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  • 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

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B1 cloud pulse sodium laser atom slow

Prof. Lene Hau: Stopping light cold

  • 208 6
    Joyce posted on 2014/07/08
Video vocabulary

Keywords

start

US /stɑrt/

UK /stɑ:t/

  • other
  • Beginning of something in place or time
  • noun
  • First time or place that a thing exists; beginning
  • First opportunity to achieve something, e.g. a job
  • Sudden action or movement because you are scared
  • verb
  • To do, be or happen for the first time; begin
  • To turn something on
create

US /kriˈet/

UK /krɪ'eɪt/

  • verb
  • To make, cause, or bring into existence
  • other
  • To cause something to happen; to give rise to a particular situation or state.
  • To invent or design something new
  • To bring something into existence; to make or produce something new.
light

US /laɪt/

UK /laɪt/

  • other
  • The natural agent that stimulates sight and makes things visible.
  • adjective
  • Not burdensome or demanding; easy.
  • Pale in color; not dark.
  • Being bright making it easy to see; not dark
  • Being pale and lacking darkness of color
  • Not heavy; weighing only a little
  • noun
  • An expression in the eyes indicating a particular emotion.
  • A source of energy that makes a room or area bright
  • A person who is a source of inspiration or guidance.
  • A lamp, bulb, or similar device used to provide illumination.
  • A traffic signal.
  • Knowledge or understanding.
  • Way in which something or someone is understood
  • other
  • To ignite or set fire to something.
  • To provide with light; illuminate.
  • verb
  • To cause something to burn; put a burning match to
  • To provide a way to see ahead
  • adverb
  • Carrying few bags when traveling
totally

US /ˈtotl:ɪ/

UK /ˈtəʊtəli/

  • adverb
  • In a complete way; completely; absolutely
  • Completely; entirely
vacuum

US /ˈvækjuəm, -jum, -jəm/

UK /'vækjʊəm/

  • noun
  • Space with absolutely no air in it
  • An electrical appliance that sucks up dust and dirt.
  • Cleaning machine with engine that sucks up dirt
  • An appliance that cleans by suction.
  • An electrical appliance that sucks up dust and dirt.
  • A space entirely devoid of matter.
  • A state of emptiness; a lack of something.
  • A space entirely devoid of matter.
  • A state of emptiness; a void.
  • An electron tube.
  • verb
  • To clean (a floor) using a sucking machine
  • other
  • To clean with a vacuum cleaner.
  • To clean with a vacuum cleaner.
  • To seal something in a vacuum.
  • adjective
  • Sealed to remove air.
  • other
  • A space entirely devoid of matter.
speed

US /spid/

UK /spi:d/

  • noun
  • How fast or slow something is or is done
  • verb
  • To move quickly when completing an action
  • To drive a vehicle faster than laws allow
special

US /ˈspɛʃəl/

UK /'speʃl/

  • adjective
  • Being additional or extra
  • Different, better or greater than normal
  • noun
  • Heavily discounted sales item
sodium

US /ˈsodiəm/

UK /'səʊdɪəm/

  • noun
  • A soft, white chemical element
cross

US /krɔs, krɑs/

UK /krɒs/

  • adjective
  • Angry and upset
  • From one side of something to the other
  • verb
  • To put one thing over another e.g. arms
  • To breed one type of animal or plant with another
  • To not to agree with someone; oppose
  • To go from one side of something to the other
  • To meet at one point
  • noun
  • (Of animals) mixture of breeds in one animal
  • Person's name
atom

US /ˈætəm/

UK /'ætəm/

  • noun
  • Smallest bit that matter can be broken down into