This Superfluid Is Alive, And It Could Power Machines of the Future


Bacteria are everywhere, and they’re incredibly
versatile. They can get us sick, they’re essential
good guys in our digestive system…and they almost defy the laws of physics to create
a fluid that basically could power a perpetual motion machine?? I didn’t see that coming. Ok, some vocab here. For fluids, friction is expressed as viscosity:
the less friction in a fluid, the lower its viscosity. Superfluids are materials that seem to not
be bound by the power of friction. They have ‘frictionless flow’ and therefore
zero viscosity, which means they aren’t stopped or slowed down by their own internal
motion, and so don’t lose momentum when moving–give it one first push, and then you’re
good. It’ll just keep going. For the most part, this property has only
been observed in liquid helium when it’s at close to absolute zero, and its behavior
is due to some funky quantum stuff. But scientists have now observed this phenomenon
in water. I mean can you imagine what could we do with
water that moves on its own?? Now, I bet you saw this coming–it’s not
just any old water. It’s water filled with E. coli. If that makes you squirm a little, trust me–I
get it. Usually when we hear the name of that bacteria
it’s in the context of a nasty outbreak of a disease we’re hoping not to catch,
but there’s a lot more to this little creature that the bad rap it catches in the press. See, usually when you add little bits of things
to water, pieces of dirt, clumps of sand, other ‘particulate matter’–the motion
of the water slows down. That’s because the surfaces of the particulate
are exerting extra friction on each other and on the water, giving the fluid a higher
viscosity, meaning it takes more energy to keep the whole thing swirling around. You’d think that adding organisms would
do the same, but that’s where you’d be wrong, my friend. Bacteria are full of surprises, and not always
bad ones. If you put E. coli in water, they swim. They all swim in their own directions with
no real organized movement, they don’t usually have their act together. But if there are enough of them, the ripples
caused by each of their little bodies’ movement starts affecting the other bacteria’s directions. Their motion starts to be more collective,
and when around 10-20% of your water is filled with bacteria, they start to form tiny swirling
currents. But at this point their direction and movement
are still pretty random, they don’t radically change the behavior of the water. But then when you add a force–say, you put
some of this bacteria-filled water between two microscope slides–the motion gets organized. The shearing force of the glass slide makes
all the bacteria align their collective movement in a particular direction because they have
these irregularly shaped, oblong bodies. This pushes on the water in a way that makes
that water exhibit superfluid properties. Zero viscosity. Those little guys could just keep rollin’
and rollin’ and no one can stop them! (*mutters to self* ok Maren tone it down,
no one can know you want bacteria to take over the world)
The experts are still a little unclear on the nitty-gritty physics specifics of exactly
how the bacteria’s motion does this. But the effect is real. The recently published experimental data is
supported by previous theoretical work, and has some crazy real-life implications. Because the motion of a superfluid is frictionless
and therefore only needs to be set into motion once, there is a potential for it to be used
as a ‘fuel’. You could set your super-water in motion–which
would take some initial energy investment–and then you watch its motion power a motor or
a turbine…essentially forever. (I say essentially because the solid moving
parts of the motor itself would probably be slowed down by friction, so you’d need to
give it a nudge every now and then.) Plus, when we’re talking about a hypothetical
motor, at this point we’re talking pretty small and not necessarily that fast. Scaling this operation up in any way is going
to require a lot more work. And then there’s the whole problem of the
fact that the bacteria are living organisms, so you have to feed them. You gotta fuel the fuel, so to speak. And they’re kinda picky–you really have
to get their care and feeding right for them to work properly, so that’s an issue that
needs to be reckoned with. There’s lots more work to be done in uncovering
the details of just how this does what it does, but superfluids powered by bacteria
are exciting. And not just for their potential as a ‘fuel’,
but also because their superfluid characteristics could allow them to move into spaces on their
own without having to be forced or injected, meaning they could help do things like clear
up spilled pollutants. But for now, we’re just inching toward that
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dot com. For more on the surprising ways E. coli can
generate energy for humans, check out my other video here on bacteria-powered solar cells,
and make sure you subscribe for all things microbes. Thanks for watching.