2. 考研
  3. We can distinguish three different realms of matter, three levels on the quantum ladder. The first is the atomic realm, which in

We can distinguish three different realms of matter, three levels on the quantum ladder. The first is the atomic realm, which in

admin2019-06-20  67
问题    We can distinguish three different realms of matter, three levels on the quantum ladder. The first is the atomic realm, which includes the world of atoms, their interactions, and the structures that are formed by them, such as molecules, liquids and solids, and gases and plasmas. This realm includes all the phenomena of atomic physics, chemistry, and, in a certain sense, biology. The energy exchanges taking place in this realm are of a relatively low order. If these exchanges are below one electron volt, such as in the collisions between molecules of the air in a room, then atoms and molecules can be regarded as elementary particles. That is, they have "conditional elementarily" because they keep their identity and do not change in any collisions or in other processes at these low energy exchanges. If one goes to higher energy exchanges, say 104 electron volts, then atoms and molecules will decompose into nuclei and electrons; at this level, the latter particles must be considered as elementary. We find examples of structures and processes of this first rung of the quantum ladder on Earth, on planets, and on the surfaces of stars.
   The next rung is the nuclear realm. Here the energy exchanges are much higher, on the order of millions of electron volts. As long as we are dealing with phenomena in the atomic realm, such amounts of energy are unavailable, and most nuclei are inert: they do not change. However, if one applies energies of millions of e-lectron volts, nuclear reactions, fission and fusion, and the processes of radioactivity occur; our elementary particles then are protons, neutrons, and electrons. In addition, nuclear processes produce neutrinos, particles that have no detectable mass or charge. In the universe, energies at this level are available in the centers of stars and in star explosions. Indeed, the energy radiated by the stars is produced by nuclear reactions. The natural radioactivity we find on Earth is the long-lived remnant of the time when now-earthly matter was expelled into space by a major stellar explosion.
   The third rung of the quantum ladder is the subnuclear realm. Here we are dealing with energy exchanges of many billions of electron volts. We encounter excited nucleons, . new types of particles such as mesons, heavy electrons, quarks, and gluons, and also antimatter in large quantities. The gluons are the quanta, or smallest units, of the force (the strong force) that keeps the quarks together. As long as we are dealing with the atomic or nuclear realm, these new types of particles do not occur and the nucleons remain inert. But at subnuclear energy levels, the nucleons and mesons appear to be composed of quarks, so that the quarks and gluons figure as elementary particles.
According to the passage, radioactivity that occurs naturally on Earth is the result of______.
选项 A、the production of particles that have no detectable mass or electric charge
B、high energy exchanges on the nuclear level that occurred in an ancient explosion in a star
C、processes that occur in the center of the Sun, which emits radiation to the Earth
D、high-voltage discharges of electricity that took place in the atmosphere of the Earth shortly after the Earth was formed
答案B
解析 事实细节题。根据radioactivity和natural定位至第二段最后一句，地球上的自然放射现象是重大星球爆炸造成的。第二段是介绍核层次中的现象，说明地球上的放射现象属于这个层次，而该段第二、三句说明这个层次会产生巨大的能力量，综上，[B]项为答案。第四句说，核过程会产生“particles that have no detectable mass or charge”，但产生的是中微子，不是放射现象，故排除[A]项；文章没有提及太阳中心的核现象，也未说到地球形成初期的情况，故排除[C]项和[D]项。
转载请注明原文地址:https://www.kaotiyun.com/show/iDra777K
本试题收录于： 翻译硕士（翻译硕士英语）题库专业硕士分类
0

翻译硕士（翻译硕士英语）

专业硕士

相关试题推荐
随机试题
最新回复(0)