[♪ INTRO]
When you think about archeologists,
you might imagine people who spend
years in the dirt, digging around to learn
about old cultures and civilizations.
But while field work is important,
there’s also a lot more going on these days.
In fact, in the last few years, archeologists
have even started borrowing and adapting
methods from other fields to advance their own work.
So today, while you will find some researchers
knee-deep in dust, you’ll find others using techniques
from computer science, meteorology, and even
astronomy to learn about people who used to
walk the Earth.
First, satellites.
These things are often associated with militaries
and tech companies, but recently, they’ve been
used to help archaeologists, too.
Satellites might not spot ancient bones
or pottery, but they can see
a whole region at once.
That lets us find larger patterns and big-picture
details we can’t pick up from the ground.
And by studying areas using different kinds
of light, satellites can also reveal hidden structures.
For example, in 2011, the BBC announced that
researchers studying Egypt had used infrared
satellite images to spot mud walls underneath the sand.
According to those researchers,
the walls absorbed water,
so they looked different in infrared
than the drier sand over them.
Further analysis of these images revealed
that there could be previously unknown
cities down there, too — including thousands
of buried homes and buildings,
and possibly a dozen or so new pyramids.
If they exist, these sites are likely around
three or four thousand years old,
and they could teach us more about how
your average Egyptian lived backed them.
Also: New pyramids!
Outside of Egypt, satellites have also helped us
discover Viking settlements in Canada
and map sites throughout Peru.
They’ve even shown traces left by those
who stole from archaeological sites.
Which is less fun, but is a major problem
in the field and something to keep track of.
Satellites can only do so much, though,
because you don’t always have
a clear view of the ground.
For example, places like Peru, Guatemala,
Belize, and even New England have pretty dense
forests that satellites can’t see through.
They’re also hard for archeologists
to reach in person.
So lately, scientists have started mapping
beneath the canopy with a method used
in everything from meteorology to self-driving cars.
It’s called LiDAR, which is short for
Light Detection and Ranging.
In this method, they fly a plane overhead
and point a laser at the ground.
Then, some of that laser light sneaks
through the leaves and gets reflected
by whatever is down there.
By measuring how long it takes for the
light to return to the plane, scientists can
calculate the distance to the canopy,
the ground, and whatever structures might
be hidden on the forest floor.
That gives them a complete
3-D map of the area.
In the last decade, LiDAR has revealed
ancient Spanish gold mines,
sunken Roman villas, and in 2018, a huge,
densely-populated network of Maya
settlements in Guatemala.
The settlements involve hundreds of
square kilometers of cities, towns, roads —
and over a thousand years ago,
more than ten million people likely lived there!
And we found it all without a single archaeologist
coming face-to-face with a jaguar.
If you think about it, satellites and LiDAR
feel like pretty intuitive technologies
for archeologists to adopt.
But this last method is a lot stranger
because it takes a page out of astronomers’ playbooks.
It involves some of the most powerful things
in the universe: supernovas.
These are huge explosions some stars
undergo at the end of their lives,
and they’re one source of high-energy particles
called cosmic rays.
These rays aren't harmful to us on the ground,
but researchers pay a lot of attention to them
for other reasons: Physicists, for example,
use them to understand the subatomic realm.
But in 2017, cosmic rays revealed something
new in archeology, when physicists used them
to discover a huge new room inside
the Great Pyramid at Giza.
They went inside the pyramid and used detectors
to measure how many cosmic rays
there were in various spots.
Specifically, they were looking for one
type of particle called muons.
The idea was that fewer muons can get through
something dense — like enormous sandstone blocks.
So if they saw an area with more muons
than normal, that would suggest there was
a room somewhere above them.
And that’s what they saw.
They noticed more muons than expected coming
from just above the Grand Gallery —
the largest room in the pyramid.
And after doing some follow-up tests,
they concluded that there was a huge,
completely unexpected room up there.
No one is quite sure why it exists,
but this was still significant, considering
that the Great Pyramid is one of the most
famous archaeological sites in the world.
It was the first new room anyone had
discovered there in more than a century,
and the researchers found it without
breaking any ancient walls.
Scientists are currently on the lookout
for more places to turn their cosmic ray detectors.
But finding a new room inside one of
the Seven Wonders of the World is
impressive enough for now.
And it’s just one more way that archaeology
is changing and embracing new technologies.
Never fear, though:
The field still hasn’t lost its roots.
After all, when something like a satellite
reveals an ancient city, someone still
has to go explore it in person.
Thanks for watching this episode of SciShow,
and thanks to all of our patrons for making it happen!
You help us keep the lights on,
develop sweet graphics, and make sure
our content is accurate.
So we really can’t say thank-you enough.
If you want to learn how to support
free science content on the Internet,
you can head over to patreon.com/scishow.
[♪ OUTRO]