Project Cyclops, A Design... - Department of Earth and Planetary ...

thinkinghasattainedsomestatusof stability,if not
maturity.Somecompetingviewpointsareexamined in
AppendixB.
Asapreludetoadetailedexamination oftheCyclops
systemandsearchstrategywefeelcompelled to offer
the readera fuller pictureof the storyof cosmic
evolution, andof theuncertainties thatremainateach
step. Since our case rests on a plausibility argument, the
reader should weigh the evidence and reach his own
conclusions as to the merits. In the following sections we
have tried to summarize present thinking about the
origin of the universe and matter, the evolution of
galaxies and stellar populations, and the formation of
planetary systems. From this point on our narrative
necessarily becomes geocentric, for we have no evidence
about the evolution of life elsewhere. However, by
examining how life evolved on Earth we can decide
whether the factors that caused it are in any way
peculiar
to this planet.
ORIGIN AND EVOLUTION OF MATTER
All stars are suns. Some are larger and some smaller
than the star that warms this earth; some are younger,
but most are older. Stars are not distributed uniformly
or randomly throughout space, but instead occur in huge
aggregations called galaxies; some of which show a spiral
form, others an ellipsoidal shape. Our Galaxy, the Milky
Way, is a spiral galaxy containing several hundred billion
stars. The universe contains over a billion galaxies, or, in
all, more stars than there are grains of sand on all the
beaches
of Earth.
Any theory of cosmology must account for the
observed fact that the galaxies (and particularly clusters
of galaxies) appear to be receding from one another with
a velocity proportional to their separation. We are not at
the center of this expansion any more than any other
galaxy is; rather we consider that all observers anywhere
in the universe would see the same recession of distant
galaxies. This assumption, known as the "cosmological
principle" implies space curvature. There is no center of
the universe and therefore no outer limit or surface.
Twentieth century cosmology has been concerned
primarily with two diametrically opposed views: instantaneous
creation and continuous creation, both of which
account for the expansion in different ways. According
to the instantaneous creation view, now known as the
"big bang" cosmology, the universe began as an awesome
primordial fireball of pure radiation. As the fireball
expanded and cooled, pair production yielded the
fundamental nuclear particles of matter and antimatter
and thermonuclear reactions produced helium nuclei.
Still further expansion dropped the temperature to the
point where hydrogen and helium atoms formed by
combination of the electrons with the protons and
helium nucleii, but elements heavier than helium were
not produced in appreciable quantities. During the early
phase of the expansion, when the ionized matter was
strongly coupled to the radiation field, the matter
distribution was controlled by the radiation field. Only
later, when the radiation density dropped below the
matter density (related by E = me 2) and the matter
deionized, could gravity forces act to enhance any
nonuniformities of density that may have existed and
thus begin the hierarchy of condensations that resulted
in galaxies, stars, planets, and satellites.
The continuous creation or "steady state" theory
proposed by Hoyle applies the cosmological principle to
time as well as to space, thereby making it a "perfect"
cosmological principle. It assumes that the universe not
only appears the same to observers anywhere, but also at
any time. As the galaxies recede, the steady state theory
maintains the average density by having neutrons appear
spontaneously in space. These then decay to protons and
electrons and form new hydrogen out of which new
galaxies condense. Thus, on the average, the density of
galaxies in space remains constant in spite of their
recession.
In addition to being consistent with the observed
expansion of the universe, the big bang theory makes
several predictions, such as (1) the primordial and most
abundant elements should be hydrogen and helium in
the (mass) ratio of about 3 to 1; and (2) there sh,,uld be
an isotropic background radiation corresponding to a
black body at about 3° K. Findings in the last decade
seem to have established the validity of both (1) a,, _ (2),
which are hard to explain with steady state c ,h;,Aogy.
A great deal of other data also conflict with '.ne steady
state hypothesis, and current opinion has swung heavily
toward big bang cosmology.
While the big bang theory answers many questions,
others still remain to be answered, among them:
1. What, if anything, preceded the initial fireball?
2. Where is the antimatter half of the universe?
3. How did galactic clusters and galaxies form out of
the supposedly homogeneously dense fireball in
which gravitational clumping was suppressed by
radiation
coupling?
A partial answer to (1) may found if future observations
(or past observations handed down to us over billions of
years by interstellar communication) show that the
present expansion is slowing down rapidly enough to
turn into a contraction aeons hence. We can then
contemplate a cyclic universe, which defeats the second
law of thermodynamics by being reborn. If the expan-