Whoa, what’s that?
It looks like a space alien puked.
Can you guess what it is?
That is an odor...
...or at least what an odor looks like.
Odors are normally invisible,
swirling around us.
But I'll tell you the secret
behind why you can see this one.
Hey there! My name is Nsikan Akpan,
and you’ve landed upon the first episode of...
ScienceScope.
Here we’ll put science itself under a microscope,
showing you how amazing discoveries are made
and the people behind them.
First up,
these trippylooking waves!
This smell-scape is brought to you by...
high-powered lasers,
a gigantic tank of water
and this guy!
You can learn more about this problem
from sitting and looking at something like this
than just about anything else.
That’s John Crimaldi,
an engineer and fluid mechanist
at the University of Colorado Boulder.
His lab studies how smells move through space.
Do they drift like clouds?
Curl like smoke?
Or do smells have another shape altogether?
The answers will lay the foundation
for a nationwide project
that is studying how animals and humans
use smells to map their surroundings.
If we have situations where we want to detect
say, a location of a chemical weapon,
or if we want to find hidden contraband,
or if we want to find somebody
that’s trapped under the snow in an avalanche
the tools we use in the 21st century
to do this are animals
Or people.
And that puts both at tremendous risk.
Crimaldi and his colleagues want to outsource this risk
to robots, by teaching them how to smell.
That sounds pretty wild, I know.
But think about it.
We have machines to replace our other senses,
such as cameras with facial recognition
and implants to restore our hearing.
But we don't have similar technology for smell.
Step 1 is learning how air carries odor into our noses.
Air isn’t static, as you might think.
It is turbulent like a river.
One of the ways to think about turbulence is
...it is a collection of rotating pieces of fluid
called eddies.
There are bigger eddies, inside those are smaller eddies,
but the point is that the flow is structured.
It has an element of randomness,
but it has a high degree of structure.
Smells are tiny chemical molecules
that get swept around by turbulent air.
But these odors can also travel underwater
where creatures like fish and hermit crabs
can smell them too.
And it turns out the physics of flows in air...
and flows in water are exactly the same.
So Crimaldi’s team measures these odors underwater.
They start by pumping 5,000 gallons of water
through a 50-foot-long tank.
Next, they spread laser light into a sheet
that slices through the water.
Finally, comes the dye.
We’re using a special dye as a surrogate for the odor.
This dye has exactly the same types of properties
that an odor would have if it were in this flow.
But it has a special property.
If we shine a laser on it, then it fluoresces.
What they find is an odor moves like taffy.
It's constantly being pulled and stretched...
into thin filaments.
If you’ve ever caught a whiff of a bakery
when you walk down the street,
You've picked up a filament.
In some areas, odors get dragged away,
leaving a blank space.
This blank space is called intermittency.
Small disturbances, like a quick sniff,
are the tugs in this smelly tug of war.
Here’s a demonstration built by Crimaldi’s team.
A tube is standing in for an animal’s nostril.
[In Lamaze voice]:
So now, breathe in,
and now exhale. Swoosh!
You create an olfactory cyclone...
that changes the structure of the odor plume.
So whenever you’re in a garden,
and you stop to smell the roses,
just remember that every sniff you make
is changing the aroma for someone else.
Next time, we’ll continue this journey
in the science of smell with Crimaldi’s colleague,
Lucia Jacobs.
She is studying the smell-tracking behavior of rescue dogs,
hermit crabs
and cockroaches.
I’m Nsikan Akpan and this is ScienceScope,
from the PBS NewsHour.