科学家们花了300年的时间，通过做实验并进行计算，才确定了光在真空中惊

Scientists have spent 300 years, by doing experiments and calculations, before deciding on an amazing light propagation velocity in a vacuum: 186,282 miles per second. <br><br>Please fill in this text box MR <br>2 <br>speed of light in air is a little slower than vacuo. <br><br>Please fill out this translation of the text box <br>3 <br>is actually in some extreme experiments have been able to slow down to light like a crawl, or even make it look like in the back. <br><br>Please fill out this translation of the text box <br>4 <br>but in our everyday life scales encountered, the light travels fast, so that we feel everything around occur in real time. <br><br>Please fill out this translation of the text box <br>5 <br>looked up at the night sky, this illusion began untenable. <br><br>Please fill out this translation of the text box <br>6 <br>is located in Greenbelt, Maryland, NASA Goddard Space Flight Center in Floyd Si Daike (Floyd Stecker) explain, said: "Light reaches the Earth needs from there time, so 'there' farther away from where the light of the time it sooner, so we see at some point all celestial bodies are past the situation. "

It took scientists 300 years, experiments and calculations, to determine the amazing rate at which light travels in a vacuum: 186,282 miles per second.<br>Please fill in the translation in this text box<br>2<br><br>Light travels slightly more slowly in the air than in a vacuum.<br>Please fill in the translation in this text box<br>3<br><br>In fact, in some extreme experiments, light can be slowed down to something like a crawl, even making it look like it's retreating.<br>Please fill in the translation in this text box<br>4<br><br>But in the scale range of our daily lives, light travels so fast that we feel that everything around us is happening in real time.<br>Please fill in the translation in this text box<br>5<br><br>Looking up at the night sky, the illusion began to hold.<br>Please fill in the translation in this text box<br>6 Floyd Stecker, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, explains: "It takes time for light to get to Earth from there, so' The farther away there, the sooner the light leaves there, so all the objects we see at some point are the past. "

Scientists spent 300 years experimenting and calculating to determine the astonishing speed of light in a vacuum: 186,282 miles per second.<br>Please fill in the translation in this text box.<br>Two<br>Light travels slightly slower in air than in vacuum.<br>Please fill in the translation in this text box.<br>Three<br>In fact, in some extreme experiments, light has been slowed down to a crawl, or even to a retreat.<br>Please fill in the translation in this text box.<br>Four<br>But in the scale range we encounter in our daily life, light travels so fast that we feel everything around us happens in real time.<br>Please fill in the translation in this text box.<br>Five<br>Looking up at the night sky, the illusion began to fail.<br>Please fill in the translation in this text box.<br>Six<br>Floyd Stecker, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, explained: "It takes time to get to Earth from there alone, so the farther you go there, the earlier you leave, so all the objects we see at some point are past."<br>