The Earth's magnetic field has diminished by perhaps as much as 6 percent in the last century alone. 仅仅在过去的一个世纪里，地球的磁场就减弱了大约6%之多。

　　Any diminution in magnetism is likely to be bad news, 磁力减弱有可能是个坏消息，

　　because magnetism, apart from holding notes to refrigerators and keeping our compasses pointing the right way, plays a vital role in keeping us alive. 因为除了确保冰箱正常运转和罗盘指着正确的方向以外，磁场在维持我们的生命方面起着重要的作用。

　　Space is full of dangerous cosmic rays that in the absence of magnetic protection would tear through our bodies, leaving much of our DNA in useless tatters. 太空里充满了危险的宇宙射线，没有磁场的保护，宇宙射线会穿透我们的身体，将我们的许多DNA撕成无用的碎片。

　　When the magnetic field is working, 如果磁场工作正常，

　　these rays are safely herded away from the Earth's surface and into two zones in near space called the Van Allen belts. 这些射线会被安全地挡在地球表面之外，被赶进近空两个名叫“范艾伦辐射带”的地区。

　　They also interact with particles in the upper atmosphere to create the bewitching veils of light known as the auroras. 它还与上层大气里的粒子互相作用，产生名叫极光的美丽光幕。

　　A big part of the reason for our ignorance, interestingly enough, is that  我们之所以无知，很大程度上是因为

　　traditionally there has been little effort to coordinate what's happening on top of the Earth with what's going on inside. 一直以来没有花多大力气去把地球上方的情况与地球里面的情况协调起来。

　　According to Shawna Vogel: "Geologists and geophysicists rarely go to the same meetings or collaborate on the same problems." 肖纳·沃格尔说：“地质学家和地球物理学家很少参加同一个会议，或者很少在同一问题上进行合作。”

　　Perhaps nothing better demonstrates our inadequate grasp of the dynamics of the Earth's interior than how badly we are caught out when it acts up, 也许，最能说明我们对地球内部的动力认识不足的，是在那种动力制造麻烦的时候我们所犯的严重错误。

　　and it would be hard to come up with a more salutary reminder of the limitations of our understanding than the eruption of Mount St. Helens in Washington in 1980. 我们很难想得出一个比1980年华盛顿州圣海伦斯火山爆发更能说明我们的认识有限的例子。