Main content
Course: MIT+K12 > Unit 1
Lesson 2: Earth and spaceThe science of warp drives
Warp drives, negative mass, exotic matter - these all sound like the stuff of science fiction. But MIT explains how our stranger-than-fiction universe could be explained by real science!
Want to join the conversation?
- where are the links? I want to know more.(8 votes)
- This is an interesting idea, but what would happen if multiple warp drives were to be used at the same time?(3 votes)
- Everything would rebound and instead of everything in your destination blasted to oblivion , everything would blated into oblivion?(3 votes)
- Could the matter 'outside' the universe be exotic mater?
Maybe this could be why the universe expands and so fast.(2 votes) - does anyone know if it's possible to warp sound and light(2 votes)
- Definitely. As the video said, enough mass can warp space. If sound and/or light travel through the space being warped, it will be warped with it.(1 vote)
- What about arranging the expansion and contraction so that the dust and radiation picked up on the way is lost in the expanding space behind and not stored around the bubble?(2 votes)
- Although he mentioned Warp Drives, and their capabilities, how exactly would science permit such space bending? Please provide a link if possible(0 votes)
- How exactly is a warp field created?(0 votes)
Video transcript
ISAAC: Suppose you wanted to
take a trip to the North Star, like, actually go there. (I hear it's lovely this
time of the century.) Well, the North Star is 4
million billion miles away, and there's a universal speed
limit-- the speed of light. Now we don't have any ships that
can go even nearly that fast. But even if we did, it
would take over 400 years to get there. But what if instead of
traveling through space, we move space around
us in order to get to our final destination. And what if instead
of taking 400 years, it took more like four months. Now this sounds like
science fiction. But NASA is actually funding
some really, really early research related to the
Alcubierre Warp Drive, which would allow us to appear to be
breaking the universe's speed limit by bending space
itself around us. If you take a slinky and
stretch it out like this, it represents the
space between Earth and the North Star,
quite a ways to travel. But if we can somehow find a way
to expand the space behind us and contract the
space in front of us, then we've made it most of
the way to the North Star without having
moved hardly at all. And that is exactly how the
Alcubierre Warp Drive works. You would contract space
far enough in front of you, and expand space far
enough behind you, leaving you with a stable
bubble to ride in your ship. The space in this bubble
hasn't been warped, so you still experience time
the same way you normally would. That's different from
if your ship itself was traveling close
to the speed of light, where time would
pass more slowly. The idea of space contracting
or expanding sounds weird, but the universe has been
expanding since the Big Bang, and has been doing so faster
than the speed of light. So the universe started
14 billion years ago from a single point
with a Big Bang. If we assume that
it started expanding in every direction at
the speed of light, then today it would be 14
billion light years wide. But astronomers have
calculated that it's actually over three times that size. So this means that it
must be expanding faster than the speed of light. It turns out that the
universe's speed limit only applies to objects
moving through space. Space itself can expand
and contract at any speed whatsoever. So if we can squish and
stretch space really fast, we can make it seem
like we travel faster than the speed of light. So how would we work
space like this? With mass. You may be familiar with
Einstein's famous equation-- energy is equal to mass times
the speed of light, squared. In other words, mass is
just another form of energy. Einstein also noticed that
a lot of energy or mass does something funny to
space-- it contracts it. But in order to get
enough contraction to build a warp
drive, you need a lot of mass, bare minimum,
something as massive as Jupiter. And that's the easy part. The hard part is figuring out
how to expand space behind us. It turns out that you
need negative mass, which is a very weird thing. An apple of negative mass
is lighter than nothing it's repelled by gravity,
and falls away from the Earth instead of towards
Isaac Newton's head. When you push it away, it
accelerates towards you. I mean, warping space is weird
enough, but negative mass? That just crosses a line, right? Turns out that negative mass
is also technically possible. In the field known to physicists
as quantum field theory, and to the rest of the
world as basically magic, you can get negative
mass by holding two conducting metal plates
extremely close to each other in a closed, empty space. In the universe,
virtual particles spontaneously and constantly
appear, bump into each other, and disappear. The total number of particles
appearing and disappearing is the same throughout space. So the overall energy
or mass throughout space is also the same. But if we bring our
plates together, then they act as a filter for
particles of certain energy, so fewer particles can
appear and disappear in the space between them. The overall energy or mass in
the space between our plates is less than that
in normal space. Effectively, it's negative mass. But it's not like a
chunk of negative mass that you could just
throw behind your ship. Plus, the positive mass of the
plates is huge in comparison to the negative mass. So any useful effects would
be totally canceled out. It's possible the chunks
of negative mass do exist, they'd be called exotic matter. But even if exotic
matter is floating around in the universe, it would be
nearly impossible to find, because it's repelled by
gravity and nowhere near us. And there are some
other reasons we're not all hopping on warp drives and
heading off to the North Star right now. Even if you did
manage to collect enough positive and negative
mass to get the warp going, the ship would be basically
unsteerable once you did, because it is impossible
to communicate with the outside of the bubble. And even if you did manage
to make it to the North Star, your warp bubble would pick
up a bunch of dust and light on the way there. And all this space junk would
build up a ton of energy at the edge of the warp bubble. So when you go to return
space to its normal shape in order to land, all that
high energy space stuff would basically blast
every living thing in your destination
into oblivion. So all NASA is
doing now is trying to create teeny, tiny
warp fields in order to see if this sort of
thing is even possible. And if it is, we're still
probably a millennium away from actually using it. If you want to learn
more, you should check out some of the links below. And until then, if you want
to get to the North Star, guess you're better
off just hitchhiking.