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Comment by j1vms | Hacker News Reader

Here's another great one - and ballpark calculations point to it being likely true:

"..the number of atoms in a grapefruit is about equal to the number of blueberries you would need to fill up the entire sphere of planet Earth." [https://capitolhillscience8.wordpress.com/2012/10/03/just-ho...]

Edit: well, except that the Earth is shaped more like an oblate spheroid [https://en.wikipedia.org/wiki/Figure_of_the_Earth]

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Actually the Earth is nearly perfect, far more perfect than most any sphere with interact with in day to day life. The equatorial bulge is 20 miles or so, which is approximately .33% Technically an oblate spheroid, but barely.

There's a great Isaac Asimov essay on this topic: http://chem.tufts.edu/answersinscience/relativityofwrong.htm

Great find, thanks!

And for comparison, the variation in surface height relative to sealevel is over 10 miles (6 miles down to the bottom of deep ocean trenches; 5 miles up to the top of mountains)

The earth is more round than a pool ball; it'd be a perfect sphere to any human eye at virtually any scale. The bulge is too small to notice.

whereas a grapefruit is a perfect sphere?

That actually makes the Earth seem small to me. I wouldn't have blinked if someone had told me the blueberries would fill up a sphere the size of the Solar System. Just shows how hard it is to visualize these numbers.

The earth is small. If you build a scale model of the solar system the size of a football field, with the sun and one end and Neptune at the other (Pluto has been laid off as a planet) then the sun will be about the size of a ping pong ball and the earth will be the size of a poppy seed (and it will be about ten feet from the sun). Jupiter is about the size of a pea at this scale. Alpha Centauri is about four miles away.

And not only do you live on a poppy seed, you live on a very thin layer on the surface of this poppy seed. Blow the poppy seed up to the size of a basketball and the habitable layer is about the thickness of a sheet of paper.

> Alpha Centauri is about four miles away.

Actually, around 500 miles.

Distance to Alpha Centauri: 4.37 light years = 276,364 astronomical units.

In your diagram, the Earth is 10 feet from the Sun. Multiply by 276,364 to get 2,763,640 feet, or 523 miles.

The scale jump from distances around the Solar System to the next closest star is mind boggling.

Wow, you're right. That'll teach me to try to do the math in my head.

Planets seem like a really big waste of mass in that sense. Computational dust in a cloud around a sun would be a more efficient allocation.

"The Integral Trees" by Larry Niven is a novel in which people live in a free-floating cloud of atmospheric gas that is gravitationally stable in a multi-star system. They live on enormous trees with canopies on each end, which are blown in opposite directions by the winds (so they look like the integral sign).

That really depends on your quality metric. If you care about computational speed (because there's only a finite amount of time before the heat death of the universe) then the speed of light starts to be a limiting factor, and concentrating all the computation in a small space makes sense.

But pretty great in surface area. Success is all about the metric you choose.

Ha! Relative to what goal, exactly, are planets a waste of mass?

To the goal of sustaining intelligent life. I'm being semi-facetious of course, but scifi authors and futurists have discussed dismantling the planets to build more mass-efficient structures for a long time.

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