- Why is an X-ray called an X-ray?
Well, the short answer is
when Wilhelm Roentgen discovered X-rays in 1895,
he called them X-rays outright
because X stood for unknown,
and he knew he had found a new, previously unknown ray.
Okay, bye!
Oh wait, I still haven't answered the question,
why did Roentgen know he had a new kind of ray,
and why did the name stick outside of Germany,
and why do they use a completely different name
for X-rays in Germany?
Well, I'll tell you.
Ready? Let's go!
(mellow guitar music)
I would like to start in the 1880s,
when an English chemist named William Crookes
sent some of his photographic plates back for a refund
as he said that they were defective.
What Crookes didn't realize was that the plates were fine.
He had actually developed the film himself with X-rays.
See, Crookes had been studying something called cathode rays
and had proved that they could melt a piece of platinum
if the rays were focused on the metal.
What Crookes didn't realize until many years later, however,
was that when the cathode rays hit the platinum,
it produces X-rays,
which can develop film even if the film is protected.
As Crookes was focused on the platinum
and not on the photographic plates,
he just got his refund and moved on.
Fast forward to 1892,
when a 35-year-old Heinrich Hertz, already famous
for discovering radio waves four years before,
decided to recreate Crookes' experiment
of melting metals with cathode rays
Hertz didn't know about the photographic plates.
So Hertz was wondering if an unfocused cathode ray
could melt an even thinner piece of metal.
So he put a super-thin gold leaf on the back of a tube.
To his shock, the cathode rays seemed
to just go straight through the gold
to make the glass behind it glow.
Hertz then found that cathode rays could make it
through all metal as long as it was thin enough.
Now he liked to do all his experiments himself,
but he was starting to get a lot of headaches,
so he suggested that his assistant, Phillip Lenard,
should experiment on this phenomenon.
Lenard then tried something radical.
See, cathode rays can only be made
inside a very strong vacuum,
but Lenard wondered if he could use aluminum
as sort of a window to move the cathode rays
from the vacuum tube into the air.
So Lenard then took a cathode ray tube,
put a small hole in it,
covered the hole with aluminum foil.
Lenard knew that cathode rays, like UV rays,
are invisible to the naked eye
but can make fluorescents glow.
When he turned on the tube,
the fluorescents glowed outside the tube.
Even more startlingly,
the fluorescents continued to glow
a few inches away from his window.
This experiment, like Crookes' experiment, produced X-rays.
And unlike Crookes experiment, Lenard was covering his tube
and examining it with fluorescents outside of the tube.
However, Lenard was using fluorescents
that were made of light elements
with low atomic numbers that were transparent to X-rays.
So he just missed out on discovering the X-ray.
Tragically, just as Lenard was publishing his results,
Lenard's advisor, Heinrich Hertz,
died on January 1, 1894 at the age of 36
from blood poisoning.
Lenard basically stopped all of his research
to focus on editing a collection of Hertz's work.
And then it then took him two years
to find a stable position at a university
to continue his research,
which is almost exactly when he learned
that 50-year-old Wilhelm Roentgen had used his Lenard tube
with a different fluorescent to discover the X-ray.
Now, Wilhelm Roentgen had been interested in Hertz's
and Lenard's work for many years
and had actually started studying it in 1894.
Roentgen even wrote to Lenard for some advice
on how to build his tube with a window.
However, Roentgen only had time
to seriously study cathode rays
by October of 1895.
Within a few weeks of study, on November 8th, 1895,
Roentgen was working late
when noticed that a fluorescent paper
on the side of a covered tube started to glow
when the tube was turned on.
The fact that the fluorescent glowed
on the side of the tube completely floored Roentgen.
As he explained in his one
and only magazine interview given in April of 1896,
he said he was shocked because quote:
"The shield which covered the sides of the tube
was impervious to any light known".
Roentgen then found that the glowing
on his fluorescent was far brighter
on the other side of the aluminum window
where it was clearly emanating.
Roentgen then started holding up everything he could find
in his laboratory between the tube producing the X-rays
and the screen glowing from the X-rays,
a book, a deck of cards, tin foil,
pine wood, aluminum, rubber, glass.
He even tried a glass of water.
While Roentgen was basically throwing everything
he could find between the tube and the screen,
he picked up a small lead disk.
And this lead disk was going to change everything,
for as he waited for the image
of a shadow of the disk to appear on the screen,
he also saw something beyond belief,
the shadows from the bones in his own hand.
No wonder he told his wife that he was working
on something that would probably make people say,
"Roentgen has surely gone crazy."
Roentgen was instantly convinced
that he was dealing with a new kind of light
that was more powerful than anything he had ever seen.
He recalled in that magazine interview, quote:
"It seemed at first a new kind of invisible light.
It was clearly something new, something unrecorded."
As this was a new ray of light,
and he already thought cathode rays
were another kind of light,
he decided to name this new kind of ray an X-ray
for brevity's sake and to distinguish them from other rays,
X being the mark of unknown in algebra.
Roentgen knew his results were fantastical
and was worried that no one would believe him.
But luckily, he was an amateur photographer
and found to his relief that X-rays could develop film
while they were still in their protective coating
just like Crookes had found.
It was for that reason on December 22, 1895
that Roentgen asked his wife Bertha
if she would come to the laboratory
and hold her hand on a photographic plate for 15 minutes.
They then created a ghostly photo
that showed the bones in her hand
and the large metal ring on her finger.
When Bertha saw this image,
the first photograph of bones in an intact hand,
she supposedly exclaimed, "I have seen my own death!"
Roentgen published on December 28th, 1895,
and within weeks, according to Roentgen,
all hell broke loose.
Almost everyone wanted to play with X-rays,
including most scientists,
and soon there were traveling X-ray exhibitions,
poetry, art, and prudish controversies
about seeing through clothes into your bones.
My favorite story about that was when a man was traveling
around the country doing X-rays.
A young woman came to him
and asked him if he could secretly do an X-ray on her fiance
to make sure everything was working properly.
Lady, that's not how X-rays work.
Roentgen wanted nothing to do with fame or controversy
and had to be convinced to give even one public talk
by the Kaiser himself,
which he did on January 23rd to a packed house.
After Roentgen took another X-ray of an attendee's hand,
the room erupted in cheers,
and everyone decided to rename X-rays Roentgen rays,
which they are called in Germany to this very day.
At first, in America, in England in France, and elsewhere,
people used both X-rays and Roentgen rays interchangeably,
like this terrible poem titled "x-actly So,"
which mentions both X-ray's ways
and these naughty, naughty, Roentgen Rays.
However, as modern purveyors
of adult films know all too well,
the X is a very attractive for advertisers.
It is used as X marks the spot, so is comforting to people,
as well as being almost never used
as a first letter of a sentence.
So it's unusual and attracts the eye.
Therefore, advertisers selling X-ray sunglasses
and X-ray proof underwear
and X-ray stove polish, which was a thing,
vastly preferred the term X-ray
to a foreign sounding Roentgen ray.
And within a few years,
the term X-ray was the universal name outside of Germany,
as you can see from this fabulous silent film
called "The X-ray Fiend" from 1897
where they never mention Roentgen once.
(playful piano music)
Wasn't that fabulous?
In Germany, of course, the name Roentgen wasn't foreign,
and using it was a way of having German pride
in its discovery.
And that's how X-rays got their name outside of Germany,
and der Roentgenstahl, sorry, got its name inside Germany.
But X-rays did more than just shock Victorians
by seeing through your skin to your bone.
It also caused a rash of new discoveries,
including the discovery of radioactive material.
How radioactive materials got their name is next time
on the Lightning Tamers.
Thanks for watching my video.
If you want more information about the physics of X-rays
or cathode rays or what have you,
I have a lot more videos.
Go check them out.
Also big thank you from my patrons.
Thank you for supporting me.
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As usual, stay safe out there.
See you later.
(mellow jazz music)