This is the kind of stuff I think of while I'm at work

My next bit of randomness centers on the lies our parents tell us. Now we've all heard the lies about going blind (from sitting too close to the TV), growing hair on our palms (from sitting too close to the microwave), and others of course. But the one I am going to focus on is about throwing rocks into things (canyons, mines, ponds, rivers, etc.)

When I was about 10 years old I visited the Grand Canyon with my parents. I did what all kids want to do. I picked up a rock and threw it into the canyon. I was instantly assaulted with the obligatory "If everyone who came here did that then the canyon would be filled with rocks." I'm going to look at this from the standpoint of everyone ON EARTH throwing a rock into the canyon.

The rock I threw wasn't very large but let's pretend it was the equivalent size of a 3" cube. (About as big as a Rubik's cube.) Here are the numbers we're working with.

The Grand Canyon

Length = 227 "river miles"
Average width is 10 miles "rim to rim"
average depth is 1 mile

So what's that in cubic miles?

227 * 10 * 1 But we'll even say the average width is 8 miles since it's bound to be more narrow at the base than at the rim.

227 * 8 * 1 = 1,816 cubic miles

"Everyone" on earth

Population in 1985 was about 4.8 billion

A three inch by three inch by three inch rock = 27 cubic inches

Now since we're dealing with a 27 cubic inch rock we need to know how many cubic inches are in the Grand Canyon (Warning for the numerically challenged...the number is absolutely massive)

There are 12 inches in a foot. There are 5280 feet in a mile. So there are 63,360 inches in a mile. If we're going to make those cubic inches in a cubic mile we have to cube them. That is to say 63,360 * 63,360 * 63,360 which equals...ready for the first big number?

254,358,061,056,000 cubic inches in a cubic mile.

But that Grand Canyon of ours is 1,816 cubic miles so we multiply that big number by 1,816 and we get:

416,914,238,877,696,000 (416 Quadrillion, 914 Trillion, 238 Billion, 877 Million, 696 Thousand)

Wow, that's a lot of inches...

We'll divide that by the size of the rock I threw (27 cubic inches) and we'll get:

17,107,934,773,248,000 rocks it would take to fill the grand canyon

Now divide that by the 4.8 billion people on earth at the time of my parents proclamation and you get:

3,564,153.07776 (basically 3 Million, 564 Thousand, 153)

So Every single person on earth would have to throw over 3.5 million rocks into the Grand Canyon before it could possibly fill up.

There are, of course, the logical amongst you who would say that the rocks are coming from near the canyon so the ground around the canyon is getting deeper as the canyon gets more shallow. In which case there would still be a CANYON. Or at least a big valley.

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Incidentally, if 4.8 billion people each threw 1 rock that was 27 cubic inches then that would be 129,600,000,000 cubic inches or 75,000,000 cubic feet or .0005095 cubic miles

75,000,000 cubic feet is equal to 2.69025 feet deep spread over 1 square mile. The Grand Canyon's floor is 2,270 square miles so that would be equivalent to .001185 feet deep spread over the whole floor. That's .0142 inches which is only a hair's breadth over 1/3 of a millimeter. That is, of course, assuming that the rocks shattered to gravel / dust on impacting the canyon floor a mile below.

So if everyone on earth in 1985 threw the equivalent of 27 square inches of something into the Grand Canyon the floor would rise about the width of this hyphen -