Lauren Younis Physics for Poets Term Paper The Big Bang Theory: Why it Works and What it Means The Beginning: the origin of matter “It is the artist who is closest to God, for it is he who shares the burden of creation.” The question of the creation of space and time can be delegated to scholars of
metaphysics, theology, and cosmology. The answers to such an abstract question lie
beyond the reaches of experimental physics, but is there some more concrete element
other than space or time that can define the meaning of “the beginning?” Twentieth century findings in popular science have yielded a definitive yes in
response to this question. To address the creation issue, cosmologists investigate the
origin of matter, the physically definable, experimentally testable stuff that composes the
earth, the stars, and human beings. In the world of physics, time began when space began. But since neither can be
quantifiably measured, the origin of the universe question derives its answer primarily
from the point at which matter first appeared. The Big Bang Theory is the most popularly
accepted theory of how the matter of the universe got here in the first place, why it is
currently behaving as does, and where it is going next. To understand the universe, both
scientifically and theoretically, is an enormously daunting task. The Big Bang Theory
aims to explain what happened at the very beginning of the universe. Before the big bang,
there was nothing; during and after it, there was the universe. But the process of creation was complex and precise. It is important to understand
that, contrary to the name’s suggestion, the big bang that created the universe was neither
“big” nor a “bang.” Rather, the universe began as an extremely small, hot, and dense
singularity. Singularities are zones of infinite density that exist in areas of extreme
gravitational pressure. And the process was not as much a “bang” as it was an inevitable
fluctuation of the foam of Planck­mass black holes that were continuously being created
and annihilated (Silk 75). This known, one can consider the cosmic clock to have begun ticking at that first
instance of fluctuation. Before that, when the universe was a mere singularity, time was 0
and density was infinite. This “infinitely dense” state, however, is a rather troubling
physical description for today’s physicists, as the concept of “infinity” eludes any
reasonable numeric definition. Nonetheless, the fact remains that from time 0 to 10^­43
second, there are no current theories which allow certain and absolute access to and
explanation for this period. Einstein’s theory of general relativity supports the idea of a
gravitational singularity, but under the existing conditions at that time, the theory is
expected to break down (Safko). Luckily for physicists, knowledge of the early universe becomes increasingly
complete as time advances. After the first 10^­43 seconds, the universe enters a state
where modern physics is indeed applicable. This period, from 10^­43, is known as the
Planck epoch. There are many definitive characteristics specific to this time, one of which
is the almost equal amounts of matter and antimatter in existence. Both, however, were
dominated by the background energy of the universe (Linder). Had this not been the case,
existence today would be impossible. Also definitive of the Planck epoch is the
unification of the four fundamental forces: gravity, electromagnetism, weak nuclear
force, and strong nuclear force. At this time, these forces were equal in strength and were
essentially one fundamental force. But it was also the Planck epoch that saw the
separation of two of the fundamental forces, the strong nuclear force and the
electromagnetic force (Guth 105). This separation produced the necessary energy for the
occurrence of the universe’s most rapid period of inflation. From approximately 10^­35
seconds to 10^­32 seconds, the universe went from being smaller than the nucleus of an
atom to being over 1 billion light years across (Lidsey 56). This rapid expansion is the
event that categorizes the universe as homogonous and isotropic. This means that as the
universe underwent the process of rapid expansion, it did not do so in a specific direction
or towards a preferred place. This is known as the Cosmological Principle, and simply
means that the universe, when viewed on a large scale, would look the same in all
directions to observers at any different points (Glendenning 26). This takes the universe to an age of just 10^­6 second, whereby it entered into its
next stage of development. So far, it has been in existence only for approximately the
same amount of time that it takes light to travel the lengths of three football fields
(Mihos). At 10^­6 second, another major development occurred: the creation of the
fundamental particles; protons, electrons, and neutrons. The separation of the weak and
electromagnetic forces created the change of the universe’s composition from that of an
electron­quark soup (Silk 87). This electron­quark soup was the hot substance of
electrons and quarks, the subatomic particles that make up protons. At this point, the
universe had cooled enough to allow the development of protons and neutrons. The
combination of quarks formed protons, and protons and electrons combined to form
neutrons (Glendenning 106). Conditions were still too hot, however, for atoms to be
formed. This happened later, during nucleosythesis. Protons and neutrons collectively are called baryons, or ordinary matter. This
period, called baryogenesis, is responsible for the abundance of ordinary matter in the
current universe in contrast to the amount of antimatter. The Planck epoch almost
certainly saw a symmetry between matter and antimatter, right after the big bang when
there were equal quantities of particles and their antiparticles (Silk 89). During
baryogenesis, however, almost all of the particles had decayed by about 10^­4 second,
but a slight imbalance of protons over antiprotons remained. The pairs of particles and
antiparticles annihilated each other, leaving behind only the excess protons. From that
point until now, the universe has been dominated by matter (Silk 70). The period lasting from the time the universe reached one second old to the time
where it reached three minutes old is known as primordial nucleosynthesis. The most
characteristic development of this period was the appearance of the nuclei of the light
atomic elements, hydrogen and helium. Neutrons interacted with protons to form the
nuclei of deuterium, or heavy hydrogen. The deuterium then gained another neutron and
became tritium, bringing the element to a makeup of two neutrons and one proton.
Finally, the tritium absorbed a final proton, equalizing the proton­to­neutron ratio and
resulting in a helium nucleus. Since there are no stable elements of mass five or eight,
additional nucleosysnthesis by a helium nucleus combining with another helium nucleus
or proton was generally not possible (Silk 94). Hydrogen and helium account for 74%
and 25% of the mass of the known universe respectively . The other 1% of the universe’s
mass is composed of heavier elements, too complex to be formed until about 300 million
years later. These heavier elements are the result of stellar nucleosynthesis, the nuclear
reaction in stars which yield the heavier elements’ nuclei. After these initial events, the elements of the universe as it is known today are
ready for formation. 300,000 years after the formation of this early universe, the energy
in matter and the energy in radiation were no longer equal, as the universe’s continued
expansion stretched light waves to successively lower energy, while matter remained
unaffected (Silk 96). Cosmic microwave background radiation, the discovery of which
would later become strong evidence supporting the Big Bang Theory, was formed. The
photons of this electromagnetic radiation now pervade the entire universe, accounting for
most of its radiation energy. The birth of stars and galaxies occurred nearly 15 billion years ago. These stars began the
process of turning the light elements, formed during primordial nucleosysnthesis, into
heavier elements. Galaxies formed shortly after by the collapse of large volumes of
matter. It is also at this time that the Milky Way saw the birth of the solar system and the
sun, a late­generation star incorporating the debris of earlier stars. This is not until about
8 billion years after the big bang, about 5 billion years ago (Mihos). The Middle: the quest for proof “A doubt if it be us, assists the staggering mind; in an extremer anguish, until it
footing find..” This explains the process of the Big Bang Theory, but what are the multiple and
complex reasons supporting and upholding it as the most probable explanation for the
universe’s creation? One of the most general observational explanations for the theory
comes from Hubble’s Law. Formulated in 1929 by Edwin Hubble, the law defines the
linear relationship between the speeds and distances of galaxies accelerating away from
the Milky Way. The light emitted from these distant galaxies is redshifted, meaning that
it has been shifted to longer wavelengths. The farther a galaxy is from earth, the greater
its redshift (Glendenning 22). This proposition supports the uniform expansion of the
universe, which was earlier proposed mathematically by Einstein’s theory of general
relativity. Hubble’s Law provides fundamental evidence that the universe was once
compacted and is now expanding, just as the theory suggests. The Big Bang Theory’s assertion that the universe was initially extremely hot
prompted exploration for some remnant of this intense heat. It was found in 1964 by
physicists Arno Penzias and Robert Wilson in the form of universal permeating radiation
(Glendenning 63). It is due largely to this discovery that the Big Bang Theory is the most
generally accepted within the scientific community today. Known as cosmic microwave
background radiation, their discovery proved to be the photons that were first emitted
during baryogenesis. Cosmic microwave background radiation is the most perfect
blackbody emission in the universe, meaning that it absorbs all electromagnetic radiation,
letting none pass through or reflect off of it. Penzias and Wilson found cosmic
microwave background radiation to be 2.725 K, close to and consistent with a blackbody
spectrum of about 3 K (Glendenning 64). Their discovery also found the radiation
isotropic, or independent of direction. This too is consistent with space’s form in the
universe. In 1989, NASA’s Cosmic Background Explorer Satellite recorded the
temperature of CMB radiation as 2.726 K, and investigations held as recently as 2003
uphold similarly accurate data (Glendenning 65). The nucleosynthesis stage, which accounts for the universe’s abundance of light
elements, is crucial to examine when proposing evidence for the Big Bang Theory. The
scarcity of the heavier elements, in addition to the 3:1 ratio of hydrogen to helium,
suggests that the light elements must have been synthesized before the heavier elements,
prior to the first stars. The heaviest element to form after the big bang was beryllium,
which, because it has eight nucleons, is unstable and falls apart almost instantly after it
forms (Silk 95). Only trace amounts of this element and lithium, considered heavy, were
formed in the ten seconds following the big bang, to comprise the 1% worth of heavy
elements that existed at the time. Further proof is suggested with the observation that
there appears to be the same helium abundance in stars that are metal­rich and metal­poor
(Guth 117). Because the metals are the heavier elements, this confirms that helium was
created not along with, but prior to, the heavier elements. The End: the possibility of a hot or cold death “From what I’ve tasted of desire, I hold with those who favor fire..” Even with no absolute proof that the Big Bang Theory is correct, the question of
“where does the universe go from here?” needs to be at least addressed, if not answered.
It used to be that the proposition of the big crunch seemed a good starting point, but the
its possibility has now been determined unlikely (Mihos). The big crunch suggests a
universe of finite time and lifespan, and claims that the average density of the universe is
enough to stop its expansion and begin contraction. This would essentially move the
universe back to a point of singularity. If this were the case, then the big bang that created
the current universe would have been immediately preceded by the big crunch of a
preceding universe. This would mean that the universe exists of an infinite sequence of
finite universes, and that each would end with a big crunch that would be the big bang of
the universe following it. Since evidence has shown, however, that gravity is not in fact
slowing the universe’s expansion, but rather accelerating it, the big crunch hypothesis has
been ruled out by most cosmologists. The fact that the universe’s expansion is accelerating has been used to make a
case for the idea of the big freeze. The big freeze suggests that the universe’s expansion
will eventually render it too cold to sustain life. To consider the realistic possibility of
this or any theory of the universe’s end, it is helpful to examine the potential shapes of
the universe. These include spherical, a ball­shaped universe; hyperbolic, a “saddle­
shaped” universe; and flat, a two­dimensional universe. For something like the big freeze
to occur, the universe would have to be hyperbolic or flat (Mihos). A hyperbolic universe
would mean that the density must be lower than the critical density so the universe
wouldn’t be heavy enough to collapse under gravity. A flat universe implies that density
would be at exactly critical point, which would also prevent its collapse. The big freeze is
based on the universe’s continuous expansion, and the fact that it will really never “end”
because it will either reach a fixed expansion rate (in the hyperbolic case) or reach an
expansion rate of zero (in the flat case). This means that if the universe were spherical, it
would be heavier than critical point and it would collapse, and therefore shrink, providing
a case for the big crunch (Mihos). It is hard to measure the universe’s current density,
however, because cosmologists cannot see most of the matter in it. The results of a big freeze would be quite similar to those of another theory of the
universe’s end, heat death. Heat death is based on the second law of thermodynamics,
which states that entropy increases or stays the same in an isolated system. This means
that the universe will approach a state where all energy is distributed evenly and the
temperature, despite the name, will be close to absolute zero. If the second law of
thermodynamics proves to be an appropriate model, the universe’s end by heat death is
highly probable (Glendenning 80). The Big Rip Theory is also contested as a means of the universe’s end. It states
that all of the universe’s elements, from the largest galaxies to the smallest atoms, will be
eventually torn apart by the universe’s expansion. It is arguable that this is happening
now, as galaxies are moving outside the observable universe at about 13.7 billion light
years away. The process would occur about 20 billion years from now, beginning with
the separation of the galaxies, then consequently the elements within them, such as the
stars and planets. A final main theory of the universe’s end relies on the probability of whether or
not the earth exists in a false vacuum. A false vacuum is a classically stable excited state
which is quantum mechanically unstable (Odenwald 88). The idea was first investigated
in 1987 by physicists Sidney Coleman and Frank DeLuccia, who claim that vacuum
decay is “the ultimate ecological catastrophe; in the new vacuum, there are new constants
of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry
as we know it (Odenwald 91).” If the earth does in fact exist in a false vacuum, and a
bubble of lower energy vacuum were to nucleate, it would approach at close to the speed
of light and destroy the earth in an instant and without warning (Odenwald 94). It was
once argued that a particle accelerator could possibly create sufficiently high energy
density to the extent that it would be capable of stimulating the decay of the false vacuum
to the lower energy one. Because cosmic ray collisions have been observed at much
higher energies than any produced in a particle accelerator, some argue that such
experiments will not pose a threat to our vacuum. The universes end by these means,
called the vacuum metastability event, is dependent upon current existence being in a
false vacuum, an issue that has not yet been resolved. There are infinite doors to be opened and ideas to be explored when determining
the states of the beginning, middle, and end of the known universe. It is indeed true, as
Einstein said, that the most incomprehensible thing about the world is that it is
comprehensible. Modern physics has proven capable of comprehending many of the
possibilities for the past, present, and future that have helped us gain great understanding
of the universe. The discovery of how and why the universe exists would be the greatest
problem ever solved by modern science, yet it may be that the true answer lies only
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