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 Creation of a Cosmology:THE BIG BANG THEORY
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Fifteen billion years ago, the entirety of our universe was compressed into the confines of an atomic nucleus. Known as a singularity, this is the moment before creation when space and time did not exist. According to the prevailing cosmological models that explain our universe, an ineffable explosion, trillions of degrees in temperature on any measurement scale, that was infinitely dense, created not only fundamental subatomic particles and thus matter and energy but space and time itself. Cosmology theorists combined with the observations of their astronomy colleagues have been able to reconstruct the primordial chronology of events known as the big bang.
Quantum theory suggests that moments after the explosion at 10 -43 second, the four forces of nature; strong nuclear, weak nuclear, electromagnetic and gravity were combined as a single "super force"(Wald). Elementary particles known as quarks begin to bond in trios, forming photons, positrons and netrinos and were created along with their antiparticles. There are minuscule amounts of protons and neutrons at this stage; approximately 1 for every one billion photons, neutrinos or electrons (Maffei). The density of the Universe in its first moment of life is thought to have been 1094g/cm3 with the majority of this being radiation. For each billion pairs of these heavy particles (hadrons) that were created, one was spared annihilation due to particle-antiparticle collisions. The remaining particles constitute the majority of our universe today (Novikov).
During this creation and annihilation of particles the universe was undergoing a rate of expansion many times the speed of light. Known as the inflationary epoch, the universe in less than one thousandth of a second doubled in size at least one hundred times, from an atomic nucleus to 1035 meters in width. An isotropic inflation of our Universe ends at 10-35 second that was almost perfectly smooth. If it were not for a slight fluctuation in the density distribution of matter, theorists contend, galaxies would have been unable to form (Parker).
The universe at this point was an ionized plasma where matter and radiation were inseparable. Additionally there were equal amounts of particles and antiparticles. The ratio of neutrons and protons albeit small is equal. When the universe aged to one hundredth of a second old neutrons begin to decay on a massive scale. This allows for free electrons and protons to combine with other particles. Eventually the remaining neutrons combine with protons to form heavy hydrogen (deuterium). These deuterium nuclei combine in pairs and form helium nuclei. The formation of matter from energy is made possible by photons materializing into baryons and antibaryons with their subsequent annihilations transforming them into pure energy (Maffei). Because of these collisions and annihilations matter was unable to remain viable for more than a few nanoseconds before a bombardment of electrons would scatter these photons. Like water trapped inside a sponge, radiation is so dense (1014g/cm3) that no light is visible. Known as the "Epoch of Last Scattering" the temperature has now dropped to a mere 1013K with the Strong Nuclear, Weak Nuclear and Electromagnetic interactions now able to exert their force. (Chown)
As the gas cloud expands one full second after the initial explosion and the temperature of our Universe has dropped to ten billion degrees, photons no longer have the energy to disrupt the creation of matter as well as transform energy into matter. After three minutes and a temperature of one billion degrees, protons and neutrons were slowing down enough in order to allow nucleosynthesis to take place. Atomic nuclei of helium was produced as two protons and neutrons each bonded. For every helium nuclei formed there were about ten protons left over allowing for twenty-five percent of the Universe to be comprised of helium. The next important phase of the expansion occurred around thirty minutes later when the creation of photons increased through the annihilation of electron-positron pairs. The fact that the universe began with slightly more electrons than positrons has insured that our Universe was able to form the way it has (Parker).
The universe for the next 300,000 years will then begin to expand and cool to a temperature of 10,000°K. These conditions allowed for helium nuclei to absorb free floating electrons and form helium atoms. Meanwhile hydrogen atoms were bonding together and forming lithium. It is here that the density of the universe has expanded to the point where light can be perceived. Until this point photons continued to be trapped within matter. Finally the expansion allowed for light and matter to go there separate ways as radiation becomes less and less dense. Matter and radiation therefore too, were bonded no longer and the oldest fossils in the Universe were born (Peebles).
In 1814 the science of spectroscopy was launched by William Wollaston, an English physicist who noticed that there were several dark lines that separated the continuous spectrum of the Sun. These lines came to the attention of Joseph von Fraunhofer, a German optician and physicist who carefully plotted the position of those lines. Then in 1850 German physicist's Gustav Kirchhoff and Robert Bunsen refined the spectroscope. They then learned to heat different elements to incandescence and using the spectroscope identified an elements corresponding lines on the visible portion of the electromagnetic spectrum(Parker).
In 1863 Sir William Huggins, an amateur astronomer viewed a nearby star through his 8 inch refractor with a spectroscope attached. He found what he had originally hypothesized, the same spectrum lines that were observed in our own Sun. Meanwhile, Kirchhoff and Bunsen had successfully categorized the spectrum lines of many elements including those of hydrogen, sodium and magnesium. Huggins found these same spectrum lines in the distant stars he had observed and correctly predicted that some of the same elements that Kirchhoff and Bunsen were cataloging were emanating from these celestial bodies (Parker).
Christian Doppler of Austria discovered twenty years earlier that the frequency of a sound wave was dependent on the relative position of the source of the sound. As a sound moves away from an observer the pitch will lower. Likewise if the source is not moving but the observer is, there will be a corresponding change in the wave frequency of the sound. Doppler theorized on this same shift for light waves yet it was the French physicist Armand Fizeau who proved in 1848 that when a celestial object moves away from an observer, the lines in the visible spectrum would shift toward the red end. Conversely, when an object moves toward the observer, Fizeau found that the lines in the spectrum shifted toward the blue end. Huggins observed a shift in the hydrogen lines of Sirius toward the red end of the spectrum. This "redshift" indicated that Sirius was moving away from us. A few years later he was able to calculate the radial velocity of the star Sirius at between 26 to 36 miles per second (Parker).
During the 1890's the Lick Observatory in California began to track and chart the radial velocity (which is actually the velocity at which the line of sight that the star is observed) of many stars, as well as gaseous and planetary nebulae. Astronomers at Lick calculated the measurements of 400 stars including their radial speed and velocity. In 1910 Vesto Slipher measured the velocity of the Andromeda Nebula at 300 km per second, thirty times greater than previously observed. Four years later, Slipher had confirmed the radial velocities of 14 spiral nebula, with the overwhelming majority shifting to the red end of the spectrum. Slipper's observations showed that the majority of spirals he measured were moving away from us (Parker).
Around 1913 several astronomers, among them Edwin Hubble, used a variable star known as a Cepheid (a star that fluctuates in intensity) to measure their period-luminosity relationship. This would accurately determine the distance to any Cepheid in the observable vicinity. Hubble became the first astronomer to discover an independent galaxy outside the confines of the Milky Way. Hubble calculated the distance of the Andromeda Galaxy to be 900,000 light years away; larger than the predicted size of our own galaxy. Using the radial velocity measurements of Slipher along with Hubble's own calculations he began to notice a correlation between the distance of these galaxies and their radial velocities. The proof was conclusive: the further away a galaxy was relative to the Earth, the greater the velocity of that galaxy. Hubble had irrefutable proof that the Universe was expanding. By 1936 Hubble had received data from galaxies more than 100 million light years away. The redshifts at this distance were so large that the spectral lines had changed color (Weinberg).
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