From Large-Scale Universe to the Milky Way

From Large-Scale Universe to The Milky Way

SCI/151

June 29, 2013

Modern Cosmology

        Cosmology is the study of the evolution, history, and structure of the universe. Cosmology also searches for answers about the fate of our universe by conducting experiments using the scientific method. Beginning with an observation of some phenomenon in space, scientists then develop a hypothesis and cycle through series of tests that will either support or disprove the hypothesis. The findings are then published for other scientists to review and retest. If the retests fail to disprove the hypothesis, it is considered a theory. Theories can be altered if new evidence disproves all or a portion of a theories findings.

        Modern understanding of the age and size of the universe began with Edwin Hubble, who observed stars and galaxies seemed to be moving away from Earth at a rapid pace. Hubble’s discoveries provided the “foundation on which modern cosmology has been built” (Bennett, 2010, pg. 623) and lead the way to the introduction of the Big Bang Theory.

Big Bang Theory

        The current accepted theory of the origin of the universe is the Big Bang Theory. The Big Bang theory states that about 14 billion years ago, there was a great explosion that “threw” energy in the form of photons into space. These eventually broke down into gases, notably helium and hydrogen, and dust into the cosmos. With the help of gravity, these gases and dust condensed into nebulas and the first stars and planets began to form.

Albert Einstein suggested that the universe should not be static, but expanding based on his theory of relativity. Edwin Hubble proved Einstein’s suggestion through his findings of red shifts. By observing the red shifts created by distant stars, Hubble documented that the universe is not static and had a beginning, meaning the known universe had not existed forever. Two other scientists, Arno Penzias and Robert Wilson discovered background “noise” while working with a microwave antenna. The noise could not be explained by any influence or object known at the time, and both were confounded. They collaborated their findings with research done by Robert Dicke, who believed there should be low-level radiation in space left over form the Big Bang. The combined findings of these three scientists, along with Hubble’s expanding universe findings, helped to solidify the Big Bang Theory as “the model standard” for the creation of the universe.

The Milky Way

Once scientists developed a viable theory on how the universe began, they were able to envision how galaxies, stars, and planets formed. As the gas and dust spread through space and “clumped” together, the gas began to heat up through nuclear fusion and stars were born. Planets form within the molecular cloud rotating around the forming star, growing and creating their own gravity. The Milky Way is an example of a spiral galaxy, which looks like “flat white disks with yellowish bulges at their centers. The disks are filled with cool gas and dust, interspersed with hotter ionized gas, and usually display beautiful spiral arms” (Bennett, 2010. Pg. 607). However, the Milky Way contains more than just stars and planets; it also has a dark side. Dubbed “dark matter,” this substance makes up about 80% of all matter in our universe, but remains difficult to detect as it does not absorb or give off light, and only interacts with gravity. Recent findings suggest that that if dark matter particles around the Milky Way interact with each other, “they would combine into atom-like structures and eventually collapse into a spinning disk” (Grossman, 2013). The Milky Way was formed from ordinary matter in much the same way, suggesting there to be a “mirror” dark galaxy much like our own.