Tuesday, June 28, 2011

The Green Pea Analogy

If you selected a hundred (102) average-sized peas, you would find that they occupy roughly a volume of 20 cm3. A million (106) peas are just enough to fill an ordinary household refrigerator and a billion (109) peas will fill a three bedroom house from cellar to attic. A trillion (1012) peas will fill a thousand houses, the number you might find in a medium-sized town. A quadrillion (1015) peas will fill all the buildings in one of our larger cities such as Seattle.

Obviously you will run out of buildings very soon. Let us try a larger measure, for instance the state of Washington. Suppose that there is a blizzard over Washington, but instead of snowing snow, it snows peas. Washington State is covered with a blanket of peas about one metre deep all the way from Bellingham to Walla Walla. This blanket of peas drifts over the roads and banks up against the sides of the houses, and covers all the fields and forests. Think of flying across the state with the blanket of peas extending out as far as you can see. This gives you and idea of our next number. There will be in this blanket about a quintillion (1018) peas.

Imagine that this blizzard of peas falls over the entire land- North America, Africa, South America, Europe, Australia, and Asia. All of the continents are covered with peas one metre deep. This global blanket will contain sextillion (1021) peas.

Then imagine that the oceans are frozen over and the blanket of peas covers the entire land and sea area of Earth. Go out among the neighbouring stars and collect 250 planets the size of Earth and cover each of these with a blanket of peas one metre deep.

Then you have a mole of peas.

Furthermore, go out into the farthest reaches of the Milky Way, and collect 250,000 planets, each the size of Earth. Cover each one with a blanket of peas one metre deep.

You now have cotillion (1027) – a number corresponding to the number of atoms in your body.

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