Just getting to the center of the Earth and surviving is impossible. The Earth's core is about 9,000°F—as hot as the sun's surface—and would instantly roast anyone who found himself there. Then there's the pressure, which can reach roughly three million times that on the Earth's surface and would crush you. But let's not sweat the details. Once you arrive in the center of the Earth, the physics gets really interesting.
Understanding gravity, the force of attraction between objects, is going to be key to wrapping your head around what is about to be a bizarre situation. The strength of gravitational attraction is determined by an object's mass and how close it is to another (more mass and closer together means increased force). The only gravity strong enough for us to feel comes from the Earth's mass, which is why we feel a downward pull on the surface.
At the center of the Earth, the situation is different. Because Earth is nearly spherical, the gravitational forces from all the surrounding mass counteract one another. In the center, "you have equal pulls from all directions," says Geza Gyuk, the director of astronomy at the Adler Planetarium in Chicago. "You'd be weightless," free-floating.
But what would happen if you tried to get out of the center by, say, climbing up a very long ladder that ends in Los Angeles? (For clarity's sake, let's assume that the Earth is uniformly dense. It isn't, but the general trend described here still holds.) At the center, the gravity from the mass beneath your feet all the way to the other side of the Earth, the Indian Ocean, will be "pulling" you down, even as the mass above your head is "pulling" you up, toward L.A. After climbing a few rungs, the total pull you feel down to the Indian Ocean will still be nearly zero. You will still feel almost weightless. But as you climb, there will be less and less mass above, and more and more below. The pull toward the core will feel greater and greater, and you will feel less and less weightless, until you are standing on the Earth's surface, staring at the Hollywood sign, feeling heavy again.
This article originally appeared in the March 2011 issue of Popular Science magazine.
Don't the basic laws of gravity dictate that one could hypothetically find a place where the 'center' is equi-distant from both ends....jump in and simply step out on the other side..when velocity would again be zero?
@Guitalife: Maybe in an airless chute, but air resistance will slow you down, meaning if it was truly equidistant, you'd never reach the other end before falling back the other way (and continually moving back and forth until air resistance stops you at equilibrium in the center).
-IMP ;) :)
Center of earth: www.youtube.com/watch?v=V7TA-5-1JkY
why has this article been removed from where it was originally published on this site, last week, and been republished here?
@Guitalife and IceMetalPunk: Yes, Guitalife in an ideal situation that is correct, and yes, IceMetalPunk, in a slightly more realistic, but still unrealistic situation, you are correct. How cool of an amusement park ride would that be? "Travel to the other side of the world and back!!!"
I think you have to look at this problem in a couple of ways:
If you fell through in a vacuum, you'd reach some kind of maximum speed based on the fact that when you started, the gravitational acceleration would be 1g but that acceleration would decrease until you reached the center of the Earth, where it would drop to 0g. However, because there would be no wind resistance, you would continue through the center at your maximum velocity which would then begin to slow due to pull from the Earth, starting at 0g and gradually increasing to 1g on the opposite side. Theoretically, you would come to a stop on the other side, right at the surface and begin falling back in again. This would continue forever.
Without the vacuum, wind resistance would limit your fall to terminal velocity which would not allow you enough momentum to continue all the way back out the other side. You'd go back and forth for a while (decreasing in distance and speed) until settling in the center of the Earth to stay there forever.
Weee enjoy the ride.
"feeling heavy again"? You callin' me fat?
Well now duh the earth is spinning. So at the equator you would start out at about 1000 mph circumferential and zero radial. At the center you would be moving very fast radial but zero circumferential. Thus you would decelerate by 1000 mph circumferentially on the way down.
You might also be sucked towards a microscopic black hole in some sort of squishy swirling motion to use technical terms. What happened next would be different depending on where the observer was (or part of the observer)
Oh yeah, if you weren't in a shaft and 'fell through' in a vacuum (sortof a vacuum with mass). Then can anybody guess what would happen next? A spiral? Would centripetal and centrifugal forces balance somewhere? Would you go into some kind of elliptical orbit inside the 'sphere'? Would you spiral back out somewhere?
What if you dropped from 30 deg. latitude? Your circumferential velocity would be less, and not perpendicular to the radial acceleration on launch. Then what?
I remember an article somewhere stating that theoretically, in a vacuum tunnel, a "train" could ferry people and goods from one point on the Earth thru to another in like 42 min using the previously stated gimmick. They were talking about transocean pipelines for quick transport. I don't even want to know how many years that would take to drill.
you know the non-gravitational part would be really cool if it were true.
Ya got another problem, too.
If you drop any where other than the north or south pole, you have to deal with angular momentum.
If you drop at the equator, you are zipping along at over a thousand miles an hour. As you fall, you would constantly be slamming into preceding wall of the tunnel.
Once you pasted the center, if any angular momentum (and/or body) is left, then it would slam into the receding wall for awhile - but, not very long or far.
If you could run unbelievably fast, you might be able to maintain ~ 1G perpendicular to the wall - as you zipped down the hole... Breaking the sound barrier could be a problem.
Robert1234 There is and can be no such thing as a microscopic black hole. To be a black hole, it has to have a minimal mass sufficient to stop light from exiting the "surface". That's pretty much the definition of a black hole. That amount of mass is not "microscopic" is size, but at least the physical size of our sun, likely much greater. When it gets smaller than that, there isn't enough mass there to act as a black hole and thus can't be considered as one. Microscopic black holes are a physicists idea of a joke.
Michael Mc Donald
The title doesn't match the story. Nowhere in the article does it say "fall" or "jump" to the center of the earth. The article deals with what happens dead center. Zero gravity. And climbing back out is oversimplified, of course, as mentioned they don't talk about the angular momentum.
And Robert1234... Micro "black holes" do exist. However they tend to "evaporate" very quickly... As for them being "black" they are still singularities and absorb anything small enough to go into their maw. I believe a physicist guy, his name is Stephen Hawking, you may have heard of him, has a chapter in A Brief History Of Time called "Black Holes Ain't So Black".
Jeesh everyone here is so unrealistic - if there were really to be a tunnel, you wouldn't smash into the sides of have to worry about angular momentum, because whoever created the tunnel is obviously some engineering mastermind and took all of that into account - you don't drill a hole through the earth just to do it wrong.
A point not considered in the article and the responses is that the center of the Earth/Moon system is thousands of kilometers from the geometric center of the Earth. Therefore, you would not be weightless at the center of the Earth, but would feel the force of gravity to the barycenter.
this is only the basic stuff if you fell through a tunnel to the center of the earth so everybody stop making all of the about what they forgot to say!!!!!
The article is wrong. Using the article's assumptions, that at the center of the earth the earth would pull equally and you would experience weightlessness completely leaves out the gravitational effects of the moon. You would essentially become a human compass, your new down would be wherever the moon was in relation to your body and this would of course track the moon as it rotated around the earth.
Just watch Total Recall, the new version, if you wish to see this in action. In the movie they dig a shaft through the earth that is slightly of center of the core. They demonstrate the effects of gravity at the center of the Earth quite well.
What if, what if... what if a hermaphrodite had a long penis and then stuck it in its own vagina and got itself pregnant. It wouldn't be considered asexual reproduction but what would it be? What if it then developed only a sexual desire for itself and not other humans? What would that be classified as psychologically? Not gay, not heterosexual...
"Do not try and bend the spoon. That is impossible. Only try and realize the truth - there is no spoon."
I suppose if we can answer this question, we then be off and venturing to the insides of black holes.
Besides, in the center is a soft goo-ie chocolate center!
If you were in the Earth's center of mass you would be orbiting the Earth-Moon barycenter, just like the Earth. So you would not move relative to the Earth. You would both be in "freefall".
Of course this is all academic since even if you could bore through the solid nickle-iron core and build a hollow tube that could withstand the pressure and heat you find there. (You can't buy the way) but even if you could, you would find that the Earth's core rotates slightly faster than the rest of the Earth. So, by the time you finished building your tube, it wouldn't be in the same place it was when you started building it.
And if you wait until the core cools to the point it stops spinning faster, then you will be burned to a crisp by our sun swelling into its red giant phase.
Here's a thought experiment whose answer I had to defend in Physics class in high school: as you go down towards the center of the earth, would you begin to feel lighter or heavier?
did anybody else notice the dates on the first 10 or so comments? 2011?!?! Did they just rehash this article and pretend it's new or am i missing something?
Pete444, Yes they did and they do.
"Do not try and bend the spoon. That is impossible. Only try and realize the truth - there is no spoon."
Its nice to see PoPSCi making good active use of recycling.
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