Dark Matter, Dark Energy

Topics: Dark matter, General relativity, Gravitation Pages: 6 (1843 words) Published: June 16, 2013
Dark Matter Dark Energy

Prepared by
Alexander Ray

Prepared for
Jennifer Weinberg-Wolf

Astronomy with Lab
SCI-224-62451
DeVry University, Arlington VA

December 8, 2012

Table of Contents
Abstract3
Dark Matter Dark Introduction4
Dark Matter Conceptualized4
Dark Matter Compositional Theories5
The Role Dark Matter Plays5
Dark Energy Conceptualized6
What is Dark Energy6
The Dark Energy, Dark Matter Relationship7
Conclusion7
Works Cited8

Abstract
It is the intent of this paper to introduce the relatively recent theories of dark matter and dark energy and their relation to each other. These theories explain the observed increase in expansion rate of the Universe as well as explain why galaxies remain intact despite the apparent lack of sufficient mass to affect the gravitational forces needed for cohesion, especially when considering that galaxies rotate at speeds that should disperse their stellar composition away from its core. Dark Matter Dark Introduction

Our understanding of the Universe is ever evolving as new discoveries are made, challenging what we have always believed. Some struggle to grasp an explanation of those new discoveries and the phenomena presented. These new discoveries are made possible with the advancement of new technologies and capabilities. The advent of powerful radio telescopes and imaging telescopes like the Hubble Space Telescope that allows one to observe the cosmos with much more fidelity. Two recent theories to explain what comprises our universe that have taken shape are the presence of dark matter and dark energy. To garner an understanding of the theories that surround dark energy and dark matter, one needs to explore what comprises dark matter and dark energy, the role they play within the universe and the relationship between dark matter and dark energy. Dark Matter Conceptualized

For centuries, our understanding of the Universe was shaped by what we could physically see; however, we have come to realize our conceptions lacked an explanation relating to some observations being made. In 1933 Fritz Zwicky, an astrophysicist, was studying the Coma Cluster of Galaxies in which he determined that even though the galaxies were bound by gravity, those galaxies were moving too fast to keep the cluster from breaking up, but in contrast, they were not (Hooper, 2013). The determination was further strengthened by the observations of Vera Ruben and Kent Ford on galaxy rotations (Hooper, 2013). The only explanation Zwicky could come up with is that the galaxies contained more mass in the form of invisible matter, which scientists now refer to as dark matter. It was not until the 1970’s when scientists, with the aid of computer simulations, conceptualized that our galaxy did not contain enough mass to keep everything in place (Hooper, 2013). Rotation should generate disintegration, shedding stars and gas in every direction (Panek, 2010). Dark matter is not directly detectable since it seemingly does not interact with normal matter except through gravity (Panek, 2010). Though dark matter is not detectable, we can observe its influences to realize it exists. One can observe that dark matter exerts strong gravitational forces by the matters ability to bend or distort light that passes through it; this effect is known as gravitational lensing where light is bent around the gravitational influence (Rishwanm, 2008). The gravitational lensing is more predominantly noticed in the halos of galaxies.

Figure [ 1 ] An example of gravititional lensing taken by the Hubble Space Telescope. NASA/ESA Dark Matter Compositional Theories
Little is known of what comprises dark matter since no one has been able to observe or measure it. It is through gravitational lensing that scientists have an idea of the quantity and distribution of dark matter within the Universe. To answer the question of what is dark matter scientists have considered the idea...

Cited: Banchi, E., & Rovelli, C. (2010, 15 July). Is dark energy really a mystery? Nature, 466, 321-322.
Caldwell, R., & Kamionkowski, M. (2009, April). Dark matter and dark energy. Nature, 458(), 587-589.
Dark Energy, Dark Matter . (2012). In R. Netting (Ed.), Dark Energy, Dark Matter . Retrieved from http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/
Hooper, D. (2013, January). Dark Matter in the Discovery Age. Sky & Telescope, 125, 26-32. Retrieved from http://web.ebscohost.com
Kirshner, R. P. (2003, Jun 20). Throwing Light on Dark Energy. Science, 300, 1914-1918.
NASA. (2012). Dark Matter. Retrieved December 09, 2012, from http://chandra.harvard.edu/xray_astro/dark_matter/
Panek, R. (2010, April). Dark-Energy-The-Biggest-Mystery-in-the-Universe. Smithsonian magazine. Retrieved from http://www.smithsonianmag.com/science-nature/Dark-Energy-The-Biggest-Mystery-in-the-Universe.html
Rishwanm. (2008, Aug 9). Dark Matter & Dark Energy [Video file]. Retrieved from http://www.youtube.com/watch?v=4f40oAAmeyA
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