Orders of Magnitude ptys 206-2 29 January 2008

Orders of Magnitude

• PTYS 206-2

• 29 January 2008

Example 1: The National Debt

Example 3: Chickens

Example 4: Piano Tuners in Chicago

• How many piano tuners are there in Chicago?

• How many people in Chicago?

• How many people per household?

• How many households have pianos?

• How often are piano’s tuned?

• How long does it take to tune a piano (include travel)?

• How many hours does a piano tuner work per year?

Example 4: Piano Tuners in Chicago

• How many people in Chicago? 5,000,000 = 5106

• How many people per household? 2

• How many households have pianos? 1/20

• How often are piano’s tuned? 1 per year

• How long does it take to tune a piano (include travel)? 2 hours

• How many hours does a piano tuner work per year? 2000

• # of Tunings/year = (5106/2) (1/20)=125,000

• Average tuner does = 2000 hours/2 hours = 1000 tunings

• There must be 125 tuners to do 125,000 tunings/year.

Example: Drake Equation

• How many civilizations are there in the Universe that we can communicate with?

Aside on Stars, Galaxies, and the Universe

Galaxies

Drake Equation

Drake Equation