The marvelous telephone and television network that has now enmeshed the whole world, making all men neighbors, cannot be extended into space. It will never be possible to converse with anyone on another planet. Even with today’s radio equipment, the messages will take minutes—sometimes hours—on their journey, because radio and light waves travel at the same limited speed of 186, 000 miles a second.
Twenty years from now you will be able to listen to a friend on Mars, but the words you hear will have left his mouth at least three minutes earlier, and your reply will take a corresponding time to reach him. In such circumstances, an exchange of verbal messages is possible—but not a conversation.
To a culture which has come to take instantaneous communication for granted, as part of the very structure of civilized life, this "time barrier" may have a profound psychological impact. It will be a perpetual reminder of universal laws and limitations against which not all our technology can ever prevail. For it seems as certain as anything can be that no signal--still less any material object—can ever travel faster than light.
The velocity of light is the ultimate speed limit, being part of the very, structure of space and time. Within the narrow confines of the solar system, it will not handicap us too severely. At the worst, these will amount to twenty hours—the time it takes a radio signal to span the orbit of Pluto, the outer-most planet.
It is when we move out beyond the confines of the solar system that we come face to face with an altogether new order of cosmic reality. Even today, many otherwise educated men—like those savages who can count to three but lump together all numbers beyond four—cannot grasp the profound distinction between solar and stellar space. The first is the space enclosing our neighboring worlds, the planets; the second is that which embraces those distant suns, the stars, and it is literally millions of times greater. There is no such abrupt change of scale in the terrestrial affairs.
Many conservative scientists, appalled by these cosmic gulfs, have denied that they can ever be crossed. Some people never learn ; those who sixty years ago scoffed at the possibility of flight, and ten years ago laughed at the idea of travel to the planets, are now quite sure that the stars will always be beyond our reach. And again they are wrong, for they have failed to grasp the great lesson of our age— that if something is possible in theory, and no fundamental scientific laws oppose its realization, then sooner or later it will be achieved.
One day we shall discover a really efficient means of propelling our space vehicles. Every technical device is always developed to its limit and the ultimate speed for spaceships is the velocity of light. They will never reach that goal, but they will get very near it. And then the nearest star will be less than five years voyaging from the earth.
The fact that it will never be possible to converse with someone on another planet shows that（）
A. radio messages do not travel fast enough
B. no object can ever travel faster than light
C. western culture has a special idea of communication
D. certain universal laws cannot be prevailed against
参考答案：A
解析：
本题考查事实细节。第一段后两句指出，“永远不可能和另一个星球人进行对话。即使有今天的无线电设备，信息传播也需要好几分钟，甚至好几个小时，因为无线电和光波都是以有限速度传播。”第二段中举了一个和火星人交流的例子，得出的结论是：“交换语言信息是可能的，但是不可能对话。”A选项指的是传播速度的限制，所以是JE确的。B选项是第三段末句的改写，是事实，但它与无法实现星际对话没有必然的联系。C选项在第三段提到，但“认为即刻交流是理所当然的文化”是人思维局限的表现，而“人无法和另外一个星球的人进行对话”是自然规律事实，后者不能表明前者。该段也提到，“时间的局限性”(即无法和外星人进行对话)提醒我们不是所有的技术都能战胜普遍规律和限制，因此这里说明的是“技术的局限性”，而不是D选项中的“规律的不可战胜性”。故正确选项为A。