费费逻辑135题，第39题求解

minigreen

39. Quasars---celestial objects so far away that their light takes at least 500 million years to reach Earth---have been seen since 1963. For anything that far away to appear from Earth the way quasars do, it would have to burn steadily at a rate that produces more light than 90 billion suns would produce. But nothing that burns at a rate that produces that much light could exist for more than about 100 million years.

If the statements above are true, which one of the following must also be true on the basis of them?

A.    Instruments in use before 1963 were not sensitive enough to permit quasars to be seen.
B.    Light from quasars first began reaching Earth in 1963.
C.    Anything that from Earth appears as bright as a quasar does must produce more light than would be produced by 90 billion suns.
D.    Nothing that is as far from Earth as quasars are can continue to exist for more than about 100 million years.
E.    No quasar that has ever been seen from Earth exists any longer.

为什么选E？看了答案也不明白~~~谢谢大牛~

mingmings

原题逻辑： Q，光线要500M年才能到地球（1963年才被观察到）。想要光线穿过这么远的距离，至少需要星球稳定燃烧产生超过90B个太阳的光线。但是这样的燃烧程度的星球从未存在超过持续100M年（都早就烧光了）。

问：上述正确的话 哪那个选项必定也正确？

A. 1963年之前的仪器不够精密。（无关）
B.  1963年才开始有Q的光线抵达地球。（无关）
C.  地球上看到Q那么亮的东西，必须要产生超过90M个太阳的光线。（错误，要是Q那种距离的才有这个要求，越近要求的光线肯定越小）
D.  距离像Q那么远的东西都不可能存在超过100M年。（错，要能被地球看见才需要剧烈燃烧，才会提前燃尽）
E. 能从地球上看到的Q 现在都已经不存在了。（对 因为Q要想被看见 要剧烈燃烧 不能存在超过100M年，而光线需要穿越500M年才能到地球，所以看见光线的时候，Q早就已经烧完了）


LZ不明白可能是因为没有读懂E选项吧~ 或者也可以稍微补充一点点星体光线的知识。我们看到的很多星星光线都是穿越了很长的距离到达地球的，很多都是在星体实际已经毁灭，但是光线还在传播的情况下看见的）

minigreen

没有知识的确没有读懂啊。读懂了就会了。
感谢