Erdös: The Man Who Loved Only Numbers
––––––
Assignments for Class #7
• Read Chapter 5, "God Made the Integers".
• Read about the harmonic series, on page 217, and then read the first few paragraphs of these two Wikipedia entries:
1) Harmonic series (mathematics), and
2) Harmonic series (music).
• Watch the first 5 minutes of this video on the harmonic series in music:
• Read the first paragraph (and any more that interests you) of the Wikipedia entry, Set (mathematics).
• Learn the basics of one-to-one correspondence by watching the first two minutes of this video:
• Even Galileo had difficulty understanding infinite sets. Watch this short video:
• Progress in understanding has been made, but it is still unintuitive. Watch this video:
Questions to Think About
• Why is the series (1/1) + (1/2) + (1/3) + (1/4) ... + (1/n) called the harmonic series ?
• What is likely to be the first one-to-one correspondence that you ever made?
Hint: it was very handy.
• You are cleaning up after a party. You started the evening with the same number of forks and spoons but now you think you may have lost a spoon. How can you tell, without actually counting either the forks or the spoons?
• Look at this picture
Step 1 starts with the interval consisting of all points on the number line between 0 and 1.
Step 2 removes the middle third of that interval, leaving 2 disconnected shorter intervals.
Step 3 removes the middle third of each of those 2 intervals, leaving 4 disconnected even-shorter intervals.
Step 4 removes the middle third of each of those 4 intervals, leaving 8 disconnected even-shorter intervals.
Subsequent steps carry on similarly, removing the middle third of each existing interval to produce more and more - but shorter and shorter - disconnected intervals
Question: Are there any points remaining after doing an infinite number of steps? If yes, how many points are left?
Other Resources
• More about the Golden Ratio at Wikipedia
• HOW INFINITE HOTEL RAN OUT OF ROOM
• We've talked about all sorts of numbers: integers, rationals, reals, imaginaries, complex ... . Confused? Overwhelmed?
Here's Matt Parker of Numberphile with an overview of "All The Numbers".
Note that other lists of types of numbers might vary in the number and contents of categories. Most Numberphile entries probably are consistent with this one. But all categorizations of types (of anything) involve personal interests and preferences to some extent.
• Here's Leonard Bernstein to demonstrate how music changes as new harmonics come to be included:
-- Book: What to Listen For in Music, by Aaron Copland,