Happy 100th Birthday to Paul Erdős!

Happy 100th!

Happy 100th!

March 26 is the birthday of one of the greatest mathematicians of all time, Paul Erdős.  Considering this fact, it should be easy to write some sort of tribute, right?  Well, maybe not.  When I originally wrote this post a few years ago to celebrate his birthday, I was very intimidated.  I was worried that, no matter what I wrote, I wouldn’t write enough to honor his memory.  I even wondered what I should write about.

Maybe I should write about the fact that he was gifted mathematician?  Erdős is said to rival Leonard Euler as the most prolific mathematician in history, having produced some 1500 mathematical papers, many with collaborators.

Maybe I should write about his quirks?  He could be known to appear at your doorstep, unannounced, for an extended visit, announcing that his “brain is open”.  Legend has it that he had trouble tying his shoes, buttering his toast and opening containers of orange juice.  He loved ping-pong.  Even his childhood was unique.

Maybe I should write about Erdős as the philanthropist?  Erdős had little need for money so most of the money he earned was donated … whether to charities, needy friends or to set up scholarships.  If there was someone, anywhere, who needed financial help, Erdős was there.

Or, maybe I should leave it up to a professional wordsmith?  In 1996, columnist Charles Krauthammer wrote a beautiful and touching tribute to Erdős, titled “Paul Erdős, Sweet Genius”.   I think I made the right choice.

If this isn’t enough and you are interested in learning more about Paul Erdős, you can read a more academic biography by clicking on this link.  If reading a book is more to your liking, here are three to consider.

  • The Man Who Loved Only Numbers by Paul Hoffman  (Click here to read my brief synopsis.)
  • My Brain is Open by Bruce Schechter  (Click here to read my brief synopsis.)
  • THE BOY WHO LOVED MATH: The improbable life of Paul Erdős by Deborah Heiligman – available in June 2013 (Click here to read the first review.  Click here to see some of the AMAZING illustrations and read an article about it in the New York Times.)

If you are interested in a few items that I have written about him, you can consider reading these.

Happy 100th Birthday, Paul!

Erdős and √2

paul erdos 2

I asked you to tell me at every step if you don’t understand something. You said nothing!

In honor of Paul Erdős’s 100th birthday (March 26), I wanted to share one of my favorite stories involving his attempt to prove the irrationality of the square root of 2 to a non-mathematician.

Now, before we get to the story, a quick mathematical refresher.  Remember that the proof uses the popular technique of “proof by contradiction” or “Reductio ad Absurdum“.  (For example, if you are trying to prove some claim “A” true, first assume instead that “the opposite of A” is true.  Then, show that the new assumption leads to some logical contradiction.  This contradiction means that “the opposite of A” is wrong and “A” must be true after all.  Tricky, isn’t it?)  I love how G.H. Hardy explains it, “it is one of a mathematician’s finest weapons. It is a far finer gambit than any chess gambit: a chess player may offer the sacrifice of a pawn or even a piece, but a mathematician offers the game.”

(Still need a little more of a refresher with the proof?  Click here.  Don’t worry if you’re not a great mathematician – it doesn’t require a lot of math to understand it.  In fact, that’s what makes it so beautiful – or “from the book” as Erdős would say!)

Now, on to the story …

One afternoon, Erdős was visiting with his life-long friend and fellow mathematician Andrew Vazsonyi.  (This is the same friend who many years ago told Erdős that he was thinking of majoring in something other than mathematics.  Erdős responded by saying that if he chose that path, “I’ll hide, and when you enter the gate of the Technical University, I will shoot you!”)  Anyway, Erdős decided to explain the magic of mathematics to Vazsonyi’s non-mathematican wife, Laura, by proving the irrationality of the square root of 2.  Unfortunately for Erdős, things didn’t go according to plan!  As Vazsonyi tells the story:

One day, Erdos got reckless and told Laura, my wife, that he will prove to her the Pythagorean “scandal,” that the square root of 2 is irrational. (According to legend, the disciple of Pythagoras, who revealed the secret to laymen, was put to death.) He started with an almost blank sheet and started the proof .  “Laura, if you do not understand a step, let me know, so I will clarify the proof,” he said. Let us assume that the square root of 2 is rational, that is it equals a/b, where a and b are whole numbers. “OK?,” Laura agreed. Then he went down, step-by-step and reached a contradiction. “See, the assumption is wrong, the square root of 2 cannot be rational.

But Laura did not like the proof. Erdos got annoyed. “I asked you to tell me at every step if you don’t understand something. You said nothing.”

“Why didn’t you tell me at the beginning that this is all wrong?” said Laura. Erdos flipped his top.

I recalled that when Albert Einstein gave one of his last talks, at the end they unscrewed the black board and sent it to the Smithsonian. So I asked Erdos to certify the document, so I could keep it for history. He signed his name and p g o m a. d, signifying Poor Great Old Man Archeological Discovery. At age 70 he started to use LD for Legally Dead, and at 75 CD for Count Dead, for reasons unknown to me. 

Here is the actual “document” from that day:


Beautiful, isn’t it.  Happy 100th, Paul!  Thanks for all the great memories – and, of course, mathematics!

If you are looking to read a little more about Erdős, you can read any of these:

Here are the sources for this post::

In honor of Pi Day … the sounds of Pi revisited

Ever wonder what Pi would sound like if it were played on musical instruments?  Well, here it is … the musical interpretation of Pi to 31 decimal places or 3.1415926535897932384626433832795.  I always knew that mathematics was visually beautiful, but I never imaged how beautiful it could sound.  Just breathtaking!  (Thanks to the musician Michael John Blake for taking the time to create it and to my colleague for finding the link for me.)

Click here to enjoy:  http://www.newscientist.com/blogs/nstv/2011/03/a-musical-interpretation-of-pi.html

I wonder what the number e would sound like?