August 31, 2006

OUR UNIVERSE

THE BEGINNING OF SPACE-TIME

Initially: The beginning of space-time B what we call our Universe B is the moment from which it makes sense to talk about time. Before the beginning of space-time, there was no time. It does not make sense to talk about time before the beginning of space-time (pp. 288-289).

The Singularity Theorem: In the early 1970=s, the English physicists Stephen Hawking (1942-) and Roger Penrose (1931-) showed that Einstein=s general theory of relativity not only explains the evolution of our Universe but also dictates that our Universe must have had a beginning. This is the ASingularity Theorem@ which posits a ABig Bang@ giving rise to our Universe from an original one point. (A point has no dimension) (pp. 91, 99, 288-290).

At the time, however, all known categories of energy had a positive pressure B all responded to gravity with attraction. The pressure was sometimes strong, such as that of photons and neutrinos, sometimes weak, such as that of elements and dark matter, but its direction was always positive (p. 290. For dark matter, see also pp. 5, 7, 9, 19, 21 and 29 of the present document).

Dark Energy: In the last few years, however, evidence has emerged for the presence of energy with negative pressure B Adark energy.@ The conditions for the singularity theorem no longer apply and it is not a given that our Universe started off from a singularity. If at any time, dark energy is the dominant type of energy in our Universe, then at that particular time, our Universe is expanding (p. 290. For dark energy, see also pp. 4, 5, 8 and 9 of the present document).

Alternative Theories for our Beginnings: Several theories have been proposed for the beginning of our Universe. Two quantum theories (one taking space-time as the starting point, the other, matter), and one Ainflation@ theory, have gained the most support.

These theories are:

1. Quantum Theories: On very small scales, quantum effects play a dominant role in the behavior of matter and the three forces B the Astrong@ (nuclear), the Aweak@ (radioactive beta decay), and the electromagnetic. Do quantum effects also apply to space-time and gravity?

The general theory of relativity proposed by Albert Einstein (1879-1955) makes clear that the connection between space-time and matter is so intimate that the quantum nature of one cannot be separated from the quantum nature of the other (pp. 292-297).

The two quantum theories proposed are:

a. The ALoop Theory@ of Space-time: Time may have behaved very differently at or near the initial singularity.

At a sufficiently small scale, gravity is so strong that space-time looks frothy, foamy B not smooth. Individual chunks of space-time can be characterized in terms of lengths, areas and volumes. They interact with each other. The fundamental quantities are Aloops@ which link up and knot themselves together, weaving a tapestry which, on a large scale, looks like space-time.

No initial Singularity: Near the singularity the quantum nature of space-time stops it from collapsing to a point. Our Universe undergoes a jerky bounce as it passes form a period of contraction to one of expansion. There is no initial singularity (pp. 292-293 and 296-297).

b. The AString Theory@ of Gravity: The Astring theory@ proposes that the most fundamental structures in our Universe are not particles but rather small pieces of Astring.@ At sufficiently high energies, photons, electrons and quarks consist of tiny strings that wriggle and vibrate as they propagate through space-time. There is only one type of string but by vibrating differently in various circumstances, this string takes on a wide range of properties, and each type of vibration corresponds to a fundamental particle or set of particles. The string theory is powerful in explaining fundamental forces.

No Initial Singularity: Going back far enough in time, our Universe was contracting. At some point, it underwent a transition from a contracting phase to the expanding phase we see today. The transition did not happen when our Universe had contracted to one point B the singularity. It happened when our Universe had reached a minimum, finite size set by the strength of gravity, the tension of the fundamental Astrings,@ and the scale at which quantum effects became important.

Even further back in time, before the contraction, our Universe had been expanding, becoming bigger and cooler.

Our Universe is without beginning: From a stage of expansion, cold and placidity, our Universe underwent a contraction, and then resumed its expansion B the expansion happening today. Our Universe is returning to a cold and placid state.

Gravity is the geometry of space-time: Gravity is a response to energy. Everything in Our Universe carries some sort of energy, and, therefore, every thing is subject to the effects of gravity. If gravity, like matter, behaves differently at the level of very small scales, then so would space-time. On a sufficiently small scale, space-time would not be smooth (pp. 294-296).

2. The Inflation within a Multiverse Theory: The inflation theory suggests that during the very early phases of our Universe, dark energy was responsible for an initial burst of inflation which stretched a microscopic region of space into a huge patch, larger than and encompassing what is now our cosmological horizon (15,000,000,000 light years).

The Amultiverse@ contains not only our own but also any number of other universes having similarly emerged from space-time.

A non-homogeneous AMultiverse@: The multiverse was non-homogeneous with regards to its energy pressure, some regions having a strongly negative pressure, others a mildly negative one, yet others a positive pressure. At a certain differential, regions of strong negativity inflated, quickly occupying a comparatively very large space. Bits of space inflated dramatically, dwarfing their surroundings. The process happened repeatedly, different regions of space developing negative pressure and suddenly ballooning at different times. Their inflation rate slowed down as the magnitude of their negative pressure decreased, ceasing entirely when their pressure became positive.

Our Universe one of many: Our Universe is one of the regions which has thus inflated to gigantic proportions. What we are able to see of our Universe is within such an immense region. We cannot know because our cosmological horizon is limited by the speed of light. If the age of our Universe is 15,000,000,000 years, then the light has only had this amount of time in which to travel. The furthest we can see is 15,000,000,000 light years.

Time existed before the ABig Bang@: The multiverse has existed forever, individual universes emerging at different times during its existence. It makes sense to talk of time before the appearance of our Universe.

Different Laws for different Universes?: The laws of nature may be different within each individual universe. Instead of gravity and the three forces (Astrong,@ Aweak@ and electromagnetic), a completely different set of forces may obtain in universes other than ours. Or, other universes may be similar to ours but without elements heavier than hydrogen, a too-quick inflation rate having pre-empted the synthesis of any heavier element. In most alternative universes, life as we know it in ours would be impossible (pp. 230 and 290-292. For dark energy, see also pp. 1, 5, 8 and 9 of the present document. For inflation, see also p. 5 of the present document).

OUR UNIVERSE

AGE: The age of our Universe is 15,000,000,000 years (pp. 123, 211, 230 and 253).

SIZE:

Size unknown: The furthest we can see is 15,000,000,000 light years. It is our current cosmological horizon. The cosmological horizon is mute with regards to the size of our Universe. It is only a description of the distance we can see at any moment in time. This does not mean that there is nothing else going on outside our visible patch. Our Universe may have been infinitely big from the outset. Our space-time, which came into existence at the moment of the Big Bang, may have had an infinite extent. Someone 100,000,000,000 light years away from us, may also have a cosmological horizon of 15,000,000,000 light years, and it will not overlap with ours (pp. 230-231 and 277).

The Theory of Inflation: The theory of inflation suggests that in the first few moments (instants) of the existence of our Universe (or our patch of it), space-time underwent a brief period of accelerated expansion during which points in space moved away from each other much more quickly than the speed of light. (This does not mean that anything moved faster than the speed of light. It only means that the distance between two points in space-time increased faster than a photon would take to traverse it) (pp. 236-241. For inflation, see also p. 4 of the present document).

If its expansion was faster than the speed of light, our Universe is much larger than our cosmological horizon (p. 237).

GEOMETRY: Our Universe has a geometry, that is, a space-time, which is determined by the energy it contains. Space-time in turn affects the motion of all the light and matter which our universe contains. The interplay between space, time and matter is at the heart of the evolution of our universe. The evolution of our universe is intimately connected to what it contains (pp. 77, 80-82, 86, 201, 225, 252, 272, 293 and 297).

Einstein=s general theory of relativity tells us how the energy within space time (our Universe) determines its curvature. This energy can take the form of photons (radiation), neutrinos, particles with masses (such as the atoms of normal elements), dark matter and dark energy. The curvature of the whole of space-time is determined by the contributions of all forms of energy within it (pp. 72 and 77. For dark matter, see also pp. 1, 7, 9, 19, 21 and 29 of the present document. For dark energy, see also pp. 1, 4, 8 and 9 of the present document).

If, as Einstein=s general theory of relativity describes, matter has a quantum nature, and if, as the theory indicates, matter and space-time are intimately connected, then space-time may also have quantum nature (p. 297).

The geometry of our Universe is Euclidean to within a few percent (p. 254).

TEXTURE: On a sufficiently large scale (like looking down at the ocean from an airplane, or looking at a Asmooth@ fabric B which in fact is not smooth when looked at from the level of fibers), our Universe is homogeneous and isotropic. This is the ACosmological Principle@ (pp. 74 and 228).

Our Universe looks identical everywhere. It looks the same wherever we are. It has no preferred position or place, no center, no heart. There is no preferred direction. There are no doors or edges to space. There is nothing special about any point in it. Physical quantities, such as temperature or brightness of light at any point in our Universe always have the same value at the same time. The temperature of our Universe as a whole may change, but it will be the same everywhere at any given time. Gravitationally, there is no concentration of mass or energy which can serve as a seed around which gravitational clustering can occur. There is no center to which everything collapses (pp. 74, 78, 80, 228 and 274).

Our Universe is populated by many galaxies, such as our own, the Milky Way. This does not negate the essential isotropy of our Universe. Although the galaxies are clumped together in structures, on average, they are distributed evenly in the sky. Looked at on a sufficiently large scale, the distribution of galaxies is even. To look at the galaxies is analogous to looking at the ocean from the level of its waves, or at a fabric from the level of its fibers (pp. 73, 225 and 228-229).

The smoothness of the cosmic microwave background (known as the Arelic radiation@), is indication that in the past also, our Universe was smooth. This radiation is smooth to the 0.1 percent. This is so even though it has been traveling toward us for most of the lifetime of our Universe (since the time of recombination, when our Universe was 300,000 years of age), spanning a distance almost equivalent to our cosmological horizon (15,000,000,000 light years). The smoothness of this radiation is unambiguous evidence that on the scale of the cosmological horizon, our Universe is homogeneous (pp. 229, 231, 242 and 247. For relic radiation, see also pp. 14, 15, 16 and 17).

MATTER: Table 1 shows the percentages of Avisible@ and dark matter in our Universe:

Table 1: Our Universe B AVisible@ and invisible Matter*

Matter	Universe (Percent)	Clusters of Galaxies (Percent)	Milky Way (Percent)
AVisible@: Seen by the eye or by visual telescopes ASeen@ by microwave, radio and X-ray telescopes Total Avisible@	1 10 11	(a) (a) 1	(a) (a) 2
Invisible (dark matter)	89	99 (b)	98
Total	100	100	100

* References: pp. 134, 176-177 and 180. For dark matter, see also pp. 1, 5, 9, 19, 21 and 29 of the present document.

(a) Data not available.

(b) In extreme cases, the percentage of dark matter may be as high as 99.9.

The Nature of Dark Matter: Dark matter is an invisible substance which responds to gravity with attraction. Identification of it is difficult. Were it to exist as large bodies, it would be detected easily. Therefore, it must be small. Were it to be light and sparse, it could not account for its dramatic gravitational effects on celestial bodies. Therefore, it must be both small and sufficiently heavy to account for a large proportion of the total mass of our Universe (pp. 183 and 219).

Objects with masses of up to 80 percent of that of the Sun do not burn, and, therefore, stay dark. Examples of such Massive Compact Halo Objects (MACHO=s) include:

a. Brown Dwarfs: Brown Dwarfs are much like planets, with sizes generally a few times that of Jupiter. However there are smaller than Jupiter because they are very dense, held together not by electromagnetic forces but by quantum effects (p. 183).

b. Black Holes: Black holes are objects which are so dense that light cannot escape their gravitational pull. With its present mass, Earth would have to shrink to a sphere a few centimeters in diameter to have the properties of a black hole. Close to the surface of black holes, gravity tears up the surrounding material into very energetic particles and radiation. This light can be seen with X-ray telescope. The signature of a black hole is much radiation from a very small region of space (p. 184).

ENERGY:

Energy Density: The energy density of a substance is the amount of energy it contains per unit of volume.

Energy Pressure: The energy pressure of a substance is a measure of how much the substance pushes outward. It is the sum of its energy density along each of the three dimensions of space.

Effects on Space-time: The force exerted by substances is equal to the sum of their energy density plus their energy pressure. It is the sum of their:

1. Energy Density.

2. Energy Pressure along the three dimensions of space:

a. Length.

b. Width.

c. Height.

Dark Energy: Dark energy is an invisible substance which responds to gravity with repulsion (p. 219).

Our Universe is expanding at an accelerating rate. In order to explain this accelerating rate, we must assume a type of substance which pervades space-time and which responds to gravity with repulsion. The substance must be sufficiently abundant to impact significantly the evolution of our Universe as a whole (pp. 197 and 218-219. For dark energy, see also pp. 1, 4, 5, and 9 of the present document).

This substance must have a negative pressure. As with a normal substance, this pressure would be the exact equivalent of its energy density. However, in this case, the pressure would be negative. Since the gravitational force of a cube filled with the substance would be the sum of its (a) Energy density, and (b) Pressure in the three directions of space, the gravitational impact of the cube would be negative (p. 202).

In an expanding Universe, the density of the substance would not be diluted. It would remain constant (p. 202).

Today, dark energy accounts for two-thirds of the total energy in our Universe (pp. 211 and 219).

The substance is called the quintessence (fifth essence, element). We must add it to our existing model of space, time and matter in order to explain the evolution of our Universe (p. 221).

Five Dominant Categories of Energy: Five types of energy predominate in our Universe and affect its size:

1. Ordinary Matter:

a. Exerting a Positive Pressure:

i. Strong Pressure:

* Photons (radiation).

* Neutrinos.

ii. Weak Pressure:

* Normal elements.

* Dark matter (For dark matter, see also pp. 1, 5, 7, 19, 21 and 29 of the present document).

2. Dark Energy:

Exerting a Negative Pressure (pp. 220-221 and 254. For dark energy, see also pp. 1, 4, 5 and 8 of the present document).

Direction of the Effect on Space-time:

1. Ordinary Energy B A Gravitational Pull: Both the energy density and the energy pressure of the ordinary substances which space-time (our Universe) contains, causes it to shrink. A substance with high pressure, such as radiation, slows the expansion of our Universe more than a substance without pressure, such as dust. A cube of protons exerts a larger gravitational pull than a cube of heavy particles (pp. 88 and 201).

2. Dark Energy: Both the energy density and the energy pressure of the dark energy which space-time (our Universe ) contains, cause it to expand (pp. 197, 202, 211, 218-221 and 254. For dark energy, see also pp. 1, 4, 5 and 8 of the present document).

EVOLUTION: Our Universe not only changes with time, it evolves with time. It changes with directionality. It is expanding and cooling. The expansion manifests itself as space stretching, any two points in space moving further and further apart as our Universe evolves. This expansion is due to the interplay between (a) Space-time, and (b) Energy in the form of matter and radiation. The evolution of our Universe is intimately connected to what it contains (pp. 81-82, 106 and 288).

EVOLUTIONARY STAGES:

Our Universe at Three Minutes:

a. Size: At three minutes of age, our Universe is 1,000,000,000 times smaller than it is today.

b. Density of Atoms: Our Universe consists of a primordial plasma of elementary particles constantly moving about, colliding with each other, annihilating and re-creating themselves at breakneck speed. Particles are dissociated and consist of neutrons, protons and electrons (pp. 117-118, 120 and 129).

The kinetic energy of nucleons accounts for an appreciable part of their total energy. In comparison, the energy contained in their mass is insignificant. Nucleons effectively behave as particles without mass (pp. 73, 89-90 and 128-129).

The density of matter is 1 gram per cubic meter (pp. 118-119).

c. Density of Radiation: In the primordial plasma of elementary particles, photons are constantly being emitted and absorbed.

The density of light is the same as that of water today (pp. 117-119).

d. Relative Energy Density of Atoms and Photons: The pressure of matter is mostly from radiation rather than dust. Photons B bundles of energy speeding at 300,000 kilometers per second B exert a very high energy density (pp. 87-88 and 108).

Most of the energy in our Universe is in the form of radiation (pp. 73, 89-90 and 127).

EVOLUTIONARY STAGES

Our Universe at Three Minutes (continued)

e. Temperature:

i. Absolute Value: The temperature of our Universe is 1,000,000,000 degrees Kelvin. (Room temperature is about 300 degrees Kelvin).

ii. Thermal Equilibrium: The interaction of particles in the hot plasma allows the photons to stay in thermal equilibrium. By colliding with the particles, they transfer energy through the system and settle down to a black-body (thermal equilibrium) state. At its beginnings, our Universe was an infinite Ablack body@ (in thermal equilibrium) (pp. 117-119).

f. Composition: Our Universe consists of hydrogen and helium. Of the total energy in these elements, 74 percent is in the form of hydrogen nuclei, and 26 percent in the form of helium nuclei. This balance between the two elements would stay almost intact to the present day (pp. 129-130).

g. Degree of Transparency: Photons interact so strongly with the surrounding charged electrons and protons that they are absorbed (and then re-emitted) almost as quickly as they are formed. Our Universe is generating a lot of light, but the photons are too short-lived to leave their immediate environment. Our Universe is very opaque (p. 120).

EVOLUTIONARY STAGES

Our Universe at Three Minutes (continued)

g. Nucleosynthesis: The synthesis of elements takes place. When a proton collides with an anti-neutrino, it is transformed into a neutron and emits a positron (the anti-particle of the electron). When a neutron collides with a neutrino, it is transformed into a proton, and emits an electron.

* At 100,000,000,000 degrees Kelvin (the probable temperature at the coming into being of our Universe), protons and neutrons are constantly converting into each other. The number of neutrons and protons is approximately equal. (Protons are hydrogen nuclei).

* At 50,000,000,000 degrees, an excess of protons over neutrons begins to manifest itself. The weight of a neutron is 1.001 times that of a proton, and neutrons are synthesized more rarely.

* At 10,000,000,000 degrees (the temperature of our Universe at almost three minutes), the nuclear forces which bind nucleons together begin to overcome the kinetic energy of particles. Nuclear forces begin to overcome the electromagnetic repulsion of protons. A neutron which collides with a proton, sticks to it and forms a deuterium nucleus (one neutron and one proton).

* At 900,000,000 degrees (the temperature of our Universe at just more than three minutes), the deuterium nuclei stay around long enough to absorb another proton and form helium-3, which in turn stays around long enough to absorb another neutron and form helium (two protons and two neutrons).

The nucleon mix at this temperature is 13 percent neutrons and 87 percent protons. After all the neutrons have combined with protons, 74 percent of the protons are still left unattached. They continue as hydrogen nuclei (pp. 107, 124, 127-129 and 141).

EVOLUTIONARY STAGES

Our Universe at Three Minutes

g. Nucleosynthesis

* At 900,000,000 degrees (continued)

By this time, almost all of the electrons have collided with positrons, with the release of energy. The small number of electrons left unattached will, in another 300,000 years, combine with nuclei to form neutral atoms.

Photons outnumber nucleons by a factor of 1,000,000,000 to 1. Most of the energy of our Universe is in the form of photons (pp. 125-130 and 144).

EVOLUTIONARY STAGES (continued)

Our Universe at 300,000 Years B ARecombination@:

a. Size: The size of our Universe is 1,000 times smaller than it is today B and 1,000,000 larger than it was at three minutes of age (p. 219).

b. Light: At a few thousand degrees Kelvin, photons no longer have the energy to rip the negatively-charged electrons off the positively charged hydrogen nuclei. The environment is now neutral, consisting of hydrogen atoms. Photons are no longer deflected from their paths. They travel in a straight line, oblivious to the presence of matter, now neutral, that surrounds them. Our Universe becomes almost completely transparent.

This light will become the Arelic radiation@ which now permeates our Universe. This radiation will keep its spectrum B the spectrum it had when it was emitted, when our Universe was 300,000 years of age and in thermal equilibrium. The energy of these photons is very low, easily distinguished from the much higher energy photons which would later be injected into our Universe by the stars (pp. 120-121, 129, 231, 238, 243, 249, 251, 253, 256 and 278-279. For relic radiation, see also pp. 6, 15, 16 and 17).

c. Matter: Matter consists of neutral hydrogen atoms (p. 120).

EVOLUTIONARY STAGES (continued)

Our Present Universe:

a. Size: Today, our Universe is 1,000,000,000 times larger than it was when it was three minutes of age.

The theory of an expanding universe predicts the recession of galaxies, the existence of relic radiation (light) and the presence of the light elements (hydrogen and helium) (pp. 119, 170, 180 and 288. For relic radiation, see also pp. 6, 14, 16 and 17).

b. Density of Atoms: Assuming that most stars and galaxies consist of hydrogen atoms, there are on average 10²³ of a gram (the mass of a few dozen hydrogen atoms) per cubic meter of space.

Note: The energy density of two particles decreases with the cube of their distance (pp. 107-188, 118-119 and 217).

EVOLUTIONARY STAGES

Our Present Universe

c. Density of Photons:

i. Relic Radiation: Our Universe is permeated by relic radiation B a faint, ubiquitous (isotropic) radiation, glowing with the same intensity at all places in space. This radiation is evidence of an early, hot phase in our Universe (the primordial fireball). Its wavelength is a very long B one centimeter. Its spectrum is dominated by microwaves (wavelength of 0.001 centimeters or more) and radiowaves (wavelengths greater than a few centimeters). Its temperature is 3 degrees Kelvin (three degrees above absolute zero) (pp. 104-105, 109, 122 and 172).

From our perspective, the relic radiation originates from the surface of a celestial sphere which surrounds us on all sides B like when we are in a planetarium. This surface is known as the Asurface of last scatter@ B the last scatter of the photons from the charged electrons and atomic nuclei just before they combined to form hydrogen (p. 122. For relic radiation, see also pp. 6, 14, 15 and 17).

ii. Overall Photon Density: There are on average 1,000,000,000 photons in every cubic meter of space. Our Universe consists mostly of radiation, with a sprinkling of atoms (pp. 107-108).

Note: The energy density of radiation decreases with the fourth power of their distance (p. 109).

EVOLUTIONARY STAGES

Our Present Universe (continued)

d. Relative Energy Density of Atoms and Photons: The energy density of photons (radiation) is 10,000 times smaller than the energy density in atoms (even though photons outnumber protons by a ratio of 10,000,000,000 to 1). Photons contribute negligibly to the overall energy budget in our Universe and have very little impact on its expansion rate (pp. 107-109 and 168).

Note: Today, most of the energy in our Universe is in the form of dust (pp. 73 and 89-90).

e. Temperature: The temperature of our Universe is 1,000,000,000 times less than it was when it was three minutes of age. The cosmic microwave background (relic radiation, cosmic light) is 3 degrees Kelvin (pp. 107, 119, 122 and 123. For relic radiation, see also pp. 6, 14, 15 and 16).

f. Composition: Of all the atoms in our Universe, 95 percent are atoms of either hydrogen or helium. The Avisible@ elements (that is, not counting dark matter) account for only 5 percent of the mass of our Universe (p. 134).

The proportion of hydrogen and helium was almost completely set within the first 3-4 minutes of the coming into being of our Universe (See p. 11 of the present document).

At three minutes, the balance of the two elements was 74 percent hydrogen and 26 percent helium. Since then, the burning of hydrogen in the center of stars has increased the helium, and the present balance is 70 percent hydrogen and 30 percent helium (pp. 107, 125, 129-130 and 134).

g. An accelerating Rate of Expansion: The expansion of our Universe is not decelerating under the pull of its own gravity. Distant supernovae are 25 percent dimmer than they would be, were the rate of expansion of our Universe slowing down. Our Universe is expanding at an ever increasing rate (pp. 209 and 212).

QUASARS

Some sources of radiowaves coincide with fairly bright objects that look like stars. They are extremely focused and do not have the spatial extent of a galaxy. Their spectra are very red-shifted, some having spectra with wavelengths that have been stretched by up to seven times. Their large red shift shows that they are at tremendous distances from us and are, therefore, very old B having existed since our Universe was in its beginnings. They are not stars and have been called AQuasi Stellar Radio Sources@ (quasars).

Quasars must emit an enormous amount of light (electromagnetic waves) to be visible at that distance. It is calculated that they radiate more energy than the brightest galaxies we can see. Some extremely bright quasars emit as much energy as 30,000,000,000,000 stars. Quasars are some of the most powerful objects in the sky.

Quasars do not necessarily emit only radiowaves. They may have a range of optical properties. They seem always to lie near the center of very massive galaxies. Quasars may be fueled by gigantic black holes with masses more than 1,000,000 times that of our Sun (pp. 173 and 268-269).

The quasar closest to the Milky Way is 800,000,000 light years away (p. 268).

CLOUDS OF VERY HOT GASES

Clouds of hot gases are exceptionally energetic processes. The turmoil of hot gas emits X-rays (wavelength 0.000,000,001 - 0.000,000,000,001 centimeter) (pp. 171 and 173).

GALAXIES

1. Number: Within our cosmological horizon, there are more than 1,000,000,000 galaxies, each of which contains about 100,000,000,000 stars (pp. 107 and 260).

2. Groups of Galaxies: There are many groups of galaxies spread throughout our Universe. These in turn may be imbedded in much larger agglomerations called clusters (p. 262).

3. Clusters of Galaxies: Clusters of galaxies are typically 15,000,000 light years across, and may go up to 30,000,000 light years across. They comprise hundreds or thousands of galaxies (pp. 231, 249 and 262).

Closest to the Milky Way are the Virgo Cluster, 50,000,000 light years away, and the Coma Cluster, 300,000,000 light years away (p. 262).

4. Dark Matter: For each galaxy (including the Milky Way), the velocity at which stars rotate is a function of their distance from the center of the galaxy B the greater their distance, the higher their velocity. This is true even for those stars which are well into the outer regions of the galaxy and which, because of their distance from the center, should be subject to a diminished gravitational pull. This phenomenon is in contrast to the Solar System where the further away a planet is from the Sun, the more slowy it rotates.

We must, therefore make the assumption that there is more mass than we actually see, and that the further away an object is from the center of the galaxy, the more mass its orbit encloses. This Adark matter@ extends from the center of the galaxy to beyond it, forming a halo around it. For clusters of galaxies, the ratio of dark to visible matter (such as stars and gas) ranges from 100 or even 1,000 to one (pp. 176-180. For dark matter, see also pp. 1, 5, 7, 9, 21 and 29 of the present document).

GALAXIES (continued)

5. Movement:

a. Direction of Motion: Distant galaxies are systematically moving away from us. The recession of the distant galaxies is the same in all directions.

Light (electromagnetic waves) has wavelengths from zero to infinity. The further away a galaxy, the more red-shifted is its spectrum. Galaxies which are so distant that their spectrum is red-shifted to outside the range of a visual telescope (wavelengths captured by the human eye, 0.000,000,4 - 0.000,001,4 centimeter), can be Aseen@ by a radio telescope (pp. 171-172).

b. Speed: The more distant galaxies are receding at speeds greater than 3,000 kilometers per second (pp. 49, 87, 90 and 95-96).

c. Relative Speeds: The more distant galaxies are moving away faster than nearby ones. The relationship between the velocity at which galaxies are receding from us and their distance from us, is the AHubble=s constant@ B 50 kilometers per second per 3,200,000 light years (50 kilometers per second per Megaparsec) (p. 97).

6. Globular Clusters:

a. At a great Distance: Globular clusters are bright spherical agglomerations of almost 1,000,000 stars which are imbedded in very distant galaxies (p. 97).

b. Very old: Globular clusters are the oldest objects in our Universe, having ages of more than 12,000,000,000 years (pp. 97 and 210; Columbia Encyclopedia 2000).

7. The Andromeda Nebula:

a. Distance from Earth: The Andromeda Nebula is the major galaxy closest to Earth. It is 2,000,000 light years away (pp. 47, 100 and 260).

b. Direction of Motion: Andromeda is moving toward Earth at a speed of 300 kilometers per second (p. 95).

GALAXIES (continued)

8. The Milky Way (Aour Galaxy@):

a. Number of Stars: Our Galaxy contains 100,000,000,000 stars. The Sun is one of these (pp. 175-176, 227 and 260).

b. Size: The disk of the Milky Way is 60,000 light years across. The hub of the disk is 3,000 light years thick (p. 260).

c. Dark Matter: Dark matter is mass we cannot see but infer is present from the fact that the clouds of hydrogen and the clusters of bright stars, both of which are much further from the center of the Milky Way than the Sun, though they are still under its pull, are rotating at speeds which are faster than that of the Sun (whose speed is 220 kilometers per second).

This dark matter is distributed spherically in and around the Galaxy. Its concentration is high at the center, forming a dense core, and then extending outward to form a halo which may have a diameter ten times that of the Milky Way we see. We may visualize the Milky Way as a bright spiral disc of stars at the center of a large ball of dark matter.

For the Milky Way, the ratio of dark to visible matter is 50 to one (pp. 176-177 and 261-262. For dark matter, see also pp. 1, 5, 7, 9, 19 and 29 of the present document).

d. Dust: Our Galaxy is permeated with dust B small particles of carbon (which absorb any light that tries to cross it) (p. 101).

e. The Local Group: The two closest neighbors of the Milky Way are the Large Magellanic Cloud (one twentieth the size of the Milky Way) and the Small Magellanic Cloud (one hundredth the size of the Milky Way). The Milky Way, the Large and Small Magellanic Clouds, the Andromeda Galaxy and a few more galaxies further out form the ALocal Group@ (p. 262).

GALAXIES

8. The Milky Way (Aour Galaxy@) (continued)

f. Closest Clusters of Galaxies: The cluster of galaxies closest to the Milky Way is the Virgo Cluster, 50,000,000 light years away, and sufficiently massive that its gravitational force is pulling the Milky Way toward it. Further away, is the formidable Coma Cluster, 300,000,000 light years away, and comprising more than 10,000 galaxies (p. 262).

g. Closest Quasar: The quasar closest to the Milky Way is 800,000,000 light years away (p. 268).

h. Space-time: The space-time encompassed by the Milky Way is relatively still, stretched only to a very slight degree by the pull of the expanding Universe. The amount of mass close to the Galaxy is sufficient to almost counterbalance the geometry of the space-time surrounding it (p. 90).

STARS

1. Beginnings: Stars arise in a region of our Universe where the environment is so dense that some of its material is squeezed into a dense ball of gas consisting of hydrogen and helium, along with very small traces of carbon, oxygen and other heavier elements. The gas becomes highly compressed and dense, and the gravitational force slowly squeezes it even more. As the star evolves, it collapses on itself and heats up, radiating some of its energy. When the core temperature of the star reaches about 10,000,000 degrees Kelvin, quantum tunneling begins and engenders the process of nuclear fusion (pp. 143-144. For quantum tunneling, see this page under Emission of Light, and p. 27 of the present document).

2. Age: Most stars are from 1,000,000,000 and 10,000,000,000 years of age. Some stars may be nearly 13,700,000,000 years of age B close to the age of our Universe. The Sun is 5,000,000,000 years of age (pp. 76 and 100; Wikipedia, Astars@ 2006).

3. Composition: Stars are 98 percent hydrogen and helium (p. 133).

4. Emission of Light: The emission of light by stars is due to nuclear fusion. In the core of stars, the nuclei of four hydrogen atoms (one neutron and proton each) are compressed together to form the nucleus of a helium atom (two neutrons and two protons). The mass of the helium nucleus is one percent less than the total mass of the four hydrogen nuclei. This difference in mass is released in the form of radiant energy B light. We know that E = mc². This is the process by which stars shine (pp. 59, 124 and 140).

Some stars have a core which reaches temperatures of 10,000,000 degrees or more B the core of the Sun, for example, is 16,000,000 degrees. At these temperatures, quantum tunneling takes place, and neutrons and protons combine to convert hydrogen into helium B with an attendant emission of light (pp. 143-144. For quantum tunneling, see this page under Beginnings, and p. 27 of the present document).

STARS (continued)

5. Evolution: As a star contracts, the motion of the particles of which it consists (atoms, nuclei and electrons) increases. As a result, they emit more light. Light is energy, and as the star emits energy, it contracts some more due to its own gravitational pull. The particles move even faster and the temperature of the star increases. The evolution of a star is in the direction of ever decreasing size and ever increasing temperature (p. 138).

6. Last Stages of Life: Over the course of billions of years, the process of nuclear fusion depletes the available hydrogen in the star, and forms a helium core in its center.

The depletion of all its hydrogen, engenders a rapid transformation of the star. Its core contracts and its outer envelope suddenly enlarges to 100 times its prior size. The star is now a Ared giant.@ Its core continues to contract (p. 144).

When the core temperature of the red giant reaches 100,000,000 degrees, the helium starts to burn B the Atriple alpha@ process begins whereby three helium nuclei combine to form a carbon nucleus (6 protons and 6 neutrons).

At some point in the process, a sufficient amount of carbon has accumulated so that carbon itself begins to react significantly with the helium nuclei to form oxygen (8 protons and 8 neutrons). The helium is slowly consumed and the star eventually consists of a very large envelope with a dense core of carbon and oxygen (pp. 124, 144 and 147).

STARS (continued)

7. Final Stage:

a. Stars whose Mass is heavier than that of the Sun by up to 40 percent: Stars whose core is sufficiently light to withstand the pull of gravity, become stable and cease collapsing. The envelope of the red giant extinguishes itself and expands outward. The core radiates most of its energy and cools down to form a dense nugget of carbon and oxygen B a Awhite dwarf.@ Some of the carbon and oxygen is expelled into space, ending up in other stars, in planets (such as Earth), or simply in the form of minute dust particles (pp. 125, 147-148 and 204).

The white dwarf sits quietly in space without emitting much light. It slowly radiates its heat, contracts, and fades away over the course of billions of years (p. 205).

b. Stars whose Mass is heavier than that of the Sun by more than 40 percent:

i. Final Stage: Stars whose core is massive cannot resist the gravitational pull of their center. As they collapse and heat up, elements combine to form even heavier ones.

The temperature at which the elements burn is:

Helium 100,000,000 degrees Kelvin

Carbon 600,000,000 A

Neon 1,000,000,000 A

Oxygen 1,500,000,000 A

Silicon 3,000,000,000 A

The star takes on an onion-like appearance, the outer layers burning the lighter elements, and the inner layers the heavier ones.

The heaviest element produced by nuclear burning is iron. This is because in the nucleus of iron, the electromagnetic repulsion between protons, is exactly counterbalanced by their nuclear force attraction. Any additional proton uses up rather than saves energy. Iron is the most stable element and (with the exception of hydrogen and helium) is the most abundant element in terrestrial, stellar and inter-stellar environments.

STARS

7. Final Stage

b. Stars whose Mass is heavier than that of the Sun by more than 40 percent (continued)

ii. The End: Quite suddenly, the various layers of the star cannot resist the pull inward. At an incredible speed and in a matter of seconds, the core of the star shrinks, reaching the density of an atomic nucleus. It then halts so rapidly that the shock wave from this sudden stop blows apart the outer layers of the star B thus fertilizing outer space with the rich array of elements synthesized during the life of the star.

The explosive event is known as a Asupernova.@ At the peak of the explosion, the brightness of a supernova can exceed that of the whole galaxy in which it is imbedded, superceding the light of more than 100,000,000,000 stars. The rise and subsequent decay in the intensity of light emitted spans about one month. The rate of supernovae occurrences is about one per galaxy per century (pp. 102, 203-205).

During a supernova, the temperature is such as to allow the production of an abundance all the heavy elements B to iron and beyond, and these are released into space (pp. 102 and 148-152).

THE SOLAR SYSTEM

THE SUN:

1. Age: The Sun is a star which has been shining with approximately the same intensity for the past 5,000,000,000 years. It is in the middle of a probable total life span of 10,000,000,000 years. Its luminosity will double during the second half of its life span (the next 5,000,000,000 years) (pp. 76, 140, 143 and 144; Arnett 2006).

2. Size: The Sun is a star of about medium size. Its diameter is 1,400,000 kilometers. It is 1,300,000 times the size of Earth (Columbia Encyclopedia 2000).

3. Mass: The Sun contains more than 99.8 percent of the total mass of the Solar System. Jupiter contains most of the other 0.2 percent (Arnett 2006).

4. Composition: The Sun is composed of hydrogen (70 percent), helium (28 percent), and Ametals@ (2 percent). These substances are held together by the pull of their own gravity (p. 204; Arnett 2006).

The Sun converts hydrogen into helium in its core, and thus its composition changes over time (Arnett 2006).

5. Temperature:

a. Surface: The surface of the Sun is 6,000 degrees Kelvin. This is a temperature at which most of the electrons are stripped away from the atoms to which they belong. Very few electrons are locked into atoms, able to absorb or emit photons (p. 132).

b. Core: The temperature at the center of the Sun is 16,000,000 degrees Kelvin (p. 141).

6. Nucleosynthesis: Quantum mechanics plays a significant role in the behavior of small objects, such as protons and neutrons. While at 16,000,000 degrees, the electromagnetic repulsion between protons still keeps them apart, quantum tunneling (going through what in classical physics would be an insurmountable barrier) enables some protons to get close enough to each other and fuse, forming heavier nuclei B with the emission of light (pp. 141-143. For quantum tunneling, see p. 23 of the present document, under Beginnings and Emission of Light).

THE SOLAR SYSTEM

THE SUN (continued)

7. Energy Output: The energy output of the Sun is 386,000,000,000,000,000,000 (386 billion billion) megawatts per second B produced by nuclear fusion. Each second, about 700,000,000 tons of hydrogen are converted into 695,000,000 tons of helium, and 5,000,000 tons of energy in the form of gamma rays. (Gamma rays are essentially very energetic X-rays B high-energy photons with a wavelength less than 0.000,000,000,1 centimeter) (Arnett 2006).

8. Location in the Milky Way: The Sun is far B 24,000 light years B from the center of our galaxy, on one of its spiral arms (pp. 73 and 260).

9. Orbital Speed: The Milky Way looks like a flat disc of stars from which two arms protrude. The Sun, located in one of the arms, some way out from the center, rotates at a speed of 220 kilometers per second, in an orbit which encompasses most of the Galaxy=s visible light (pp. 175 and 260).

10. Number of Rotations completed: The Sun has completed about 30 rotations around the Milky Way since the coming into being of the Galaxy (10,000,000,000 years ago) until today (pp. 100 and 260).

THE SOLAR SYSTEM (continued)

EARTH:

1. Life: Earth is the only planet known to support life (Columbia Encyclopedia 2000).

2. Age: The age of Earth is 4,500,000,000 years (pp. 100 and 210).

3. Diameter: The diameter of Earth is 13,000 kilometers (p. 43; Columbia Encyclopedia 2000).

4. Distance from the Sun: The distance from the Earth to the Sun is 150,000,000 kilometers B a distance which light travels in 8 minutes (p. 43; Columbia Encyclopedia 2000).

5. Orbital Speed: The orbital speed of Earth is 30 kilometers per second. This speed counteracts the pull of the Sun exactly, keeping the radius of the Earth=s orbit almost constant (p. 174).

6. Orbit: The orbit of Earth is 600,000,000 kilometers in length (p. 43).

7. Path through Dark Matter: As it rotates around the Sun, Earth sweeps through the sea of dark matter particles in which the disc of our Galaxy is situated (p. 192. For dark matter, see also pp. 1, 5, 7, 9, 19 and 21 of the present document).

8. Time and Space: Neither Earth nor its planets are touched by the expansion of our Universe. Earth does not fly apart and its planets do not move away from each other. The mass of objects close to Earth is sufficient to counteract the geometry of space-time (our Universe). Even though our Universe expands B space-time stretching over time and dragging along everything that it contains B the forces of the objects around Earth counterbalance the pull of the rest of our Universe, and keep the space-time around Earth almost static (p. 90).

THE SOLAR SYSTEM (continued)

THE OTHER PLANETS OF THE SUN:

1. Distance from the Sun: In terms of distance, Earth is third among the planets of the Sun:

Mercury 58,000,000 kilometers from the Sun

Venus 108,000,000

Earth 150,000,000

Mars 228,000,000

Jupiter 780,000,000

Saturn 1,400,000,000

Uranus 2,900,000,000

Neptune 4,500,000,000 (Arnett 2006).

2. Diameter: In terms of diameter, the Earth is fourth among the planets of the Sun:

Mercury 5,000 kilometers in diameter

Mars 7,000

Venus 12,000

Earth 13,000

Neptune 50,000

Uranus 51,000

Saturn 121,000

Jupiter 143,000 (Arnett 2006).

3. Mass: In terms of mass, the earth is fourth among the planets of the Sun:

Mercury 3²³

Mars 6²³

Venus 5²⁴

Earth 6²⁴

Uranus 9²⁵

Neptune 1²⁶

Saturn 6²⁶

Jupiter 2²⁷ (Arnett 2006).

THE SOLAR SYSTEM (continued)

THE MOON:

1. A Satellite of Earth: The Moon is the single natural satellite of Earth.

2. Age: The age of the Moon is 4,000,000,000 years (p. 139).

3. Diameter: The diameter of the Moon is 3,000 kilometers (Arnett 2006).

4. Distance from Earth: The distance from the Moon to the Earth is 400,000 kilometers (Columbia Encyclopedia 2000).

5. Orbital Speed: The orbital speed of the Moon is 1 kilometer per second (Columbia Encyclopedia 2000).

ATOMS, PARTICLES AND RADIATION

ATOMS:

Hydrogen: Of all the atoms, hydrogen is the lightest. The hydrogen atom consists of a nucleus in the form of one proton (one unit of positive charge), orbited by one electron. The nucleus accounts for 99.5 percent of the mass of the atom, the electron, 0.5 percent. The radius of the nucleus is 100,000 times smaller than the radius of the atom. The atom can be thought of as essentially empty space (p. 106).

Helium: Helium has a nucleus which consists of two protons and two neutrons. The force which keeps the neutrons and protons in the nucleus is the Astrong@ (nuclear) force.

PARTICLES:

Neutrinos: Neutrinos are (almost) massless particles which interact with other particles only through the weak force (radioactive beta decay). When four hydrogen nuclei form a helium nucleus, with the generation of energy, beta decay occurs, leading to the production of two positrons and two neutrinos. The process by which stars synthesize helium is a constant source of neutrinos. Neutrinos travel at the speed of light and greatly outnumber protons and neutrons (pp. 126, 144, 163, 187-188 and 220-221).

RADIATION:

Light: Radiation (light) is a superposition of electromagnetic waves propagating itself at a speed of 300,000 kilometers per second in a vacuum, in all uniformly moving reference frames. Its speed of propagation is independent of the motion of the observer. (Note that sound propagates through air at a speed of 0.33 kilometers per second, in the reference frame in which air is at rest) (pp. 33, 37, 43, 50-51, 87 and 114).

Electromagnetic waves exist only in discrete lumps of energy (quanta). These quanta collide with atoms much as one particle collides with another. Light behaves both as a wave and a particle (the photon) (p. 117).

THE THINGS I HAVE LEARNED

1. Three theories about the beginning of our Universe. On sufficiently small scales, space-time and gravity may be subject to quantum forces, just as are atoms and radiation. Space-time at the beginning of our Universe would then differ widely from the space-time we know today.

The inflation theory proposes many universes within a multiverse. It would then make sense to speak about a time before the coming into being of our Universe. If our Universe is bigger than our cosmological horizon (15,000,000,000 light years), we would not know it, because we cannot see further than 15,000,000,000 light years.

2. The relationship between the energy space-time contains (as either mass or radiation) and its shape (curvature). This is Einstein=s general theory of relativity.

The homogeneity and isotropy of our Universe. The structures that we see in our Universe (Earth, the Solar System, stars, galaxies, quasars), are as obvious as they are because we are very close to them. We are looking at these structures from the level of the structures themselves. Looked at from the level of our cosmological horizon, however, our Universe is homogeneous and isotropic.

4. The presence of dark matter. Dark matter accounts for 95 percent of the mass in our Universe.

5. The presence of dark energy. Dark energy accounts for 66 percent of the total energy in our Universe. It is responsible for the expansion of our Universe. It is not diluted by the expansion of our Universe.

6. On Earth, space-time is still, not expanding. Earth is untouched by the pull of our expanding Universe. Around Earth, the forces of the surrounding objects are sufficient to counterbalance the expansion of our Universe.

The space-time encompassed by the Milky Way is relatively still, the forces of the objects surrounding it, being sufficient to almost counterbalance the pull of our expanding Universe.

7. The evolution of our Universe:

a. At three minutes:

i. The density of matter is 1 gram per cubic meter of space.

ii. The density of light is the same as that of water today.

iii. Most of the energy in our Universe is in the form of radiation.

iv. Helium, the second lightest element (after hydrogen), is synthesized B at 900,000,000 degrees Kelvin.

b. At 300,000 years:

i. Our Universe becomes neutral and transparent.

ii. Light begins to travel in a straight line. After 14,999,700,000 years, it is still traveling and permeates our Universe as Arelic radiation.@ It has the same spectrum as it had originally. Its energy is low B its wavelength is one centimeter and its temperature 3 degrees above absolute zero.

c. At present:

i. The density of matter is 10²³ of a gram (equivalent to the mass of a few dozen hydrogen atoms) per cubic meter of space.

ii. The density of light is 1,000,000,000 photons per cubic meter of space.

iii. Most of the energy in our Universe is in the form of dust.

iv. The rate at which our Universe is expanding is accelerating. The further a galaxy, the faster it is receding from us. This unstable behavior of our Universe is due to the predominance in it of dark energy which responds to gravity with repulsion.

8. Nucleosynthesis:

a. Ninety-five percent of the atoms in our Universe are either hydrogen or helium atoms. The balance between these two elements is 70 percent hydrogen and 30 percent helium. Ninety-two percent of the helium was synthesized during the first three minutes of the existence of our Universe B at 900,000,000 degrees Kelvin.

b. In the core of the stars, at temperature around 10,000,000 degrees Kelvin, quantum tunneling engenders nuclear fusion, enabling the synthesis of helium from hydrogen. This has changed the original balance of hydrogen and helium (74 percent hydrogen, 26 percent helium) to the present 70 percent hydrogen and 30 percent helium.

c. When a small star is in its final stages, it becomes a red giant and its core reaches 100,000,000 degrees Kelvin. Carbon is then synthesized and when a sufficient amount of it has accumulated, oxygen is synthesized. A small amount of these two elements is ejected into space as the star becomes a white dwarf.

Large stars synthesize iron by nuclear burning, and then, during their final stage as supernovae, synthesize all the heavy elements B iron and beyond. These are released into space. This is the origin of the elements we have on Earth.

9. Quasars are fueled by gigantic black holes. Black holes are objects which are so dense that light cannot escape their gravitational pull. Some quasars emit as much energy as 30,000,000,000,000 stars.

10. Andromeda is moving toward Earth at 300 kilometers per second.

11. The Virgo Cluster is pulling the Milky Way toward it.

12. Our Sun is one of the 100,000,000,000 stars in the Milky Way.

CONCLUSION

The grandeur of our Universe (or of the multiverse) baffles the mind. For most of us, the forces are beyond comprehension and even beyond conceptualization.

Astronomical forces exist in what Ken Wilber (1949-) has described as the Aexterior collective@ domain of all holons (all types of existence). Wilber=s chart of the four domains of all holons is reproduced on page 37 of the present document (Wilber 1995/2000, inside front cover. For a summary of Ken Wilber=s description of the four domains, see Hall 2005, pp 4-6).

The grandeur and force in the interior individual domain B consciousness, the self, the soul, Spirit B are equivalently majestic, awesome and for most of us, beyond comprehension and even beyond conceptualization.

REFERENCES

All page numbers refer to:

Ferreira, Pedro. 2006. The state of the universe B a primer in modern cosmology. London, UK: Weidenfeld & Nicolson.

Other references are:

Arnett, Bill, AA Multimedia Tour of the Solar System B one Star, eight Planets and more.@

http://www.nineplanets.org.html. Updated August 25, 2006. Accessed September 9, 2006.

Columbia Encyclopedia. 2000. New York: Columbia University/Gale Group.

Hall, Francoise, 2005. AA Transpersonal View of War B War as a Substitute for Cosmo-centrism and Immortality during the Egoic Stage in the Development of Consciousness.@ November 5 (103 pages, unpublished).

Wikipedia, Astars.@

http://en.wikipedia.org/wiki/Star. Updated September 10, 2006. Accessed September 11, 2006.

Wilber, Ken. 1995/2000. Sex, ecology and spirituality B the spirit of evolution. Boston, MA: Shambhala.

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