The present authors never cease to be amazed at the amount of material on mathematics in general, and mentions of Pi in particular, that have been appearing in the popular media in recent years. We hope this is evidence of a resurgence in both interest in and knowledge of mathematics, although only time will tell if this has any lasting impact.

#### Mathematics in the movies

A remarkable number of recent movies have dealt with mathematics and mathematicians. The 2001 movie A Beautiful Mind featured the life of mathematician John Nash. In the 2005 movie Proof, Gwyneth Paltrow plays the daughter of a brilliant but mentally disturbed mathematician, played by Anthony Hopkins. In the 2012 movie adaptation of Yann Martel’s The Life of Pi, the title character writes hundreds of digits of the decimal expansion of Pi on a blackboard. The 2014 movie The Imitation Game depicted the life and career of the brilliant 20th century mathematician/computer scientist Alan Turing, played by Benedict Cumberbatch. And remarkably deep principles of mathematical physics played a key role in the 2014 movie Interstellar.

A very interesting new movie The Man Who Knew Infinity features the life of famed 20th century Indian mathematician Srinivasa Ramanujan, from his birth and upbringing in Madras, India to his admittance to Cambridge during World War I, and ultimately to his discovery of extraordinarily deep new mathematical principles. The title role is played by Dev Patel (from Slumdog Millionaire), and Jeremy Irons (from Margin Call) plays British mathematician G.H. Hardy. For additional details, see this Conversation article by one of us.

#### Popular appearances of Pi

As expected, Pi is one of the most popular mathematical themes in the media. Here are just a few of its recent appearances:

- On 5 November 2013, the American quiz show Jeopardy featured an entire category of clues on Pi. One of these was “You can find the area of this oval geometric shape with pi x A x B, if A & B are half of its longest & shortest diameter.” (Ans: What is an ellipse?).
- On 29 January 2013 Google (now Alphabet) offered a Pi-million dollar prize for successful hacking of the Chrome Operating System on a specific Android phone. A few years earlier (2005), Google offered 14,159,265 new slices of rich technology in their initial public stock offering.
- On 14 March (Pi Day) in 2007, the New York Times crossword puzzle featured clues, where, in numerous locations, the Pi character (standing for the two letters “PI”) must be entered at the intersection of two words.
- In the first Matrix movie (1999), the lead character Neo has only 314 seconds to enter the “Source.”
*Time*noted the similarity to the digits of Pi. - The 1998 thriller Pi received an award for screenplay at the Sundance Film Festival.
- In the 6 May 1993 episode of The Simpsons, Apu declared “I can recite Pi to 40,000 places. The last digit is 1.” This digit was supplied to the screenwriters by one of the present authors.
- In Carl Sagan’s 1986 book Contact, the lead character (played by Jodie Foster in the movie) searched for patterns in the digits of Pi, and after her mysterious experience sought confirmation in the base-11 expansion of Pi.

Just as this piece was being written, one of the present authors noted another interesting play on Pi: In the latest (2015) edition of Microsoft Excel for Macintosh systems, when one selects a date entry, then selects “Format” followed by “Cells,” the possible date formats are all for the date 14 March 2015, which, in North American notation, is “3/14/15.”

#### Pi in “Person of Interest”

One of the more intriguing appearances of Pi was in the American TV show Person of Interest, in an episode appropriately entitled 2-Pi-R.

This show delves into the question of the normality of Pi, namely the conjecture that the digits of Pi are statistically random in a certain sense (in particular, each m-long string of decimal digits appears in the expansion of Pi with the limiting frequency 1/10^{m}, and similarly in other number bases). If proven, this would mean that the digits of Pi contain every possible digit sequence and, hence, every possible alphabetic sequence encoded as digits — the works of Shakespeare as well as your computer files. Numerical evidence to date suggests that this may well be true, although no one yet has any idea how to prove it — for technical details see our Pi Day paper.

Here is a brief synopsis of this show’s treatment of Pi, which evidently presumes that the Pi normality conjecture is true:

Harold Finch, the show’s mysterious billionaire-computer guru played by Michael Emerson, substitutes as a teacher in a high school math class, in an attempt to reach out to Caleb Phipps, one of the students in the class, whose number has just come up as a “person of interest,” and thus potentially in jeopardy.

Finch, addressing the class, mentions the problem to sum the numbers from 1 to 100. Finch then explains that in the 18th century, Carl Friedrich Gauss found a fast way to calculate this. Finch writes on the blackboard, as a hint, “100 (100 + 1).” Finch looks at Phipps and asks him if he can solve this, but Phipps looks bemused and says “You lost me with Friedrich.” The bell rings, and on the way out Phipps throws some paper that he had been scribbling on into the trashcan. Finch retrieves the paper from the trash. It is clear from the writing on the paper that in fact Phipps knew exactly how to solve the problem and had even written down the correct answer (5050).

In a subsequent classroom scene, Finch, evidently trying a more sophisticated approach to reach Phipps, draws a circle and a diameter on the blackboard, with 3.1415926535 written to one side, and then says:

[Finch:] “Pi. Can any of you tell me what it means? [no answer] I’ll settle for an intelligent question here.”

[Girl in class:] “… What is any of this good for, and when would we ever use it?”

[Finch:] “Let me show you. Pi — the ratio of the circumference of a circle to its diameter. And [pointing to the digits on the board] this is just the beginning. It keeps on going, forever. Without ever repeating. Which means that contained within this string of decimals is every single other number. Your birth date, the combination to your locker, your social security number.” [Finch writes down another ten digits of Pi on the blackboard as he is talking.]

[Finch, looking directly at Phipps:] “It’s all in there somewhere. And if you convert these decimals into letters, you would have every word that ever existed in every possible combination. The first syllable you spoke as a baby, the name of your latest crush, your entire life story from beginning to end. Everything we ever say or do, all of the world’s infinite possibilities rest within this one simple circle. Now what you do with this information, what it’s good for, well, that would be up to you.”

Near the end of the show (during which Finch helps save Phipps’ life), Finch hands Phipps two sheets of paper, covered with digits. The top sheet is nearly 100% visible on the screen, and, as far as the present authors could check, contains (correctly) the first 1890 digits of Pi.

[Phipps, after looking at the two sheets:] “Pi, the first 3,000 digits.”

[Finch:] “My number is in there somewhere. You’re smart, you’ll figure it out.”