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 future.
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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.