英语听力：自然百科 探索世界奥秘之Alien Neighbors (寻访外星人) Unit12（在线收听）

How likely that technology will destroy those who invented it? The Drake Equation doesn’t exactly narrow the field. Depending on the variables, the number of intelligent civilizations could be zero or a billion or any number in between. Richard Dawkins thinks the last factor in the equation might explain why the heavens are so silent.

"It’s been rather pessimistically suggested that when a civilization anywhere in the universe becomes advanced enough to, say, develop radio telescopes or the ability to communicate by radio over vast distances. That level of technology, almost inevitably, is close to...., destroying itself by atom bombs or similar weapons of mass destruction. Now if this is true, it could be an answer to the question--why haven’t we heard from other forms of life."

It’s also possible that an intelligent civilization might have more in common with our machines than ourselves.

"A really advanced civilization might have gone beyond biology to develop machine intelligence. Machine intelligence could spread throughout the galaxy a lot more easily than biology could. So it maybe that if we pick up a signal, it’s not from biology at all, it’s from a machine, a thinking machine."

If thinking machines populate another world, they may have evolved not from carbon molecules as we did, but from silicon, the same kind of silicon that’s the basis of computer technology. Silicon is not all that different to carbon.

"Just possibly, you could imagine a kind of fantasy science fiction life which was not carbon-based but silicon-based. But you don’t have to go to silicon, you could, you could have other kinds of carbon-based organic life which would be very, very different from life on this planet as we know it and still be living. "

To stand a chance of supporting carbon-based life, there must be water. Water is essential to life as we know it. We have no evidence that life could exist on another moon or planet without water. As new moons and planets are discovered, there are bursts of hope that some life, other than life familiar to us, is out there.

1995 saw great excitement when a brand-new planet was detected. Two Swiss astronomers spotted the planet beyond our own solar system. For the first time, a planet had been found orbiting another star. Within a year of this discovery, more new planets were announced. This time, the glory belonged to two American astronomers using the Licht Telescope in San Francisco. It was this great instrument that caught the light from a distant star and showed the world that planetary systems may be common. The planet finders were Jeff Marcy and Paul Butler, and no one was as surprised about it as they were.

" When Jeff first suggested that we might find planets, it seemed like an outrageous idea, but still, it was, you know, a lot more exciting than most anything else I could imagine, so I jumped at the chance to look for planets, I didn’t know if it would ever work and it’s been a long long struggle to get here. "

words in this passage

populate：to live in an area or place 居住在…中。

eg:The settlers began to move inland and populate the river valleys.

science fiction :books, films or cartoons about an imagined future, especially about space travel or other planets科幻,科学幻想小说（亦作： sci-fi）

stand a chance of :有...的希望

see: 这里的用法与witness相同: When a place or period witnesses a particular event, the event happens in that place or during that period

eg: The past few years have witnessed momentous changes throughout Eastern Europe.

brand-new: completely new, especially not yet used:崭新的

jump at sth:to accept something eagerly:欣然接受

eg:She jumped at the chance of a trip to Paris.