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ASTRONOMY AND COSMOLOGY:

The Description, Origin, and Development of the Universe

DISCLAIMER

At the outset of this Section the writer (N.M. Short) wishes to let the reader know that I am

not an astronomer or cosmologist by profession. But as a geologist I do have enough

background in Science to have taught myself nearly everything you will encounter in thisSection. There are probably errors or misconceptions - if you discover any, I'd appreciate

your contacting me through my email.

Preparing this Section has been a revelation - almost a life-changing experience. It has

given me a profound philosophic comprehension of the most intimate nature of existence

itself. I am now constantly revising my understanding of what all beings, life, and myself

are all about. Night after night, as I prepare for sleep, I keep asking myself two deep

questions: How do we fit into this vast Universe, and why is it there at all? As I approach

my end (at this writing 82 and in poor health), I am discovering renewed hope that answers

will be found in an afterlife. For those who read through the Section, I trust you will

re-examine your outlook based on realizing your place in the grand scheme of things.

More than 10 years after I began this Section, I purchased a Cosmology DVD course

available from The Teaching Company, which specializes in providing college level courses

covering almost all areas of knowledge. The course is conducted by Dr. Mark Whittle, a

Professor at the University of Virginia. It is an extraordinary offering which thoroughly and

clearly surveys the entire field. It is my hope to be able to incorporate ideas and material

from this course into this Section, thereby revising it by modifying and expanding the

content.

Note: 1) Most of the pages in this Section are image-intensive, so that the large number of

illustrations can lead to a lengthy download time for those using modems connected to

telephone lines; 2) Some parts or ideas presented in this Section may seem repetitious, i.e.,

are stated more than once; some of this reiteration is deliberate - much of the topics

covered tend to be complex and unfamiliar to the non-specialist reader (those who are not

astronomers, cosmologists, physicists), so that repeating is a helpful aid in reminding one

of these previously developed ideas and tying them (making them relevant) to the other

subjects where they later appear.

te Sensing Tutorial Page Section 20-1 http://rst.gsfc.nasa.gov/Sect20

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There will be no individual page summaries in Section 20 which deals with Cosmology: The Origin,

Composition, Structure, Development, and History of the Universe (or Universes, if there are more

than one). This is largely because of the complexity and wide range of ideas on each page: this

does not lend itself easily to synopsize. The reader instead should work through the knowledge

imparted on each page without the aid of a preview or reduction to a simplified digest. If the field is

new to you, several readings of this Section may be needed to facilitate mastery of this ultimate

subject: the Origin of Everything. Also, if a novice, you should profit from working through the

excellent online "textbook" in Astronomy prepared by Dr. J. Schombert at the University of Oregon,

which have been referenced in the Preface . In keeping with the Overview and the 20 Sections that

have followed, every illustration will be accompanied by a synoptic caption.Despite this absence of

page summaries, we will attempt to abridge the overall ideas underlying Astronomy and Cosmology

in this synopsis shown in green:

ASTRONOMY deals mainly with the description of the objects, materials, structure, and distribution

of everything that appears to exist beyond the Earth itself.COSMOLOGY deals with the origin,

development, and future expectations of/for the Universe Thus, Astronomy is mostly concerned

with the "what" and "where" whereas Cosmology is more concerned on the "how" and "why". Both

focus on the subjects of stars, galaxies, interstellar/intergalactic gases, and the void called "space",

but from differing perspectives.

Astronomy as an observing "science" traces its roots to early civilizations such as the pre-Christian

era Babylonians, Egyptians, Greeks, and Chinese and the Mayans and Aztecs in the New World.

Star groupings, the constellations, were established and became involved in myths that suggested

deity controls of how the World (i.e., the Universe) is able to function. ,.

Ideas of an Earth-centered Universe began in early times, with both myths and theological

explanations for the meaning and cause(s) of the physical (natural) World (including and beyond

the Earth) gradually being supplanted by scientifically-based observations. Key ideas that provide

this basis include the postulates by such Greek philosophers as Pythagoras, Euxodus, and

Aristotle (the latter proposed the Earth as the center of the Universe, with the Moon, Sun, and starsbeing embedded in crystal spheres that rotated around Earth) and the later (ca. 140 BCE)

Ptolemaic description of epicyclic "heavenly" motions; these persisted largely as philosophical

musings until the advent of Copernicus in the 16th Century CE who posited the heliocentric theory

for the Solar System (but that had been suggested - and discounted - by Aristarchus in 280 BCE),

followed by important contributions from Tycho Brahe (detailed measurements of motions of

celestial bodies) and Johannes Kepler (Laws of planetary movements) soon thereafter. Galileo was

the first to use the telecope for astronomical observations; his observations confirmed Copernicus's

revolutionary idea that the Earth was not the center of the Universe nor the Solar System. Isaac

Newton provided the foundation for the movements of stars and planets with his Laws of Gravity

and Motion. William Herschel in the late 1700s CE provided the first proof that the Milky Way, in

which the Sun is located. is an "Island Universe", namely a huge cluster of stars comprising a

galaxy; Herschel surmised that other such galaxies must exist. This led to the beginning of the

modern era of Cosmology stemming for work by Edwin Hubble and others in the 1920s, who

showed that there were many galaxies beyond the Milky Way and some of these were located at

huge distances from Earth. Hubble also confirmed the idea of expansion from a Big Bang that had

been put forth by the Abbe Lemaitre in the early 1920s. Of great importance to cosmologists was

the new framework for a proper understanding of the Universe and of the laws of physics that affect

it that was established by Albert Einstein's theories of Special and General Relativity (see Preface).

Before the beginning of this (there may be more than one) finite Universe there was (at least for


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those within it) no time nor space, no energy (in the discrete forms we know) nor matter - at least in

the sense that we perceive these fundamental "qualities". What may have existed is some as yet

undefined quantum state in an endless void in which fluctuations in the "emptiness" - the void - led

to extremely fleeting "particles" containing the essence to grow into a Universe. Essentially all such

evanescent moments ended with the disappearance of these particles (still unidentified entities:

energetic virtual (potential non-yet existing particles which may be those constituting the Dark

energy that dominates the Universe [see this page and Pages 20-8 and 20-9] have been proposed).

But the potential was there for one such particle to spring to existence at a moment (the singularity)

that witnessed "creation of space and matter" from when our Universe sprang. This diagram may

help as you work through the next three paragraphs (variations will appear later on this page):

The singularity particle was so unstable that it "exploded" into what is known colloquially as the"Big Bang". That took place some 13.7 billion (+/- 200 million) years ago (seepage 20-9 for a

discussion as to how this value has been reached and has changed several times in recent years).

What actually happened is not a true explosion but a process that is described as the creation of

"space" which has been expandingever since. The first minute of Universe time was the critical

stage leading to the state of the Universe we observe today. We can trace theoretically events

during the minute back to 10-43 sec(onds) - an instant known as the Planck time - when the

Universe was infinitesimally small. (Experimentally, astrophysicists can actually reconstruct the

sequence and verify the essential physics of the Universes early conditions back to 10-12

seconds and to particle sizes as small as 10-17meters; better yet, a significant number (most?) of

the particles and forces [and fields through which they interact] have now been defined and all but afew actually found and identified under laboratory conditions.) Initially, the fundamental forces

(strong; weak; electromagnetic; gravity) were unified (as may be explained through one new theory

in physics called "superstrings"). But, they quickly separated systematically into the individual four

prime forces. Although expansion was rapid, at about 10-35seconds, there was a one-time only

extreme acceleration of this minute Universe through a process called Inflation. Inflation may be

responsible for the likelihood that the Universe is much larger than the 13.7 billion l ight year limit of

the observable Universe imposed by the speed of light.

Thereafter, in this first minute as expansion continued and the proto-Universe cooled to lower


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energy levels, the fermions (matter), controlled by the appropriate bosons (force), began to

organize into the protons and neutrons (both composed of quarks), electrons, mesons, neutrinos,

and others of the myriads of particles continually being discovered in high energy accelerator

experiment in physics labs.

As the first minute ended, some particles began to associate with others (while probably all the

anti-matter that should have been created was destroyed). In the first few minutes, particles began

to organize into nuclei that were part of a plasma state in which the mix included electrons,

photons, neutrinos and others. In the next 380,000 years or so, this particle-radiation statewitnessed the beginnings of organization into atoms, mostly of Hydrogen and some helium. After

that time the Universe became "transparent" so that communication through photon (light) radiation

was possible between segments of the Universe close enough to exchange information at the

speed of light. The Universe was almost completely homogeneous and isotropic on a grand scale

but locally tiny fluctuations in the state of matter (mostly H and He), as appear in the irregularities

in the Cosmic Background Radiation (greatly cooled Big Bang "afterglow' that pervades the

Universe and marks its observable edge), led to gravitational clumping (into nebulas) that grew

simply because these slight increases in density continued to increase the organization through the

force of gravitational attraction. From this eventually, in the first billion years, stars began to form

and to arrange in clusters called galaxies. These adopt specific shapes, such as spiral, elliptical, orirregular. This diagram, a classification of forms first put forth by Edwin Hubble, shows the range of

shapes (note: it is not an evolutionary chain ):

A star is defined as a massive, spherical astronomical body that is undergoing (or has undergone)

burning of nuclear fuels (initially Hydrogen and, if hot enough, Helium); as it evolves elements of

greater atomic number are consumed as well) so as to release energy in large amounts of bothluminous and non-luminous radiation (over a wide range of the EM spectrum); stars eventually

change significantly in mass, size, and luminous output with some finally surviving only as very

dense cores (neutron stars) of minimal luminosity. Stars burn their Hydrogen at high temperatures,

during which (depending on their size) they convert this fuel to heavier elements (largest ones can

produce elements up to iron in the Periodic Table). Large stars die out rapidly (a few hundred

thousand to one or more billion years); small stars can persist for times that are comparable to the

total li fe of the Universe. During their stable lifetimes, the stars hold together by a fine balance

between inward contraction under gravity, involving internal heating up, and the outward pressure of

the radiation produced by nuclear processes. Many stars can explode as supernovae. Various types


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of stars evolve over time through distinct pathways; among these are Red Giants; White Dwarfs;

Brown Dwarfs, and Neutron Stars. Black Holes are another, perhaps widespread, constituent of

space. As a star forms out of nebular material - gases mainly of some Hydrogen and helium, and

other elements in various forms, including particulate dust), some of this material not drawn into the

growing star may collect in clots that would form planetary bodies - rocks and gas balls - similar to

those making up our Solar System.

The composition of the Universe has only recently been determined fairly precisely. Ordinary

matter, making up the stars, galaxies, gas/dust clouds and a small fraction of the so-called emptyspace, accounts for about 4% (most of that is Hydrogen and some Helium). The rest is present in

Dark Matter (undetected directly by any technique so far; includes the WIMPS and MACHOs

discussed on page 20-9) which seemingly increases around galaxies, and makes up about 23% of

a Universe and Dark Energy (about 73%), tied to a still mysterious force that seems to act like the

anti-gravity force first postulated by Einstein,which he called the Cosmological Constant, and is the

prime candidate for causing the recent observation that the Universe now is once again expanding

after slowing down for the first seven or so billion years.

The fate of the Universe depends ultimately on how much mass (and its convertible form, energy) it

has. If that number is high the Universe

s expansion may slow down and eventually reverse(contract) so that all matter and energy collect again at a superdense point which may undergo

another Big Bang. Or the matter/energy is insufficient to slow expansion and the Universe enlarges

forever. The shape of the Universe will depend on the nature of the expansion; recent evidence

indicates that it may be "flat". At large scales the Universe is subject to the laws of Relativity (but

equally as important is the role of matter/energy at the smallest - quantum - scales). Recent

information favors endless expansion and the possibility that the rate of expansion is now

increasing.

Add to all of this the theoretical (quantum-driven) possibility that there may be multiple universes,

unable to communicate with one another, with new ones forming at various times and perhaps old

ones dying in some way. The mind boggles at this point. But even more amazing is the realizationthat there is something we humans recognize as "mind" - our most valuable property and

objectively the most powerful entity so far discovered in the Universe. Our minds have identified the

ways in which planets form, including those suited to hosting living creatures, and the very nature

of life itself.

Humankind has in the last 400 years, and especially the last 50 years, developed the skills and the

will to explore our Universe. We now obtain data of great explanatory/interpretive value using

telescopes that gather in radiation from all parts of the EM spectrum. Thus, there are now

specialized observing systems that sample in the gamma-ray, x-ray, ultraviolet, visible, near and far

infrared, and radio wavelength regions of the spectrum. Astronomy is probably the prime user of

nearly all segments of that spectrum, as it gathers its information almost exclusively by remotesensing methods.

The big advance during the last 50 years has been to place astronomical telescopes into space, in

orbits above the Earth's atmosphere. The most famed of these is the Hubble Space Telescope

(HST) which has dazzled astronomers, other scientists, and the world public with its abundance of

extraordinary images. There have been other great space observatories; we mention most of the

best known in this Overview: the Compton Gamma-Ray Observatory (CGRO); the Chandra X-Ray

Telescope; XMM-Newton; Extreme Ultraviolet Explorer (EUVE); the International Ultraviolet

Explorer (IUE); the Far Ultraviolet Explorer (FUSE); the Galaxy Evolution Explorer (GALEX); the


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Infrared Astronomical Satellite (IRAS); the Infrared Space Observatory (ISO); the Space InfraRed

Telescope Facity (SIRTF; renamed the Spitzer Space Telescope. Only two radio telescopes have

yet been orbited but plans are underway for more. A pictorial overview of the major space

observatories is presented in this illustration:

Some of these observatories are considered in this Section; others are not. If curious about the

latter, check any out through Google or Yahoo. Note: those with green bars were scheduled forlaunch after this chart was prepared. Links to these and other (unnamed here) astronomical

observatories are given on this OAOSweb site.

THIS IS A GOOD PLACE, IN THIS SYNOPSIS, TO MENTION SOME OF THE MAJOR

INDIVIDUALS OF THE 20TH CENTURY AND THEIR CONTRIBUTIONS TO COSMOLOGY

(MORE DETAILS WILL FOLLOW ON THIS AND LATER PAGES):

MAX PLANCK: THE ORIGINATOR OF SOME OF THE IDEAS THAT LED TO QUANTUM

PHYSICS.


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VESTO SLIPHER: DISCOVERED THE "RED SHIFT" OF STELLAR SPECTRA, INDICATING

GALAXIES WERE MOVING AWAY FROM THE EARTH AS AN OBSERVING PLATFORM.

ALBERT EINSTEIN: THE "GIANT INTELLECT" WHOSE CONCEPTS OF RELATIVITY CHANGED

PHYSICS AND RECAST OUR UNDERSTANDING OF THE UNIVERSE; STATED THE NOTION

OF SPACETIME AND DEVISED NEW CONCEPT OF GRAVITY; HE BELIEVED IN A STEADY

STATE UNIVERSE.

WILLEM DE SITTER:FROM HIS SOLUTION OF EINSTEIN'S GENERAL THEORY OFRELATIVITY EQUATIONS, CONCLUDED THE UNIVERSE WAS EXPANDING.

ALEXANDER FRIEDMANN: THE RUSSIAN MATHEMATICIANT WHO CONFIRMEDED THE

POSSIBILITY OF AN EXPANDING, FINITE UNIVERSE.

GEORGES LEMAITRE: THE BELGIAN PRIEST WHO CONCEIVED OF THE UNIVERSE'S

EXPANSION FROM A VERY SMALL VOLUME (THE PRIMORIDAL ATOM; SIZE ROUGHLY THAT

OF THE SOLAR SYSTEM) THAT "EXPLODED" AT THE BEGINNING OF TIME (SINGULARITY)".

EDWIN HUBBLE: THE ASTRONOMER WHO DISCOVERED GALAXIES BEYOND THE MILKY

WAY AND PRESENTED EVIDENCE FOR EXPANSION.

GEORGE GAMOW: THE PHYSICIST WHO EXPLAINED HOW STARS FORM AND BURN THEIR

HYDROGEN FUEL.

FRED HOYLE: THE ASTRONOMER WHO EXPLAINED HOW ELEMENTS HEAVIER THAN

HELIUM ARE PRODUCED BY FUSION IN STARS; HE ALSO COINED THE TERM "BIG BANG"

(AS A DERISION OF EXPANSION CONCEPTS) AND CHAMPIONED A STEADY STATE

UNIVERSE.

BRANDON CARTER: THE PHYSICIST WHO PROPOSED THE MODERN CONCEPT OF "THE

ANTHROPIC PRINCIPLE" - THE UNIVERSE HAS JUST THE RIGHT SET OF PROPERTIES TOALLOW LIFE TO DEVELOP WITHIN IT AT SOME EVOLUTIONARY STAGE (AND REQUIRES

INTELLIGENT LIFE TO REALIZE THAT IT EXISTS).

ALAN GUTH: THE COSMOLOGIST WHO PROPOSED THE IDEA OF THE BRIEF

SUPEREXPANSION KNOWN AS INFLATION THAT BEST ACCOUNTS FOR THE UNIVERSE'S

SIZE AND PROPERTIES.

ARNO PENSIASAND ROBERT WILSON: THE TWO ENGINEERS WHO FORTUITOUSLY

DISCOVERED THE COSMIC BACKGROUND RADIATION (BEING SOUGHT THEN BYROBERT

DICKE'S GROUP AT PRINCETON UNIVERSITY); PREDICTED BY EINSTEIN, THIS RADIATION

IS STRONG EVIDENCE FOR THE BIG BANG AND IT HELPS TO ESTABLISH THE "TRUE" AGEOF THE UNIVERSE (IN TERMS OF EARTH YEARS).

We close this Overview summary with a map that shows the main features of the Observed

Universe; other kinds of maps are possible and several will appear later in the Section.


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The first page consists of:

A GENERAL OVERVIEW OF THE COSMOS:

With regards to:

The Big Bang; The Overall Characteristics and Structure ofthe Universe; The First Few Minutes; The Nature and Origin

of Matter; The Early Eras; The Subsequent History ofExpansion

Before we enter this long page, the writer (NMS) would like to present his own definition of a word -

perhaps setting a precedent. Many readers are familiar with the famed astronomer Carl Sagan's TV

series on the "Cosmos". But it is not easy to find a good working definition of that term that all

agree on. Typing in the word on Google led to many entries not related to astronomy. TheWikipedia entry gave this information (reproduced here as two italicized parts extracted from that

Website):

In physical cosmology, the term cosmos is often used in a technical way, referring to a particular

space-time continuum within the (postulated) multiverse. Our particular cosmos is generally

capitalized as the Cosmos. The philosopher Ken Wilber uses the term "kosmos" to refer to all of

manifest existence, including various realms of consciousness.

Using this for support, we will define this use of "Cosmos" in this way: Everything that can

be conceived to exist in a real and physical way which includes all that is within our


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Universe, any other Universe (Multiverse concept) and any of the vacuum containing virtual

particles that fills the (non)space between the (possibly infinite number of) multiverses.

Thus, when we refer specifically to the "Universe", we will mean this (our) Universe; when

we refer to the Cosmos, we are taking into account the speculation by scientists, and by

science fiction writers, that there can be more than one Universe, even though at present

there is no way to prove the actual existence of anything beyond the limits of our

observations through telescopes. So far then, the notion of any physical reality beyond

these limits is conceptual rather than factual.

While we are redefining terms, lets consider "space" itself. The Space Program in its broadest

connotation refers to monitoring activities connected with Earth, to the exploration of the Solar

System, and to the observations of the farthest reaches of the Cosmos (at least to the detectable

photons making up the Cosmic Background Radiation and to the first stars [or more properly the

first galaxies since individual stars at great distances cannot be resolved]). Space in a "geometric"

sense is easily visualized as that which includes all detectable cosmic objects (stars, galaxies, gas

clouds, etc.) and everything between any two such objects. The "between" however is not empty.

Even if nothing can be detected by present means, quantum theory holds that such space contains

vacuum energy and even virtual particles which can "pop" in and out of active existence. In this

sense, space is that which resides within the Cosmos regardless of whether there are any markersthat establish the "between". It would not be surprising if such 'space' is eventually shown to be

infinite.

For now, all we can talk about from direct contact is the Observable Universe. The subject of the

Observable Universe will be explored several times in this Section. For those anxious for a preview,

check out this Wikipedia website.

Introduction

Before beginning this Section, we urge you to read through a page called the Preface (once there,hit your BACK button on the browser you use to return to this page). The Preface contains four

major topics: 1) the role of remote sensing in astronomy; 2) some suitable references for additional

information; and basic principles of 3) Relativity, and 4) Quantum Physics. The Preface contains a

list of some very readable books and a number of Internet links to reviews or tutorials on

Astronomy/Cosmology. Also, most of the illustrations in this Section were made from images and

data acquired by spaceborne Observatories. A brief description of those Observatories is given on

this Wikipedia website. Most of the ground-based Observatories are listed in this Caltech site.

As we did in Section 19, we begin with this statement: Astronomy and Cosmology depend

almost entirely on remote sensing technology (mainly telescopes with various sensors) to

gather the data and mold these into information about every thing in space beyond our

Solar System.

Cosmologists - those who study the origin, structure, composition, space-time relations, andevolution of the astronomical Universe (and the possibility of a Cosmos as defined above) -

generally agree that the Universe had a finite beginning and that it is expanding at a steady rateso that any two points (e.g., galaxies) move away from each other at speeds proportional to theirseparation. (The expansion of space has been referred to as the Hubble Flow, to honor Edwin

Hubble who first verified the expansion). This beginning is commonly referred to as the Big Bang,which is not an explosion in the sense of, say, the detonation of dynamite but is an "explosion" of


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space itself as a continuing expansion accompanied at the outset by the creation and release ofall energy and matter now occupying the ever growing Universe. (The Big Bang received itsdescriptive name as a disparaging comment from the astronomer Fred Hoyle, who advocatedinstead an infinitely large Universe of constant matter density [requiring continuous creation ofnew particles to maintain the density even as the Universe expanded within its infinite limits] asdescribed in his [now rejected] Steady State model [developed in consort with Hermann Bondi andThomas Gold]. This model also infers its Universe to have always existed [no creation event] andwill exist largely unchanged [except for its expansion] forever; variants of this and other models

have been put forth, as described on page 20-9).

As of 1990 the time of the Big Bang had been placed between 12 and 16 Ga ago (Ga = 1 billionyears [b.y.]) ; the current best estimate (derived from observations made by the Hubble telescopeand WMAP [a cosmic background radiation satellite]) lies close to 14 Ga (13.7 Ga is nowrecognized as the most accurate value [see page 20-9]). This is derived by measuring the timeneeded for light to have traveled from the observable outer limit of the Universe to Earth in terms

oflight years*, which can be converted to distances. In a sense, the term "light year" has a dualmeaning. Thus, when the value of 2000 light years is stated for a star or galaxy, one could think in

terms of distance: the entity is 2 x 103 x (3600 x 24 x 365.4 [the number of seconds in a year] x

2.998.... x 108

m/sec (see first footnote *), approximately 11.8 quintillion kilometers, away from theEarth as the observing platform. Or, one might think in terms of age: relativistically, we see theentity as it was 2000 years ago when the light first left it; cosmically we always look back in timewhen observing stars and galaxies. Both distance and age are valid connotations.

At this outset, let us define the term "Universe". The (this; ours) Universe will be specified aseverything that l ies spatially within the outermost limit of matter and energy that has participated in

the expansion of Space since the moment of the Big Bang. In this definition, the Universe (theone we live in; in principle, there may be other Universes [see page 20-10]) is finite in both spaceand time (note: it had a beginning and seemingly will last in some state for many billions of years

to come [possibly infinitely]). This Universe is said to be homogeneous and isotropic.

Homogeneity means that the entities involved are the same in all locations. Isotropy means thatthe entities are the same in all directions. These terms imply uniformity at some scales - generallylarge (cosmic). Thus, the Universe would appear much the same at any point within it. If we wereto observe the Universe around us from a planet in some other galaxy, we would see generally thesame set of physical conditions and the same general appearance and distribution of othergalaxies elsewhere in the Universe as we now actually do from Earth. This must be modified bythe scale of observation. The Universe shows apparent inhomogeneities, such as clumping ofenergy and clustering of galaxies, in regions that are less than about 200 million light years insize. But at larger scales the Universe approaches a more uniform or smooth status. (A broadermeaning often applied to "Universe" holds it to include all that can be conceived to exist eitherphysically and/or metaphysically; but as stated above we prefer using the term "Cosmos" for this

idea.)

The Cosmological Principle, which is deducible from the postulates of homogeneity and isotropy,states that the Universe will look the same no matter where the observer is located within it. Acorollary of this states that there is no real center for the Universe. But an observer at any locationmay think he/she is at the center. That notion as applied to Earth dwellers persisted until the 16thCentury when Nicolaus Copernicus presented arguments that negated the geocentric viewfavored by philosophers and theologians and replaced it with the heliocentric view (the Sun is thecenter for the planets). (Galileo got into deep trouble with the Catholic Church for his support ofCopernican centricity). The Sun was dismissed as a candidate for the Universe's center when,


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first, its place in the Milky Way was determined to be about a third of the way out from our galaxy'scenter, and then the galaxy itself was shown by Edwin Hubble in 1923 to be just one of many bothnearby and far away from the Sun's galaxy.

The physical conditions that guaranteed the present Universe must have burst into existencealmost instantaneously. During the first minute of the Universe's history, many of the fundamentalprinciples of both Quantum Physics (or, as applied to this situation, Quantum Cosmology) andRelativity - the two greatest scientific discoveries of the 20th Century (see Preface, accessed by

link above) - played key roles in setting up the special conditions of this Universe that have beenuncovered and defined in the 20th Century. Quantum processes were a vital governing factorduring the buildup and modifications of the particles and subparticles that arose in the earlieststages. Likewise, Relativity influenced the space-time growth of the Cosmos from the very start.

In the most widely accepted current model of the Universe, there is no starting place or time in the

conventional sense of human experience. Space**, as now defined and constrained by the outer

limits of the observable Universe, did not yet exist (see below); also, sequential events, embeddedin a temporal continuum, had not begun. The observable Universe is just the visible or detectablepart extending to that part of the Universe where objects or sources of radiation have sent signalstraveling at the speed of light over an elapsed time not greater (usually somewhat less) than the

time (age) of the start of expansion. Most cosmologists now feel with some confidence that there issomething real and physical beyond the observable Universe (be it the unseen parts of ourUniverse or some other Universe(s) but it is too far away for light to have had enough time to reachEarth's ground or orbiting telescopes). That observed part plus the unobserved part together

make up the Cosmos.

Everything that exists physically is included in the Cosmos. (One can debate whether things"spiritual" are only the thought processes that have a physical basis, or do these things really existindependently.) As this Section unfolds, you will come to realize that there is a hierarchy that dealswith the physical entities within the Universe, arranged (in part) by a progression of decreasingsizes. That hierarchy, in its simplest form, is:

?? --> THE ABSOLUTE VACUUM (THE COSMOS) --> OUR UNIVERSE (PERHAPS OTHER

UNIVERSES)-->THE INTERGALACTIC MEDIUM (VOIDS CONTAINING GAS, PHOTONS, AND

OTHER PARTICLES) --> GALACTIC CLUSTERS --> GALAXIES --> INTRAGALACTIC GASES

--> STAR CLUSTERS --> STARS --> PLANETARY SYSTEMS --> PLANETS --> SATELLITES

(MOONS) --> FIRST ORDER SURFICIAL AND INTERIOR FEATURES ON PLANETS --> LOCAL

FEATURES --> INDIVIDUAL ENTITIES (FOR EXAMPLE, HUMANS) --> ATOMS AND

MOLECULES --> SUBATOMIC PARTICLES --> SUPERSTRINGS -->?

A Broad View of the Universe's Organization and Evolution

The mysterious Absolute Vacuum (the writer's term) will be considered later in this Section (sufficeto say now that it a rather abstract concept that considers the possibility of a dimensionlessemptiness that stretches to infinity; time also is eternal, having no real beginning or end). The

initiating event which started our Universe from out of that Vacuum, referred to as the Big Bang

(BB), began at a point so small that the notion of spatial three-dimensions [3-D] has noconceptual meaning. The event sprang from some sort of quantum state of still-being-definednature that marks the inception of space/time (thus, without a preceding "where/when";philosophically "uncaused"), from which all that was to become the Universe can be mentally

envisioned to have been concentrated. This singularityis described as a state that is not quite a


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point (dimensionless) condition which has extreme curvature and before which there was no"yesterday". The singularity is the first event in Universe history, so that it connotes a beginning-of-time aspect in addition to its beginning-of-space implication. At the very beginning, its physicalnature transcends the laws of physics (including relativity); these laws break down, i.e., do notapply, but almost immediately came into existence. This extremely small point conditionnevertheless contained all the energy within the eventual Universe. This singularity energy ismeasured as a temperature that reached to bill ions of degrees centigrade. The density of the pointat the moment of singularity was extremely high - far greater than that characteristic of Black

Holes.

At the very beginning of this (our) Universe, multidimensional space and time came into being andbegan to take on physical characteristics. But at the cosmic scale, these two fundamentalproperties must, according to Special Relativity, comprise the 4-dimensional spacetime Universe(see Preface for a definition of spacetime) we now observe (according to some theories discussedbelow 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 (for an excellent review of time,

readAbout Time: Einstein's Unfinished Revolution by Paul Davies, 1995); also consult his Website on "What happened before the Big Bang" at this site (the host site contains many interestingand provocative articles; click on Albert Einstein within the page that comes up to get to the parent

site). There is, of course, the conventional time of everyday experience on Earth (years, days,seconds, etc.), measured fairly precisely by atomic clocks (e.g., the pulsating beat of a cesiumatom, used to define the 'second') and less so by mechanical timepieces or crystal watches. Thereare the redefining ideas of time consequent upon Special Relativity, in which the perception oftime units proceeds faster or slower depending on frames of reference moving at different relativevelocities. There is the notion of "eternity" in which time just is - has no specific beginning orending.

But, all these measures and concepts are difficult to extrapolate to that nebulous temporal state (ifreal) which was before the singularity at which our Universe came into being. But, time had toseparate at that instant and become measurable in terms we have set forth to use its property of

steady progression of a temporal nature. If nothing existed prior to the singularity event, thenscientists presently have no means to determine and measure the nature of the time that wasinvolved as a prior state. If ours is not the only Universe (see the discussion of multiverses onpage 20-10), and other Universes existed before the one we observe, then time in some way can

be pushed backward to their inceptions. One possibility is an infinite number of Universes in time

and space, with no end points for starts and finishes (read Paul Davies' book for the philosophicalas well as physical implications of time, and the still unresolved dilemmas in specifying themeaning of time).

For our purposes in studying the Cosmology of the one known Universe, we will assume timestarted at the moment the Universe sprang into existence. Arbitrarily, we postulate that time is

immutable (a second at the beginning is of the same duration as a second is defined by today);there are models that postulate variable time values but we will ignore these. We accept thesubsequent progression of time as being comprehensible in the units we define for Earth l iving.Thus, the Universe, under this proposition, can be dated as to its age in years - the year is anarbitrary unit, being the present day time involved in the Earth's complete revolution around theSun.

At the very beginning, the fundamental energy within the singularity point may have been (or been

related to) gravitational energy that controlled the nature of what existed at the singularity

moment. An alternative driver now being investigated is some form ofrepulsive energy (similar to


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that once proposed by Albert Einstein as his 'Cosmological Constant'; but with a differentnumerical value) such as Quintessence (see page 20-10) which may prove to be related to the"Dark Energy" (page 20-9) that seemingly dominates the present Universe. (It is now customary tothink of gravity as a positive effect and this repulsive energy as countering gravity as a negativeeffect [it may be, or be equivalent to, Dark Energy].) At the instant of singularity, the initial energy(some of which was about to become matter) was compressed into a state of extremely highdensity (density = mass or amount of matter [or its energy equivalent] per specific [unit] volume),

estimated to be about 1090 kg/cc (kilograms per cubic centimeter) and extraordinary temperatures,

perhaps in excess of 1032 K (K = Kelvin = 273 + C [C = degrees Centigrade]). (Note: the term"vacuum density" has been used in reference to this pre-Big Bang state; the density in this case

refers to energy [which is a surrogate for mass according to E = mc2]; this vacuum density is saidto be very large.) Both high values are without any counterpart in the presently observed Universe;particle accelerators are not yet close to reproducing these ultrahigh temperatures. As you will seebelow, certain forms of matter came from the pure energy released during the first fraction of a

second 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 the Big Bang's singularity, the particle (whatever its nature; the term "particle"also refers more generally to any of the fundamental entities such as protons, photons, muons,etc. that constitute matter and energy [see below on this page]) proved exceptionally unstable andproceeded to "come apart" by experiencing something that has been likened to an "explosion",

which goes under the popular name of the "Big Bang" (BB). In TV shows that have an astronomytheme, such as seen on the History and Discovery channels, the depiction of the BB resembles adetonation or explosion (in the shows you usually hear a banging noise; this is meaningless sincethe BB moves into a true vacuum, which cannot support sound), and the terms have been applied

(incorrectly) to the event. There is this fundamental difference: In a conventional explosion, every

thing involved is hurled outward from the point of initiation as an advancing and enlarging front that

moves into existing space, leaving the volume between the front and the point devoid of the

explosive debris; this volume increases in size as the debris progresses outward. To depict thisvisually, look at this animation of the explosion around the star Eta Carinae (you must be on theInternet):


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In the Big Bang, there is no real hurling away of the material released; instead all the material

(from eventual galaxies down to subatomic particles) simply expands around the singularity point

creating its own space as it enlarges. The explosion is described as "not into space" but "of

space". No center (in space today) can be specified for the BB since all points in the new finite but

growing space simply draw apart more or less equally as space stretches under conditions inwhich pressure and density remain uniform and isotropic everywhere.

Several Internet sites actually have movies that simulate the expansion. This one works on the

writer's computer; it should work on yours if you have the right software program installed:

This difference in behavior between conventional and BB is clarified in the two illustrations (readtheir captions for more information) below taken from (Six) Misconceptions about the Big Bang, by

C.H. Lineweaver and T.M. Davis, Scientific American, March 2005, cited again on pages 20-8 -20-10.

A Conventional Explosion


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The Big Bang Expansion

ILLUSTRATIONS COURTESY OF ALFRED T. KAMAJIAN

Intuition suggests that the dots in the above illustration would also be expanding (enlarging).These yellow dots represent galaxies. But in fact they remain roughly the same size during theexpansion and move as a unit. The star distances within the galaxies stay about the same. This isdue to the strong interstellar gravitation that holds a galaxy, once formed, to a near constant size.Over time as galaxies spread apart from expansion their mutual interactive gravitational attractionweakens and this may disturb their shapes and shift the stars; but the distances between stars ina galaxy remain more or less the same (i.e., are not affected by the general space expansion)owing to the countering effects of gravity.

Note that in the diagram, the expansion seems to start from a specific point. But for the Big Bangone cannot speak of a "there" in reference to the singularity point because the space thatcharacterizes our Universe did not start to form until the moment of its beginning. It is difficult tothink of any "there" since no 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 thefalse vacuum). What might have preceded this moment at which the Universe springs into beingand how the singularity point came to be (become) remains speculative; theoreticians in theSciences have proposed inventive, although somewhat abstract, solutions but the alternative andtraditional views of philosophers (metaphysicians) are still taken seriously by many in the scientificcommunity. This last idea is treated again near the bottom of Page 20-11.

Expansion is continuing through the present and into the future in part because the inertial effects(evident in the observed recessional motions of galaxies, etc.) imposed at the initial push stillinfluence how space grows and, now it is believed, in part due to the continuing action of theabove-mentioned repulsive energy. After the freeing of gravity from the other fundamental forces(see below), it has since been acting on all particles, from those grouped collectively into starsand intragalactic hydrogen/helium clouds making up the galaxies to individual nucleons, photons,etc. - thus at macro- to micro-scales. Gravity therefore exacts one controlling influence on the rateof expansion, serving to slow it down. But, this rate should be decreasing over time becausegravity between the Universe's constituents weakens as expansion forces them further apart

(Newtonian inverse square of distance r effect [1/r2]). As we shall elaborate later, recent evidence

suggests that there are also anti-gravity forces (enabled by the repulsive energy of presentlyuncertain nature) that act to overcome the restraining effects of gravity; these forces seek toincrease the expansion rate and over time push matter apart in a general dispersion. It is nowbelieved that these forces are becoming greater than the countering force of gravity thateventually would have reversed expansion and caused a general collapse.

Gravity and the Kinetic Energy of outward expansion together constitute the total energy releasedfrom the Big Bang. By convention, the Kinetic Energy is taken as "positive" and GravitationalEnergy as "negative". The two major energies comprise the Total Energy of Expansion. Thus; KE+ GE = TE. Evidence favors a TE > 1, so that the Universe is likely to expand forever. The history


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of the expansion has been one of three successive stages: rapid deceleration, modestdeceleration, and then exponential acceleration. This last step results from the increasinginfluence of Dark Energy (which maintains a constant density). Matter is thus said to be "fallingoutward" in the expanding sphere that comprises the observable Universe. This illustrationgeneralizes the expansion history of the Universe:

This diagram also has implicit reference to the above three major stages in the Universe'sevolution: 1) initial acceleration accompanied by the dominance of radiation in the first fewhundred thousand years of expansion; 2) the major role of matter as a factor in gravity over thenext 7 billion or so years; and 3) the increasing importance of Dark Energy (or some other drivingforce) as the cause of re-acceleration since then.

Some readers may wish to acquire a broader insight into the topic of Universe expansion thatdescribes a simplied Model, using an enlarging balloon as an analogy for the spacetime

expansion of the Universe that has continued after the first eras of the Big Bang. This and relatedsubjects are considered in more detail on pages 20-8, 20-9, and 20-10. But if you want to acquire

a better understanding of the nature of Universe expansion before proceeding on this page, youcan access a relevant review now on the separate page 20-1a. Check especially the paragraph inred at the bottom of page 20-1a, which alludes to models other than the Big Bang that couldcause expansion and different sets of fundamental cosmological parameters.

This is an appropriate point to insert comments about the concept of the Instanton. This is an

alternative version of the notion of the Singularity event described in previous paragraphs. It is a

different version of what happens just prior to the Big Bang. The Instanton is a condition that

derives from Yang-Mills Gauge theory which is a part of what is known as Quantum

Chromodynamics (QCD). We will not delve further into Instantons (a rather difficult to follow

summary is given at this Wikipedia website). Cosmologists such as Stephen Hawkings and NeilTurok have adapted Instanton theory to the conceptualizing of what was before and led up to the

Big Bang, or any of the competing ideas for the Universe's inception. In a nutshell, they envision a

process by which a quantum fluctuation in the vacuum or void prior to the initiation of the Big Bang

led to the appearance of energy by a quantum tunneling process. Their "Pea Instanton", which had

such high temperatures and pressures that it had to "explode", was created in this way. Rather than

pursue this topic further here, we refer you to the Cambridge University link at the bottom of the

Preface and to the links on this additional Web site: J.T. Wong.


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Many scientists believe that what may have "existed" prior to the Universe was a quantum state (ina sense, analogous to the condition of "potency" in ancient Greek philosophy) which influenced atrue vacuum (no matter whatsoever) that somehow possessed a high level of energy (of unknownnature but not, however, as photon radiation). As will become evident in this Section,astrophysicists now believe that no total vacuum exists anywhere -- all of space (the Cosmos)contains some form of energy having as yet an undetermined quantum nature. Countless

quantum fluctuations (which in quantum theory are said notto depend on [obey] metaphysical

cause/effect controls and are notsubject to time ordering) in this vacuum energy density produced

sets of virtual particles and anti-particles (analogs to positrons, the positively-charged equivalentof an electron; neutrons and anti-neutrons, etc) that could (according to quantum theory) intoexistence out if the Cosmos for very brief moments but then nearly all were annihilated. Thenature of these particles is currently not well known but they may relate to the so-called DarkEnergy that dominates the Universe.

Rarely, annihilation did not occur (as would be consistent with the probabilistic nature of QuantumPhysics), so that a particle could grow and trigger a 'phase transition' that led to the Big Bangevent from whence all that entails our Universe - with its internal matter, energy, space, and time -came into being. In this quantum model, particles could either be destroyed by interacting withantiparticles or could emerge from the vacuum from time to time and survive, leading to mulitple

universes that, as far as we know theoretically, cannot have any direct contact. If so, the numberof unconnected Universes may be very large, or very small if the success rate of a particleconversion to a Universe birth is near infinitely low frequency of occurrence. Though no one yethas offered any proof of a multiverse Cosmos, the likelihood is that the vast majority of virtualparticles do not explode into individual Universes, but statistically some do; each Universe mayhave its own set of parameters and laws of physics and these conditions may never be "rightenough" to foster life.

This non-contact status is one example of prohibition by relativistic limits, in which informationtravelling at the speed of light cannot reach us from beyond the horizon of our own observable

universe. For our Universe, the concept of the Cosmological Horizon refers to the boundary or

outer limits of the Universe that we can establish contact with, i.e., the farthest extent of theobservable Universe that can be seen through the best telescopes. This is approximated by thecurrently observed farthest galaxies that formed in the first billion years of time in our Universe'shistory. This Horizon is also conceptualized as the surface dividing spacetime (which includes alllocatable 4-dimensional points) into what we can see and measure from what is hidden and

unobservable. The observable therefore must lie within ourLight Cone, an imaginary surface thatencloses all possible paths of light reaching us since the beginning of time. (The fifth illustrationbelow is an example). Check page 20-10 for further discussion of these ideas.

If the Universe is about 14 bill ion years old, then light leaving just formed protogalaxies near theobservable spatial limit (outer horizon) of the Universe departed some 13+ bill ion years ago but

this radiation is only now reaching us, since it had to traverse across a Universe that wasexpanding (ever increasing the distances from Earth to the outer edges) and drawing theprotogalaxies away from us. Scientists actually have detected cosmic background radiation (CBR),the "afterglow" (see below and page 20-9), which pervades the entire Universe. Its firstconfirmable appearance was only about 380,000 years after the BB, at the time when detectableradiation could penetrate ion clouds that blocked its escape. This appearance of CBR is thepresent limit to the farthest lookback time involved, i.e., the extent to which we can peer into thepast to find the earliest discernible event; nothing that occurred between the BB and the 300,000years following it up to the first detection of CBR can be directly detected or measured.


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The Hubble Space Telescope has now seen faint galaxies that are close to the cosmologicalhorizon. Light from these left them about 13 billion years ago. At that time all the earliest galaxieswere much closer to each other. Over the next 13 billion years - to the present - the Universe hasbeen expanding, so that the light initially emitted "way back then" has had to traverse an everenlarging distance which we perceive as the observable Universe.

The ultimate size of the observable Universe - a term we have applied several times earlier onthis page - is still an open question. It is also a very complicated question, as you would deduce if

you read this Wikipedia website that contemplates the possibilities of Universes of different sizes,depending on the definitions and assumptions used.

Cosmologists are inclined to cite as one specifiable size some specific observable Universe whichis the subset of a possibly much larger Universe that lies beyond the event horizon (limit of thespacetime distribution within which the earliest light has traveled to our planet); in this conception,what is being seen from Earth is just that part of a still larger assemblage of galaxies from whichlight has had enough time to reach our telescopes since the Big Bang 13.7 billion years ago. Wesee outward in all directions to those galaxies at the limit, as they were in their earliestappearances (they formed about 0.5 to 1 billion years after the Big Bang), and they appear muchthe same no matter what direction we look at them. Thus we can imagine a sphere of galaxies

whose radius is at least that of the first galaxies, e.g., let us say 13 billion light years away (to thefirst recordable event horizon). The diameter of the sphere of the observable Universe is thus 27.4billion l ight years. For this sphere, in our frame of reference, we perceive ourselves as being at thecenter. But someone observing from a planet in a galaxy elsewhere would see the same thing (thesphere thus seems centered at that planet). In this conception the presumption is that there aremany billions of galaxies situated beyond the limit of detection that has been set by the time sincethe Big Bang over which light has traveled at its apparently constant speed. Perhaps thesediagrams will help visualize this:


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In these diagrams the regions beyond the event horizon (which defines the observable Universe)were formed at the same time as those within. The extent of galaxies beyond the observable limitcan be even much larger than shown in the diagrams but may(?) be finite (see two paragraphsdown). Just how large is still unknown, is still conjectural, and is still dependent on which modelor theory is being used. Two values show up in an Internet search of "the size of the Universe": aradius of 42 billion light years and a radius of 78 billion light years. Explanations of how these andother values have been reached are obtusely documented (as an example, see the 8th entry inNed Wright's FAQs) and reasons for the mechanisms that lead to sizes beyond the observableUniverse are glossed over. The most common argument states that the greater proposed radii arethe consequence of Inflation (see next paragraph and again elsewhere on this page) which carriedthe earliest products of the Big Bang to distances much farther than the 13.7 billion light year limitimposed by observation.

Thus, there seems to be a paradox here. How can there be more galaxies outside the observablesphere? Inflation, which occurs almost at the beginning of the Big Bang, increases the rate (whichhas varied in the past) of expansion of the Universe by a very large factor (one proposed value =

10

50

; higher and lower rates have been proposed for various models). This is much greater thanthe speed of light (this does not violate the Einsteinian tenet that radiation within the Universe

cannot go faster than light speed, which applies to movements of photons within space,

whereas it can be argued that space itselfcan move faster the speed of light). Thus, there area multitude of galaxies and other matter/energy outside of that spherical portion of space that canbe observed that are part of the vast segment of megaspace (all space out to the farthest extent ofthe Universe) produced by the Big Bang + Inflation; we can't see them simply because they aretoo far for light from them to have had time to reach us since the beginning.

The concept of Inflation, coupled with the illustrations above, seems to be a straightforward andeasily grasped clue to envisioning how there can be matter and energy - perhaps even as galaxies

- beyond the 13.7 billion light year horizon. But there is a competing relativistic explanation thatleads directly to the extension of the Universe's limits or size to values quoted above, to suchnumbers as 42 and 78 bill ion light years. The writer (NMS) first encountered this explanation inLecture 8 of the Cosmology DVD, presented by Dr. Mark Whittle, that was cited at the beginning ofthis page. A search of all the main Internet references and several Cosmology textbooks failed tofind anything comparable to his review.

Whittle begins that lecture by defining four terms: 1) demit = the distance light has traveled (to us)

since it set out; 2) dnow = the distance that the galaxy actually is from us today; 3) dLT = the

distance that a photon of l ight has traveled since it first left its source until now: and 4) thelookback time tLT = (tnow - temit, which is numerically equal to dLT but in units of years. These


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distances always have this interrelation: demit < dLT < dnow.

Two other terms are used in his calculations: 1) Scale factor S(t), which ranges from 0 (at the BigBang) and 1 (now), and describes the extent of expansion at any stage; and 2) the so-called

redshift of electromagnetic radiation (l ight) (defined as the displacement of spectral lines of

elements such as H and Fe [whose wavelengths have reference values determined in their rest

state in laboratories on Earth] towards longer wavelengths owing mainly to the outward expansion

with progressively increasing velocities of the Universe; discussed below and on page 20-9)

expressed as a variant known as the Redshift Stretch Factor (RSF). RSF = dnow/demit = now/emit,which ranges from 1 to infinity. (The RSF has a value of 1000 associated with the CosmicBackground Radiation that is detectable about 400000 years after the Big Bang). (Note: redshiftstook on large values during the first part of the Universe's expansion, especially during the firstminute of the BB; this is quantified on page 20-9.)

It is not practical to try to reconstruct the details of his calculations as presented in the lecture.The specification of demit, which is just any time one chooses to start the journey of a photon

(light) from a galaxy at any time between the beginning and now, and dLT, which is synonomous

with the st(age) of the light source (a galaxy specified to be seen today as it was, say, 8 billionyears ago is said to be 8 billion light years away), are readily understandable. But when dnow for

this galaxy is stated as a number greater than 13.7 billion light years, the situation seemsbewildering and counterintuitive.

Whittle gives two examples with concrete values that specify the various distances. In the first, hestarts with a galaxy whose RSF = 3. This means that the Universe was 3 times smaller, so S(temit)

was 1/3. Referring to the appropriate S(t) curve, temit is found to be 10.5 billion years ago, so that

dLT is 10.5 billion light years. But since then, the Universe has been expanding so that the

distance that light travels at a constant velocity keeps enlarging. This means that the present day(now) distance is greater than dLT. To determine this one must resort to calculus and integrate the

distance of many small, ever changing increments over time. For a small interval, this distance =ct; over the full time of stretching (expansion) from then to now, the relevant S(t) must be used inthe integration of the varying ct. The calculus formula for this is:

c/S(t)dt

(Note: The html editor program used for this Tutorial has no character for the integral symbol,which was here extracted from the Internet, nor does it allow the formula to its right to be placedon the same line; so, in the above equation just mentally place the integral symbol next to theformula.)

For this set of parameters, the integrated dnow becomes 15 billion light years. Using the same

approach, and specifying the Redshift Stretch Factor as RSF = 1000, dLT comes out as 13.7billion light years, dnow is calculated to be 46 billion light years, and demit is found to be 26 million

light years (a reasonable estimate for the very early Universe's limits).

These seem to be strange numbers, and the concept is hard to visualize. The writer (NMS) cameup empty after seeking to find a dynamic illustration (or even a set of sequential static pictures) onthe Internet. So, I have decided to make my own - which is only an approximation. Consider these:

At t(0)


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OO

At t(1)

O


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The writer (NMS) has tried to find a description of what may lie beyond the 13.7 billion light yearlimit for the observable Universe. An Internet search found hundreds of citations - mostly blogs -which range from inconclusive to gibberish. I do not have an answer but this seems plausible: Ifthere is organized matter (from nebulae to possible protogalaxies) beyond the observableUniverse, then it should be similar to the earliest galaxies observed so far; or it might just be anextension of the Cosmic Background Radiation which can be traced to the "edge" of the observedUniverse.

As is true for most earthbound illustrations that try to depict relativity and spacetime, this is animperfect diagram. But it may give you some insight beyond what the exposition of the Whittlelecture calculations provided. Let's return to a consideration of plausible models for our, andperhaps other, Universe(s).

In one school of thought megaspace (the Cosmos - all possible space, not just that within theobservable space of our limited Universe) is infinite. In another view, space is finite but much of itis beyond our detection. (What is outside of this megaspace is still conjectural). There is a variantof this (see page 20-10) embodied in the concept of Multiverses. In one model, each Universe canbe likened to an expanding bubble and the bubbles may not be in contact (but in principle couldinteract) - the space between them itself also expands. Multiverses may be finite or infinite. Here isa pictorial example:


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A corollary: In the Standard Model for the Big Bang, there have been and are parts of the Universewhich cannot directly influence each other because there hasn't been enough time for light fromany one part to have reached some others. Thus, the 'horizon' relative to Earth as the observing

point (but any other position in the Universe is equally as valid an observing point) refers to thespatial or time limit that demarcates between what we can establish contact with in any part of theUniverse and what lies beyond. This means that if an observer at one point in the observableUniverse (as a sphere) sent a message shortly after the Big Bang to an observer at an antipodalpoint, there hasn't been enough time for the message to be received. This figure illustrates anextreme example of parts that cannot mutually communicate:

This gives rise to a seeming paradox that is implicit in the "Horizon problem". Simply stated: howcan these isolated regions have very similar properties (such as similar densities of Dark Matter,Cosmic Background Radiation, and numbers of galaxies) if they are not in contact. This appears toviolate the fundamental principle of universal causality, which holds that during expansion all partsof the Universe would need to have been in communication (by light transfer or other means ofexchanging energy) so that the fundamental principles of physics would have ample causalopportunity to influence each other. This is seemingly necessary if at a gross scale the Universe isto maintain uniformity (the essence of the Cosmological Principle which postulates broad

homogeneity and isotropism within the Universe as a whole). One explanation that accounts forthe causality needed to obey this principle is given below in the subsection dealing with Inflation.

Nevertheless the isolation of regions of the Universe from one another is a real fact, as evident inthe above illustration. And, specifically there were situations whereby some parts of the Universewere not in causal contact shortly after the Big Bang, and thus not visible to one another duringearly cosmic history, but will eventually, as expansion proceeds, become known to each other.Consider this next diagram based on spacetime light cones (see Preface):


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

Start with hypothetical observers at two points A and B not then in contact in early spacetime.Over expansion time, their light cones would eventually intersect, allowing each to see (at time t1)

other parts of the Universe in common but not yet one another. At a later time, beyond t2 ("now")in the future, the horizons of A and B (boundaries of the two light cones) will finally intersect,allowing each to peer back into the past history of the other.

These intriguing ideas just discussed actually don't tell the full story. One model of Universeexpansion arrives at a Universe whose farthest opposite points are now about 42 billion light yearsapart. Check this diagram:

From: Misconceptions about the Big Bang, by C.H. Lineweaver and T.M. Davis, Scientific

American, March 2005ILLUSTRATIONS COURTESY OF ALFRED T. KAMAJIAN

On the left side is the model that equates the radius of the observable Universe with the age(rounded off here at 14 b.y.). This just assumes a "static" condition in which the age is determined


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by light speed alone. Light from the yellow spiral galaxy (which is the most distant from Earth) inthe top panel left 14 b.y ago and arrives now in the bottom panel. But, in actuality, during that 14billion years, the Universe has continued to expand. If one assumes a expansion factor of threeduring the 14 b.y. time interval, the situation is as pictured on the right. The light emitted from the

galaxy has in 14 b.y. had to travel an ever enlarging space, so that today the galaxy is at least 42billion years distant from Earth. Since we don't know where Earth really is in this finite Universe, itis currently impossible to determine the actual farthest points in opposing directions [on thesphere model, or on the flat model. But this diagram is important in indicating the Universe is

really larger than the 28 billion l ight year dimensions cited above. How much larger is stillspeculative: Since we haven't any direct information about the extent of galaxies beyond theobservable Horizon, we cannot specify a known size; several proposed models arrive at differentdimensions including those greater than 42 billion l ight years.

Perchance at this point you may be confused a bit by these "heady" concepts. Some insight and afresh look might result by checking these Expansion of Space, Gary Felder, Wikipedia and Prof.Seligman Internet sites.

Commenting further on the Universe's geometry: One view holds the present Universe to be finitebut without boundaries. Its temporal character is such that it had a discrete beginning but will

keep on existing and growing into the infinite future (unless there is sufficient [as yetundiscovered] mass to provide gravitational forces that slow the expansion and eventually causecontraction [collapse]). A much different model considers the Universe to be infinite in time andspace - it always was and always will be (philosophically, these can be tied to concepts thatequate God as an "intellectual presence" distributed throughout this naturalistic Universe)

Models for the Universe's shape hold it to be analogous to spherical, hyperbolic, or flat. Aparameter called critical density () determines the shape (page 20-10). This diagram illustratesthe three types:

In addition to specifying the Universe's shape, cosmologists seek to know whether it is open orclosed, whether it is presently decelerating or accelerating, and whether it is infinite or finite in timeand space - these topics are treated in detail on pages 20-8, 20-9, and 20-10. For now, lets

preview these topics by saying that the prevailing view is that the Universe is flat, is open, and is

accelerating its expansion.


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Einstein, in particular, showed that any three-dimensional expansion must also consider theeffects of the fourth dimension - time - to account for the behaviour of l ight traveling greatdistances in a vast "volume" (without known boundaries) making up what we conceive of as"space". He also deduced that space (within the Universe) must be curved (and light and otherradiation will therefore follow curved paths as the shortest distance between widely separatedpoints) and would, in his view, expand dynamically in a 4-dimensional spherical geometry (aspacetime dimensionality). (Einstein, at least in his early thinking, also considered the Universe tobe finite and eternal; he did not take a firm stand on its overall shape.) As was considered in the

Preface, the internal curvature of space was deduced by Einstein to be the consequence of theinteraction between matter (responsible for gravity) and the "fabric" of space. These two diagramsdepict this:

The next figure is a spacetime diagram that summarizes the history of the expanding and evolving

Universe in terms of the general or Standard Big Bang (BB) model for its inception:


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

Each major step in this time history of the creation and development of the physical Universe will

be reviewed in some detail later on this page. For now, the diagram lets us extract this sequence:1) By the end of the first millionth of a second, hadrons (quarks that make up baryons [includingprotons and neutrons] and mesons) had formed; 2) in the next interval of time up to 1 secondleptons (electrons, muons, and neutrinos) came into existence; 3) over the next 1000 or soseconds nucleosynthesis of mostly Hydrogen, some Deuterium, priordial Helium, and a tinyamount of Lithium occurred, that is, their nuclei started to form; 4) as expansion continued overthe next several hundred thousand years, the particles in this young Universe would remaininvisible to any backward-in-time-looking detector because of "opaqueness" imposed on thephotons by the free electrons (not yet coupled with atomic nuclei) that interact with the photon"fog"; 5) thereafter, the nucleons consisting of H and He protons and neutrons began to combinewith electrons in the process of decoupling; 6) during the post-decoupling stage in the first million

years the now stable atoms of Hydrogen and Helium started to clump together into gaseousclouds and then stars to form the first galaxies.

A variation of this figure with additional information appears below:


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The Big Bang as an expansion theory traces its roots to ideas proposed by A. Friedmann in 1922to counter ideas attendant to Albert Einstein's Theory of General Relativity, from which that t itanhad (erroneously) derived a model of a static, non-expanding, eternal universe (he eventuallyabandoned this model as evidence for expansion was repeatedly verified and he realized hisGeneral Relativity proved very germane to the expansion models). This fundamental equation,which introduces the Scale Factor R (see page 20-8), can take several forms, one of which is (see

caption for units):

Multiplying each term by R2 yields this equation which expresses the rate of change of the cosmicScale Factor R with time:

(dR/dt)2

= (8 G)/3 R2

- kc2

The Abbe George Lemaitre (a Belgian Catholic priest - a Jesuit) in 1927, as an outgrowth of hisPh.D. thesis at MIT, set forth another expansion model that started with his proposed "Primeval (orPrimordial) Atom", a hot, dense, very small object. (Lemaitre is credited with moving the idea ofexpansion into the mainstream of cosmology, but as indicated above, A. Friedmann had devisedan expansion model 5 years earlier) The nature of a Big Bang was refined and embellished by theteam of G. Gamow, R. Alpher, and R. Hermann and by others in the 1930s; their calculationsshowed that Hydrogen and some Helium are the dominant atomic species (with minor amounts ofLithium) that could form from their model of the Big Bang and its consequences. (The heavierelements up to Iron are produced by nucleosynthesis in the hot interiors of stars, as first


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demonstrated by Fred Hoyle and colleagues at the University of Cambridge.) Confirming evidencefor expansion came from Edwin Hubble in the late 1920s. (Hubble's other major achievement wasto prove the existence of galaxies outside of the Milky Way; he developed methods for determiningdistances to Andromeda and other nearby clusters of stars that were greater than the dimensionsof the Milky Way.) The Big Bang can be mentally related to the above-mentioned singularity event

by imaginingthat the expansion is run in reverse (like playing a film backwards): all materials thatnow appear as though moving outward (as space itself expands) would, if reversed in direction,then appear to ultimately converge on a "point of origin".

As described later in this Section (page 20-9), the BB concept drew its principal support from theobservations by Edwin Hubble and others on radiation redshifts associated with the distribution ofgalaxy velocities. These redshifts (changes in the frequency [a decrease] of the EM radiation fromexcited atoms, resulting in relativistic increases in wavelengths owing to accelerations analogousto the Doppler effect [which causes a drop in pitch of a train whistle as it recedes from the listener;see page 20-9]) rise in value as light and other radiation from galaxies comes from ever fartherpositions in the expanding Universe. Those galaxies with higher redshifts are also ones thatdisplay as we see them now younger conditions - thus, we see them as they were in the earlierstages of cosmic time; being farther away it has taken longer for emitted light to get from thestarting point to detectors at Earth.

The italicized segments below were taken from the University of Virginia's website on Cosmology:

The Doppler Redshift results from the relative motion of the light emitting object and the observer. If

the source of light is moving away from you then the wavelength of the light is stretched out, i.e.,

the light is shifted towards the red. These effects, individually called the blueshift, and the redshift

are together known as doppler shifts. The shift in the wavelength is given by a simple formula

(Observed wavelength - Rest wavelength)/(Rest wavelength) = (v/c)

so long as the velocity v is much less than the speed of light. A relativistic doppler formula is

required when velocity is comparable to the speed of light.

The Cosmological Redshift is a redshift caused by the expansion of space. The wavelength of light

increases as it traverses the expanding universe between its point of emission and its point of

detection by the same amount that space has expanded during the crossing time.

The Gravitational Redshift is a shift in the frequency of a photon to lower energy as it climbs out of

a gravitational field.

The general pattern of redshift change with distance (which in this diagram is given as the ages ofthe galaxies examined in terms of how long it has taken light from each to reach the Earth [thus

those farthest away are shown as the youngest) follows this plot (shown for four values of theHubble Constant H (see two paragraphs below), of which 72 is the current most favored value) isshown in this plot:


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The exponential shape of this curve is carried over to the next plot which is a generalizedrepresentation of the cosmological redshift versus time since the Big Bang (set at 0 [13.7 b.y. ago],

with the present age being 1). So far, the largest redshift actually measured is about 10, for a faintgalaxy (observed by the Hubble Space Telescope) that may be as old as 13.4 billion years. /p>

The Universe has been enlarging ever since this first abrupt Big Bang, with space itself doing the

expanding, and galaxies drawing apart, so that the size of the knowable part of this vast collectionof galaxies, stars, gases, and dust is now measured in bill ions of light years (representing thedistances reached by the fastest moving material [near the speed of l ight] since the moment of theBig Bang [~14 bill ion years ago]). This age or time since inception is determined from the HubbleConstant H (which may change its value) which is derived from the slope of a plot of distance (to

stellar or galactic sources of light) versus the velocity of each source (see page 20-9).

The Hubble Constant H is a fundamental cosmological value that determines the rate ofexpansion of the Universe. It is a part of this key equation:

v = Hd

This, the Hubble equation, implies that the velocity of any point in expanding space (such as thelocation of a galaxy) has some current fixed value. Of greater import, the Hubble expansiondirectly leads to this conclusion: The galaxies are moving away from Earth at recessional velocitiesthat increase systematically with distance from our planet (with corresponding increases in


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redshift). This is shown in this diagram, for galaxies up to a few bill ion light years away:

This plot shows that the speed of recession increases as one progresses outward (towards theouter limits of the observed Universe) by an amount derived from the value of H. This makessense in that if all points began, at the Big Bang, from the same point at the moment of singularityand have now spread apart by expansion, the outermost points (earliest stars and galaxies) musthave moved the fastest and those at the full range of distances along a line of sight going back tothe point of observation are moving at progressively lesser velocities. In this way, one can say thateverything is expanding, at a rate determined by the value of H. That value has now beendetermined to an accuracy of +/- 10% and is given as: 71 km/sec/Megaparsec or 21.5 km/sec

/million light years. This diagram shows how H (given as H0) is determined as the slope of astraight line plot, using distances determined by different methods (page 20-9):


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The Hubble constant affords a measure of the age of the Universe, as will be developed on page20-9. As a quick preview, consider this: Replace velocity in the above equation with d/t. Theequation then becomes: d/t = Hd. Divide both sides by d and invert t, so that: t = 1/H0. An age of

13.7 billion years is the current best estimate.

The Hubble Constant also is applied to determining how fast galaxies at the observable Universehorizon are traveling. Starting with 71 km/sec/Megaparsec as the rate (and assuming this rate tobe constant [it may have been slower in the past and is now faster], so this is an average) ofexpansion, the distance to a 13.7 billion light year object (if it could be seen) is about 4200

Megaparsecs (about 1.3 x 1023

km or 9 x 1022

miles). At 100 Megaparsecs, the velocity of areceding galaxy (as the observed object) is ~7000 km/sec (from a plot of velocity versus distancefor an H of 71 km/sec/parsec). The velocity at that distance would then be 7000 x 42 = 294000 kmsec - almost the speed of light

Aside from quantum speculation, nothing is really known about the state of the Universe-to-be just

prior to the initiation of the Big Bang (a moment known as the Planck Epoch). The Laws and the

20 or so fundamental parameters or factors that control the observed behavior of all that isknowable in the Universe today become the prevailing reality at the instant of the Big Bang, butScience cannot as yet account for the "why" of their particular formulation and values, i.e., whatcontrols their specifics and could they have come into existence spontaneously without any

external originator, the "Creator" or "Designer". Among these conditions that had to be "fine-tuned"just right is this partial, but very significant list: homogeneity and isotropy of the Universe (theCosmological Principle); relative amount of matter and anti-matter; the H/He and H/deuteriumratios; the neutron/proton ratio; the degree of chaos at the outset; the balance between nuclearattraction and electric repulsion; the optimal strength of gravity; the decay history of initialparticles; the total number of neutrinos produced early on; the eventual mass density whichaffects the Critical Density; the specific (but varying) rates of expansion after the Big Bang; thedelicate balance between Temperature and Pressure, both during the first moments, and muchlater during star formation; the ability within stars to produce carbon - essential to life; and muchmore. (See also another list at the bottom of page 20-11a.)


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Some of these are interdependent but the important point is that if the observed values of these

parameters/factors were to differ by small to moderate amounts, the Universe that we live in

could almost certainly not have led to conditions that eventually fostered intelligent life

capable of evolving during the history of the Universe as we know it. Also presumablynecessary: beings that can attest to the Universe's existence and properties by makingobservations and deductions that lead to knowledge of the Universe. This requires the eventualappearance of "conscious reasoning" 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 thetenets in what is refe

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