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Signals from aliens
来自外星人的信号
The Search for Extra-Terrestrial Intelligence Institute （SETI）, listening to the cosmos for signs of signals from alien civilizations, may be monitoring the wrong “channels,” a U.S. astrophysicist says.
一位美国天体物理学家表示，地外智能生命搜寻研究所（SETI）一直以来探索宇宙外星文明信号的方法可能是“走了弯路”。
Gregory Benford of the University of California, Irvine,
美国加州大学欧文分校的科学家格雷戈里·本福德近日称，
says such a civilization wanting to announce its presence would transmit “cost-optimized” narrowly focused signals,
试图跟人类建立联系的外星人很可能从“成本最优”方面考虑只发送较短的定向信息，
not the continuous omni-directional signals the SETI program has been scanning for, a university release said recently.
而不是漫无方向地持续发送信息。而SETI 一直以来搜索的信息正是后者。
“This approach is more like Twitter and less like War and Peace, ”James Benford, Gregory Benford`s twin and fellow physicist, says.
“这种发送消息的方法更像是推特（Twitter），而不是场面宏大的《战争与和平》，”格雷戈里·本福德的孪生兄弟，物理学家詹姆斯·本福德说。
“Whatever the life form, evolution selects for economy of resources. Transmitting signals across light years would require considerable resources.”
“不论是何种生命形式，进化的方向都是节约资源。穿越光年发送信息，要花费相当巨大的资源。”
They says alien signals would not be blasted out in all directions
他们还说，外星人不会向外漫无目的地全方位传送信号，
but narrowly directed in the one-to-ten gigahertz broadband signal range and SETI’s broad sweeping search could leave many days when brief Twitter-like flashes of “ here we are” from alien civilizations go undetected.
而只会在1-10千兆赫的波段内定向发送。但SETI 采取的是大范围的信号扫描方式，这样一来，在外星文明发出“我们在这儿！”的信号时，可能就已经错过SETI 的扫描了。
Such short, targeted blips, dubbed Benford beacons, should be the targets of SETI efforts, a growing number of scientists say.
越来越多的科学家支持他们的观点，认为这种简短、定向的信息（被称为本福德信号）才应该是SETI 搜索的目标。
And the Benfords also suggest concentrating the search on our own Milky Way galaxy, especially its center where 90 percent of its stars are located.“
本福德兄弟还建议将搜索地点锁定在我们自身所处的银河系，特别是90％恒星所在的中心地区。
The stars there are a billion years older than our sun,” Gregory Benford says,
“那里的恒星寿命比太阳还早10 亿年，”格雷戈里·本福德说，
“which suggests a greater possibility of contact with an advanced civilization than does pointing SETI receivers outward to the newer and less crowded edge of our galaxy. ”
“这意味着那里更有可能存在高等智慧生命。这比将SETI 的天线对准银河系边缘更年轻恒星、也更稀疏的区域要好得多了。”
