Hole through the Earth Good or bad

It has often been postulated that a hole dug through the center of the Earth, from some location in the United States, would land the burrower in China. But what would be the effects of such a hole? Would jumping through really land one on the other side of the world?

Forget for a second that the project is virtually impossible, would probably cause catastrophic consequences to the planet, and may get you eaten by a T. Rex. Bugs bunny and that ilk aside, the crust (outer covering of the earth; like enamel on your teeth) has never been fully breached. The deepest mine in the world, at this time, is in South Africa and is a reported 3585 meters (or about 2.2 miles) deep. The deepest shaft ever drilled into the Earth is about 15 km (9.3 miles.) The crust extends approximately 35 -70 km below the Earth’s surface. But, lets forget about these facts for the sake of speculation.

If such a hole were excavated, would we survive the trip?, would we need parachutes as we shot through the other side?, or would their need to be a rope to pull us out? Well, lets first have a look at gravity. Gravity is the interaction between two objects. It is measured via the masses of the two objects and the distance between them. Every object in the universe is attracted to every other object via gravity. However, the proximity of the object’s centers determines the strength of the attraction. So, your center (on most people somewhere around their stomach) and the Earth’s center are getting closer. The attraction gets stronger and stronger. You are sucked violently toward the Earth’s core and then … you can go no further. You would need someone on the other end of a rope to pull you out. Maybe you could invent some type of antigravity device that would propel you out of the core and then you would probably have to turn it off and use a parachute after you blasted through the other side.

Another factor would probably be the Earth’s magnetic force in consort with your own. However, I think that gravity would be a much stronger force (as demonstrated by the fact that your magnetism is dwarfed significantly by the Earth.)

So there you have it. A difficult problem solved. Any further thoughts?

19 thoughts on “Hole through the Earth Good or bad”

  1. The what if in this is very difficult because gravity doesn’t pull you towards the center of the earth, rather it pulls you towards its mass. So if you made a hole that went perfectly through the center of the earth, and ignoring that the earth isn’t a perfect sphere, then as you approach the center of earth via your tunnel then you have equal amounts of the earth in every direction. You would feel the same amount of gravity but rather than all of it pulling you down, you’d feel the pull in all directions. The lucky thing for you is that you are already traveling at terminal velocity at this point, this assumes the tunnel was not constructed in a manner to allow a vacuum environment, so you’ll pass through the center of the earth without getting stuck. As you begin to rise up the other side of the tunnel gravity from the section of the planet above you will continue to pull you forward, but more and more of the planet is behind you trying to pull you towards it, slowing you down. Chances are that you would not have enough velocity moving forward to get to the end of the tunnel, and you would stop moving toward the end and begin to fall toward the end of tunnel from which you entered. Of couse since you didn’t have enough force to get through the whole tunnel you are not going to have enough force to make it back to where you entered from, so you become a human yo-yo until you finally come a stop at the center of the tunnel in the center of the earth held in the middle by equal parts of the earth’s mass pulling you in every direction equally. You are a puppet but without the strings. Now assuming the tunnel is constructed in such a manner to allow a vacuum environment inside the tunnel you wouldn’t hit terminal velocity and your chances of getting to the other side successfully increase significantly. Or those are my thoughts on the subject anyways.

  2. This is a well-known mathematical problem, and I’m afraid that you’ve got the wrong answer. The key thing to know is that a point inside a spherical shell experiences no force at all due to the gravitational attraction of the shell. How does this apply to your problem? A sphere can be thought of as a whole lot of concentric spherical shells all inside each other, kind of like a pea inside a hazel nut inside a walnut inside a tennis ball inside a softball inside a basket ball inside a … you get the idea. When you stand on the earth’s surface you experience gravity due to all the “shells” that make up the earth. When you are at the centre of the earth, you experience no gravity due to the earth at all, because you are inside all the shells. When you are part way to the centre, you experience a fraction of the gravity at the surface. In fact, the force you experience due to gravity is proportional to the distance from the earth’s centre. These are exactly the conditions needed for “simple harmonic motion”, which is the same sort of motion as a pendulum. And that’s exactly what would happen if you jumped into that hole. You would fall faster and faster as you approached the centre, and as you passed it you would begin slowing down, until you reached a speed of zero at the surface on the other side. You could step off there, but if you didn’t you would begin to fall back again. The journey each way would take about 42 minutes. What’s even more interesting is that the journey time is the same for any straight tunnel through the earth, even if it doesn’t go through the earth’s centre.

  3. @Chris

    Stumblerz is not entirely wrong, the post was more of a fun view of the whole paradox.

    Here is what I have to say —

    Ask yourself what happens when a child plays on a swing (just sitting on the swing after getting it going high, not pumping). Gravity is obviously the force involved in both cases. Gravity pulls toward the center of the earth. The swing picks up speed while it is falling towards the center (the force due to gravity INCREASES the kinetic energy) but once it passes the bottom the kinetic energy keeps it moving and it starts to move away from the center of the earth. Now the force
    due to gravity DECREASES the kinetic energy. The child then reaches the top of the swing’s arc (all of the kinetic energy is gone — converted to potential energy due to height) and starts to fall back again.
    Hope this helps.

  4. the object you drop will yo-yo back and forth on both sides of the center of the earth,
    until all the kinetic energy is gone, and the object will then be suspended at the center. (Of course, since the center of the earth
    is molten, this is a completely academic question, but interesting to think about anyway…)

  5. here is another possible answer –

    Theoretically, the object would stop at the center of the Earth since everything “falls” towards that point. It is the point at which objects are attracted, so the thing you drop could get not past that point. Of course, it depends on the speed you drop/throw it.

  6. @Lucky – If someone was traveling at the speed of light when they entered the hole then their momentum would carry them back out the other side and continue going. Now, if you took a mass that was big enough and did the same thing it would result in the same outcome as jumping in the hole on Earth.
    The closer you get to the the center of any object the less it’s gravity affects you. Take the moon for example. You are on the surface of the moon. It affects you much less than being on the surface of the Earth. When you are the same distance to the center of the Earth as you are to the center of the moon (If the density/mass was equal) then you would have exactly the same gravitational force being applied to your body regardless of your initial speed. (i.e. Jump up with little effort then jump up with a lot of effort. You will rise off the ground more with the most effort, but gravity is still affecting you the same.
    Anyway, a couple of the previous comments were “point on”. If everything was perfect then you would have a yo-yo or pendulum effect. Just because you are going through the center of the object wouldn’t change the end results. You’d end up stopping in the middle just like swinging. You end up at the middle of your swing arc.
    Merry Christmas!

  7. you are all $%$%%$, with one or two exceptions! the simple harmonic motion is the correct solution. that, of course, is neglecting wind resistance. and for the gentleman who said that the transit time is the same for any tunnel, even those that don’t transit the core . . . you couldn’t make it through a tunnel that didn’t go through the core, because the earth’s center would attract you and make you hit the inside wall.

    why is this a question? have none of you taken 10th grade physics?

    Fixed by Stumblerz –

    I have fixed your comment, you need manners and respect. Next time you call someone retarded, look at yourself in a mirror and try to distinguish what gives you the right to call someone retarded and what is the difference between yourself and a retarded. I must say you are still young.

  8. Has anyone speculated about how the answer to this question might differ with other planets in our solar system? In particular, Neptune and Uranus. Those planets have more gravity but their atmospheres are much thinner and they have relatively small solid cores. If the tunnel extends through their atmospheres, and not just through the solid parts, I would think that an object falling down such a tunnel could attain a very high velocity.

    By the way, before anyone decides to make this joke on their own, I am aware of the fact that a transvestite theater group called the Coquettes performed a musical titled “Journey to the Center of Uranus”.

  9. it would be impossible even if you met antigravity protocal because of the extreme temperatures. man or machine would disentigrate in the unnatural heat.

  10. @Chris
    Wouldn’t the matter above you pull you also, so you stop at the center. But i guess there would be less dense matter, so less mass, resulting in some velocity when you pass through the core. Then the matter above you would pull you up while the more dense matter below you pulls you down. They all balance out in the end. You wouldn’t stop in the center, if you disregard air resistance.

  11. You don’t need math for this, providing you use proven theories / facts. Once you breached the crust, magma would rise and kill you. You’d most likely create a volcano in the process.

    Even if this didn’t happen, the deeper you go, the hotter it gets, and pressure. Even if we could survive the temp, the pressure would crush you like a bug.

    Good luck tunneling through the core. We don’t even know what it is. We have GUESSED it’s nickel/iron. It’s so dense and under so much pressure, you’d never tunnel through it. Let alone even dent it.

    Gravity is basically the earths mass exerting force on you. At the center of the core, there wouldn’t be much gravity as there’s nothing to pull u in more. However, gravity still has another way to get you, it’s pulling everything inwards creating mass pressure, you’d be crushed. Nothing we could make could survive this, and the energy to repel such force would be beyond our abilities

    Gas giants have solid cores, but remember gas IS matter and does have gravity. The SUN is a big giant fireball of gas… Look at it’s gravity ;). That’s how a sun forms. Lots of gas coming together forming a gravity well, pulling in and compressing more gas. Pressure and compression heats things up. That’s also what keeps our mantle and core from freezing long ago: pressure/friction (plus radioactive decay).

    Math did prove this all at one point, but I don’t need it as I’m basing this all on already proven theories.

  12. If something DID manage to punch a hole in the earth, it would not be pretty, it would probably shatter the core, and even it something did make a hole, magma would erupt from both sides. The impact to make such a hole would also fracture the crust.. Making new faults , fractures, volcanos etc

    If some magical beam cut through with no harmful side effects, once done, the core would compress and close the core hole, magma would fill the tunnel in the mantle and magma would erupt through the holes on both sides.

  13. And I DON’T believe in mini black holes (pin head, golf ball size) unless someone can show me the math to prove otherwise.

    A black hole needs enough mass to create a large enough gravity well so light, and nothing else (expect X-rays) can escape it. A “mini black” hole would lack the mass to be a black hole.

    Mini is also a subjective term…. It would be interesting to see what the required minimum mass would be to create a gravity well so light can’t escape. Find that answer, and you find out the smallest size a black hole can be ;)

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