Can You Drill Through Earth? | Through the Core - video Dailymotion

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00:00Planet Earth weighs about 6 sextillion tons.

00:04It has a surface area of 197 million square miles

00:09and a diameter of between 7,900 and 7,926 miles.

00:15If it were possible to drill through it,

00:18you'd pass through the crust, the mantle,

00:21the outer and inner cores,

00:23and then the same again in reverse.

00:26Would you make that journey?

00:31First off, what is Earth actually made of?

00:34At its simplest, it consists of crust,

00:36either oceanic or continental,

00:38with sections known as tectonic plates

00:40covering the entire surface.

00:42The crust is then always made of rock,

00:44but of different kinds of rocks in different places

00:46and at different layers.

00:48Below this topmost layer, there's the mantle,

00:50which is Earth's magma source.

00:52And then, finally, we have the core,

00:54both the inner and outer.

00:56The core is a thousand miles down,

00:58incredibly dense, and billions of years old.

01:01Here, at the heart of our planet,

01:03it's made of super-hot, super-dense iron and nickel,

01:06and temperatures can be more than 10,000 degrees Fahrenheit.

01:10We know, then, that inside the Earth

01:12isn't exactly a welcoming place,

01:14but nevertheless, humans are still intrigued

01:17by all that's below us.

01:19Ideas about the Earth perhaps being hollow

01:21and hosting unknown ecosystems

01:23have appeared in science fiction for a long time,

01:26but although hollow Earth theory doesn't actually hold up,

01:28there certainly are strange

01:30and genuine underground realms

01:32that are intriguing, even bewitching.

01:34The deepest known natural cave on Earth

01:36is Virovkina Cave in Eastern Europe.

01:38At about 10 miles long

01:40and more than 7,000 feet deep,

01:42it's an extreme and unique environment.

01:44If it were an ocean instead of a cave,

01:46its depth would put it firmly

01:48in what's known as the bathypelagic zone,

01:50with pressure hundreds of times greater

01:52than what's found at the surface.

01:54Unfortunately, and perhaps unsurprisingly,

01:56some explorers have died

01:58inside Virovkina Cave.

02:00Ultimately, though, it's very likely

02:02that Virovkina is even deeper than we currently know,

02:04and also that there are other,

02:06far deeper cave systems out there

02:08that haven't even been discovered yet.

02:10What really puts the scale of the Earth

02:12into perspective, however, is that in all cases

02:14we are still a long way away

02:16from reaching down into even Earth's

02:18second layer, the mantle,

02:20let alone further still to the core

02:22and out the other side.

02:24Do man-made caves offer any improvement?

02:26To some degree, yes.

02:28Virovkina Cave is about 1.3 miles deep,

02:30but the deepest mine in the world,

02:32the Mpana Gold Mine in South Africa,

02:34is almost double that,

02:36reaching 2.5 miles.

02:38If we abandon traversable underground systems,

02:40i.e. if we look at the deepest

02:42locations but ones that humans

02:44can't travel down into,

02:46then we come to what's truly the deepest

02:48man-made hole in the world.

02:50The Kola Superdeep Borehole in Russia.

02:52It is more than 7.6 miles deep,

02:54and is a real benchmark

02:56in the field, given that it was

02:58a drilling project conceived solely

03:00to see how deep it was possible

03:02to drill into the Earth's crust.

03:04Thankfully, the borehole is only about nine inches

03:06wide and is now sealed off,

03:08so there's no danger of anybody falling into it.

03:10But even if you did, you'd still,

03:12and again, be way off how deep

03:14you'd need to go to reach the core

03:16or to emerge out the other side.

03:18There's simply nothing on Earth

03:20currently that takes us even close.

03:22The middle of the core

03:24is about 4,000 miles below the surface,

03:26meaning we'd need to dig

03:28an 8,000 mile tunnel

03:30to punch through to the other side of our planet.

03:32The longest still-in-use tunnel in general,

03:34going across the Earth and not down

03:36into it, is the Delaware Aqueduct

03:38in the U.S., but it is only about

03:4085 miles long.

03:42We'd need, then, almost 100 times more,

03:44and it would all have to

03:46withstand untold pressure and temperature.

03:48In reality, drilling

03:50through the Earth, as simple as it sounds,

03:52isn't something that's yet technologically

03:54possible for humanity.

03:56But say that money is no object,

03:58some kind of tech solution is discovered,

04:00and that the entirety of our species

04:02has, for some reason, decided that we

04:04really, really need to create this passage.

04:06What then? First,

04:08we'd need a material not only to build

04:10the tunnel out of, but also our

04:12drilling apparatus. Again, that

04:14material would need to be capable of withstanding

04:16extreme temperatures and depth.

04:18There are those highs of around 10,000

04:20degrees Fahrenheit, while the pressure

04:22would top out at about 3.6 million

04:24atmospheres. For context,

04:26the deepest known point in the ocean,

04:28Challenger Deep in the Marianas Trench,

04:30has about 1,000 atmospheres

04:32of pressure. Even it just isn't

04:34comparable. When thinking of material that

04:36could work, you might immediately go to

04:38diamond, which can cope with up to

04:40five times as much for the pressure.

04:42However, the melting point of diamond

04:44is a paltry 7,200 degrees

04:46Fahrenheit, so it would inevitably

04:48melt partway through our journey.

04:50Which is a shame, because a diamond

04:52drill for a diamond tunnel seems

04:54like it would be a pretty cool thing.

04:56Scientists have researched

04:58this specific problem, however, and before

05:00come up with a new material that combines

05:02hafnium, nitrogen, and carbon

05:04– hafnium being a lesser

05:06known transition metal. But even

05:08this fares only slightly better

05:10than diamond, with a melting point

05:12of 7,460 degrees.

05:14Even our most thoroughly

05:16researched custom materials, then,

05:18only get us to the edge of the

05:20Earth's core. And, of course, only in

05:22theory. Staging any kind

05:24of practical test for what we'd need

05:26– some kind of new wonder metal or

05:28element – is basically impossible.

05:30But, hypothetically, say we do have

05:32such a material, what other obstacles

05:34would our Earth-splitting tunnel face?

05:36The consistency, or rather

05:38inconsistency, of Earth is another

05:40problem. Drilling through rock is one

05:42thing, and in fact is the only thing we

05:44know… but eventually you get to the

05:46mantle, full of heavy, molten lava.

05:48So, in carving our tunnel, we would need

05:50a craft that can drill through the ground,

05:52yes, but it would then need to become

05:54the most extreme submarine ever,

05:56capable of wading through magma.

05:58And then it would need all of those

06:00temperature and pressure resistance

06:02qualities in order to survive the core.

06:04Anything that could do all of that

06:06would be some machine. But,

06:08hypothetically, say we do have

06:10such a machine. Next, we'd have

06:12severe navigation problems, since there

06:14would be literally zero visibility

06:16for the very vast majority of our

06:18mission. And then, the heat

06:20remains a major issue, even with an

06:22indestructible, hypothetical wonder material.

06:24Because, just because something won't

06:26melt when subjected to thousands of

06:28degrees, doesn't mean it won't get

06:30so hot inside that humans can't

06:32survive. The conditions on the inside

06:34of our tunnel through Earth would be

06:36hellish. More than that, they would

06:38boil you alive. So, here's hoping

06:40we develop some ultra-advanced climate

06:42control systems, as well. But maybe we

06:44have all of that, too. We've got our

06:46tunnel made from an impossible material,

06:48the incredible machine needed to actually

06:50build it, some super-advanced air

06:52conditioning, and some sort of vehicle

06:54that can withstand the entire journey.

06:56How long would the journey take?

06:58Again, we have 8,000 miles

07:00to traverse. The fastest train in

07:02the world is currently the Shanghai-Maglev

07:04in China, which travels at 286

07:06miles per hour. At that constant

07:08speed, we're talking nearly

07:1028 hours to tunnel through the planet,

07:12which is longer than it would take to just fly

07:14between the two points on an airplane.

07:16But here's where one final and crucial

07:18consideration comes into play. Because when

07:20drilling through the Earth, we're actually not beholden

07:22by how fast trains, or anything,

07:24can move on the surface. The force of gravity

07:26messes all that up. As it's

07:28pulling everything directly towards the core

07:30all the time, we know that the journey to

07:32the centre of the Earth would, in reality, be

07:34much shorter. It would potentially take

07:36less than an hour. However, there

07:38is a catch. And a big one. Because

07:40with gravity pulling you in, how can you ever

07:42hope to get away? Your journey

07:44from the centre of the Earth, the second half

07:46in terms of plane distance, just isn't

07:48going to happen. Unless you manage

07:50to conduct the entire journey also in a

07:52total vacuum, then no matter what you do,

07:54gravity will always mean that

07:56it's actually impossible for you to leave.

07:58So, even if you've managed to build a

08:00tunnel to withstand the pressure, which means

08:02you haven't been crushed, you'd still find

08:04yourself hopelessly cast adrift,

08:06trapped in a tomb of your own making,

08:08waiting to starve and eventually

08:10die. Which isn't really

08:12the ending we were hoping for. But what do you

08:14think? Would digging a tunnel through the Earth

08:16be worthwhile? Or would it just be completely

08:18absurd, even if it were possible?

08:20For now, the want to explore

08:22is usually to be applauded. But sometimes,

08:24even the most fundamental laws

08:26of physics are telling you that it's probably

08:28a bad idea. And that's

08:30what would happen if you drilled through

08:32the Earth. What do you think?

08:34Is there anything we missed? Let us know

08:36in the comments, check out these other clips

08:38from Unveiled, and make sure you subscribe

08:40and ring the bell for our latest content.

Can You Drill Through Earth? | Through the Core

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