科技英语阅读答案unit 2.doc

1Appendix I Reference AnswersUnit 2 PhysicsPart I EST ReadingReading 1 Section A Pre-reading TaskWarm-up Questions: Work in pairs and discuss the following questions.1. What is quantum physics?Quantum physics is the study of the behavior of matter and energy at the molecular, atomic, nuclear, and even smaller microscopic levels. In the early 20th century, it was discovered that the laws that govern macroscopic objects do not function the same in such small realms.2. Do you know anything about dark matter?Dark matter is a hypothesized form of matter particle that does not reflect or emit electromagnetic radiation. The existence of dark matter is inferred from gravitational effects on visible matter, such as stars and galaxies.A small percentage of the gravitational effects observed are from visible matter (some estimates are as low as 4% of total gravitational effects). The remaining 96% is presumed to result from dark matter or dark energy, though these terms are somewhat indicative of our ignorance of the exact nature of these unknown quantities, as they have never been directly observed.One possible candidate for dark matter are theoretical particles known as weakly interacting massive particles (WIMPs), which are being searched for by the Cryogenic Dark Matter Search (CDMS) experiment.3. What is dark energy? Dark energy is a hypothetical form of energy that permeates space and exerts a negative pressure, which would have gravitational effects to account for the differences between the theoretical and observational results of gravitational effects on visible matter. Dark energy is not directly observed, but rather inferred from observations of gravitational interactions between astronomical objects, along with dark matter. The term "dark energy" was coined by the theoretical cosmologist Michael S. Turner.4. Have you ever heard of the big bang theory? Can you give an account of it?The Big Bang is the dominant (and highly supported) theory of the origin of the universe. In essence, this theory states that the universe began from an initial point or singularity which has expanded over billions of years to form the universe as we now know it.2In 1927, Roman Catholic priest and physicist Georges Lemaitre independently calculated the Friedman solution and again suggested that the universe must be expanding. This theory was supported by Hubble when, in 1929, he found that there was a correlation between the distance of the galaxies and the amount of redshift in that galaxy's light. The distant galaxies were moving away faster, which was exactly what was predicted by Lemaitre's solutions. In 1931, Lemaitre went further with his predictions, extrapolating backwards in time find that the matter of the universe would reach an infinite density and temperature at a finite time in the past. This means the universe must have begun in an incredibly small, dense point of matter - a "primeval atom."5. How do you understand string theory?String theory is a mathematical theory that tries to explain certain phenomena which is not currently explainable under the standard model of quantum physics.String theory was initially developed in the 1970s in an attempt to explain some inconsistencies with the energy behavior of hadrons and other fundamental particles of physics. As with much of quantum physics, the mathematics that applies to string theory cannot be uniquely solved. Physicists must apply perturbation theory to obtain a series of approximated solutions. Such solutions, of course, include assumptions which may or may not be true. The driving hope behind this work is that it will result in a "theory of everything," including a solution to the problem of quantum gravity, to reconcile quantum physics with general relativity, thus reconciling the fundamental forces of physics.Section C Post-reading TaskReading Comprehension1. Directions: Work on your own and fill in the blanks with the main idea.Part 1 (Paras. 1-3): Brief introduction to dark energyPara. 1: Dark energy is an unexplained force which tugs galaxies away from each other.Para. 2: Dark energy is somewhat like anti-gravity.Para. 3: Dark energy is scientists’ hypothetic form of energy to explain the universe’s expansion.Part 2 (Paras. 4-9): The discovery of dark energy: confounding expectationsPara. 4: The discovery of dark energy is a case of science confounding expectations.Para. 5: Experts expected that gravity had slowed down the universe’s rate of expansion.Para. 6: The universe’s rate of expansion was speeding up.Para. 7: The result was beyond experts’ expectations which caused much nervous laughter.Para. 8: The measurements of supernovae provided the evidence that the universe’s rate of 3ballooning was speeding up.Para. 9: The scientists observed many supernovae at different distances to determine how fast they are speeding away from us.Part 3 (Paras. 10-13): The rate of the expansion of the universe: shocking resultsPara. 10: The rate of the univers。