- You don't have to be a Jedi to use the force on light.
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I don't know about you guys, but I was totally blown away
by the Star Wars 7 trailer.
And there's so much I can geek out about right now,
but I'm being told that I need to show at least a modicum
of self-restraint, so I'll just say squee!
Okay, there's a lot we could cover here,
but I want to concentrate on lightsabers.
Is there any way we could ever make a real one?
Now if you remember our episode on holograms,
you know we're not exactly experts on bossing light around.
We can't tell a ray of light to just stop in mid-air,
but some researchers at the Harvard-MIT Center
for Ultracold Atoms, which is awesome,
have come up with a way to make massless photons,
those particles of light, to behave as if they are
atoms in a molecule.
Now this is amazing, because photons normally
don't interact with each other at all.
That's why you can turn on a couple of flashlights
and pass the beams through each other
without any interference.
But the researchers found out that, depending upon
the medium you use, you can make things a little weird.
Now to start, they took some rubidium atoms in gas form
and they super-cooled them with a laser,
which is also weird because don't lasers burn things?
Alright, let's back off a bit.
Heat is essentially movement.
The more a particle moves, the hotter it is.
So imagine that you've got an atom coming right at you
and you aim a laser at that atom.
The photons in that laser are essentially massless
but they still have momentum, and that momentum
slows down the oncoming atom.
If you do this enough, the atom becomes
essentially motionless and super cooled.
Alright, let's go back to those molecular photons.
When a photon enters this gas of super-cooled
rubidium atoms, it transfers some of that momentum,
that energy, to an atom.
That slows down the photon, which means that light
is traveling slower than the speed of light.
This is just a good reminder that light speed
depends upon the medium through which it travels.
Now when that photon gets through that gas cloud,
that energy rejoins the photon and everything
is right with the universe.
It's kind of like the way light travels through
a glass of water, but on a bigger scale.
But what happens if two photons enter the cloud?
Here's where things get odd in an awesome way.
You see, there's this weird effect
called the Rydberg blockade,
which states that if you excite an atom,
you can't excite nearby atoms to that same degree.
So when photon one enters the cloud and starts to excite
rubidium atoms, photon two can't do the same thing.
There's this push-pull relationship between
the two photons.
It's kinda like two lightsabers hitting each other,
you know, going (imitating electrical buzzing).
But it probably doesn't make that cool sound effect.
So does this mean I can finally build my own
working lightsaber?
Sadly, no.
But there are some cool applications for this technology.
One could be that photon interactions could become
the basis of quantum computing.
And I think my mind just melted a little bit.
But beyond that, lead research Mikhail Lukin says
we may one day be able to make three-dimensional objects
like crystals out of pure light.
Okay, I'm gonna need some time to process all of this,
but in the meantime I have a question
for all you guys out there.
What science-fiction gadget or gizmo or vehicle
do you most wanna get your hands on right now and why?
Let me know in the comments below,
and remember you will like this video.
You will subscribe to our channel.
And then make sure you check out these other
awesome videos over here.
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