I got it... "42"

[QUAZAR]

How long will it take to dig the hole?

Should I just start walking the "long way"?

[James Lehman]

Just use that multi-terawatt laser to blast a hole!

James.

[gottaluvlasers]

i always wondered this-

if i dig a hole right smack dab through the center of good ole earth and jumped in, once i hit the middle area, i would float right??

the force of gravity would be equal on both sides wouldnt it?? therefore, i would be Mr floatie??

[buffo]

if i dig a hole right smack dab through the center of good ole earth and jumped in, once i hit the middle area, i would float right??

If you could stop yourself at the exact center, then yes - you would float. But when you reach the center you're going to be moving very fast, so in actuality you'd shoot right past the center. Assuming no air in the hole (thus no friction) you'd end up on the other side of the earth in 42 minutes. You'd slow to a stop just as you reached the far side of the planet. Of course, you'd be up-side down...

In practice, assuming you could construct such a hole in the first place, if there was air in the hole you would reach terminal velocity rather quickly. Thus you would not have enough momentum to make it all the way through. You'd stop at some point past the center and start falling back towards the middle. Eventually you'd come to rest at the exact center, and yeah, then you would be floating.

The real bitch is drilling the hole in the first place!

Adam

[trwalters001]

Hanging around in the center would start to get a little warm fairly quickly!!
Especially with no beer!

Tim

[buffo]

No beer? Screw that! What's the point in hanging around weightless at the center of the earth if there's no beer?

Adam

[DZ]

Hmm, good point about terminal velocity. *If* a hole could be drilled to the center of the earth, your decent would be slowed by the friction of the air, as you get closer to the center, it would seem that terminal velocity would decrease since you would now have less downward gravitational pull, while upward gravitational pull is increasing. With a distance of roughly 3900 miles to the center of the earth, there is no way it could be made in 21 minutes as you would have to travel at around 11,000 miles per hour, far beyond terminal velocity.

Another thought, I wonder if you would spin, since at the surface we are traveling at around 1000 miles per hour. Lots of physics and math!

[trwalters001]

Would the air density change as you approached the center? On one hand, you've got a thousands-of-miles tall column of air in the hole. On the other, gravity is decreasing as you approach the center. On the 3rd hand () would this difference in air pressure create a wind? OW! My brain hurts!! (I'll go get that beer now...)

[buffo]

Air density will increase as you go deeper. Forget about the earth's pull on the air *in* the hole; you've got two large columns of air on either side of the hole attracted towards the center. That's going to compress the air in the hole.

Incidentally, this is one of the factors that makes the drilling of the hole impractical. The density of the material at the center of the earth is considerably higher than it is at the crust, for the same reason as above. Thus, the hole would tend to collapse fairly rapidly. The sides of the hole would need to withstand both tremendous heat *and* incredible pressure. My guess is that you'd have to make them out of unobtanium.

Adam

[James Lehman]

All of this is assuming that the structural integrity of the Earth would remain intact with a hole all the way through it!

There would also be considerable differences in the nature of the hole if it was from Pole to Pole or Equator to Equator.

Let's not forget about The Van Allen Belt!

Maybe the trick is to line the inside of the hole with an Earth sized carbon nano tube.

James.