国家地理-2008-04-17 New Search For ET 寻找外星人（上）（在线收听）

Is anyone out there? For over 40 years scientists have been searching for extraterrestrial intelligence, but they’ve found nothing. Now the new Allen Telescope Array, a string of 350 radio telescopes, is being built 300 miles north of San Francisco and is breathing new life into the search. Find out why SETI scientists now say we might be hearing from ET sooner than you think.

Ok, imagine you are at the beach, in order to figure out if there are fish in the ocean, you dip an empty glass into the water and look inside. No fish in the glass? Well, there must be no fish in the ocean.

 Not too logical, is it? But that's exactly the type of reasoning that's plagued Dr. Jill Tarter for years. Astronomers like Tarter began searching for alien intelligence in our galaxy about four decades ago. In that 40 years, they've only managed to search 1000 star systems, 1000 glasses of water, while an unexplored cosmic ocean lay right in front of them.

“40 years needs to be put in the context of how big the universe is, how enormous this cosmic haystack is that we are trying to search through. And so we've just begun.”

  Dr.Tarter knows a little something about SETI, the Search for Extraterrestrial Intelligence. She is an astronomer and the current director of the Center for SETI Research in Mountain View, California. Tarter, like many SETI scientists, was drawn into the search by the early work of astronomer Frank Drake. Drake looked at the makeup of our galaxy and created an equation to determine the likelihood that other intelligent life exists. By factoring invariables like the fraction of stars with orbiting planets, the percentage of planets they go on to develop intelligent life and the length of time that an intelligent race lasts. Drake’s equation made it clear. Scientifically, the odds are pretty good that we are not alone.

 But if you are hunting for ET, where do you start? What would the sign of a technically sophisticated alien culture look like? It could look something like this. Television and radio signals like this are examples of artificially focused electromagnetic waves, and we've been leaking them into space for over 80 years. That means any planet within 80 light-years of Earth is receiving them. Signals like this are simple to generate and use, and carry well over vast distances. That's why SETI scientists believe alien cultures might be leaking them just like we are.
 
 In 1979, as a young graduate student, Jill Tarter joined the hunt for these telltale signals.
 
“I was so enthralled by the idea that I lived in the first generation ever of human beings that could try and answer the "Are we alone" question by doing an experiment rather than just asking the priests and the philosophers what they believed.”
 
By the early 1990s with NASA funding, Tarter was heading up the search at the largest facility in the world, the Arecibo Radio Telescope in Puerto Rico. Tarter became the poster child for SETI. Even Hollywood embraced her. Tarter is generally thought to be the inspiration for Ellie Arroway, the character played by Jodie Foster in the classic science fiction movie "Contact". It seemed that the golden age of SETI had arrived. Then in 1993, Congress abruptly shut off all federal SETI funding. But that wasn't the end.
 
Today, nearly 15 years later, something big is happening in this remote valley near Hat Creek, California. SETI's look may be about to change. These radio telescope dishes signal the beginning of what many believe will be a SETI renaissance. If there is to be a breakthrough, the new alien telescope array is the best bet.
 
The reversal of SETI's fortune has largely been made possible by a 25-million-dollar grant from Paul Allen, one of the founders of Microsoft. On October 11th, 2007, Allen pushed the silver button, bringing the first 42 radio dishes online. When completed, the Allen Telescope Array will consist of 350 separate dishes. Together, they can operate as a single virtual dish over 2,700 feet across, making it one of the largest and most sensitive radio telescopes in the world. It will be the fastest tool ever built to hunt for signals of extraterrestrial intelligence.
 
haystack：a large, firmly built pile of hay.(AmE idiom：needle in a haystack）
 
telltale signals/signs/marks ect: signs etc that clearly show something has happened or exists, often something that is a secret
 
enthral: to make someone very interested and excited, so that they listen or watch something very carefully
 
poster child: A person who is a prominent example or type of something