April 9, 2025 • 33 mins
What's the deepest hole we can dig? And what would we find there? Jorge digs deep with drilling engineers to get to the bottom of things.
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Speaker 1 (00:00):
Hey, Welcome to Sign Stuff, a production of iHeartRadio. My
name is Jorge cham and today we are digging deep
into the question what happens if you dig a hole
to the center of the earth. It's a question most
of us have asked when we were making a hole
in our yards or at the beach. Is it actually
possible to dig all the way through? Or would you
perish in the process. We're going to talk to people
(00:21):
whose jobs it is to dig the deepest holes humans
have ever dug, and we're going to take a journey
with one of them to see how far we can get.
So let's dive in and answer the question what happens
if you dig a hole to the center of the Earth.
I promise it won't be a bore. Welcome to sign Stuff. Okay,
(00:44):
here's a list of the top five deepest holes humans
have ever dug. Numbers five through three are oil wheels
that were dug in the Gulf of Mexico or at
least what do you speak called the Gulf of Mexico
near the coast of Texas and Louzy. They have names
like two to five, that zero one or GC five
one two number one, BP two and they go down
(01:06):
to about the same depth, which is around ten and
a half kilometers straight down. The second deepest hole ever
dug is called tiber Kse one two, and it's also
an oil well. But notably it was dug in two
thousand and nine by deep Water Horizon, the powerful digging
rig that seven months later, while trying to drill its
(01:27):
next hole, exploded and caused the largest oil spill in
human history. Tiber Kse one two is a hole that
goes down ten kilometers six hundred and eighty three meters
straight down. But the deepest hole ever dug by humans
is a little bit deeper. It's called SG three or
the coalis Super Deep borehole, and it was dug over
(01:48):
a period of twenty years as a classified, top secret
research project by Russian scientists. It's in the part of
Russia that borders Norway and Finland, in the Scandinavian Peninsula.
The hole is about nine inches wide and it goes
down to a death of twelve kilometers two hundred and
sixty two meters or about twenty eight Empire state buildings
(02:10):
stacked on top of each other. Now, these are really
deep holes in human terms, but they're actually kind of
shallow if you compare them to the size of the Earth.
The Earth is twelve thousand, seven hundred and fifty six
kilometers wide, which means the deepest holes we've ever dug
are barely zero point one percent of the way through.
(02:33):
So the main questions we're answering today are why did
the people making these holes stop digging, what would have
happened if they had kept going? And is it even
possible to get to the center of the Earth. To
answer these questions, we're going to do three things. We're
going to find out why so hard to dig a
really deep hole, Then we're going to talk about the
(02:53):
cool technology people are using to dig deeper and deeper,
and then at the end we'll ask experts if it's
it's even possible to dig all the way to the
center of the earth. Okay, So the first thing I
did was I reached out to people whose job it
is to dig super deep holes. The first person I
talked to was doctor Eric van Ord, the professor in
(03:16):
the Department of Petroleum and Geosystems Engineering the University of
Texas at Austin, and he is an expert in drilling
hydraulic fracturing and geomechanics. I basically asked him point blank,
why is it so hard to dig a really deep hole?
So here's my conversation with doctor Eric van Ort. Well,
(03:36):
thank you so much, professor van Ord for joining us.
Speaker 2 (03:39):
Happy to be here.
Speaker 1 (03:40):
Now. You're expert in drilling engineering, and so I have
a lot of questions for you that I really want
to drill into but intended. Yeah, can you talk to
us a little bit about what are some of the
challenges that you run into when you try to drill
into the ground.
Speaker 2 (03:55):
Well, we drill into the ground to explore and produce
oil and gosh, but also to explore and produce geothermal heat,
to store CO two and waste underground. Sometimes even build
repositories for nuclear waste that could be stored underground. So
different wells have different challenges. Formations are unconsolidated. That means
(04:16):
that they're not holding together right as a problem with
the stability of the well board that you could sometimes see.
Speaker 1 (04:22):
Okay, the first challenge in digging a really deep hole
is that deep holes don't want to stay holes for
very long. They tend to collapse. Like deferend Or compares
it to trying to dig a hole in the sand
at the beach.
Speaker 2 (04:36):
If you've ever been digging a hole on the beach
as a kid, you get very frustrated, right, because will
you want to drill the deepest hole possible, right, go
to the center of the earth, right, and you're thwarted
by the fact that you can only get to a
certain depth and no deeper right.
Speaker 3 (04:51):
Right.
Speaker 1 (04:52):
So that happens even in solid rock.
Speaker 2 (04:54):
Even in solid rock, I mean, when you drill a borehole,
what the Earth wants to do is close that borehole.
Speaker 1 (04:59):
Again, what do you mean that nature wants to close
the hole?
Speaker 2 (05:03):
Well, in the earth, right, you have stresses acting on
the borehole. The weight of the rock on top is
the vertical stress, and then there are horizontal stresses because
of tectonic movements, and those stresses act on the borehole
and they would collapse the borehole and you would lose
it eventually.
Speaker 1 (05:19):
So, just like digging a hole in the sand at
the beach, eventually deep holes collapse. Even when you're digging
through solid rock. Eventually, the sheer weight of all the
rock around your hole is going to want to close
your hole. There is a clever solution for that.
Speaker 2 (05:37):
So we need to stabilize the hole as we're drilling it.
We typically do that by circulating a drilling fluid that
provides kind of hydrostatic pressure to keep the borehole open
it meaning.
Speaker 1 (05:48):
You fill it with like water or oil.
Speaker 2 (05:51):
Water or oil that we can change the density of.
So we have the ability to change the density and
thereby the hydrostatic pressure that is being exerted onto the
poorhole wall.
Speaker 1 (06:01):
And that prevents the whole from caving in.
Speaker 2 (06:03):
That prevents the hole from collapsing.
Speaker 1 (06:06):
The other thing that makes being really deep whole heart
is temperature.
Speaker 2 (06:11):
In the center of the Earth, the temperature is six
thousand kelvin. It's the same temperature as the surface of
the Sun. The sun, of course, at its core is
millions of degreas, but the surface of the Sun is
about six thousand calvin And that's also the temperature in
the center of the Earth.
Speaker 1 (06:29):
Wow.
Speaker 2 (06:30):
And then there's a temperature gradient going to the outside.
Speaker 1 (06:33):
Meaning six thousand degrees of the center. But it gets
cooler as you go up to the surface.
Speaker 2 (06:37):
Yep. But the deeper you go into the Earth, the
higher the temperature.
Speaker 1 (06:41):
And why is the earth hot inside.
Speaker 2 (06:42):
It's because of the formation of the Earth. So what
we call primordial heat, heat that got trapped when the
Earth formed.
Speaker 1 (06:50):
So the Earth is hot inside, which is a little
odd to think about because which is the giant rock
floating out in the coldness of space? So where did
all that heat come from? Well, it came from two places,
according to doctor Van Ord. Number one, when the Earth
was formed, meaning when all those rocks and dust in
the early Solar systems scrunched together to form the Earth.
(07:12):
The scrunching generated a lot of heat, and also the
Earth kick getting hit by asteroids and giant rocks that
were zooming around the early Solar System. It's sort of
like if you take a mass of clay and you
beat it with your hands that were mallet Eventually it
heats up, and that's what happened to the Earth. In fact,
at some point the Earth was so hot it was
(07:32):
just a big ball of lava. And number two, the
Earth is also hot because there are radioactive elements inside
the Earth, like uranium and plutonium that are decaying, essentially
nuking the Earth from the inside. So as you dig deeper,
it gets hotter. How hot here's how doctor Van Ord
(07:53):
puts it.
Speaker 2 (07:55):
The Earth is a really good insulator. The amount of
heat that it chops is obsolutely massive. It's an amazing
amount of heat is phenomenal. And even though Earth radiates
heat into cold space all the time, to give you
a comparison, if you look at all the energy that
humanity uses around the world at any given point in time,
(08:16):
it's about fifteen tertra wats, and the Earth radiates into
the space about fifty terrawatts of heat energy all the time.
Speaker 1 (08:24):
Oh wow.
Speaker 2 (08:25):
Even then with that phenomenal amount of energy that it loses,
even over forty billion years, it has hardly lost any
significant amount of heat.
Speaker 1 (08:34):
So it's like we have a little sun almost at
the center of the Earth.
Speaker 2 (08:38):
So we call that kind of the heat beneath our feet.
Speaker 1 (08:42):
What that means is that as you dig deeper, it
gets horder. How hard it gets depends on where you
make the hole, but generally speaking, near the surface, digging
a hole gets harder about fifteen degrees celsius for each
kilometer you go down. So at the Cola super borehole
in Russia, the deepest humans I've ever dug, they reach
temperatures of one hundred and eighty degrees celsius or around
(09:06):
three hundred and fifty six fahrenheit, which is around the
temperature you would say you're oven two to cook roast beef. Now,
those are the two main reasons digging hole is hard.
There are other reasons too, like pressure.
Speaker 2 (09:20):
We need to deal with not only hort temperatures but
also high pressures. So not only does the temperature get higher,
the pressure gets higher as well.
Speaker 1 (09:27):
So whatever you put down there basically gets squished. Yeah.
Speaker 2 (09:32):
As you get deeper and deeper and the temperatures get higher,
and the pressures get higher, and the rocks get harder.
Speaker 1 (09:38):
Waight the rocks get harder.
Speaker 2 (09:40):
Yeah, because of again that weight of the overlying informations.
The rocks start to consolidate, and then they also start
to change under the influence of pressure and temperature.
Speaker 1 (09:49):
Oh, they get more dense.
Speaker 2 (09:51):
Yeah, really hard stuff to drill.
Speaker 1 (09:55):
Also, when you're drilling under the ground, you're kind of
drilling blind. Example, you might accidentally hit some lava.
Speaker 2 (10:04):
That's generally not good, but it has happened. In Iceland,
they drilled a well called the ice Iceland Deep Drilling
Project at a price called Kravla. They actually drilled into
an active volcano, So they actually drilled into a.
Speaker 1 (10:19):
Magma chamber on purpose or by accident.
Speaker 2 (10:22):
By accident, so they encountered a nine hundred degrees centigrade
temperatures well over two thousand degrees fahrenheit. There's a ridiculous
amount of temperature that we saw there. Now, luckily the
chamber was not pressurized and low and behold, they were
able to temporarily keep that hole and actually briefly turn
it into a geothermal well which was producing kind of
(10:44):
thirty five megawatts of power. Wow, and you can run
a small city of that, right, It's pretty amazing.
Speaker 1 (10:51):
And then, of course what makes digging a really deep
hole heart is that you have to dig through solid rock.
So when we come back, we'll talk to a different
professional hole digger about the different technologies we use to
dig through rock. They involve diamonds, lasers, and microwaves. Stay
with us, you're listening to sign stuff. Hey, welcome back. Okay,
(11:23):
we talked about why drilling a deep hole is hard,
and in the next section we're going to talk about
whether it's possible to dig a hole to the center
of the Earth. But first I was curious to learn
how exactly you dig a hole that deep, what's the
technology you use? And let me just preview this by saying,
there are going to be lasers involved, big lasers to
(11:45):
guide us through this. I talked to another person whose
job it is to dig deep holes.
Speaker 3 (11:49):
So my name is Roman Short. I'm associate professor here
at Texas A and M University. I work a lot
in drilling, drilling automation optimization for subservice energy.
Speaker 1 (11:58):
Well, thanks for joining us, doctor sh So how do
you drill a hole in the ground through rock.
Speaker 3 (12:03):
The way that you typically do it? You need a
really big drill, A drilling rig comes on site and
same thing like that drill bit that you're using in
your wall. Just imagine a really long drill bit. Tap
top start rotating it, the bottom rotates eventually, and then
you lower down until you hit the ground and then
the bit is a failing rock.
Speaker 1 (12:20):
Yeah, it's literally just the drill, but imagine one that's
nine to ten inches wide and that sits at the
end of a ten kilometer long steel rod. Now I
have a drill at home, and when I drill, the
bits that get cut spiral up the drill and usually
fall to the ground. But in a ten kilometer deep hole,
(12:41):
what happens to all the stuff you drill out? Here's
what doctor Shore said.
Speaker 3 (12:46):
That's another use for that drilling fluid. So that water
you pump it down the drill pipe comes out the
drill bit, and it captures all those pieces of rock
and then moves them back up to the surface. So
you're helping clean this well bore using this fluid. I'll
also provide you stability for that whole. So it's like
kind of cool how that drilling mud use does build
things at once.
Speaker 1 (13:06):
Okay, I know that's the second time we mentioned this
drilling fluid, but trust me, it's going to be important later. Now,
is it a drill bit like the drill I have
at home, like the spiral metal thing, or it's similar.
Speaker 3 (13:18):
So rock is a little bit harder than the dry
wall or the word that you typically drill through. So
a lot of these rodary drill bits now use that
technology called polycrystaline diamond. So there's these little tiny diamond
cutters that are embedded into this bigger spiral. Effectively, you
can think of your spiral drill bit. Just think of that,
but much larger, and you have little tiny diamond cutters
(13:39):
along the edges of each of those teeth, so they
act like teeth as they're rotating.
Speaker 1 (13:44):
Yes, that's right. To dig to rock, you use diamonds.
Speaker 3 (13:48):
Yeah, so it's an artificial diamond. You put that under
ground and that can drill for hundreds to thousands of feet,
sometimes even miles.
Speaker 1 (13:56):
Yeah, diamonds are pretty cool. But contrary to what they
say or not forever, the problem with the drill, doctor
Shore says is that they wear out, even the ones
with diamonds, and replacing something at the bottom of a
ten kilometer hole is not easy. So scientists of engineers
have been coming up with new technologies to dig or
(14:17):
blast their way through rock. And you said there's other
technologies like using lasers. Yep, you describe some of those exactly.
Speaker 3 (14:25):
So what I've been talking about so far is called
rotary drilling. Other technologies that people have been looking at
is can you use that's say, a microwave to literally
firmly degrade the rock and melt it, burn it out
of the way.
Speaker 1 (14:39):
Wait, just shoot, just shoot the rock with Yeah.
Speaker 3 (14:43):
Just with the microwave being you're just like not quite
star star trek Pew pew. But it's the same journal. Yes,
like you just imagine this energy being forced pointed at
this rock.
Speaker 1 (14:53):
What that works? Like if I shoot a microwave at
a rock, it'll actually disintegrate eventually.
Speaker 3 (14:59):
Yes, it takes a lot of energy, but it does.
It turns into vapor. So it just turns into a
gas and then you can if you just circulate air
just comes out as as a gasified.
Speaker 1 (15:09):
Rock vaporized rock. Whoa, Because the microwaves are hitting the
rock and that's basically blowing off the rock atoms from
the surface.
Speaker 3 (15:19):
So the atoms themselves stay constant. I think it's breaking
a lot of the molecular bonds and also some of
the weaker bonds that are between let's say a different
molecules different grains.
Speaker 1 (15:28):
So one technology they're exploring is to zap the rock
with a microwave, just like the one you use at
home to reheat your food, well not quite like the
one in your kitchen.
Speaker 3 (15:39):
So but the problem with this is how do you
generate microwaves that are high enough energy close enough to
that rock surface. So, like your microwave at home is
a kilowat and that's what you use to heat your food.
In order to melt rock, you need a thousand times
more power, give or take like a million what, yeah, exactly,
(16:00):
so a million wats. There are people trying to figure
out ways to take out washing machine and make it
really skiy. So you just stack it up so it
all fits in. It could work. We'll see what they
come up with over the next time.
Speaker 1 (16:11):
And you said lasers or is that the same technology?
Speaker 3 (16:13):
Oh, lasers are another thing that people are thinking about.
This is now on the visible light spectrum. Now that
laser hits the rock, same thing, burning it melts it.
Speaker 1 (16:23):
That's right. Forget drills. There's a way to shoot your
way to the center of the Earth. And for anyone
having flashbacks to the depth Star laser in the movie
Star Wars, don't worry. These are not that big, just
enough to cut a small hole ten kilometers into the ground. Now,
are lasers and microwaves better than drills? I asked doctor
(16:43):
sure this question, and these methods laser, MicroID that's going
to be more efficient or better than a drill.
Speaker 3 (16:51):
So it may be faster because your typical rotary drill
bits if you're looking at easy to drill rock, So
just a nice easy sandstone, you can drill at hundreds
of feet per hour, So if you want to drill
a mile, it'll take maybe a day if you're drilling
it harder rock. So I just say you're drilling into
granite or quartz sites, that rock is a lot harder.
(17:14):
It's the same type of rock that use for your countertop.
So now if you have a rock like this, erotary
drill bit could only go at tens of feet per hour,
so that same mile might take a week or maybe
I'd say even a month. Sometimes with laser and microwave,
it doesn't care what the rock is. It just sees matter,
so it's able to go through any hardness of material
(17:35):
use it just by blasting it with energy. You just
maybe crank up the energy intensity a little bit too,
because if you have more material there.
Speaker 1 (17:41):
Whoah, well, when they build it, they should definitely build
in some sound effects like pew pew pew.
Speaker 3 (17:47):
Great exactly that or maybe well, I don't know. The
usually the depth star sud might be a little.
Speaker 1 (17:53):
Bit okay, So to recap, the deepest holes in the
world have all been dug with drills that make holes
about nine inches wide, which is about the diameter of
a soccer ball at the end of a ten kilometer
or more steel tube or rod, and you typically fill
that tube with something drilling engineers called mud, which is
(18:16):
basically water with things like clay or other ceramics added
to make it heavier to keep the hole from collapsing. Now,
the question is how deep can you make that hole?
Can you make it to the center of the earth.
When we come back, we're going to answer that question.
So stay with us. You're listening to sign stuff. Welcome back. Okay,
(18:45):
we're now going to get to the question of whether
it's possible to dig to the center of the earth.
We talked about why it's hard to dig really deep
holes and the technologies humans used to dig them. Now
the question is what's the deepest hole we could make.
I asked this question to both of our experts, and
they disagree. They each gave a different answer. Here's what
(19:07):
doctor van Ord said. Can you take us on a journey.
So let's say I start digging from the surface. What
am I going to be seeing?
Speaker 2 (19:14):
Okay, so the outer part of the earth, which is
what we call the crust, is relatively thin zero to
seventy zero to one hundred kilometers deep. But remember that
the deepest we've ever drilled, which is cola super deep
hole in Russia, only went about thirteen kilometers deep. So
you're still only a small ways into the crust. If
(19:35):
the rest of the crust is one hundred kilometers.
Speaker 1 (19:37):
Right, what is the crust made out of?
Speaker 2 (19:39):
Crust is made out of aluminum and manganese silicates, so
that's sandstone and limestone, and then deeper down when you
get the basement rock kind of granite and buzzle, and
then when you go through the crust you go to
the mantle.
Speaker 1 (19:51):
All right, here, it's fourteen A side note, I think
most people know that the inside of the Earth is
made up of layers, but maybe not a lot of
people know why it layers. Remember I said earlier that
after the Earth formed, it was just a big ball
of lava. Well, when it was in that fluid state,
all the things in it started to settle. The heaviest
elements sank to the bottom. In this case, it was
(20:13):
mostly iron. Then the heavier rocks hung around the middle
and the lighter rocks floated to the top. I usually
describe it as a boba drink, or like making sangria,
where the boba or the fruit sink to the bottom,
the ice floats to the top, and most of the
liquid hangs out in the middle. That's why the earth
is made up of layers, but in this case there's
(20:33):
circular layers because the earth is round. Okay, back to
the conversation.
Speaker 2 (20:39):
And then below the crust is the mantle. The mantle
is about three thousand kilometers.
Speaker 1 (20:44):
So the mantle is also rock, but it's still pretty
hard and hot.
Speaker 2 (20:48):
Yeah, and the temperatures start to become higher and higher, right,
it becomes thousands of the grease centigrade and fahrenheit as
we go towards the core of the earth.
Speaker 1 (20:57):
So after the crust is a mantle. This is kind
of the meat of the earth, if Earth was like
a fruit. The mantle is about two thousand, eight hundred
kilometers thick, and it's also solid rock, but because of
the temperature and pressure, the rock actually flows. The rocks
inside the mantle are constantly moving. They heat up when
they get close to the center of the earth, which
(21:19):
makes them expand, and so they float up to the crust.
Then they cool down and sink again. It's kind of
what happens in a lava lamp or a pot of
boiling water where you see the water churning up and down.
And it's that constant movement that pushes the crust around,
moving all the continents over millions of years. And as
(21:39):
sucufan Ort said, the mantle gets pretty hot pretty fast.
At about five hundred kilometers down, the temperature is almost
two thousand degrees celsius. And at the bottom of the mantle,
or almost three thousand kilometers deep, the temperature is thirty
five hundred degrees celsius. That's where you get to the
Earth's core.
Speaker 2 (22:01):
The outer core is liquid iron and nickel, and then
the core itself. The scientists are still investigating that. They
think it's either solid or it's plasma behaving as a solid.
That is kind of six thousand calvins. So you wouldn't
be able to drill a borehole through that. In fact,
if you get to the outer core, right, it's just
a liquid of iron. Any steel tools that you would
(22:22):
use would melt going through there.
Speaker 1 (22:26):
Basically, Yeah, if you took a bunch of iron and
melted it and then you try to dig through a
pool of liquid iron.
Speaker 2 (22:32):
Yeah, I don't think you can stabilize a borehole at all.
Speaker 1 (22:36):
Well, you know, I've heard that at the center of
the Earth there are dinosaurs in kin Kong.
Speaker 2 (22:40):
Creatures not from scientists.
Speaker 1 (22:44):
So the outer part of Earth's core is a layer
of molten iron that's about five thousand degrees celsius. And
then when you get to the bottom or to the
center of the Earth, it's a solid ball of iron
six thousand degrees celsius. Doctor event Or doesn't think we
could ever even get there. Well, let's maybe put on
(23:05):
our imagination hads or creative hats, and let's say that
if for some reason we needed to dig to the
center of the earth, what would be required? How would
you do it? And I gave you a trillion dollars?
Now it wouldn't be enough, all right, ten trillion dollars.
Now there's no money enough right now because the technology
(23:27):
doesn't exist to do it. What would be the things
that fail?
Speaker 2 (23:32):
Well, right now, we require kind of boattholes, right that
we need to stabilize on our way down. And you
just run out of the ability to do that as
you get deeper and deeper. As I said, you need
to come up with some kind of death Star weapon, right,
some kind of high powered laser where you could just
blash your way through the core of the Earth. But
if you do that, I think you'll blow up the
(23:52):
Earth in the process as well as the death Star
is meant to do.
Speaker 1 (23:57):
What's the problem? The rockets too hard or too hot both.
Speaker 2 (24:01):
We have to go through a lot of hard rock
initially that is a very very high temperature.
Speaker 1 (24:06):
What if I somehow, I mean I gave you a
lot of money and some we figure out how to
make things at a diamond, which is the hardest thing
we know about. Right, What if I made a borehole
pipe that was made out of diamonds and SOMEO Now
all my tools and cables were made out of diamonds.
Speaker 2 (24:21):
No, it's a diamond, diamonds decomposed I think at around
twelve hundred degrees cent grade. I might be wrong there,
but you can actually burn up a diamond. So the
diamonds would eventually fail as well. What and you end
up with just a bunch of CO two. It just
would revert back to carbon and then you just burn
the carbon.
Speaker 1 (24:39):
Okay, I checked this, and it's true. Diamonds in the
presence of air or oxygen burn into CO two at
around nine hundred degrees celsius, which would only get you
down to about fifty kilometers or zero point four percent
of the way to the center of the Earth. In
other words, when you get down to about fifty kilometers
(24:59):
now into the earth, your diamond tools would spontaneously burst
into flames. And even if you stucked all the oxygen out,
your diamond tools would melt at around fifteen hundred kilometers
or about a quarter of the way down to the
center of the earth. Wait, even if I build everything
out of diamonds, at some point, it would just evaporate. Yeah,
(25:21):
so we wouldn't get very far even into the mantle.
Speaker 2 (25:24):
No, I personally think it'll be a very long time
before we can get out of the crust and into
the mantle.
Speaker 1 (25:32):
All right, So our dream of going to the center
of the Earth just went up and smoke right along
with our cool diamond drills, or did they. I decided
to ask doctor Share the same question, and he came
up with a possible way we might be able to
get down to the Earth's core. And the answer is
(25:52):
to use the liquid that you fill your hole with,
the one keeping the hole from collapsing as a coolant.
This is what they do. When you're drilling and you
hit a pocket of lava or magma.
Speaker 3 (26:05):
The cool thing is that drill bit can drill into
that magma. The reason why is the water so that
fluid that you're using is cooling the rock. So that
layer of magma now it sees that fluid first and
it solidifies. In Hawaii and in Iceland, they have drilled
through magma dikes. Sometimes it's been on purpose, sometimes it's
(26:25):
been not and they were able to drill through it.
It cools off because the water is absorbed all that heat.
So you have this little tiny layer now around your
hole that's solid rock and then it's magma.
Speaker 1 (26:37):
And it doesn't remelt.
Speaker 3 (26:39):
As long as you're flowing the water. So as long
as you're still pumping and pumping cool fluid, now it
stays water.
Speaker 1 (26:45):
To you're building a tunnel through lava.
Speaker 3 (26:49):
H as long as you continue flowing fluid and cooling,
that whole stays stable.
Speaker 2 (26:53):
Right.
Speaker 3 (26:54):
But now you can keep going even deeper than that.
It's imagine we keep cool they canna say we're using
liquid nitrogen or something. We can now technically keep making
this whole.
Speaker 1 (27:02):
This is the mantle, right, Yes, for an hour, and
they're layer beneath the crust, and.
Speaker 3 (27:06):
The temperatures are going to be increasing through thousands of
degrees fahrenheit.
Speaker 1 (27:10):
Now is that survivable? Because now you're talking about thousands
of degrees and you know the surfaces of the sun
is six thousand degrees fahrenheit. Is your drill bit still intact?
Speaker 3 (27:22):
The drill bit itself would have melted hours ago. Part
of the reason why we're still able to keep drilling
is because we have this cool layer of rock that's
solidified around us. So if we somehow found a way
to continue pumping some form of cool fluid, maybe liquid nitrogen,
Maybe we find a fluid where it reacts and it
(27:42):
absorbs heat, so you can pump down let's say two materials.
They combine and become extremely cold. So as long as
the rock is solid, the bit will be fine because
the bit melts right about the same temperature as the rock.
Speaker 1 (27:55):
Right, So if we can keep our drill cool, maybe
using some kind of system, you could technically keep digging. Now,
this is an extremely difficult problem, but maybe technically possible.
We're kind of using our imagination here, but that would
get us to the core.
Speaker 3 (28:14):
Eventually, after about two thousand miles, you've now hit the
outer core. The outer core now is still liquid, it
is now extremely hot, so four thousand and five thousand
degrees fahrenheit. And then at the very center, now you
have a solid inner core. That solid inner core is
not mostly metal, and it's spinning, and it's spinning at
(28:35):
a different speed than the surface of the Earth. So
the reason why we as a planet have a magnetic
field is the center of the Earth is spinning. The
outside of the Earth is stationary, so it's a big dynamo.
So that is what is generating this magnetic field that
protects the planet from all this solar radiation.
Speaker 1 (28:52):
It's a spinning magnet in the center of the Earth exactly.
Speaker 3 (28:55):
Which is why Mars does not have a magnetic field anymore,
is because their core became solid and it stopped rotating
at some point several billion years ago.
Speaker 1 (29:06):
Whoa, but wait, but trying to dig through molten metal iron.
Speaker 3 (29:12):
That's going to become even harder and again it's moving,
which is the bigger problem. So we have this hole
that's cooled around us. We're still somehow cooling it. I
don't know how. And we've now hit this moving metal ball.
Where we touch it, it's going to move away. And
now if we start making a hole, it's going to
start dragging our hole with it because it's moving in
(29:33):
relation to us. So how would we continue drilling at
that point? I don't know.
Speaker 1 (29:40):
Well what I have an idea? What if we drill
from the north pole?
Speaker 3 (29:44):
That could actually work. But if you find the pole
of that inner core, then yes, that would work.
Speaker 1 (29:49):
Oh, you'd have to hit it just right in the
spin axis in the inner.
Speaker 3 (29:55):
Core exactly, so it has a rock tube transition to
a metal tube. Now you're in solid metal, but around
you the core is thousands of degrees fahrenheit. So you
now need to have enough cooling that the inside of
your hole is one hundred degrees or couple hudgrees fahit.
So you may have to get creative and call NASA
because NASA has some really cool insulators.
Speaker 1 (30:16):
Yeah, hold on, let me call NASA right now. Actually
we do have it all night phone.
Speaker 3 (30:23):
Okay.
Speaker 1 (30:24):
So to recap, if you drill down from the north
or south poles, and if you can figure out a
way to super cool your whole as you dig down
through six thousand degrees celsius molten and solid iron, you
could technically drill down to the center of the Earth.
I feel like maybe we delved a little bit into
science fiction, a little bit or a lot of just
(30:46):
a little bit, But in your opinion, it's possible as
long as we have the right engineering.
Speaker 3 (30:52):
If we need to and we put our brains to it,
we probably could come up with aspects of a solution
that could work. Will we be able to cool against
six thousand degrees fahrenheit two thousand miles into the Earth's core?
Probably not, but should we find a way so. For
the geothermal industry today, what they're trying to do is
(31:13):
they're trying to find a way to drill down to
rock that is six hundred degrees fahrenheit.
Speaker 1 (31:18):
Okay, this brings us to one of the main reasons
why you would want to dig a deep hole in
the first place, geothermal energy, that is, using the energy
of the Earth as energy instead of oil or carbon.
Because this energy is free and it's clean, and you
don't have to go down that deep to get it.
(31:39):
Scientists think if we can get technology towards easy to
drill down to about twelve kilometers, which is about the
deepest we've ever dug. Then you could have geothermal wells everywhere.
Here's how doctor Shore describes it.
Speaker 3 (31:52):
I think someone's done the calculations, and there's enough heat
energy in the Earth in order to provide enough energy
for humanity for a hundred million years. So there is
a huge amount, but it's not unlimited. So it's now,
how do you sustainably pull out heat and make sure
you're not changing the geology significantly from that heat being removed.
(32:14):
I see, So there has to be a little bit
of thought put into it. But one hundred million of
years worth of energy sounds pretty good.
Speaker 1 (32:22):
And that sounds good to me too. So when you
hear politicians say drill, baby, drill, just make sure they
mean for geothermal energy. All right, I think we answered
today's question. What happens if you dig a hole to
the center of the earth. It might be possible to
do it, but you might not need to might not
be that deep. A solution to all of our problems
(32:44):
could be right beneath our feet. That is the whole truth.
Thanks for joining us. See you next time you've been
listening to science stuff. The production of iHeartRadio written and
produced by me or Hey Chham, edited by Rose Seguda,
executive producer Jerry Rowland, and audio engineer and mixer Ksey Pegram.
(33:07):
And you can follow me on social media. Just search
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Be sure to subscribe to sign stuff on the iHeartRadio app,
Apple Podcasts or wherever you get your podcasts, and please
tell your friends We'll be back next Wednesday with another episode.
Hey, Welcome to Sign Stuff, a production of iHeartRadio. My
name is Jorge cham and today we are digging deep
into the question what happens if you dig a hole
to the center of the earth. It's a question most
of us have asked when we were making a hole
in our yards or at the beach. Is it actually
possible to dig all the way through? Or would you
perish in the process. We're going to talk to people
(00:21):
whose jobs it is to dig the deepest holes humans
have ever dug, and we're going to take a journey
with one of them to see how far we can get.
So let's dive in and answer the question what happens
if you dig a hole to the center of the Earth.
I promise it won't be a bore. Welcome to sign Stuff. Okay,
(00:44):
here's a list of the top five deepest holes humans
have ever dug. Numbers five through three are oil wheels
that were dug in the Gulf of Mexico or at
least what do you speak called the Gulf of Mexico
near the coast of Texas and Louzy. They have names
like two to five, that zero one or GC five
one two number one, BP two and they go down
(01:06):
to about the same depth, which is around ten and
a half kilometers straight down. The second deepest hole ever
dug is called tiber Kse one two, and it's also
an oil well. But notably it was dug in two
thousand and nine by deep Water Horizon, the powerful digging
rig that seven months later, while trying to drill its
(01:27):
next hole, exploded and caused the largest oil spill in
human history. Tiber Kse one two is a hole that
goes down ten kilometers six hundred and eighty three meters
straight down. But the deepest hole ever dug by humans
is a little bit deeper. It's called SG three or
the coalis Super Deep borehole, and it was dug over
(01:48):
a period of twenty years as a classified, top secret
research project by Russian scientists. It's in the part of
Russia that borders Norway and Finland, in the Scandinavian Peninsula.
The hole is about nine inches wide and it goes
down to a death of twelve kilometers two hundred and
sixty two meters or about twenty eight Empire state buildings
(02:10):
stacked on top of each other. Now, these are really
deep holes in human terms, but they're actually kind of
shallow if you compare them to the size of the Earth.
The Earth is twelve thousand, seven hundred and fifty six
kilometers wide, which means the deepest holes we've ever dug
are barely zero point one percent of the way through.
(02:33):
So the main questions we're answering today are why did
the people making these holes stop digging, what would have
happened if they had kept going? And is it even
possible to get to the center of the Earth. To
answer these questions, we're going to do three things. We're
going to find out why so hard to dig a
really deep hole, Then we're going to talk about the
(02:53):
cool technology people are using to dig deeper and deeper,
and then at the end we'll ask experts if it's
it's even possible to dig all the way to the
center of the earth. Okay, So the first thing I
did was I reached out to people whose job it
is to dig super deep holes. The first person I
talked to was doctor Eric van Ord, the professor in
(03:16):
the Department of Petroleum and Geosystems Engineering the University of
Texas at Austin, and he is an expert in drilling
hydraulic fracturing and geomechanics. I basically asked him point blank,
why is it so hard to dig a really deep hole?
So here's my conversation with doctor Eric van Ort. Well,
(03:36):
thank you so much, professor van Ord for joining us.
Speaker 2 (03:39):
Happy to be here.
Speaker 1 (03:40):
Now. You're expert in drilling engineering, and so I have
a lot of questions for you that I really want
to drill into but intended. Yeah, can you talk to
us a little bit about what are some of the
challenges that you run into when you try to drill
into the ground.
Speaker 2 (03:55):
Well, we drill into the ground to explore and produce
oil and gosh, but also to explore and produce geothermal heat,
to store CO two and waste underground. Sometimes even build
repositories for nuclear waste that could be stored underground. So
different wells have different challenges. Formations are unconsolidated. That means
(04:16):
that they're not holding together right as a problem with
the stability of the well board that you could sometimes see.
Speaker 1 (04:22):
Okay, the first challenge in digging a really deep hole
is that deep holes don't want to stay holes for
very long. They tend to collapse. Like deferend Or compares
it to trying to dig a hole in the sand
at the beach.
Speaker 2 (04:36):
If you've ever been digging a hole on the beach
as a kid, you get very frustrated, right, because will
you want to drill the deepest hole possible, right, go
to the center of the earth, right, and you're thwarted
by the fact that you can only get to a
certain depth and no deeper right.
Speaker 3 (04:51):
Right.
Speaker 1 (04:52):
So that happens even in solid rock.
Speaker 2 (04:54):
Even in solid rock, I mean, when you drill a borehole,
what the Earth wants to do is close that borehole.
Speaker 1 (04:59):
Again, what do you mean that nature wants to close
the hole?
Speaker 2 (05:03):
Well, in the earth, right, you have stresses acting on
the borehole. The weight of the rock on top is
the vertical stress, and then there are horizontal stresses because
of tectonic movements, and those stresses act on the borehole
and they would collapse the borehole and you would lose
it eventually.
Speaker 1 (05:19):
So, just like digging a hole in the sand at
the beach, eventually deep holes collapse. Even when you're digging
through solid rock. Eventually, the sheer weight of all the
rock around your hole is going to want to close
your hole. There is a clever solution for that.
Speaker 2 (05:37):
So we need to stabilize the hole as we're drilling it.
We typically do that by circulating a drilling fluid that
provides kind of hydrostatic pressure to keep the borehole open
it meaning.
Speaker 1 (05:48):
You fill it with like water or oil.
Speaker 2 (05:51):
Water or oil that we can change the density of.
So we have the ability to change the density and
thereby the hydrostatic pressure that is being exerted onto the
poorhole wall.
Speaker 1 (06:01):
And that prevents the whole from caving in.
Speaker 2 (06:03):
That prevents the hole from collapsing.
Speaker 1 (06:06):
The other thing that makes being really deep whole heart
is temperature.
Speaker 2 (06:11):
In the center of the Earth, the temperature is six
thousand kelvin. It's the same temperature as the surface of
the Sun. The sun, of course, at its core is
millions of degreas, but the surface of the Sun is
about six thousand calvin And that's also the temperature in
the center of the Earth.
Speaker 1 (06:29):
Wow.
Speaker 2 (06:30):
And then there's a temperature gradient going to the outside.
Speaker 1 (06:33):
Meaning six thousand degrees of the center. But it gets
cooler as you go up to the surface.
Speaker 2 (06:37):
Yep. But the deeper you go into the Earth, the
higher the temperature.
Speaker 1 (06:41):
And why is the earth hot inside.
Speaker 2 (06:42):
It's because of the formation of the Earth. So what
we call primordial heat, heat that got trapped when the
Earth formed.
Speaker 1 (06:50):
So the Earth is hot inside, which is a little
odd to think about because which is the giant rock
floating out in the coldness of space? So where did
all that heat come from? Well, it came from two places,
according to doctor Van Ord. Number one, when the Earth
was formed, meaning when all those rocks and dust in
the early Solar systems scrunched together to form the Earth.
(07:12):
The scrunching generated a lot of heat, and also the
Earth kick getting hit by asteroids and giant rocks that
were zooming around the early Solar System. It's sort of
like if you take a mass of clay and you
beat it with your hands that were mallet Eventually it
heats up, and that's what happened to the Earth. In fact,
at some point the Earth was so hot it was
(07:32):
just a big ball of lava. And number two, the
Earth is also hot because there are radioactive elements inside
the Earth, like uranium and plutonium that are decaying, essentially
nuking the Earth from the inside. So as you dig deeper,
it gets hotter. How hot here's how doctor Van Ord
(07:53):
puts it.
Speaker 2 (07:55):
The Earth is a really good insulator. The amount of
heat that it chops is obsolutely massive. It's an amazing
amount of heat is phenomenal. And even though Earth radiates
heat into cold space all the time, to give you
a comparison, if you look at all the energy that
humanity uses around the world at any given point in time,
(08:16):
it's about fifteen tertra wats, and the Earth radiates into
the space about fifty terrawatts of heat energy all the time.
Speaker 1 (08:24):
Oh wow.
Speaker 2 (08:25):
Even then with that phenomenal amount of energy that it loses,
even over forty billion years, it has hardly lost any
significant amount of heat.
Speaker 1 (08:34):
So it's like we have a little sun almost at
the center of the Earth.
Speaker 2 (08:38):
So we call that kind of the heat beneath our feet.
Speaker 1 (08:42):
What that means is that as you dig deeper, it
gets horder. How hard it gets depends on where you
make the hole, but generally speaking, near the surface, digging
a hole gets harder about fifteen degrees celsius for each
kilometer you go down. So at the Cola super borehole
in Russia, the deepest humans I've ever dug, they reach
temperatures of one hundred and eighty degrees celsius or around
(09:06):
three hundred and fifty six fahrenheit, which is around the
temperature you would say you're oven two to cook roast beef. Now,
those are the two main reasons digging hole is hard.
There are other reasons too, like pressure.
Speaker 2 (09:20):
We need to deal with not only hort temperatures but
also high pressures. So not only does the temperature get higher,
the pressure gets higher as well.
Speaker 1 (09:27):
So whatever you put down there basically gets squished. Yeah.
Speaker 2 (09:32):
As you get deeper and deeper and the temperatures get higher,
and the pressures get higher, and the rocks get harder.
Speaker 1 (09:38):
Waight the rocks get harder.
Speaker 2 (09:40):
Yeah, because of again that weight of the overlying informations.
The rocks start to consolidate, and then they also start
to change under the influence of pressure and temperature.
Speaker 1 (09:49):
Oh, they get more dense.
Speaker 2 (09:51):
Yeah, really hard stuff to drill.
Speaker 1 (09:55):
Also, when you're drilling under the ground, you're kind of
drilling blind. Example, you might accidentally hit some lava.
Speaker 2 (10:04):
That's generally not good, but it has happened. In Iceland,
they drilled a well called the ice Iceland Deep Drilling
Project at a price called Kravla. They actually drilled into
an active volcano, So they actually drilled into a.
Speaker 1 (10:19):
Magma chamber on purpose or by accident.
Speaker 2 (10:22):
By accident, so they encountered a nine hundred degrees centigrade
temperatures well over two thousand degrees fahrenheit. There's a ridiculous
amount of temperature that we saw there. Now, luckily the
chamber was not pressurized and low and behold, they were
able to temporarily keep that hole and actually briefly turn
it into a geothermal well which was producing kind of
(10:44):
thirty five megawatts of power. Wow, and you can run
a small city of that, right, It's pretty amazing.
Speaker 1 (10:51):
And then, of course what makes digging a really deep
hole heart is that you have to dig through solid rock.
So when we come back, we'll talk to a different
professional hole digger about the different technologies we use to
dig through rock. They involve diamonds, lasers, and microwaves. Stay
with us, you're listening to sign stuff. Hey, welcome back. Okay,
(11:23):
we talked about why drilling a deep hole is hard,
and in the next section we're going to talk about
whether it's possible to dig a hole to the center
of the Earth. But first I was curious to learn
how exactly you dig a hole that deep, what's the
technology you use? And let me just preview this by saying,
there are going to be lasers involved, big lasers to
(11:45):
guide us through this. I talked to another person whose
job it is to dig deep holes.
Speaker 3 (11:49):
So my name is Roman Short. I'm associate professor here
at Texas A and M University. I work a lot
in drilling, drilling automation optimization for subservice energy.
Speaker 1 (11:58):
Well, thanks for joining us, doctor sh So how do
you drill a hole in the ground through rock.
Speaker 3 (12:03):
The way that you typically do it? You need a
really big drill, A drilling rig comes on site and
same thing like that drill bit that you're using in
your wall. Just imagine a really long drill bit. Tap
top start rotating it, the bottom rotates eventually, and then
you lower down until you hit the ground and then
the bit is a failing rock.
Speaker 1 (12:20):
Yeah, it's literally just the drill, but imagine one that's
nine to ten inches wide and that sits at the
end of a ten kilometer long steel rod. Now I
have a drill at home, and when I drill, the
bits that get cut spiral up the drill and usually
fall to the ground. But in a ten kilometer deep hole,
(12:41):
what happens to all the stuff you drill out? Here's
what doctor Shore said.
Speaker 3 (12:46):
That's another use for that drilling fluid. So that water
you pump it down the drill pipe comes out the
drill bit, and it captures all those pieces of rock
and then moves them back up to the surface. So
you're helping clean this well bore using this fluid. I'll
also provide you stability for that whole. So it's like
kind of cool how that drilling mud use does build
things at once.
Speaker 1 (13:06):
Okay, I know that's the second time we mentioned this
drilling fluid, but trust me, it's going to be important later. Now,
is it a drill bit like the drill I have
at home, like the spiral metal thing, or it's similar.
Speaker 3 (13:18):
So rock is a little bit harder than the dry
wall or the word that you typically drill through. So
a lot of these rodary drill bits now use that
technology called polycrystaline diamond. So there's these little tiny diamond
cutters that are embedded into this bigger spiral. Effectively, you
can think of your spiral drill bit. Just think of that,
but much larger, and you have little tiny diamond cutters
(13:39):
along the edges of each of those teeth, so they
act like teeth as they're rotating.
Speaker 1 (13:44):
Yes, that's right. To dig to rock, you use diamonds.
Speaker 3 (13:48):
Yeah, so it's an artificial diamond. You put that under
ground and that can drill for hundreds to thousands of feet,
sometimes even miles.
Speaker 1 (13:56):
Yeah, diamonds are pretty cool. But contrary to what they
say or not forever, the problem with the drill, doctor
Shore says is that they wear out, even the ones
with diamonds, and replacing something at the bottom of a
ten kilometer hole is not easy. So scientists of engineers
have been coming up with new technologies to dig or
(14:17):
blast their way through rock. And you said there's other
technologies like using lasers. Yep, you describe some of those exactly.
Speaker 3 (14:25):
So what I've been talking about so far is called
rotary drilling. Other technologies that people have been looking at
is can you use that's say, a microwave to literally
firmly degrade the rock and melt it, burn it out
of the way.
Speaker 1 (14:39):
Wait, just shoot, just shoot the rock with Yeah.
Speaker 3 (14:43):
Just with the microwave being you're just like not quite
star star trek Pew pew. But it's the same journal. Yes,
like you just imagine this energy being forced pointed at
this rock.
Speaker 1 (14:53):
What that works? Like if I shoot a microwave at
a rock, it'll actually disintegrate eventually.
Speaker 3 (14:59):
Yes, it takes a lot of energy, but it does.
It turns into vapor. So it just turns into a
gas and then you can if you just circulate air
just comes out as as a gasified.
Speaker 1 (15:09):
Rock vaporized rock. Whoa, Because the microwaves are hitting the
rock and that's basically blowing off the rock atoms from
the surface.
Speaker 3 (15:19):
So the atoms themselves stay constant. I think it's breaking
a lot of the molecular bonds and also some of
the weaker bonds that are between let's say a different
molecules different grains.
Speaker 1 (15:28):
So one technology they're exploring is to zap the rock
with a microwave, just like the one you use at
home to reheat your food, well not quite like the
one in your kitchen.
Speaker 3 (15:39):
So but the problem with this is how do you
generate microwaves that are high enough energy close enough to
that rock surface. So, like your microwave at home is
a kilowat and that's what you use to heat your food.
In order to melt rock, you need a thousand times
more power, give or take like a million what, yeah, exactly,
(16:00):
so a million wats. There are people trying to figure
out ways to take out washing machine and make it
really skiy. So you just stack it up so it
all fits in. It could work. We'll see what they
come up with over the next time.
Speaker 1 (16:11):
And you said lasers or is that the same technology?
Speaker 3 (16:13):
Oh, lasers are another thing that people are thinking about.
This is now on the visible light spectrum. Now that
laser hits the rock, same thing, burning it melts it.
Speaker 1 (16:23):
That's right. Forget drills. There's a way to shoot your
way to the center of the Earth. And for anyone
having flashbacks to the depth Star laser in the movie
Star Wars, don't worry. These are not that big, just
enough to cut a small hole ten kilometers into the ground. Now,
are lasers and microwaves better than drills? I asked doctor
(16:43):
sure this question, and these methods laser, MicroID that's going
to be more efficient or better than a drill.
Speaker 3 (16:51):
So it may be faster because your typical rotary drill
bits if you're looking at easy to drill rock, So
just a nice easy sandstone, you can drill at hundreds
of feet per hour, So if you want to drill
a mile, it'll take maybe a day if you're drilling
it harder rock. So I just say you're drilling into
granite or quartz sites, that rock is a lot harder.
(17:14):
It's the same type of rock that use for your countertop.
So now if you have a rock like this, erotary
drill bit could only go at tens of feet per hour,
so that same mile might take a week or maybe
I'd say even a month. Sometimes with laser and microwave,
it doesn't care what the rock is. It just sees matter,
so it's able to go through any hardness of material
(17:35):
use it just by blasting it with energy. You just
maybe crank up the energy intensity a little bit too,
because if you have more material there.
Speaker 1 (17:41):
Whoah, well, when they build it, they should definitely build
in some sound effects like pew pew pew.
Speaker 3 (17:47):
Great exactly that or maybe well, I don't know. The
usually the depth star sud might be a little.
Speaker 1 (17:53):
Bit okay, So to recap, the deepest holes in the
world have all been dug with drills that make holes
about nine inches wide, which is about the diameter of
a soccer ball at the end of a ten kilometer
or more steel tube or rod, and you typically fill
that tube with something drilling engineers called mud, which is
(18:16):
basically water with things like clay or other ceramics added
to make it heavier to keep the hole from collapsing. Now,
the question is how deep can you make that hole?
Can you make it to the center of the earth.
When we come back, we're going to answer that question.
So stay with us. You're listening to sign stuff. Welcome back. Okay,
(18:45):
we're now going to get to the question of whether
it's possible to dig to the center of the earth.
We talked about why it's hard to dig really deep
holes and the technologies humans used to dig them. Now
the question is what's the deepest hole we could make.
I asked this question to both of our experts, and
they disagree. They each gave a different answer. Here's what
(19:07):
doctor van Ord said. Can you take us on a journey.
So let's say I start digging from the surface. What
am I going to be seeing?
Speaker 2 (19:14):
Okay, so the outer part of the earth, which is
what we call the crust, is relatively thin zero to
seventy zero to one hundred kilometers deep. But remember that
the deepest we've ever drilled, which is cola super deep
hole in Russia, only went about thirteen kilometers deep. So
you're still only a small ways into the crust. If
(19:35):
the rest of the crust is one hundred kilometers.
Speaker 1 (19:37):
Right, what is the crust made out of?
Speaker 2 (19:39):
Crust is made out of aluminum and manganese silicates, so
that's sandstone and limestone, and then deeper down when you
get the basement rock kind of granite and buzzle, and
then when you go through the crust you go to
the mantle.
Speaker 1 (19:51):
All right, here, it's fourteen A side note, I think
most people know that the inside of the Earth is
made up of layers, but maybe not a lot of
people know why it layers. Remember I said earlier that
after the Earth formed, it was just a big ball
of lava. Well, when it was in that fluid state,
all the things in it started to settle. The heaviest
elements sank to the bottom. In this case, it was
(20:13):
mostly iron. Then the heavier rocks hung around the middle
and the lighter rocks floated to the top. I usually
describe it as a boba drink, or like making sangria,
where the boba or the fruit sink to the bottom,
the ice floats to the top, and most of the
liquid hangs out in the middle. That's why the earth
is made up of layers, but in this case there's
(20:33):
circular layers because the earth is round. Okay, back to
the conversation.
Speaker 2 (20:39):
And then below the crust is the mantle. The mantle
is about three thousand kilometers.
Speaker 1 (20:44):
So the mantle is also rock, but it's still pretty
hard and hot.
Speaker 2 (20:48):
Yeah, and the temperatures start to become higher and higher, right,
it becomes thousands of the grease centigrade and fahrenheit as
we go towards the core of the earth.
Speaker 1 (20:57):
So after the crust is a mantle. This is kind
of the meat of the earth, if Earth was like
a fruit. The mantle is about two thousand, eight hundred
kilometers thick, and it's also solid rock, but because of
the temperature and pressure, the rock actually flows. The rocks
inside the mantle are constantly moving. They heat up when
they get close to the center of the earth, which
(21:19):
makes them expand, and so they float up to the crust.
Then they cool down and sink again. It's kind of
what happens in a lava lamp or a pot of
boiling water where you see the water churning up and down.
And it's that constant movement that pushes the crust around,
moving all the continents over millions of years. And as
(21:39):
sucufan Ort said, the mantle gets pretty hot pretty fast.
At about five hundred kilometers down, the temperature is almost
two thousand degrees celsius. And at the bottom of the mantle,
or almost three thousand kilometers deep, the temperature is thirty
five hundred degrees celsius. That's where you get to the
Earth's core.
Speaker 2 (22:01):
The outer core is liquid iron and nickel, and then
the core itself. The scientists are still investigating that. They
think it's either solid or it's plasma behaving as a solid.
That is kind of six thousand calvins. So you wouldn't
be able to drill a borehole through that. In fact,
if you get to the outer core, right, it's just
a liquid of iron. Any steel tools that you would
(22:22):
use would melt going through there.
Speaker 1 (22:26):
Basically, Yeah, if you took a bunch of iron and
melted it and then you try to dig through a
pool of liquid iron.
Speaker 2 (22:32):
Yeah, I don't think you can stabilize a borehole at all.
Speaker 1 (22:36):
Well, you know, I've heard that at the center of
the Earth there are dinosaurs in kin Kong.
Speaker 2 (22:40):
Creatures not from scientists.
Speaker 1 (22:44):
So the outer part of Earth's core is a layer
of molten iron that's about five thousand degrees celsius. And
then when you get to the bottom or to the
center of the Earth, it's a solid ball of iron
six thousand degrees celsius. Doctor event Or doesn't think we
could ever even get there. Well, let's maybe put on
(23:05):
our imagination hads or creative hats, and let's say that
if for some reason we needed to dig to the
center of the earth, what would be required? How would
you do it? And I gave you a trillion dollars?
Now it wouldn't be enough, all right, ten trillion dollars.
Now there's no money enough right now because the technology
(23:27):
doesn't exist to do it. What would be the things
that fail?
Speaker 2 (23:32):
Well, right now, we require kind of boattholes, right that
we need to stabilize on our way down. And you
just run out of the ability to do that as
you get deeper and deeper. As I said, you need
to come up with some kind of death Star weapon, right,
some kind of high powered laser where you could just
blash your way through the core of the Earth. But
if you do that, I think you'll blow up the
(23:52):
Earth in the process as well as the death Star
is meant to do.
Speaker 1 (23:57):
What's the problem? The rockets too hard or too hot both.
Speaker 2 (24:01):
We have to go through a lot of hard rock
initially that is a very very high temperature.
Speaker 1 (24:06):
What if I somehow, I mean I gave you a
lot of money and some we figure out how to
make things at a diamond, which is the hardest thing
we know about. Right, What if I made a borehole
pipe that was made out of diamonds and SOMEO Now
all my tools and cables were made out of diamonds.
Speaker 2 (24:21):
No, it's a diamond, diamonds decomposed I think at around
twelve hundred degrees cent grade. I might be wrong there,
but you can actually burn up a diamond. So the
diamonds would eventually fail as well. What and you end
up with just a bunch of CO two. It just
would revert back to carbon and then you just burn
the carbon.
Speaker 1 (24:39):
Okay, I checked this, and it's true. Diamonds in the
presence of air or oxygen burn into CO two at
around nine hundred degrees celsius, which would only get you
down to about fifty kilometers or zero point four percent
of the way to the center of the Earth. In
other words, when you get down to about fifty kilometers
(24:59):
now into the earth, your diamond tools would spontaneously burst
into flames. And even if you stucked all the oxygen out,
your diamond tools would melt at around fifteen hundred kilometers
or about a quarter of the way down to the
center of the earth. Wait, even if I build everything
out of diamonds, at some point, it would just evaporate. Yeah,
(25:21):
so we wouldn't get very far even into the mantle.
Speaker 2 (25:24):
No, I personally think it'll be a very long time
before we can get out of the crust and into
the mantle.
Speaker 1 (25:32):
All right, So our dream of going to the center
of the Earth just went up and smoke right along
with our cool diamond drills, or did they. I decided
to ask doctor Share the same question, and he came
up with a possible way we might be able to
get down to the Earth's core. And the answer is
(25:52):
to use the liquid that you fill your hole with,
the one keeping the hole from collapsing as a coolant.
This is what they do. When you're drilling and you
hit a pocket of lava or magma.
Speaker 3 (26:05):
The cool thing is that drill bit can drill into
that magma. The reason why is the water so that
fluid that you're using is cooling the rock. So that
layer of magma now it sees that fluid first and
it solidifies. In Hawaii and in Iceland, they have drilled
through magma dikes. Sometimes it's been on purpose, sometimes it's
(26:25):
been not and they were able to drill through it.
It cools off because the water is absorbed all that heat.
So you have this little tiny layer now around your
hole that's solid rock and then it's magma.
Speaker 1 (26:37):
And it doesn't remelt.
Speaker 3 (26:39):
As long as you're flowing the water. So as long
as you're still pumping and pumping cool fluid, now it
stays water.
Speaker 1 (26:45):
To you're building a tunnel through lava.
Speaker 3 (26:49):
H as long as you continue flowing fluid and cooling,
that whole stays stable.
Speaker 2 (26:53):
Right.
Speaker 3 (26:54):
But now you can keep going even deeper than that.
It's imagine we keep cool they canna say we're using
liquid nitrogen or something. We can now technically keep making
this whole.
Speaker 1 (27:02):
This is the mantle, right, Yes, for an hour, and
they're layer beneath the crust, and.
Speaker 3 (27:06):
The temperatures are going to be increasing through thousands of
degrees fahrenheit.
Speaker 1 (27:10):
Now is that survivable? Because now you're talking about thousands
of degrees and you know the surfaces of the sun
is six thousand degrees fahrenheit. Is your drill bit still intact?
Speaker 3 (27:22):
The drill bit itself would have melted hours ago. Part
of the reason why we're still able to keep drilling
is because we have this cool layer of rock that's
solidified around us. So if we somehow found a way
to continue pumping some form of cool fluid, maybe liquid nitrogen,
Maybe we find a fluid where it reacts and it
(27:42):
absorbs heat, so you can pump down let's say two materials.
They combine and become extremely cold. So as long as
the rock is solid, the bit will be fine because
the bit melts right about the same temperature as the rock.
Speaker 1 (27:55):
Right, So if we can keep our drill cool, maybe
using some kind of system, you could technically keep digging. Now,
this is an extremely difficult problem, but maybe technically possible.
We're kind of using our imagination here, but that would
get us to the core.
Speaker 3 (28:14):
Eventually, after about two thousand miles, you've now hit the
outer core. The outer core now is still liquid, it
is now extremely hot, so four thousand and five thousand
degrees fahrenheit. And then at the very center, now you
have a solid inner core. That solid inner core is
not mostly metal, and it's spinning, and it's spinning at
(28:35):
a different speed than the surface of the Earth. So
the reason why we as a planet have a magnetic
field is the center of the Earth is spinning. The
outside of the Earth is stationary, so it's a big dynamo.
So that is what is generating this magnetic field that
protects the planet from all this solar radiation.
Speaker 1 (28:52):
It's a spinning magnet in the center of the Earth exactly.
Speaker 3 (28:55):
Which is why Mars does not have a magnetic field anymore,
is because their core became solid and it stopped rotating
at some point several billion years ago.
Speaker 1 (29:06):
Whoa, but wait, but trying to dig through molten metal iron.
Speaker 3 (29:12):
That's going to become even harder and again it's moving,
which is the bigger problem. So we have this hole
that's cooled around us. We're still somehow cooling it. I
don't know how. And we've now hit this moving metal ball.
Where we touch it, it's going to move away. And
now if we start making a hole, it's going to
start dragging our hole with it because it's moving in
(29:33):
relation to us. So how would we continue drilling at
that point? I don't know.
Speaker 1 (29:40):
Well what I have an idea? What if we drill
from the north pole?
Speaker 3 (29:44):
That could actually work. But if you find the pole
of that inner core, then yes, that would work.
Speaker 1 (29:49):
Oh, you'd have to hit it just right in the
spin axis in the inner.
Speaker 3 (29:55):
Core exactly, so it has a rock tube transition to
a metal tube. Now you're in solid metal, but around
you the core is thousands of degrees fahrenheit. So you
now need to have enough cooling that the inside of
your hole is one hundred degrees or couple hudgrees fahit.
So you may have to get creative and call NASA
because NASA has some really cool insulators.
Speaker 1 (30:16):
Yeah, hold on, let me call NASA right now. Actually
we do have it all night phone.
Speaker 3 (30:23):
Okay.
Speaker 1 (30:24):
So to recap, if you drill down from the north
or south poles, and if you can figure out a
way to super cool your whole as you dig down
through six thousand degrees celsius molten and solid iron, you
could technically drill down to the center of the Earth.
I feel like maybe we delved a little bit into
science fiction, a little bit or a lot of just
(30:46):
a little bit, But in your opinion, it's possible as
long as we have the right engineering.
Speaker 3 (30:52):
If we need to and we put our brains to it,
we probably could come up with aspects of a solution
that could work. Will we be able to cool against
six thousand degrees fahrenheit two thousand miles into the Earth's core?
Probably not, but should we find a way so. For
the geothermal industry today, what they're trying to do is
(31:13):
they're trying to find a way to drill down to
rock that is six hundred degrees fahrenheit.
Speaker 1 (31:18):
Okay, this brings us to one of the main reasons
why you would want to dig a deep hole in
the first place, geothermal energy, that is, using the energy
of the Earth as energy instead of oil or carbon.
Because this energy is free and it's clean, and you
don't have to go down that deep to get it.
(31:39):
Scientists think if we can get technology towards easy to
drill down to about twelve kilometers, which is about the
deepest we've ever dug. Then you could have geothermal wells everywhere.
Here's how doctor Shore describes it.
Speaker 3 (31:52):
I think someone's done the calculations, and there's enough heat
energy in the Earth in order to provide enough energy
for humanity for a hundred million years. So there is
a huge amount, but it's not unlimited. So it's now,
how do you sustainably pull out heat and make sure
you're not changing the geology significantly from that heat being removed.
(32:14):
I see, So there has to be a little bit
of thought put into it. But one hundred million of
years worth of energy sounds pretty good.
Speaker 1 (32:22):
And that sounds good to me too. So when you
hear politicians say drill, baby, drill, just make sure they
mean for geothermal energy. All right, I think we answered
today's question. What happens if you dig a hole to
the center of the earth. It might be possible to
do it, but you might not need to might not
be that deep. A solution to all of our problems
(32:44):
could be right beneath our feet. That is the whole truth.
Thanks for joining us. See you next time you've been
listening to science stuff. The production of iHeartRadio written and
produced by me or Hey Chham, edited by Rose Seguda,
executive producer Jerry Rowland, and audio engineer and mixer Ksey Pegram.
(33:07):
And you can follow me on social media. Just search
for PhD Comics and the name of your favorite platform.
Be sure to subscribe to sign stuff on the iHeartRadio app,
Apple Podcasts or wherever you get your podcasts, and please
tell your friends We'll be back next Wednesday with another episode.
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