英语时差:粉碎原子
Yael: Y'know Don, you're nothing but a bunch of quarks. Don: Huh? Y: It's just that when you get right down to it we're all made of subatomic particles like quarks and photons. D: I thought you were commenting on my quirky habit of annoying, tuneless whistling. Y: That is annoying--but I said "quark" not "quirk"--and I was just marveling at the fact that we can actually detect subatomic particles with giant particle accelerators and detectors. D: How? Y: There are several different kinds of accelerators and detectors, but they share basic principles. Particles, like electrons or atomic nuclei, are collected and then shot at close to the speed of light through metal pipes that can stretch for miles underground. To reach these speeds, the particles are pushed by electric waves that are generated by devices called klystrons, which are like very powerful microwave ovens. Giant electromagnets steer the particles and keep them focused in a narrow beam. When the high-energy beam slams into a thin piece of foil or another beam traveling in the opposite direction, the impact breaks the particles apart. Then the stuff they're made of--quarks, gluons and so on--shoot out and become visible for a minute fraction of a second. D: You mean we can actually see them? Y: No. But detectors positioned near where the particles come apart can record traces. Some detectors use liquids that vaporize almost instantly when particles pass through, leaving behind telltale bubble tracks. By analyzing the tracks, physicists are able to piece together what these particles are and how they work. D: That's really interesting. Well, back to work. [TUNELESS WHISTLING] Y: Uh, Don? D: The whistling? Y: That's one "quirk" I can really do without.
- 频道推荐
- |
- 全站推荐
- 推荐下载
- 网站推荐
