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Language: en
I'm Neil Degrass Tyson, host of Nova
Science Now. You ever wondered what
would happen if you dug a hole from one
side of the Earth through the center out
the other side and then jumped in?
Before we show you a few disclaimers, if
there was any air in the hole, air
resistance would slow me down. So, let's
ignore that. Earth's molten core is
11,000° F. On the way past, you'd simply
be vaporized. So, let's ignore that,
too. We would also have to ignore
Earth's spin, which would make me
ricochet from side to side down the
hole. And please don't try this
experiment on the actual Earth. All
right, here we go.
I fall, gaining speed as Earth's mass
pulls me towards the center. 14 minutes
into my fall, halfway to the center, and
I've accelerated to more than 15,000 m
an hour. Here, there's only half the
force of gravity than on the surface.
So, I'm still gaining speed, but at a
slower rate than when I first jumped in.
21 minutes into my fall, and I'm at the
center of the Earth and going my
fastest, about 18,000 m an hour. As I
pass the center, gravity now works
against me, slowing me down. And by the
time I make it halfway between the core
and the other side of the Earth, I'm
back down to about 15,000 mph. It'll
take only 42 minutes to make the entire
trip to the other side, at which point
I'll slow to a full stop. Just like when
I started, all of Earth's mass will pull
me back towards the core. Unless
somebody catches me, I'll fall down the
hole again and yo-yo back and forth
forever. Thank you. No problem. I'm Neil
Degrasse Tyson. Watch No NOVA Science
Now, Wednesdays starting in June on most
PBS stations.