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Want to Calculate a Large Number?

Look closely at this spot .
Do you see a pile of neutrinos?

Your first task...find out what a neutrino is. A good start is Dave Casper's web site.

One place that collects evidence of neutrinos landing is Japan's Super-Kamiokande, which cost only about 100 million dollars. Holding 12.5 million gallons of water, the Super-K basically is a cylinder (41.4 meters high, 39.3 m diameter) whose surface is covered by glass photomultiplier tubes that detect the light emitted when a neutrino lands and collides with the water.

Since 1956, an estimated total of 725,000 neutrinos have been detected. Yet, neutrinos reach earth at a rate of 60 billion neutrinos per square centimeter per second.

Question: How many neutrinos reach the total surface of the earth each second? In a day? In a year?

Source: Wired, June 2006, p. 27