Good morning. I am currently reading The Disordered Cosmos: A Journey into Dark Matter,
Spacetime, and Dreams Deferred by Chanda Prescod-Weinstien
and I was at the part where she talks briefly about the “Pillars of Creation” photo taken by
the Hubble Space Telescope. There is a picture of this photo in the book which I showed to my wife,
Kate. I attempted an impromptu explanation of this photo and completely failed. I love my wife. I’ve
known her since I was 16 years old. She has a degree in opera and a degree in social work. She
is intelligent. So, when she said essentially, “I understand all the words you are using,
however, when you put them into sentence format, they make absolutely no sense to me.”,
I considered her inability to understand my impromptu “Pillars of Creation” description
a failing of my own, not hers. So, Kate, here is my second, and hopefully more cogent, attempt to
explain to you what the “Pillars of Creation” are. ♪ Flipping Physics ♪
Kate, my goal with the “Pillars of Creation” is to answer the following four questions.
“Where are they?” “How far away are they?” “How big are they?” and “What are they?” So,
Kate, are you ready? Great. Here we go. Let’s answer the question “Where are the Pillars of
Creation?” To answer that, let’s start with a view of our galaxy, the Milky Way galaxy.
This video which starts here and zooms in quite a bit, comes to us via NASA, the European Space
Agency, and the Hubble Space telescope. So, thank you for that. Let’s zoom in a little bit and pause
so we can see the constellation Sagittarius, which looks like a little teapot. Here is its handle.
Here is its spout. Sorry Kate, I had to. The spout of the teapot points towards the center of our
galaxy. And the top of the teapot points towards Messier object 16 or M16. Let’s zoom in on M16.
And you can see that inside M16 is the Eagle Nebula. And inside the Eagle Nebula
are “The Pillars of Creation”. That’s where they are. Next, “How far away are
the ‘Pillars of Creation’? ” The “Pillars of Creation” are roughly 7,000 lightyears away.
That’s it. Question answered. The “Pillars of Creation” are roughly 7,000 lightyears away.
What? Okay, I get it. That doesn’t really help either of us understand how far away they are.
I’ll try again. First, you need to understand how far a lightyear is. I know.
A lightyear is a distance measurement, not a time measurement. It sounds a bit strange because the
word “year” is in there, however, trust me, a lightyear is a distance. Specifically, a
lightyear is the distance light travels in a year. Light travels at roughly 3.00 times 10 to the 8th
meters per second or 300 million meters per second, which is 186 thousand miles per second.
I know, it’s fast. In order to understand what this really means, realize the Earth is,
on average, roughly 93 million miles from the Sun. That means we can calculate how
long it takes, on average, for light to travel from the Sun to the Earth.
Starting with the equation for speed, speed equals distance traveled over time elapsed. I
know Kate. We just need this one equation for the whole explanation. Just one. Okay?
Yes, just 1. Rearranging the equation for time gives us that the time it takes to travel from
the Sun to the Earth equals the distance from the Sun to the Earth divided by the speed of light.
So, 93 million miles divided by 186 thousand miles per seconds gives us 500 seconds, or roughly 8 and
one third minutes, for the time it takes light to travel from the Sun to the Earth. Yeah, that
did not really help with how far a lightyear is, did it. I’m sorry Kate, I know. I’ll try again.
Let’s just determine how far a lightyear is in miles. To do that,
we first need to know how many seconds there are in a year. There are 365.242 days in a year.
One year is not exactly 365 days because of leap year for example. There are 24 hours in a day and
3600 seconds in an hour. That means there are roughly 31 million 560 thousand seconds in a year.
Going back to the equation speed equals distance over time, we can solve to get distance equals
speed times time. That means the distance of one lightyear equals the speed of light, 186
thousand miles per second, times the time in one year, 31 million 560 thousand seconds. In other
words, one lightyear is roughly 5 trillion 870 billion miles. But, we need to know how far it
is to the “Pillars of Creation”. So, we multiply that number by 7,000, because they are 7,000
lightyears away. And we get that the “Pillars of Creation” are roughly 41 quadrillion miles away.
I know Kate, that’s still kind of just a number and it is hard to really know what that means.
So, let’s compare that to the distance between the Sun and the Earth. If we divide the distance
to the “Pillars of Creation” by the average distance from here to the sun,
we get 440 million. In other words, the “Pillars of Creation” are 440 million times farther away
from us than the Sun. Yeah, Kate. I know that knowing the “Pillars of Creation” are roughly 440
million times farther away from us than the Sun helps the distance make some sense. Yep. It is
far away. The next question I want to answer is “How big are they?” So,
looking at the “Pillars of Creation”, and zooming in on the left “Pillar”. The distance
from the base of the left “Pillar” to the top is roughly 4 lightyears.
Again, Kate, I know this distance doesn’t mean a whole lot to you. So, we can calculate, just
like we did before, that the distance from the base to the top of the left “Pillar” is roughly
250,000 times farther than the distance from here to the Sun. Take a moment to appreciate that. The
vertical distance in this photo is one quarter of a million times larger than the distance
between the Earth and the Sun. Agreed. And now, we answer “What are the ‘Pillars of Creation’?”
First, they look like pillars, so, that’s why they are called “Pillars”. Second,
stars are being created here. Kate, we are looking at the birth of stars. I know. It’s amazing.
The “Pillars of Creation” are clouds of gas and dust that are clumping together to form stars.
In fact, if we zoom in on the top of the leftmost “Pillar”, we can see what is most likely a star
being born. When stars form, they often eject giant jets of radiation in opposite directions.
This bright line is likely the jets from a newborn star. Evidently, these jets are moving away from
this new star at about half a million miles per hour. Which is pretty cool. I know Kate.
Now, unfortunately, there is evidence that a supernova, a giant exploding star,
occurred roughly 6,000 years ago near the “Pillars of Creation” and the blast wave from
the supernova likely blew apart the “Pillars of Creation” and they no longer exist. That’s right,
most likely this beautiful structure, the “Pillars of Creation” was destroyed 6,000 years ago.
Right Kate, I hear you. How can we be looking at something that was destroyed 6,000 years
ago? Well, remember the “Pillars of Creation” are roughly 7,000 lightyears away. That means, because
light takes 1 year of time to travel 1 lightyear of distance, we are looking at what the “Pillars
of Creation” looked like 7,000 years ago. Again, this is because the light has taken 7,000 years
to get to us from the “Pillars of Creation”. Okay, I can see you are still confused. Let’s try this.
I am standing roughly 175 meters away from the camera. That little speck is me.
Let’s zoom in so you can actually see me. I am about to do a demonstration I remember my
5th grade teacher, Mr. Brown, doing. Thanks. Mr Brown! Alright watch what happens when I,
while wearing ear protection, whack this hammer against this metal pole.
Because sound at this air temperature travels at roughly 350 meters per second through air,
and it takes sound roughly half a second to travel this distance, you see the hammer
hit the pole roughly half a second before you hear the hammer hit the pole. This is the same reason
we see lighting first and then a short while later we hear the thunder.
In reality, the lightning and thunder happen at the same time. It’s just that we do not hear
what happens as it happens; We only hear what happens when the sound waves get to our ears.
Typically, we do not notice that we do not see what happens as it happens, we only see what
happens when the light waves get to our eyes. The reason we do not notice this is because, again,
light travels at 186 thousand miles per second. This is so fast that, in our normal,
everyday lives, we do not need to account for how long it takes light to travel the short
distances we experience. However, because the “Pillars of Creation” are 7,000 lightyears away,
it takes 7,000 years for the light to travel through space to get to us, and we are seeing
7,000 years in the past, just like you hear the hammer hit the pole half a second in the past.
Good I’m glad that makes sense. Actually, we can go back to a calculation we did at the beginning.
The Sun is roughly 8 light-minutes from Earth. In other words, when we look at the Sun which you
should absolutely only do through appropriate solar glasses, we are looking at what the Sun
was like 8 minutes ago. If the Sun were to suddenly disappear, we actually would not
know it happened until 8 minutes after it disappeared. I know it’s a bit overwhelming.
Lastly, we are seeing the “Pillars of Creation” as they existed 7,000 years ago
and 6,000 years ago they were likely destroyed by a supernova blast. So, the “Pillars of Creation”
likely do not exist anymore, however, it will be 1000 years before we know that for sure. I don’t
know about you, however, I am definitely going to set a calendar reminder to check on that.
I’m thinking January 1st, 3001! See you then! Kate, I hope you learned a few things today,
thank you for being such a good sport about all of this, thank you. You know I love you very much.
And thanks for pre-screening every single one of my Flipping Physics videos for the last nine and a
half years. To the rest of you thank you very much for learning with me, I enjoy learning with you.