Placeholder Image

字幕列表 影片播放

  • the speed of light is basically

  • is fast as you ever get

  • What is it in American units, something like one hundred and eighty six

  • thousand miles a second

  • but on our account we can slow them down to 38 miles per hour- that's what

  • we did in our first experiment

  • and then we actually slowed them down all the way to to one mile an hour and

  • then you can actually

  • you can basically crawl faster than light

  • what we do is we a bunch of atoms, and we use what I call sodium atoms, exactly what

  • you have in table salt

  • and then we cross-manipulate these atoms in very special ways with

  • laserbeams and then we can cool these atoms down to a few billionths of a degree above absolute

  • So, of course, that's really cold. It's actually the coldest place in the universe.

  • And then once we create a cloud

  • of such really cold atoms we illuminate that cloud with one laser beam

  • and then we send a light pulse

  • into the cloud from the other side and we can now slow that light pulse down to the

  • speed of a bicycle and it sort of chuffs along.

  • And then, if we feel like it, we can actually completely stop that light pulse inside our atom

  • cloud

  • and then leave it there for a while, park it there, and then when we feel like it,

  • cloud send the light pulse back on its way, revive it, regenerate it, and out it comes.

  • what we are seeing here

  • is actually the atom pool, really, because as I mentioned, we create these really cold atoms

  • and we need laser beams to do that.

  • And eventually these laser beams are really running around,

  • criss cross on the optics table.

  • And then they converge on the vacuum chamber where all the action is happening.

  • And then up here, behind, we have a very special atom source-

  • that's where the sodium

  • atoms are coming from. And they are hot to start-

  • we actually have to heat them to create a gas of sodium atoms... And at the time when we 0:02:00.190,0:02:02.299 started to go after cold atoms

  • I did not have a clue that some years later I would start to look at slow light forces. And that's really

  • an example of,

  • if you get your hands on an exciting new system,

  • you start to poke it

  • and see what comes out

  • And what you hope is that something totally unexpected, totally exciting

  • will come out and and i think that's what happened in this case.

the speed of light is basically

字幕與單字

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B1 中級

侯麗娜教授。熄燈 (Prof. Lene Hau: Stopping light cold)

  • 56 3
    Joyce 發佈於 2021 年 01 月 14 日
影片單字