Hello everyone…this is my first time with you folks. I have a question that has plagued me most of my 48 years of existence. Here it is: If I starting digging a hole in my back yard and continued straight down through the center of the earth why wouldn’t I continue to dig straight “down” until I came out in the Philippines or wherever feet first upside down. Please don’t tell me that gravity and the core of the earth would make me immobile forever at the center or that the molten core would melt me - stuff like that - but what would happen? Help!!!
But that’s the answer, so I have to tell you that. As you get closer to the center of the earth, gravity will become less and less as the mass above you begins to cancel out the mass below you. Once you pass the core, there is more of the earth’s mass in the direction you came from than in the direction you’re going, so the direction you came from becomes “down”, and the direction you’re going becomes “up”.
You’d then fall “down” in the direction you came from, until you passed the core again, and your “up” and “down” would flip. You’d keep falling past the core in opposite directions until friction brought you to a stop in the center of the earth.
After a certain depth, the rocks become unable to maintain their own shape under the increasing pressure and tempurature, and it becomes difficult to keep a boreshaft open.
If you somehow managed to open a shaft all the way through the earth, you could jump into it and come out the other side. You’d speed up all the way through to the center, where you’d start to slow down on your way up the other side. If you removed all the air from the shaft, you’d eventually make it back up to the altitude that you initially jumped from ( and never stop going back and forth). If not, you fall short of that hight and occilate back and forth before finally settlling at rest in the core.
Not sure what else you needed to know, your question isn’t really that clear.
Welcome. I am 46 and, as a child, did try this. What happens is: you get about four feet down, then you’re called in for supper, then someone notices the hole, then you get spanked and sent to your room for the night. Then you have endure about a week of really nasty looks from your dad.
Do you have some practice walking on the ceiling or something? Because once you pass the core, the hole you’ve been digging will be “below” you, and the part where you need to keep digging will be “above” you.
Actually, the molten core would do nasty things to your body. However, if you managed to get a heat-protected boring machine, you could then probably figure a way to defeat gravity. After all, the most gravity you would encounter would be at the surface, so if your boring device used some method to keep itself attached to the sides of the hole it was digging, you could keep from falling back into the hole.
However, once you got through, you’re going to drown, since you are going to emerge at the bottom of the Indian Ocean, in the Australian Basin, about 200 miles north of the Australian Ridge, in water that is from 2,000 to 4,000 meters deep.
From Perth, Australia to your point of emergence is 1165 miles (1875 km) (1012 nautical miles) at a bearing from Perth of West (278.3 degrees).
(To find your antipodal position on the world, take your Latitude North or South and reverse it. Clearwater is at 27:58:46N, so the opposite position is at 27:58:46S. Then take your Longitude and figure its complement to 180° and exchange the East and West indicators. Thus, Clearwater, FL at 82:45:56W has a complement to 180° of 97:14:04E.
There were two threads going, both with good answers. I have merged the two and deleted the extra OP and a reference to the other thread.
bibliophage
moderator GQ
Thanks bibliophage. I was beginning to think a Member with 0 posts is a bigger mystery than the answer to “What would happen if you dug a hole straight down to China?”
Thanks for all of your quick answers…I’ve tried writing this reply 3 times and I keep getting a “can’t do” response…so I’ll try again. Let’s imagine that we are sitting inside Dr. Evil’s Vulcan Project earth boring maching and we start digging down. This is one heck of a powerful machine and it’s able to withstand the heat and overcome the gravity. What happens when we get through the center and start going the ‘other way’? Am I now going upside down; and once we break through on the other side do we ‘fall out’ or will we immediately drop back into the hole? Gosh, I’m a minister, not a physicist - this is making my head spin! Can someone logically and simply work this out for me (I’ve already read some good answers - thanks!)…Randy p.s. if we broke through in the Indian Ocean, would all the water drain into my back yard?
“Down” will always be towards the center of the Earth. Simple enough?
Wherever you are underground just find the center of the Earth and that will be down. Once you pass through the center, you will be digging “up”. If your machine doesn’t have a way to keep itself from falling (the hole you dug is “below” you once you pass the center of the Earth), you won’t get very far. When you break through the other side, you won’t fall out as “falling” will be back into the hole. You will need to climb out, same as with any hole.
The water will fall into the hole (“down”) and accelerate very quickly. Once it reaches the center, it will be going very fast and keep going, even though it is now going “up”. It will slow down as it continues to go “up”. Eventually, after a long, long period of time, the top of the water in the hole will be at sea level. If you are 2,000’ above sea level, the hole will be 2000’ before you hit water. If you are below sea level, the water will pour out of the hole. I think.
You’ll be digging up, against gravity.
Gravity allways pulls toward the center of the earth (I could explain why if you really want to know). As you approach the core, you’ll be getting lighter and lighter. When you reach the core, you will feel no gravity. As you get further away from the core, you’ll get heavier and heavier. Once you finally reach the surface on the other side, you’ll climb out of the hole just as you would climb out of any other hole.
At some point, before you reach the antipodal surface, your “ceiling” will give way, and the Indian Ocean will begin being sucked down into your tunnel, until it’s eventually filled with water from end to end. This would, of course, lower the sea level worldwide, and depending on the diameter of your tunnel, have cataclysmic repercussions.
At any rate, you should secure commercial rights before starting this project. Undoubtedly, there’s a big market for a tunnel connecting the Indian Ocean to Clearwater, FL. For one thing, you can go fishing in your back yard, and catch species not native to this part of the world. Not to mention, bragging rights of being the owner of the Center of the Earth!
Well, I suspect that the “gravity Yo-yo™” would not actually occur.
A couple of points:
As you tunnel up from the center of the Earth, the magma is going to follow you, but if your vehicle is not hundred of meters in diameter, the amount of magma is not going to be significant. Barring some unexpected pressure, the magma is going to suffer the same affects of gravity as it does now, and it will not come all the way to the surface. (Recall that we already have holes in the Earth that extend down to the magma–we call them volcanoes.) So there is not going to be some massive magma “fist” pushing you up once you have gotten above its current level. On the other hand, the Indian Ocean is going to be a lot colder than the surrounding rock. And water tends to do explosive things once it is heated. So the most likely scenario as you get to the bottom of the ocean is that the water will pour into the hole, and a superheated boiling explosion will occur. However, the water rushing into the hole is going to cool the magma as it boils, probably causing the magma to cool and plug the hole you left. (You will most likely die in the original steam explosion, of course, but you may rest easy, knowing that you have not actually killed off your family.)
(Similarly, on the hole that you originally dug down from Clearwater, when you break out of the crust and into the magma, there will probably be an initial “lurch” of magma into the hole you have left behind, but without significant pressure from below, it will not continue fountaining up and spraying Clearwater. It may not even reach the surface. While the hole will not be a safe place to hang out for a while (what with poisonous fumes and unstable earth surrounding it), it will probably eventually “heal” with a magma plug.)
You also have to consider what you are doing with the earth and stone you displace as you burrow through the Earth. The method requiring the least energy would be to simply pass it back behind the vehicle to fill the hole you have come through. Therefore, aside from the fact that it has been broken up and loosened, it will continue to have the same mass as there was in that place before the hole was dug. Any magma trying to get free of the Earth’s core will not have a nice cleanly bored hole to shoot up, but will need to move the same mass of stone (albeit loosened) that it needed to move before you came through disrupting things.
You could decide to vaporize the rock in order to bore through it, but that would mean that the rock actually expanded to a superheated gas and you would still need to pass it behind the boring machine to get past it. Once it was behind the boring machine, it would initially tend to float toward the surface as you were digging down, (endangering Clearwater), but the farther you went, the less it would move, as the weight of the cooling gas in the narrow hole began countering with gravity the effect of the rising gas.
Thus, at some point going down and then continuing all the way up, you would have an ever growing ball of hot vapor trapped in the hole behind you. This is the exact principle on which large cannons are designed, so you will need to worry about finding a way to remove the stone from in front of you at an ever quickening pace, otherwise the vaporized stone will “shoot” you into the stone ahead of you at a speed faster than you can remove that stone. Nothing like being shot into a wall by your own effluent. I’d suggest that you stick with boring the dirt out, mechanically, and passing it back to fill the hole.
The question about what would happen with the ocean is a valid one. After all, it would be natural to reinforce the walls of the tunnel, so it doesn’t just collapse and fill with dirt and magma behind you as you continue. So assuming you do have a stable Unobtanium tunnel straight through the center of the world, leaving aside the matter of how you built it in the first place, and then break through to the ocean… what happens?
I’m assuming that at some point the water will vaporize, but with no actual matter to stop its descent, and plenty of still-liquid water applying pressure on the steam front as the ocean continues to drain into the tunnel, this could be an interesting event…
Didn’t Cecil do a column on this?
Found it: link. It’s not exactly the situation stated in the OP, but close enough.
Look you have forgotten one thing The reverend randy (or whatever) is in Dr Evils Vulcan Project Machine and is more than likely to have a 1920s Style Death ray with him.
Now as we all now this Death ray is capable of some pretty awesome things apart from erm, death raying people.
For one thing if you switch the button on the side of it from kill people to eat earth and magma and other encumbrances and then move the button on the other side to locate Australia and guide me there then the good rev will end up just under Sydney Harbour Bridge.
It is then a simple matter to fling out the inflatable rubber rafts, paddle ashore and have a few beers before lunch.
Oh yes almost forgot “Welcome aboard your Holiness”
Good 'ere innit?
Quite apart from the antipodes tunnel idea, there is a tunnel concept that would link far away points and provide cheap, safe travel (once you’d paid for the tunnels, that is).
If one were to dig a tunnel far underground, and arc the curve of the tunnel to follow a ‘great circle’, and seal and evacuate the tunnel (so there was no or very low air pressure), then train cars could actually ORBIT the Earth underground, and quickly travel from one spot to another.
Maglev technology could help keep the car centered in the tunnel, and an electromagnetic catapult system at each end could accelerate and decelerate the car to the stations.
Remember, orbiting is falling at exactly the same rate as your radial acceleration, and a body can orbit a large mass at any distance from that center of mass.
If we had some efficient tunnel-boring technology (say, a 1920’s style Death Ray) this could be an effective alternative to air travel.
~Wolfrick
Credit to the Dean: I learned of this concept from Robert Heinlein’s writings.