Astronomy Assignment Paper on Development of the universe

Development of the universe

Critical Density of the Universe

            The term critical density is often used to define the overall density of a substance or a compound at its most critical point. In Astronomy, this term usually defines the material density of a spatially level universe. Critical density thus refers to the value at which the balance of the universe is maintained and constant expansion is stopped. According to Cindi (2013), critical density defines the average compactness of matter that might be required to stop the constant expansion of the universe. It is a term that is closely linked to the cosmic density, which defines the ratio of the actual density to the critical density of the universe. This is because the balance of the universe, which describes the critical density, occurs when the cosmic density is one and the universe is flat. Critical density thus marks the boundary of value prevailing between open and closed models. Open models define the universe models that allow the universe to open forever, and they occur when cosmic ratio is greater than one, while closed models define the models that allow the universe to close forever thereby recollapsing, which occur when cosmic ratio is less than one (Denise, 2009).

Comparing Actual Density of the Matter with Critical Density of the Universe

            The actual density of matter in the universe defines the total density of luminous material of the universe that defines the competition prevailing between the attractive and expansion forces of the universe. According to Denise (2009), the actual density of matter can be measured by the total gravitational attraction that may often be exerted from the center of an uninformed sphere that might be randomly extracted from the universe. While the actual density of matter is constant, it helps to determine the total critical density that might be required to establish the balance that should prevail in order to halt the constant expansion that might cause the universe to open or constant attractiveness that can cause the universe to recollapse. The actual density matter in the universe can be termed as being at par with the critical density if the average amount of luminous material of the universe is exactly at the same point as the critical level, which indicates that the attractive and the expansion forces of the universe would be in balance. The expansion force would however be great if the actual density is lower than the critical density, which indicates that the earth would constantly expand and eventually open. Conversely, the attractive force would be great if the actual density is more than the critical density, which would cause the universe to constantly close and eventually recollapse (Cindi, 2013).

Curvature of Space and Gravitational Lensing

            Curvature of space defines a concept that is equivalent to the gravity of the universe, and often measured by the total amount of matter comprising of the entire universe. Curvature of space is usually measured in terms of its lensing capacity upon the spots prevailing on the microwave background. The spatial curvature can cause the universe to recollapse when it has a big lensing effect, which can make the universe to end in a huge crisis. According to Cindi (2013), the concept of curvature of space and gravitational lensing states that light on a curved space of the universe travels in a manner that appears like it is travelling through lens. Curvature of space determines the fate of the universe by showing its overall curving space that results from the impact of gravity. While a relatively curved universe would thus make small objects to appear larger, objects lensed on the microwave background would indicate the overall curving space of the universe, which is usually determined by the total mass of the universe. With large amount of mass creating a bigger curvature of the universe, this halts constant expansion of the universe, which causes it to close and eventually recollapse (Denise, 2009).

The Cosmic Microwave Background Radiation

            The Cosmic Microwave Background Radiation (CMBR) defines the type of electromagnetic radiation that results from the Big Bang. CMBR defines the electromagnetic radiation that results from the lighting in the sky, and is usually employed in observational cosmology as the oldest form of lighting in the universe. As explained by Denise (2009), the gap connecting the stars and galaxies, which is commonly known as the background, is usually dark, but a faint glow is usually detected when a radio telescope is used. This glow is often thought to be similar in all directions but CMBR usually portray tiny variations with specific patterns. While cosmologists present CMBR as a snapshot of the earliest form of lighting of the universe that was developed on the sky, the tiny radiations represent fluctuations in temperature that match regions of distinct densities, which represent today’s starts and galaxies. CMBR represents the type of radiation that emerged as a leftover of prehistoric advancement of the universe as well as the remains that can prove the existence of the big bang theory (Cindi, 2013).

How Cosmic Microwave Background Radiation Relates To Big Bang

            The Cosmic Microwave Background Radiation is directly related to the big bang as it represents a landmark that can be used to explain the Big Bang theory of development of the universe. CMBR is usually described as the radiation that resulted from the earliest development stages of the universe. The universe during its initial stages of development before the stars or the planets had formed was denser and with extremely high temperatures and it was packed with a uniform glow that originated from hot plasmatic hydrogen (Cindi, 2013). Constant expansion of the universe caused the plasma and its radiations cooling down after which protons and atoms integrated to create neutral atoms. The atoms could no longer be able to attract the thermal radiation, which caused the universe to develop into a transparent object rather than an opaque fog. The Big Bang theory is thus important in explaining CMBR as it can help us to understand the unique temperature fluctuations as well as the degree of radiations prevailing in it (Denise, 2009).

Cosmic Inflation

            Cosmic inflation defines the drastic exponential expansion that took place during the first development stages of the universe. This expansion was driven by the principal background energy of the density of the universe, and it caused the universe to increase by a factor estimated at 1078 in volume. Inflation is important in responding to the unanswered questions relating to the big bang theory as it explain the total volume at which the linear dimensions of the universe changed during the first period of its evolution. According to Cindi (2013), expansion during the inflation period lasted between 10-36 and 10-33 seconds, which is a relatively short duration of time compared to the amount of time the universe has taken in subsequent expansions. Inflationary theory is equally important in explaining how the observable modern day universe emerged from a merely connected region. It also responds to a basic question about the Big Bang theory relating to why the universe tends to correspond to the basic cosmological principles in that it is flat, similar in nature and isotropic rather than being heterogeneous and curved as the basic assumptions of the physics of the Big Bang explains (Denise, 2009).


Cindi, S. (2013). Universe: Journey Deep into Space, Journal of Science and Children, 50(7):88-112.

Denise, S. (2009). The Universe: its Yours to Discover and Share, Journal of Science Scope, 32(8):12-40.