.`

:sub:`` <>`__** It is often difficult to find a clear definition ofthe term “space” in most textbooks (just look for the word in theirindex - it is almost always absent). We tend to think first of the “outthere” that has been reached and explored by unmanned probes and byastronauts as the “space” of interest. One definition recentlyencountered describes space as ‘the dimensionality that is characterizedby containing the universal gravity field’. The writer (NMS) has triedto think up a more general definition. It goes like this: Space is thetotality of that entity that contains all real particles ofmatter/energy, both dispersed and concentrated (in star and galaxyclots), which fill and are confined to spatial dimensions that appear tobe changing (enlarging) with time. Anything one can conceive that liesoutside this has no meaning in terms of a geometric framework but can beconceptualized by the word “void” which in the quantum world ishypothesized as occupied by virtual particles capable of creating newmatter and space if a fluctuation succeeds in making a (or perhaps many)new Universe(s).`

:sub:`` <>`__*** Symmetry in everyday experience relates togeometric or spatial distribution of points of reference on a body thatrepeat systematically when the body is subjected to specific regularmovements. When rotated, translated, or reversed as a reflection, thepoints after a certain amount of movement are repeated in their samerelative positions (e.g., a cube rotated 360° around an axis passingthrough the centers of two opposing faces will repeat the squareinitially facing the observer four times [90° increments} as it returnsto its initial position). The concept of symmetry as applied tosubatomic physics has other, although related, meanings that depend onconservation laws as well as relevance to spatial patterns. In generalterms, this mode of symmetry refers to any quantity that remainsunchanged (invariant) during a transformation. Implied are thepossibilities of particle equivalency and interchangeability (the term“shuffled” may be used to refer such shifts). Expressed mathematically,certain fundamental equations are symmetrical if they remain unchangedafter their components (terms) are shuffled or rotated. In quantummechanics, gauge (Yang-Mills) symmetry involves invariance when thethree non-gravitational forces (as a system) undergo allowable shifts inthe values of the force charges. At the subatomic level in the firstmoments of the Big Bang, symmetry is applied to a state in which thefundamental forces and their corresponding particles are combined,interchangeable, and equivalent; during this brief time, particles can“convert” into one another, e.g., hadrons in leptons or vice versa. Whenthis symmetry is “broken”, after the GUT state, the forces and theircorresponding particles become separate and distinct.`

The progressive breaking of symmetry during the first minute of the BigBang has been likened (analogous) to crystallization of a magma (igneousrock) by the process of differentiation. At some temperature (range), acrystal of a mineral with a certain composition precipitates out; if itcan leave the fluid magma (crystal settling), the remaining magma haschanged in composition. At a lower temperature, a second mineral speciescrystallizes, further altering the magma composition. When the lastmineral species crystallizes, at still lower temperatures, the magma isnow solidified. All the minerals that crystallized remain, each with itsown composition. In the Big Bang, as temperatures fall, differentfundamental particles become released, altering the energy state of theinitial mix, as specific temperatures are reached (and at differenttimes) until the final result is the appearance of all these particles,which as the Universe further expands and cools become bound in specificarrangements (e.g., neutrons and protons forming H and He nuclei; laterpicking up electrons to convert to atoms) that ultimately reorganize instars, galaxies, and the inter- and intra-galactic medium of near emptyspace.

:sub:`` <>`__**** Energy can be said to be quantized, that is, isassociated with quanta (singular, quantum) which are discrete particleshaving different units of energy (E) whose values are given by thePlanck equation E = hc/λ where h = Planck’s constant, c = speed of light(~300,000 km/sec), and λ = the wavelength of the radiation wave for theparticular energy state of the quantum being considered; the energyvalues vary with λ as positioned on the electromagnetic spectrum (a plotof continuously varying wavelengths).`

:sub:`` <>`__***** This extremely rapid enlargement reflects theearlier influence of inflation with its initially higher expansionrates. Keep in mind that many of the parametric values cited incosmological research are current estimates or approximations that maychange as new data are acquired and/or depend on the particularcosmological model being used (e.g., standard versus inflationary BigBang models). Among these, the most sought-after parameter is H, theHubble Constant (discussed later in this review), being one of the primegoals for observations from the Hubble Space Telescope`.

Primary Author: Nicholas M. Short, Sr. email:nmshort@nationi.net