- Hello, and thank you to Wisconsin PBS
for the opportunity to speak today.
My name is Minhal Gardezi, and I'm a graduate student
at the University of Wisconsin-Madison
in the physics department.
I took my first class in physics ten years ago
as a sophomore in high school, and from then on,
I knew I wanted to study it for the rest of my life.
I ended up taking two and a half years of physics classes
in total in high school,
and then went on to major in physics
and computer science in college.
I then did a research fellowship in physics for a year
before beginning my physics PhD here in Madison.
And even though it sounds like I've been
pretty single-mindedly glued to physics for my whole life,
I've actually always been interested in other fields.
Even though I took and enjoyed every STEM class
in my high school,
my favorite classes were actually in the humanities.
And for that reason, I chose to go to a liberal arts college,
where even though I double majored in STEM,
I was also guaranteed the opportunity to study things
like English, poetry, history, religion,
all fields that are typically divorced from STEM.
But I've never really liked that seeming division
in the first place,
this idea that you're either very scientific
and mathematical and robotic
or you're very artistic and dreamy and human.
Surely you're allowed to be both at the same time,
and surely incorporating both into what you do
is beneficial to both realms of study.
Coming into graduate school,
I knew it was going to be the time to hyperfocus
down into physics, but I still wanted to do research
in a way that incorporated all the things I learned
from my non-STEM education,
things like artistic creativity and effective communication
and cultural understanding.
At Madison, I received the opportunity
to do interdisciplinary physics research.
And from a typical physicist perspective,
interdisciplinary usually means crossover
with other STEM fields like chemistry or biology,
material science or engineering.
But the research I've gotten to do is interdisciplinary
in a way I never really encountered before,
as it has crossover with the humanities.
I conduct cultural heritage studies
using X-ray spectroscopy.
Cultural heritage refers to the remnants of humanity
that build up our cultural identity.
It includes tangible things like artifacts and buildings
as well as intangible things like language and folklore,
and even natural things like landscapes or biodiversity.
Cultural heritage studies allow us to understand
how our past led to our present.
It can help us connect to our roots and even reveal roots
that we didn't know existed,
as well as ties between different cultures
and centers of knowledge.
Cultural heritage studies are typically conducted
by historians and anthropologists, and in general,
people who are scholarly experts in specific cultural histories.
Cultural heritage artifacts are of particular interest.
These are things like artwork or documents or fossils,
things that you might typically find in a museum.
These artifacts tend to be highly protected,
as they're often the only tangible connection
we have to our past.
However, while historical and cultural studies
are hugely important
to understanding these objects and understanding our past,
there's only so much of that type of information available.
Eventually, scholars will hit a block
where there is no longer any additional hard information
to be extracted by human means alone.
And that is where physics comes in.
Spectroscopy is a study of how light interacts with matter.
And when light is in the form of X-rays,
we refer to it as X-ray spectroscopy.
In my research,
I take those cultural heritage artifacts and I study them
using X-ray spectroscopy.
We can think of these artifacts as chemical time capsules
that can be opened up using X-rays.
X-rays allow us to see beyond the limits of our eyes,
and they generate hard scientific data
that can help aid cultural studies
to uncover new information about our past.
Simply put, I blast artifacts with X-rays
and learn new things about the old things.
And today, I'd like to walk you through what it is
I actually study, and in doing so,
illustrate just how meaningful this type
of interdisciplinary work can be.
Beginning on the cultural heritage side of things,
my research aims to uncover more information on early print.
And here, print specifically referring to the process
of creating documents through mechanical means.
And when I say early print,
I'm referring to the first instances
of these printing machines, which were printing presses.
These presses used what is called movable type
to mass-produce documents.
And the way they work is you cast individual letters
or entire words in metal,
and then you arrange them to form a page.
And then you ink that page and press a paper down onto it,
effectively printing a single document.
And you can print that document over and over and over again
to produce multiple copies,
and then rearrange all of your types
to produce another page
until you've effectively mass-produced an entire book.
Now, when I was told I would be studying early print,
this was about the extent of my knowledge.
I knew how the printing presses worked,
but I didn't know much in the way of cultural heritage.
So to broaden my knowledge, I turned to the place
where all great research endeavors begin,
which is, of course, Wikipedia. [audience chuckling]
On the page for printing press,
one thing immediately jumped out:
the name Johannes Gutenberg.
It's a name familiar to me, and maybe you recognize it too.
I remember learning it in school
that Gutenberg was the father of the printing press
or the inventor of the printing press,
and he printed these famous Gutenberg Bibles.
But once I actually started reading the page,
something else jumped out at me:
this sentence right here at the end of the first paragraph,
which reads, "Typically used for text,
"the invention and global spread of the printing press
"was one of the most influential events
in the second millennium."
That's a pretty bold statement to make, and it surprised me.
Not because I didn't think it was true,
but because I'd never really considered just how important
the printing press was.
In fact, if you google "most important inventions,"
you'll find the printing press always makes the list.
And again, there is no mention of the printing press
without Gutenberg's name attached to it.
At this point in my research, I had two main questions.
Why was the printing press so important,
and what exactly was Gutenberg's role?
To answer those questions,
I had to dive deep into the history of print.
And I'll lay out what I learned here.
So here's a basic timeline, and for reference,
here are the centuries
encompassing the European Renaissance.
Johannes Gutenberg created his famous press
near the beginning of the Renaissance.
He printed his first 42-line Gutenberg Bible
right around 1450 in Mainz, Germany.
As soon as those Bibles entered Europe,
use of the printing press spread like wildfire.
Craftsmen around Europe recreated
and modified Gutenberg's press,
developing their own printing centers.
And in just 50 years,
an estimated 20 million volumes were printed.
By the end of the Renaissance, it had increased to 200 million.
The press outproduced hand-copying by so much,
it wasn't even a contest.
And this led to mass communication, and as a result,
a boom in literacy.
So it's not just that Gutenberg invented his press
near the beginning of the Renaissance;
rather, it's more like Gutenberg's press
is one of the causes of the Renaissance.
Mass-produced print made education more accessible
to lower class communities.
It allowed for the spread of news,
leading to social organization and even revolution.
The average person now had more knowledge
and therefore more power.
The printing press revolutionized the dissemination
of information, and in that way, it's very comparable
to the modern invention of the internet
in terms of its impact,
especially in how immediate and widespread that impact was.
Following the Renaissance,
the press made its way to colonial America,
and then together, the Western powers entered
what is known as the Industrial Revolution.
During this time, there was a huge transition
away from hand-powered printing presses
towards steam-powered rotary presses,
which were much more powerful.
But even though the presses were evolving a lot,
they still employed Gutenberg's fundamental printing principles.
Gutenberg's direct influence remained all the way up
until the late '80s, when we saw a transition
towards digital print, which is what we use today.
And the field of print continues to advance
every single day, even into the third dimension
with 3D printing.
But even though the nature of printing is evolving
far beyond Gutenberg's press,
he was emblematic of the spirit of human ingenuity
and the development of new technology
for greater accessibility of knowledge.
All together, Gutenberg's impact was profound,
and there is no question
that his press completely changed the world.
However, Gutenberg's printing press is only a piece
in the larger history of print.
He was a key figure, no question,
but to call him the inventor of print
is a little misleading.
The first books he printed were the Gutenberg Bibles.
And although many of them remain preserved to this day,
the oldest extant document
printed on a movable metal type press that we have preserved
is not one of those Bibles.
It was not printed on a Gutenberg press
and it wasn't even printed in Europe.
It was printed on the other side of the world.
It is a Buddhist text called Jikji
printed in Cheongju, Korea in 1377,
nearly 80 years prior to Gutenberg's Bibles.
And in fact,
that 80-year gap is just the tip of the iceberg.
There is a rich history of East Asian printing
that stretched hundreds of years before even the timeline
shown on the screen.
And it should be noted that
while this pre-Gutenberg printing
existed throughout East Asia, and particularly in China,
I'm gonna focus specifically on Korean printing,
like the printing of the Jikji.
Before the advent of the metal type presses
that printed the Jikji,
much of the early East Asian printing utilized woodblocks.
There were these big slabs of wood into which entire pages
were carved at once.
And sets of these woodblocks have been very well-preserved
to this day.
Like the Jikji,
many woodblock printed documents were Buddhist texts,
but there were also woodblocks
used for the daily history keeping
and record of everyday life.
And it's in one of those preserved woodblocks
that we actually see the first mention
of movable metal type presses
being used in Korea back in 1234.
So that is nearly 200 years
before Gutenberg's press was made.
Any documents potentially printed in Korea
between 1234 and 1377 have not yet been discovered,
if they exist.
And the Jikji remains the oldest extant document
printed on a metal movable type press.
But it wasn't until the end of the 19th century
when a French diplomat acquired Jikji
and brought it to Paris
that the Western world at large was even made aware
of East Asian printing.
It was donated to the
Bibliotheque nationale de France,
and finally in 2001, it was declared
a UNESCO Memory of the World.
Jikji has remained in the BNF to this day.
It's actually sitting there right at this moment.
And in fact, just two weeks ago,
the Jikji was brought out for display
for the first time in 50 years.
It's a very highly protected document.
Just looking at the red and blue here,
we can summarize the history of print with two big facts.
One, the Gutenberg press had a much larger impact
on the world than the Korean press.
But two, the Korean press undeniably came first.
Now, if you didn't know about this Korean printing history,
you're not alone.
Not many people outside of East Asia have any knowledge
that printing presses existed before Gutenberg,
much less that there is such a rich printing tradition
throughout East Asia.
This trend of knowledge indicates
that the Gutenberg press had almost a global impact,
whereas the Korean press had much more of a local impact.
There are several reasons why this could be.
The first is the context of the invention.
Before Gutenberg,
Europeans predominantly relied on handwriting
to create documents.
The invention of movable type print
specifically for producing documents was revolutionary.
But in Korea, investigations into different means of printing
and even papermaking and inkmaking
had been done extensively for centuries.
Movable metal type was an invention
that pushed the boundaries, creating a new frontier
in a field that was already extensively explored
and adopted in everyday life.
In Europe, there was almost an immediate widespread adoption
of movable metal type printing, while in Korea, both metal type
and the preexisting woodblock method were used.
Another major factor is the difference in language.
Gutenberg was using the 26-letter Roman alphabet,
and the cost and labor of casting hundreds of copies
of each character was well worth the benefit
of the mass production of print.
But early Koreans, on the other hand,
were using a Chinese-based script,
which contains tens of thousands of characters.
It required significantly more metal to make a full typeface
and it may not have been so justifiable
to divert so much metal to the cause at the time,
especially considering the need for metal weapons
during the wars of the Goryeo dynasty.
The much simplified 24-character Hangul alphabet,
which is used today, was developed back in 1443
in an effort to increase literacy.
However, it would not be widely adopted
for another 500 years.
And for this reason, although metal movable type
was an ingenious invention in Korea,
there was no direct urgency behind a widespread transition
to that movable type as there was in Europe.
Overall, each printing press was developed
under completely different conditions
and went on to have completely different impacts.
Nonetheless, each one is an example of human ingenuity,
and it's really something to marvel at,
that two completely different peoples
on completely different sides of the world
arrived at the same type of technology.
However exciting these inventions may be,
much remains unknown about them.
In terms of overall knowledge,
very little is actually known about the Gutenberg press.
There's no official documentation
of Gutenberg's design process,
no record of his notes, and no record of even what
the press itself looked like.
There are some artistic depictions that were made
many, many, many years later,
but no original hard documentation of his work.
On the other hand, there is extensive documentation
on the Korean printing tradition,
dating back hundreds of years
before even the life of Gutenberg.
This is documentation on how these presses were set up,
how the pages were made,
how the paper was made, how the ink was made.
There's a lot of knowledge.
When it comes to preserved artifacts,
there are no remaining original presses
from either printing center.
There are also no preserved types from the Gutenberg press,
meaning we actually have no idea what metals Gutenberg used
to cast those types, or how he arrived at their production.
There are, however, many early Korean types preserved today,
although it is unclear if the earliest ones,
like the ones used to print the Jikji, have been discovered.
These early types are understandably very important
and protected objects, and are therefore difficult for us
to gain access to, at least at this stage in our research.
Many of these types are preserved in Korea,
particularly in Cheongju at the Cheongju Printing Museum.
But there are some that exist in other parts of the world.
And for example, the Library of Congress
actually has a pretty substantial collection
of these early Korean types.
When it comes to prints though, those are much more abundant.
Many of the original Gutenberg Bibles
are printed to this day, and are sort of scattered
all over the world in different libraries.
And similarly,
many early Korean prints of all kinds have been preserved,
including the famous Jikji, which is in the BNF.
It is through studying these prints using X-ray spectroscopy
that we hope to uncover more information on early print
and potentially fill in some of those other gaps
in our knowledge.
If it is possible to learn about the presses themselves
from these prints, we can gain a lot more insight
into the inventive pathways going on back then.
And it may be even possible to tackle even bigger unknowns,
particularly in the question of connection.
Was there any type of knowledge transfer between East Asia
and Europe that led to Gutenberg's invention,
or were the two inventions truly independent?
This is all...
These are all questions that my research seeks to answer,
contained in the main question,
can X-rays trace the origins of printing?
To answer this question,
my PI and I are part of a larger UNESCO-funded collaboration
called "From Jikji to Gutenberg."
It brings together print scholars
from across Europe, Korea, and America.
On the team are paper experts, ink experts, type experts,
conservationists, librarians, private collectors,
over 50 people, including two physicists, my PI and myself.
Through the collaboration,
we have gained access to a wealth of historical documents,
namely individual Western and Korean leaves,
and most notably, leaves of an original Gutenberg Bible
printed in the 1450s,
and an entire bound Confucius text printed in Korea
about a decade earlier.
It should be noted that despite the collaboration's name,
"From Jikji to Gutenberg,"
we don't actually have access to the Jikji itself,
as it is a hugely important artifact
held under lock and key.
Nonetheless, these documents that we did scan
are priceless cultural heritage artifacts
well worth examining for the advancement
of our overall cultural heritage understanding
of early print.
So, and with that, we should be caught up
on the cultural heritage side of my research,
which means we can move into the science part.
As I mentioned before,
I use a technique called X-ray spectroscopy.
And I would like to introduce you all to X-rays
and the specific technique of X-ray fluorescence.
X-rays are one of many types of electromagnetic waves
included on the electromagnetic spectrum.
Electromagnetic wave is just a fancy way of saying light.
And it comes in many different forms,
depending on its energy and wavelength.
Wavelength is a measure of the physical distance
between the peaks of a wave.
The shorter wavelength electromagnetic waves
have higher energy, and the longer ones have lower energy.
Each type of wave carries a certain type of information
and can be picked up using a certain type of detector.
For example, starting on the left here
at the longest wavelength and lowest energy,
we have radio waves.
These waves carry sound information and are detected
by things like radios and televisions.
They have wavelengths on the order of miles,
and have such low energy
that they don't really affect any organic life
they may come into contact with.
Beyond that are microwaves,
which can carry signals detected by telephones,
but are most commonly used in microwave ovens.
These waves have just enough energy to jostle the electrons
in your food so that it heats up.
The energy is still relatively low though,
which is why it's recommended to use a rotating plate
and to mix your food in between microwaving
so the waves can thoroughly reach all parts of your food
and heat it up.
In the center of the spectrum here, we have visible light.
As the name implies,
these are light waves that humans can see.
The waves carry information on the color
and appearance of matter in the world around us,
and our eyes serve as the detectors.
The lowest energy visible light is red,
and just below that is infrared light.
Infrared waves are emitted by sources of heat
like the Sun or fires, and they carry information
about how hot that heat source is.
Some animals actually have eyes that can detect infrared light.
That is, they can see heat with their eyes.
But humans cannot do that.
But there are ways to shift up that infrared light
into the visible spectrum,
allowing us to see heat signatures.
The highest energy visible light is violet,
and just beyond violet is ultraviolet.
Ultraviolet or UV light is emitted
by high-energy sources like stars.
And although we can't see it with our eyes,
we are exposed to UV light every day from the Sun.
UV light is the beginning of the relatively high energy side
of the electromagnetic spectrum.
And while a single UV wave does not have enough energy
to do that much impact on organic matter,
prolonged exposure to UV light can do damage,
which is why it's very important to wear sunscreen
and sunglasses, both of which protect from UV exposure.
At the far end of the spectrum are gamma rays,
which are incredibly dangerous and are only used
in extreme circumstances,
as they can be highly damaging to organic matter.
But in the sweet spot between UV and gamma rays are X-rays.
X-rays are high enough energy to penetrate matter.
For example, X-rays are commonly used by doctors
to see inside you.
They have enough energy to penetrate
through the squishy things
like your organs and your blood vessels,
but are not energetic enough to penetrate
through dense things like bone or metal.
Doctors will expose you to controlled, low energy X-rays
very briefly to generate images of your skeleton
and also any metal that might be in your body.
Areas of the body not meant to be scanned
are usually covered in lead-lined vests.
Like when you go to the dentist,
they put a big vest on your chest because that lead vest
will block any potential stray X-rays.
And a similar and more rudimentary setup
is used at airport security checkpoints
to search for any metal in your clothes or belongings.
However, X-rays that are used on humans
are what we call soft,
as they use the lowest possible energy to get the job done
while minimizing any risk to a person.
X-rays in general can have much higher energies,
high enough that they can interact
with the subatomic particles that make up matter.
These high energy X-rays, called hard X-rays,
have accordingly shorter wavelengths,
actually down to the scale of individual atoms.
This means that because of their...
Sorry.
Together, this means that X-rays, when shown on matter,
can reveal very high-resolution information
on the atomic scale.
And it is those hard, high energy X-rays
that I work with as an X-ray spectroscopist.
To generate those high-quality hard X-rays
for use in experimental setup,
we have to go to a facility called a synchrotron.
And here's a schematic of a typical synchrotron facility.
A synchrotron is a system of circular particle accelerators
that form a radiation light source.
And this image here is actually the logo
for a synchrotron called SSRL,
or Stanford Synchrotron Radiation Light Source.
Now, those are all some pretty cool-sounding words
I just said, but in English,
a synchrotron generates very high energy light like X-rays
that can be used in a controlled matter for experiments.
The way it works is first, there's a smaller booster ring
that takes electrons from some material
and accelerates them around in a circle.
Using electric and magnetic fields
that are timed precisely,
the electrons are brought up to a fraction
of the speed of light, which is very, very fast.
Those sped-up electrons are then fed
into the much larger storage ring.
Again, electric and magnetic fields are applied,
but this time, they're synced up to the electrons in a way
that keep them moving at the same speed,
this very, very high speed.
When very low mass charged particles
are moving very fast, like these electrons,
they must send off energy in order to change direction.
You can think of this as kind of
a conservation of energy, momentum situation.
In order to turn one way,
the electrons need to push the other way,
and their push is in the form of released light,
specifically X-rays that are released radially outward.
These radially projected X-rays are caught at several points
along the ring and funneled into separate,
high-quality X-ray beams,
which are here represented by all those arrows.
Scientific workstations called beam lines are constructed
all around the storage ring to utilize those X-ray beams
for experiments.
At a typical synchrotron,
each beam line is optimized for a different type
of spectroscopic phenomenon.
When it comes to X-rays hitting matter,
several different physical phenomena occur.
But my research involves a particular one
called X-ray fluorescence or XRF.
To explain XRF,
I'm going to use this rudimentary model of an atom
where the nucleus of the atom is shown in red
and the electrons orbit around it in shells.
Now in reality,
electron behavior is a little more complicated
and abstract than this,
but I'm going to use this very simple model to explain.
The closer an electron is to the nucleus,
the more energy it takes to pull that electron away.
And that energy is actually on the same scale
as X-ray energies.
In X-ray fluorescence spectroscopy,
first you expose an X-ray to the sample.
It hits that atom
and it transfers its energy to the atom.
And the X-ray's energy is powerful enough
to actually eject a core electron from that atom.
It knocks it out, leaving behind a hole in that inner shell.
By the rules of electron arrangement,
that hole must be filled,
so a nearby electron drops down from its shell
to take the ejected electron's place and fill that hole.
This backfilling electron is moving
from a higher energy state to a lower energy state.
So in order to make that backfilling action,
it must get rid of some energy.
It does this by releasing an energy packet called a photon.
A photon is the particle version of light.
And the release of photons is called fluorescence.
In this case, the photon will be high enough energy
that it is also an X-ray,
hence the name X-ray fluorescence.
All together, we shine X-rays on atoms,
which causes them to fluoresce X-ray photons back out.
But why is that useful?
Well, if you actually look at the photon,
it's not just that it was released
because the backfilling electron
had to get rid of some energy to drop down.
That photon is in fact actually the exact energy difference
between the original shell of the electron
and the backfilling shell, the shell that it moved to.
So if we measure the energy of that photon,
we are going to actually measure the exact energy difference
between those two shells.
And that is significant
because if we look at the periodic table,
the factor that distinguishes an atom
of one element from another is its atomic number,
which is the number in the top left.
And that is actually the number of protons
that are in the nucleus.
So the more protons that are in a nucleus,
the more positive that nucleus is
and the larger that nucleus is,
meaning the more pull it will have on those electrons.
And from element to element, that nucleus will grow larger
as we move down the periodic table,
but the electrons stay the same.
What this means is that the difference in energy
of those first two shells of an atom
is going to be different
depending on the element we're looking at.
It's going to be a unique value for every element.
In other words,
that photon is going to have an element-specific energy.
So if we measure the photon that is released
after exposing an atom to X-rays,
the photon can actually tell us
exactly what type of element that atom belonged to.
The entire XRF pathway allows us to determine
the elemental makeup of a sample.
We hit it with X-rays, measure the fluorescence,
and determine exactly which elements
were in the spot that we just hit.
Once we've collected the fluorescence,
we create what is called an XRF spectrum.
On the x-axis is the fluorescence energy,
and on the y-axis is the intensity,
which is a measure of the number of photons
that we recorded.
A peak on the energy axis indicates the presence
of a specific element that are labeled above those peaks,
whereas the height of the peak on the intensity axis
tells us relatively how much of that element
was present in the sample where we hit it with an X-ray.
In the sample that created this spectrum, for example,
there was a pretty large amount of calcium, iron, and copper,
but lower amounts of other elements like manganese.
These spectra are the type of data
that I most commonly work with.
And while these spectra hold very valuable information,
it can take some time to develop the intuition
to interpret these peaks.
So if this image is a little confusing to you at this point,
don't worry; it's understandable.
However, there is another exciting application
of this spectroscopy method
that can yield much more intuitive and beautiful data,
and that is elemental mapping.
To illustrate elemental mapping,
let's use this example of a piece of parchment.
This is the sample that we're gonna be studying with X-rays.
And that image there is a camera image.
It's what you actually can see
if you were holding this parchment in your hand.
We want to determine which elements are in the parchment
and if there's any significance to those elements.
So we will use XRF spectroscopy.
We aim an X-ray beam at a point on the paper
and measure the fluorescence that comes off,
and produce an XRF spectrum that tells us
exactly which elements are sitting at that point.
However, this single spectrum does not encompass the data
for the entire sample,
nor does it give us any sense of the spatial distribution
of these elements.
Instead of taking a single point of XRF data,
we can instead raster scan the sample behind the X-ray beam,
like this animation shown here.
Here the yellow beam is the X-ray beam,
which hits the sample and produces the fluorescence
shown in red and green.
And the detector on the left continuously collects
that fluorescence signal.
A computer program then connects the collected signal
to the location at which
the scanning beam produced that signal.
It allows us to effectively take an X-ray image
of the sample.
For each pixel on the sample,
there's an entire XRF spectrum like the one showed here.
We can then take the grid of pixels and filter each pixel
to only display the relative amount of one element,
generating an elemental map.
In other words, a spectrum shows the relative amount
of all the elements at a single pixel,
but a map shows the relative amounts
of a single element at all pixels.
Here, for example, is an iron map for the parchment,
where higher signals of iron are shown in white
and lower signals are darker.
Now, this map may look like a picture,
but it is formed from pure X-ray data.
And it represents something
far beyond the capabilities of a camera.
In fact, if you look closely here at the top of the map,
you can actually see that it reveals some text
going along and across the page.
This parchment is actually a piece of a larger text
called the Archimedes Palimpsest.
A palimpsest is something that once contained
writing or artwork, but was later effaced or covered up
to display something new.
Here, the parchment was effaced
to display religious texts and images,
which is what we see on the left there
and what we see if we were
to look at the document with our eyes.
But a few hundred years before that was done,
the parchment actually contained a copy
of Archimedes' original notes.
Using XRF elemental mapping, those notes were uncovered,
restoring several of Archimedes' works thought to be lost.
This research was actually conducted almost 20 years ago
by my PI, and it was very influential
in cementing XRF as a valuable cultural heritage tool.
XRF spectroscopy and elemental mapping have similarly
been used for many different cultural heritage studies.
For example, my PI also studied the Galen palimpsest
in the middle here.
Galen was a 2nd-century Greek physician
whose work hugely influenced Western medicinal practices
for many centuries.
This is a palimpsested copy of his notes written in Syriac,
once again revealed using X-rays.
My PI also studied an intact skeleton of an archaeopteryx,
which is the dinosaur predecessor of all birds.
He used X-rays to learn more
about what this animal looked like when it was alive,
including the color pattern on its feathers.
There are countless other examples
of cultural heritage studies done using X-ray spectroscopy.
It is clearly an effective method to access information
inaccessible through other means.
What's extremely important to note, however,
is that this research isn't conducted by physicists alone.
Experimental decisions and data analysis are all informed
by the knowledge of scholars who are experts
in the preexisting cultural heritage of these objects.
This collaboration is essential to generating new knowledge.
And with that, we are all set on the cultural heritage
and the physics side of my research,
and we are ready to discuss the actual experiment
conducted on early print.
So as an overview,
kind of taking everything I had just discussed
and putting it all together for my experiment,
we begin by acquiring several early print artifacts.
Then we bring them to a synchrotron, specifically
the Stanford Synchrotron Radiation Light Source
I mentioned earlier, which is in Menlo Park, California.
Then we conduct XRF spectroscopy
and elemental mapping on the prints.
Then we work with scholars through our collaboration
to interpret that data
and hopefully generate new knowledge.
We began our experiment last July, in July of 2022,
with a week-long experiment at SSRL,
studying several of these documents.
We have since had a second experiment in December of 2022,
and have had several meetings with our collaborators
to discuss our results.
Here's what SSRL looks like from above.
It's actually pretty spot-on to that logo.
And our work was done in beamline 7-2,
which is actually right here in that little circle.
Here's an image inside the beamline.
This giant blue door is the gateway into the hutch
where the X-ray beam and experimental setup are.
The door and the glass window pane on the door
are all lead-lined to prevent any stray X-rays
from passing through.
But in general,
there are a lot of safety protocols going on here
and the entire setup is overall very safe.
Inside the hutch is our XRF scanning setup.
In this image,
there's a document mounted in that metal plate back there.
All of our samples were actually specially mounted
to fit that metal plate by Stanford Library conservators.
The mounting process was an aspect of this research
I didn't even think about going into it,
and I'm very grateful to the librarians
who did all the heavy lifting for us.
But when it came to the actual bound texts
like the Gutenberg leaves and the Confucius texts,
we had to get a little more creative
in the mounting process.
Here, my PI and I are testing out ways
to safely mount the Gutenberg Bible leaves.
And we then checked our method
with one of the conservators in the beamline hutch.
These documents that we were working with
are over 600 years old,
so the careful handling of those documents was definitely
a priority when conducting these experiments.
Here's a closeup on the sample mount in the hutch,
and that's actually the Confucius text
I mentioned earlier mounted in there very carefully.
Coming in from the right is the X-ray beam,
coming out from the wall from the synchrotron
and funneling through that sort of pie-shaped appendage.
It hits the sample,
the sample fluoresces, and the detector on the left
measures the fluorescence.
Neither the beam nor the detector move
during an experiment.
They stay fixed in place
and the sample on its mount moves behind them.
Here is an example of one of the elemental maps
for this scanned document.
Here, red indicates a high signal of the element
while blue is low,
the meaning that this particular element
is very strongly present
in the printed regions of this document.
Now, you may look at this image and think,
"Wow, that's a really pretty picture."
And that's certainly what I was thinking last July
back at the beamline
when we were scanning for the first time
and this image slowly appeared on our computer screen.
It wasn't until I turned around and saw
all of the beamline scientists standing there
with their jaws on the floor
that I actually really understood
the importance of this image.
Think back to the Archimedes palimpsest.
In this instance,
the goal here was to determine if there was underlying text
beneath this top image and if X-rays could reveal that text.
The underlying text was believed to be written
in iron gall ink, so when they flipped to the iron channel,
the text appeared.
But in our experiment,
we were not certain X-rays could pick up any trace
of the materials used to make the document at all.
This is because we've been informed by our Korean scholars
in particular that the inks were largely carbon-based
and presumably only contained elements
that were lighter than phosphorus.
This is important because our specific beamline setup
is only suited to detect elements
heavier than phosphorus.
So if there are elements lighter than phosphorus,
we won't really see a clear signal for them.
What's more, we were not examining
something like a palimpsest, looking for underlying texts.
We instead wanted to gain as much information
as possible on the prints' chemical makeup
in order to determine if there was anything hidden
in that data that could give us a clue
about the presses themselves.
In essence, we weren't really sure what we would find,
but there was always a possibility
that it would be very little.
Instead, we saw beautiful, clear images like this one,
showing a strong spatial correlation of elements
to specific regions of the document,
like in the printed ink versus the paper.
You can even see a little smudge on this map
in the bottom left corner corresponding to the spot
where people pick up and turn the pages of the book.
So hundreds of years of page turning left a trace
that our X-ray could pick up.
To illustrate the sensitivity of our instrument,
I wanna show a couple different maps.
And these are of a Korean document printed much later
in the 18th century.
This right here is the camera image.
Again, what you would see with your eyes.
There is writing printed in black
and then red emphasis circles painted on in red ink.
Here is a map of an element that seems to have been present
in both inks used.
And as a reminder,
this is pure X-ray data, showing that for this element,
it really showed up in these printed regions.
And conversely, here's a map of an element
that was only used in the red ink,
and there's very little signal of it
anywhere else on the page.
If we only ever saw this map
and not the actual document itself,
we would have no way of knowing if any text
was actually printed or what was really going on on this
because no data showed up for it in the elemental channel.
So I really just wanna highlight that
all these images are constructed from pure X-ray data.
It's completely different from something like Photoshop.
And finally, this is kind of a fun one.
This is a calcium map.
Calcium is present throughout the paper
in that green signal, which is to be expected,
as usually there's a lot of calcium
in things that have come into contact with water.
But interestingly,
this map also reveals these little blemishes on the page.
And you can actually see that top blemish
in the visible image if you look back.
I didn't notice that with my eyes
until I saw the X-ray image.
So it's very interesting that our data can pull out
all sorts of random details like that.
We even sometimes see fingerprints
in the chlorine channel
from the sweaty hands of readers 600 years ago.
All of this, again, pure, hard X-ray data.
The difficulty comes
in interpreting why the elements we see
are there in the first place.
For example, those red circles actually come from mercury.
That is a mercury map.
And consulting with scholars, that makes sense,
as mercury was a known ingredient to turn inks red.
But if we hop back to the map I showed earlier
of that Confucius text, as I mentioned,
it's a pretty big deal
that we saw such a beautiful, clean image for an element,
but it's actually much more of a big deal
than we could have imagined
because this is in fact a map for copper.
The reason this is so surprising
is because our Korean scholars informed us
that they didn't really believe copper
would be a direct ingredient of the ink used
to print this document.
Sometimes in some of the Western prints,
there are metal ingredients that are used to act
as a drying agent in the ink or a binding agent.
But based on the way that the East Asian inks were made,
that was often not the case.
Which begs the question, where did this copper come from?
And in fact, in all of the other maps
for our Korean-printed documents
and most of the Western-printed documents,
we continued to see this very strong metal signal,
very often in copper for the Korean prints
and lead for the European prints.
There is a possibility that the metal could be coming
from the ink as it is some type of ingredient in the ink,
whether added intentionally or not.
It could be something that is bound to the ink,
organic ingredients in the ink.
Or it maybe could have come from the tools that were used
to make the ink.
If the ink was, for example,
boiled in a copper vessel or some sort of copper tool
was used to spread the ink,
perhaps that transferred the copper.
But the most exciting possibility
for where this ink could have come from
is from metal used in the types.
Now, if we could prove that the metal in these documents
is from the types, that is a huge discovery.
It means that our question of,
"Can X-rays trace the origin of printing?"
The answer to that question is yes.
And that by looking at these documents
and looking at these strong metal signals in the documents,
we can kind of fingerprint the types used to print them.
This would also allow us to try to reconstruct
the specific metal alloys
that were used to cast these types.
We can learn a lot about the resources the early printers
had access to and potentially what informed their decisions
in making these different types.
These are very specific alloys that would have to be used
to make these prints, as if your alloy is too hard,
you could pierce through the paper, but if it's too soft,
it could become degraded with very few prints.
The reason that determining the alloy is so important,
not only can we fill in the gaps
in our knowledge of printing presses,
particularly when it comes to the Gutenberg press,
where we know nothing about the alloys used to print it.
But fingerprinting these metal alloys
used to print these documents could also
give us a basis for comparison
between the two printing domains.
If the types are very similar, for example,
it could help back some theories that suggest
that there was a crossover.
But if the types are very different,
it would back the theory
that these two inventions were created
completely independent from each other.
But in order to jump to any conclusion like that,
we need to do heavy analysis
of all of the data that we have collected.
And particularly, we need to come up with a way to eliminate
potential sources of this metal that are not from the types.
In order to do that,
we have set up hand-printing experiments.
Now, these are a collaboration
with several of the other people on our team
that are experts in things like casting types
and making paper and printing ink.
And actually, through these scholars,
we were able to hand-cast the types shown here on the left,
which are very specific and controlled metal alloys,
in this case of tin, antimony, and lead.
And then another scholar handmade the paper
according to European papermaking processes.
And a third scholar handmade the ink.
And he was very careful not to introduce
any direct metal content into that ink.
And the same was done for the paper;
no direct metal ingredients in the paper.
So all together,
we generated these pressed documents' printing
using these types and these ink.
And by analyzing this data,
we hoped to determine if the metal signal we see changes.
Or first of all, if the metal signal is present at all,
because that would indicate really there's only one source
it could have come from.
But also if the metal signal changes
depending on if the ink is exposed to the types or not.
That is, we can actually learn
if metal is coming from the types,
if it is just being brushed off,
or if it's actually being leached out from the ink.
All of these sort of experimental questions
will help us determine whether or not it's possible
to fingerprint these types.
And sort of in conclusion,
determine the answer to this question of,
"Can X-rays trace the origins of printing?"
Now, in terms of the data analysis so far,
that is ongoing, and it involves a lot of crossover
with the other scholars on our team.
We are sort of checking all of our boxes and making sure
the data that we see and the conclusions that we're drawing
are true before revealing the information.
Although I can show you some other maps to kind of give you
an idea of what these documents are looking like.
For example, here is a 15th-century Korean document.
And in one channel,
we see the clear copper signal, and then the other,
this is a manganese channel, in which we don't see anything.
And I put this print up to display kind of
what the document looks like when we don't see a signal.
Here's an interesting one.
This is actually a printing of The Canterbury Tales,
specifically "The Knight's Tale," done in 1476 in Europe.
On the left here is a map of zinc,
whereas on the right is a map of copper,
indicating too potentially some different type
of metal alloy, if the metal is coming from the type.
Once again, here's a 15th-century Korean document.
And what's interesting about this is there's actually
significant water damage done to the document.
And that's interesting because we can actually see
how the metal interacts with water, how it spreads
through the paper, and get a different chemical sense
of the type of metal that's in there.
And finally, this is an interesting one,
Speculum historiale printed in 1474.
This is a document, like many of the documents,
which contains what we call rubricking,
or sort of hand embellishments done after printing.
So the signals that are appearing in red
are actually done with red ink,
embellished on the printed paper afterwards.
And we can see how the ink composition
in the printed ink versus the embellished ink
differs between the documents.
But overall, I would really like to emphasize
that the work done in this project could not be done
without all of our collaborators coming together.
And in fact,
even though we as physicists were handed these
historical documents and we were able to scan them,
we could not interpret the meaning behind anything we saw
without consulting the scholars.
And it's actually consultation from the scholars
that allows us to inform our next steps.
The only reason we decided
to try to make our own hand printing
is because we worked together with scholars
to determine that is probably the best next step.
And similarly, moving forward as we analyze the data,
we will develop more and more new experiments
to try to test new hypotheses.
And it's this interplay between the science side of things
and the cultural historical humanities side of things
that allows us to conduct this research.
I hope that overall,
our project will really illuminate the importance
of doing this type of interdisciplinary work
and encourage other physicists and hard scientists
to consider applying their very heavily, sorry,
consider other physicists and other hard scientists
to consider applying their techniques to fields
that you wouldn't typically associate with those sciences.
It is also my hope that our research here
will shed more light and, I guess, awareness
on the history of Korean print.
Printing overall was a hugely influential invention.
And both printing centers in Europe and in East Asia
developed and arrived at this hugely important invention.
In 2027, we hope to produce scientific results
that will give us some information
that we didn't know before about these presses.
And working together with all of the scholars
on this collaboration, we'll be holding several exhibitions
around the world, hopefully, but mainly in Cheongju, Korea
that put on display these documents
and reveal to the public what we have learned.
That year, 2027, will actually be the 600th anniversary
of the discovery of the Jikji.
So it's all a very big, full-circle moment
in the world of printing.
Our research is ongoing,
but you can track the progress of it on this link here
to the " Jikji to Gutenberg" collaboration.
Thank you so much for your time,
and I hope you learned a lot about printing today.
[audience applauding]