Học tiếng Anh hiệu quả, nhanh chóng: http://www.facebook.com/HocTiengAnhVOA, http://www.voatiengviet.com/section/hoc-tieng-anh/2693.html. Nếu không vào được VOA, xin hãy vào http://vn3000.com để vượt tường lửa. Các chương trình học tiếng Anh miễn phí của VOA (VOA Learning English for Vietnamese) có thể giúp bạn cải tiến kỹ năng nghe và phát âm, hiểu rõ cấu trúc ngữ pháp, và sử dụng Anh ngữ một cách chính xác. Xem thêm: http://www.facebook.com/VOATiengViet
Luyện nghe nói và học từ vựng tiếng Anh qua video. Xem các bài học kế tiếp: https://www.youtube.com/playlist?list=PLD7C5CB40C5FF0531
Imagine a camera that can take one hundred billion pictures a second — that is enough to record the fastest movements in the universe. Now, a scientist has invented such a camera. He calls it an imaging system. Lihong Wang is a biomedical engineer at Washington University in St. Louis, Missouri. He leads a team of researchers who have discovered several new imaging methods. He says now humans can see light pulses traveling at the speed of light. The speed of light is almost 300 million meters per second. At that speed, it would take just one second to travel around the world seven and a half times. Mr. Wang photographs light particles moving at that speed using an unusual camera. He says his “streak” camera allows them to convert time into space. He says his researchers are able to turn light, photons, into electrons called electrons. Then they pull the electrons at different rates. Unlike other streak cameras, Mr. Wang’s does not need special lighting. Mr. Wang says his camera produces two-dimensional images like regular photographs unlike other streak cameras. The camera is very fast, taking one image every 10 trillionths of a second. Brian Pogue is a biomedical engineer at Dartmouth College in New Hampshire. He reviewed the new imaging system for the science publication Nature. He says this new way of seeing the movement of light could lead to major scientific discoveries in areas like optical cloaking. “Cloaking” is technology that could make an object seem to disappear. Lihong Wang says the new camera might be used in molecular biology and astronomy.
