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History of the Theory of Irrational Numbers

The discovery of irrational numbers is usually attributed to Pythagoras, more specifically to the Pythagorean Hippasus of Metapontum, who produced a (most likely geometrical) proof of the irrationality of the square root of 2. The story goes that Hippasus discovered irrational numbers when trying to represent the square root of 2 as a fraction (proof below). However Pythagoras believed in the absoluteness of numbers, and could not accept the existence of irrational numbers. He could not disprove their existence through logic, but his beliefs would not accept the existence of irrational numbers and so he sentenced Hippasus to death by drowning.

From an encyclopedia entry for "Irrational number" at TheFreeDictionary.com.

Read again. The discoverer is sent to death, and the guy who gave the order gets the credit for the discovery. Fair?

Makeup Class. We will hold a makeup class to make up for the two hours lost last week, next week on Monday October 4 at 2-4PM at Lash Miller room 162 (just south of Sydney Smith, on the other side of Willcocks Street). There will be a further announcemnt later on about makeup for the tutorials thus lost.

Class Photo. Today (Sep 30) at 10:55, on the south end of the long stairs outside Sydney Smith, facing St. George Street. The class photo will be on the class' web site in a day or two and then you are required to do the following by Friday October 8:

  1. Register yourself to CCNET if you haven't already done so. If CCNET doesn't recognize you, it means your student number is not on the class list. Contact me and don't worry too much - the system is not that reliable.
  2. Find yourself in the class photo and send me an email, from within CCNET, containing information as below.
  3. Where are you in the picture? (Use the labels on the picture and in case of possible confusion add a descriptive comment).
  4. Your name.
  5. Your email address.
  6. Your telephone number (optional).
  7. Which of the last four pieces of information do you allow me to post on the web? If you don't write anything about this, I'll assume that all information can be posted. The information will be posted within CCNET so it will only be available to registered students, though I cannot guarantee the security of this arrangement.

If you aren't in the picture at all, let me know and I'll take a (small) picture of you on the spot and edit it into the main picture.