# Why 2 Is the Greatest Quantity and Different Secrets and techniques from a MacArthur-Profitable Mathematician

“Many individuals don’t understand that there are math questions that we don’t know reply,” says mathematician Melanie Matchett Wooden of Harvard College and the Radcliffe Institute for Superior Examine at Harvard. She not too long ago gained a MacArthur Fellowship (or “genius grant”) for her work looking for options to a few of these open issues. The award honors “terribly gifted and inventive people” with an $800,000 “no strings connected” prize.

Wooden was acknowledged for her analysis “addressing foundational questions in quantity idea,” which focuses on the entire numbers—1, 2, 3, and so forth, reasonably than 1.5 or 3/8, as an illustration. Prime numbers, complete numbers which can be better than 1 and solely divisible by 1 and themselves (similar to 2 and seven), additionally fascinate her. A lot of her work makes use of arithmetic statistics, a area that focuses on discovering patterns within the habits of primes and different varieties of numbers. She has tackled questions in regards to the nature of primes in programs of numbers that embrace the integers (these are zero, the entire numbers and unfavorable multiples of the entire numbers) however which can be “prolonged” to incorporate another numbers as properly. For instance, the system a + b√2 (the place a and b are integers) is such an extension. She additionally makes use of a smorgasbord of instruments from different areas of math when invoking these concepts might assist resolve difficult questions.

“The character of the work is ‘Right here’s a query that now we have no methodology to unravel. So give you a technique,’” Wooden says. “That’s very completely different from most individuals’s expertise of arithmetic at school. It’s just like the distinction between studying a e-book and writing a e-book.”

Wooden spoke to *Scientific American *about her current win, her favourite mathematical instruments and tackling “excessive threat, excessive reward” issues.

[*An edited transcript of the interview follows*.]

**What makes a mathematical query intriguing?**

I’m drawn in by questions on foundational constructions, similar to the entire numbers, that** **we don’t actually have any instruments to reply. [These] constructions of numbers underpin every part in arithmetic. These are exhausting questions, however that’s actually thrilling to me.

**When you had been to construct an imaginary software belt with among the mathematical devices and concepts you discover most helpful in analysis, what would you set in it?**

A few of the key instruments are being prepared to have a look at lots of concrete examples and attempt to see what phenomena are rising—bringing in different areas of math. Despite the fact that, perhaps, I work on a query in quantity idea about one thing like prime numbers, I exploit instruments from throughout arithmetic, from chance, from geometry. One other is the power to attempt issues that do not work however study from these failures.

**What’s your favourite prime quantity?**

Two is my favourite quantity, so it’s undoubtedly my favourite prime quantity.

It appears so easy. But such wealthy arithmetic can come out of simply the quantity 2. For instance, 2 is form of chargeable for the idea of whether or not issues are even or odd. There’s a large richness that may come from simply contemplating issues in difficult conditions, about whether or not numbers are even or odd. I prefer it as a result of regardless that it’s small, it’s very highly effective.

Additionally, right here’s a enjoyable story: I used to be an undergraduate at Duke [University], and I used to be on our [team for the William Lowell Putnam Mathematical Competition. For the math team, we have shirts with numbers on the back. Many people have numbers like pi or √5—fun irrational numbers. But my number was 2. When I graduated from Duke, they retired my math jersey with the number 2 on it.

**Have you always approached your number theory research from the perspective of arithmetic statistics?**

Starting with my training in graduate school, I have always come from this arithmetic statistics perspective, in terms of wanting to understand the statistical patterns of numbers, [including] primes and the way they behave in bigger quantity programs.

An enormous shift for me, particularly these days, has been [bringing] extra chance idea into the strategies for engaged on these questions. Likelihood idea, classically, is about distributions of numbers. You possibly can measure the size of fish within the ocean or efficiency of scholars on a standardized check. You get a distribution of numbers and attempt to perceive how these numbers are [spread out].

For the form of work that I’m doing, we’d like one thing that’s extra like a chance idea, the place you’re not simply measuring a quantity for every information level. You may have some extra complicated construction—for instance, perhaps it’s a form. From a form, you would possibly get numbers, similar to “What number of sides does it have?” However a form isn’t just a quantity or a few numbers; it has extra data than that.

**What does profitable this MacArthur prize imply to you?**

It is a large honor. It’s, specifically, thrilling to me as a result of the MacArthur Fellowship actually celebrates creativity, and most of the people affiliate that extra with the humanities. However to make progress on math questions that nobody is aware of reply additionally requires lots of creativity. It makes me comfortable to see that acknowledged in arithmetic.

**Harvard mathematician Michael Hopkins described your work on three-dimensional manifolds as “a stunning mixture of geometry and algebra.” What’s a three-dimensional manifold?**

It’s a three-dimensional house that, should you simply go searching in a small space, appears to be like just like the form of three-dimensional house that we’re used to. However should you go on an extended stroll in that house, it may need shocking connections. Like, you stroll in a single course and find yourself again the place you began.

Which may sound form of loopy. However take into consideration two completely different two-dimensional areas. There is a flat aircraft, the place you possibly can stroll straight in each course, and also you’ll by no means come again to the place you begin. Then there’s the floor of the sphere. When you stroll in some course, you’ll ultimately come again round. We are able to image these two completely different sorts of two-dimensional areas as a result of we stay in three-dimensional house. Effectively, there are in truth three-dimensional areas which have these humorous properties which can be completely different than the three-dimensional house that we’re used to interacting with.

**What’s the essence of the ****work**** you’re doing on these areas?**

We discover that sure sorts of three-dimensional areas exist with sure properties having to do with how one can stroll round and are available again to the place you began in them. We don’t exhibit, assemble or describe these areas. We present that they exist utilizing the probabilistic methodology.

We present that should you take a random house in a sure method, there may be some constructive chance that you simply’ll get a sure form of house. It is a lovely method that mathematicians know one thing exists with out discovering it. When you show that you are able to do one thing randomly, and there’s some constructive likelihood, irrespective of how small, which you can get it from some random building, then it should exist.

We use these instruments to point out that there exist three-dimensional areas which have sure sorts of properties. Despite the fact that we don’t know of any examples, we show they exist.

**Final 12 months you gained a $1-million Alan T. Waterman Award from the U.S. Nationwide Science Basis. The Harvard Gazette **famous

**that you simply deliberate to make use of that funding to deal with “**

**high-risk, high-reward initiatives**

**.”**

**What are some examples?**

This course of creating chance idea for extra difficult constructions than numbers is an instance. It’s high-risk, as a result of it’s not clear that it’s going to work, or perhaps it gained’t change into as helpful as I hope. There’s no clear blueprint for the place it can go. But when it does work out, it might be very highly effective.