高级英语Unit2-A

1. What does it mean to say that the universe is accelerating? 2. What are the difficulties in studying and understanding the universe?
Einstein’s Repulsive Idea
What is Cosmology?
For thousands of years, astronomers wrestled with basic questions about the size and age of the universe. Does the universe go on forever, or does it have an edge somewhere? Has it always existed, or did it come to being some time in the past?
Einstein’s Repulsive Idea
History of expansion: A rough picture of how the universe's expansion decelerated, then began to accelerate. Fate is not known.
16th Century: Nicolaus Copernicus (Physics of Newton)
Model: Sun-centered Cosmology
20th Century: Edwin Hubble (Physics of Einstein)
Model: Big Bang Cosmology
Einstein’s Repulsive Idea
This diagram reveals changes in the rate of expansion since the universe's birth 15 billion years ago. The more shallow the curve, the faster the rate of expansion.
• Science is an ongoing process - forcing us to test our model through prediction and observation. The more tests it passes, the greater is our confidence in it.
“Normal Matter” 4% Dark Energy 73%
Dark Matter 23%
Conclusions • Big Bang model describes our current understanding of the universe.
• New discoveries, such as dark matter and accelerating expansion (Dark Energy), lead us to refine our model.
Earth-centered Cosmology: Claudius Ptolemy, 100-170 AD
Big idea: Earth was viewed as a stationary center of the universe, with sun, moon, and stars revolving about it in circular orbits and at a uniform rate.
Unit 2
Section A
Einstein’s Repulsive Idea
Albert Einstein (1879---1955)
Do you have any idea about the formation of our universe before reading this article?
New technology has made cosmology one of the most exciting sciences today, but not all the answers have been found. Watch the video segment the Gravity and the Expanding Universe and answer the following two questions.
A human being is part of the whole called by us universe, a part limited in time and space. We experience ourselves, our thoughts and feelings as something separate from the rest. A kind of optical delusion of consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from the prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty. The true value of a human being is determined by the measure and the sense in which they have obtained liberation from the self. We shall require a substantially new manner of thinking if humanity is to survive.
Some theorists think the Universe is filled with a mysterious dark energy, a sort of negative gravity.
The Hubble Space Telescope recently captured light from a supernova located farther from Earth than any previously seen.
---Albert Einstein, 1954
An Overview of Cosmology
Objectives • Develop perspective on the history of human knowledge of the universe • Understand the process of scientific exploration of the universe • Contemplate the current state of astronomy and think about future missions
The scientific style is dictated by the purpose of the type of writing. The scientist or engineer will generally write to describe a phenomenon, an experiment or a process, or to explain a theory. Hence they belong to the category called exposition. In this text, the author explains Einstein’s repulsive idea and its relationship to the latest research of expanding universe.
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Big Bang Cosmology: Edwin Hubble and Albert Einstein
Big idea: The universe had exploded and expanded from a small, hot, dense state into what we see today.
The finding has bolstered cosmological models for the universe's expansion and a mysterious “dark energy” pervading it. The supernova, or exploding star, is located 10 billion light-years from Earth.
Key words in the text
cosmological term general relativity gravity and antigravity supernova
Sun-centered Cosmology: Nicholas Copernicus 1473-1543
Big idea: Copernican system placed the sun motionless at the center of the solar system with all the planets, including the earth, revolving around it.
Big Bang Theory
the theory of the cosmic explosion that marked the origin of the universe. According to the big-bang theory, at the beginning of time, all of the matter and energy in the universe was concentrated in a very dense state, from which it exploded, with the resulting expansion continuing until the present. This big bang is dated between 10 and 20 billion years ago. In this initial state, the universe was very hot and contained a thermal soup of quarks, electrons, photons, and other elementary particles. After many millions of years the expanding universe, at first a very hot gas, thinned and cooled enough to condense into individual galaxies and then stars.
Our View of the Cosmos - the story of scientific models
Three scientific revolutions in cosmology
2nd Century: Claudius Ptolemy (Physics of Aristotle)
Model: Earth-centered Cosmology