If the earth unraveled.

[daniel l.]

If you were to unravel the entire earth into a string 1 atom thick, how far would it stretch?

[Dfthu]

Assuming every atom is one angstrom I got this   105 700 083 402 000 000 000.00 light-years

[GeneralVeers]

From a couple random web sites (well, one was Wikipedia) the Earth has somewhere between 10⁵⁰ and 10⁶⁰ atoms in it. Then, from Wikipedia, I got one ten-billionth of a meter for the size of your average atom (assuming an atom that stays in shape and doesn't eat too many neutrinos......)

Multiply 10⁵⁰ by 10^-10 and you get a string 10⁴⁰ meters long, or approximately 10²⁴ light-years. In other words, a few billion times longer than the diameter of the known universe. Might wanna pack a lunch.

[daniel l.]

Wow, Well thats pretty long! I was expecting half the galaxy 

[Bill Phil]

Even the all the DNA and RNA on Earth will get you light years, if completely unraveled.

[Findthepin1]

What about a human?

[kerbiloid]

Interesting.
According to wiki, the Earth consists of ~1.4e50 atoms. Mostly Fe, O and Si.

Radius on atom ~100 pm = 1e-10 m.
Total length ~ 1e50 * 1e-10 / 1e16 = 1e24 light years.

Visible Universe radius ~1e10 l.y., perimeter ~1e11 l.y.
So, you can make ~1e24/1e11 = 1e13 turns around the visible Universe.

Every turn is, of course, 1 atom ~1e-10 m thick.

So, width of the monoatomic band spooled around the visible Universe ~ 1e13 * 1e-10 ~ 1e3 m ~ 1 km.

Total area of this thread is ~1e50 * 1e-10 * 1e-10 ~=1e30 m2.
Radius of a sphere of this area ~ sqrt(1e30 / 4 * pi) ~ 1e14 m ~ 0.01 l.y. ~ 1000 AU.

Of course, if no calculation mistake here.

TODO: A super-civilization with Dyson sphere around the whole Universe.

70% of human is water, so 3 atoms. All of them are of ~60 pm radius.
Say, total body is water.
70 [kg] / 18e-3 [kg/mol] * 6e23 [1/mol] * 3 * 60e-12 / 1e16 ~ 10 l.y.