Aerospace Engineering Course

http://open.umich.edu/

Open.Michigan is a University of Michigan initiative that enables faculty, students, and others to share their educational resources and research with the global learning community.

Courses & Training

		The University of Michigan offered the first program in aeronautical engineering in the United States more than 80 years ago. Since then, we have graduated more than 4,000 aeronautical and aerospace engineers. Our graduates have gone on to distinguished careers in the aerospace industry, related fields, government and academia. "To provide students with a solid foundation in the component disciplines of aerospace engineering, and to expand existing knowledge through leading edge research"
	University of Michigan Aerospace Engineering

Department of Aerospace Engineering, University of Michigan, Ann Arbor
FXB Building 1320 Beal Avenue Ann Arbor, Michigan 48109-2140
For problems or questions about this site, contact enochc@umich.edu.

Asumsi Dasar untuk Membangun Ilmu Kosmologi

Before observational evidence was gathered, theorists developed frameworks based on what they understood to be the most general features of physics and philosophical assumptions about the universe. 

When Albert Einstein developed his general theory of relativity in 1915, this was used as a mathematical starting point for most cosmological theories including the Big Bang and the Steady State theories.

In order to arrive at a cosmological model, however, theoreticians needed to make assumptions about the nature of the largest scales of the universe. The assumptions that the Big Bang relied upon are:

1. the universality of physical laws – that the laws of physics don't change from one place and time to another,
2. the cosmological principle – that the universe is roughly homogeneous and isotropic in space though not necessarily in time, and
3. the Copernican principle – that we are not observing the universe from a preferred locale.

These assumptions when applied to the Einstein field equations naturally result in a universe which has the following features:

1. an expansion of the universe,
2. the universe emerging from a hot, dense state at a finite time in the past,
3. the lightest elements were created in the first moments that time existed as we know it, and
4. a cosmic microwave background pervading the entire universe should exist, which is a record of a phase transition that occurred when the atoms of the universe first formed.

These features were derived by numerous individuals over a period of years; indeed it was not until the middle of the twentieth century that accurate predictions of the last feature and observations confirming its existence were made. Non-standard theories developed either by starting from different assumptions or by contradicting the features predicted by the Big Bang.

Sumber;

Wikipedia

Memahami Kosmologika Fisika

Physical cosmology is the branch of physics and astrophysics that deals with the study of the physical origins and evolution of the Universe. It also includes the study of the nature of the Universe on its very largest scales. In its earliest form it was what is now known as celestial mechanics, the study of the heavens. 

The Greek philosophers Aristarchus of Samos, Aristotle and Ptolemy proposed different cosmological theories.

In particular, the geocentric Ptolemaic system was the accepted theory to explain the motion of the heavens until Nicolaus Copernicus, and subsequently Johannes Kepler and Galileo Galilei proposed a heliocentric system in the 16th century. This is known as one of the most famous examples of epistemological rupture in physical cosmology.

With Isaac Newton and the 1687 publication of Principia Mathematica, the problem of the motion of the heavens was finally solved. Newton provided a physical mechanism for Kepler's laws and his law of universal gravitation allowed the anomalies in previous systems, caused by gravitational interaction between the planets, to be resolved. 

A fundamental difference between Newton's cosmology and those preceding it was the Copernican principle that the bodies on earth obey the same physical laws as all the celestial bodies. This was a crucial philosophical advance in physical cosmology.

Modern scientific cosmology is usually considered to have begun in 1917 with Albert Einstein's publication of his final modification of general relativity in the paper "Cosmological Considerations of the General Theory of Relativity" (although this paper was not widely available outside of Germany until the end of World War I). 

General relativity prompted cosmogonists such as Willem de Sitter, Karl Schwarzschild and Arthur Eddington to explore the astronomical consequences of the theory, which enhanced the growing ability of astronomers to study very distant objects. Prior to this (and for some time afterwards), physicists assumed that the Universe was static and unchanging.

In parallel to this dynamic approach to cosmology, one long-standing debate about the structure of the cosmos was coming to a climax. Mount Wilson astronomer Harlow Shapley championed the model of a cosmos made up of the Milky Way star system only; while Heber D. Curtis argued for the idea that spiral nebulae were star systems in their own right – island universes. 

This difference of ideas came to a climax with the organization of the Great Debate at the meeting of the (US) National Academy of Sciences in Washington on 26 April 1920. 

The resolution of this debate came with the detection of novae in the Andromeda galaxy by Edwin Hubble in 1923 and 1924. Their distance established spiral nebulae well beyond the edge of the Milky Way.

Subsequent modelling of the universe explored the possibility that the cosmological constant, introduced by Einstein in his 1917 paper, may result in an expanding universe, depending on its value. 

Thus the Big Bang model was proposed by the Belgian priest Georges Lemaître in 1927 which was subsequently corroborated by Edwin Hubble's discovery of the red shift in 1929 and later by the discovery of the cosmic microwave background radiation by Arno Penzias and Robert Woodrow Wilson in 1964. 

These findings were a first step to rule out some of many alternative physical cosmologies.

Recent observations made by the COBE and WMAP satellites observing this background radiation have effectively, in many scientists' eyes, transformed cosmology from a highly speculative science into a predictive science, as these observations matched predictions made by a theory called Cosmic inflation, which is a modification of the standard Big Bang model. 

This has led many to refer to modern times as the "Golden age of cosmology".

Sumber: Wikipedia