- Hey there, just about to
enjoy a fresh latte here
with its own high-tech viscous,
dissipating protective bubble layer.
You've been alive on
this planet long enough
to know a thing or two
about sloshed beverages.
Sloshed sodas are sticky,
sloshed beers are disgusting,
and sloshed coffee can give you
hellacious third-degree burns.
Sloshing sucks.
It's the enemy of responsible
beverage consumption,
but you have an ally in this
battle and it's called foam.
Yep, I'm talking about that frothy head
on a freshly pulled lager,
as well as the creamy crown
atop a steaming hot vanilla latte.
And if you don't believe me,
then believe the physics behind it.
In a 2015 study published in
the journal Physics of Fluids,
a team of Princeton researchers revealed
how a trusty head of foam
dissipates the energy
of a sloshing liquid through friction
with the sides of the container.
Now while a little pub
and coffee house time
may have inspired this study,
the research itself was
a bit less drinkable.
First, they filled a
narrow glass rectangle
with a solution of water, glycerol,
and Dawn dishwashing detergent.
Then they injected air to fire
up a thick layer of bubbles.
And finally, they jolted and
rocked the glass container
back and forth under the watchful gaze
of a high-speed camera.
They found that a good five layers
of three millimeter diameter
bubbles seemed to be key.
More than that didn't help.
And no amount of bubbles
mattered if the foam
wasn't flush with the
sides of the container.
Scientists call this viscous dissipation,
in which the foam dampens the waves
that are created by motion.
Now before you question the value of latte
and beer foam scientific research,
know that sloshing can prove problematic
any time we transport liquids.
That means carrying a cup
of coffee across the office,
but it also includes transporting
hazardous fuels and chemicals.
So the researchers contend that
potential applications here
reach well beyond the local beer hall.
So will futuristic oil tankers benefit
from a little frothy protection?
Only time will tell.
Hey, in the meantime,
be sure to let me know
what you think about this
study in the comments below.
And hit that subscribe button
so we can keep these videos coming at you.
- Under federal regulation
in the United States,
you can't call something decaffeinated
unless it has less than 2.5%
of the original caffeine.
- And you can't call
me at all unless I have
at least 2.5% caffeine in my bloodstream.
- Previous to the 1600s,
people nipped at alcohol
day and night because it
was much more sanitary
than their local water supplies.
But when the English coffee
house arrived on the scene
in the 1600s, it changed everything.
People woke up.
- Have you ever ordered a
beer, or if you're some kid,
a root beer, and the
bartender held the glass
at a 45 degree angle
when he or she poured it?
That was actually what's
called the perfect pour.
