RECENT ARTICLES

A radical theory replaces the cosmic crunchers with fuzzy quantum spheres, potentially solving the black-hole information paradox and explaining away the Big Bang and the origin of time.

Why physics and astronomy communities must take diversity issues seriously in order to do good science.

Einstein’s relativity pushes physicists towards a picture of the universe as a block, in which the past, present, and future all exist on the same footing; but maybe that shift in thinking has gone too far.

Resolving the black hole firewall paradox—by calculating what a real astronaut would compute at the black hole's edge.

Defining a ‘quantum clock’ and a 'quantum ruler' could help those attempting to unify physics—and solve the mystery of vanishing time.

FQXI ARTICLE

May 26, 2018

Quantifying Occam

Is the simplest answer always the best? Connecting Medieval monks to computational complexity, using the branch of mathematics known as category theory.

FQXi Awardees: Noson Yanofsky

August 17, 2014

Noson Yanofsky

Brooklyn College

The principle was first articulated in the 14th century by a monk called William from the village of Ockham in southern England. It has guided scientists’ work for centuries, but it’s only in the last 50 years that we have developed the mathematical language and understanding to be able to attempt to pin-down why it seems right. Or perhaps our gut feelings are wrong and the simplest explanation isn’t always the best description of nature? Now, Noson Yanofsky, who is based at the computer science department at Brooklyn College, New York, is hoping to make some concrete progress on these deep questions.

I’m meeting with Yanofsky at Churchill College, Cambridge; we escape the pavement heat to sit in the college’s quiet coffee lounge. He is in Cambridge for a conference on category theory, the mathematical language he will use to tackle Occam’s Razor and other topics. Category theory is an increasingly popular and important branch of modern mathematics that allows mathematicians to describe mathematical structures by their transformations, in other words, how they map from one to the other. Many parts of mathematics have been “categorified,” but it has also proved useful in computer science, particle physics, quantum mechanics, and even linguistics. (See, “The Quantum Linguist.”) “I still find it fascinating that you have this language that can talk about so many different things,” he says.

Yanofsky charts his interest in category theory back to the 2nd year of his PhD at the City University of New York, when a course taught by Alex Heller “woke” him up. Heller became his dissertation adviser, and the pair continued meeting twice a week to discuss philosophy, mathematics and politics long after Yanofsky graduated. “He was an amazing genius and his range of knowledge was astonishing,” says Yanofsky.

The Outer Limits

My first impression of Yanofsky is of someone friendly and generous, a brilliant ambassador for mathematics, but not just because of his personality—he has worked hard on writing two universally-lauded books, one about quantum computing, and one more recently about the limits of knowledge,

The notion of simplicity

of a scientific theory

does not have a

precise meaning unless

it is formalized in

some way.

of a scientific theory

does not have a

precise meaning unless

it is formalized in

some way.

- Olivia Caramello

Yanofksy has a unique take on any problem that he tackles because his academic background bridges a number of disciplines. As a teenager his passion was computing, and he spent many hours programming Pac-Man and other games in the 1980s. Naturally he chose computer science for his first degree, but then veered into mathematics for his postgraduate studies. And writing his books has drawn him into physics, particularly into the foundations of quantum mechanics and quantum computing.

Mathematician Olivia Caramello, of the Institut des Hautes Etudes Scientifiques in France, says Yanofsky’s broad perspective is one of his key strengths. “He’s a very original and eclectic researcher with an extremely broad knowledge,” she says. “His exquisitely inter-disciplinary attitude means he is able to combine ideas from different areas and conceive generalizations and unifying patterns across them.”

Complex Categories

In his latest project, funded by an FQXi grant of nearly $50,000, Yanofsky is taking a tool from computer science, called Kolmogorov complexity, and applying it to categories. Kolmogorov complexity was pioneered in the 1960s, and defines how much information is contained in a string of letters or numbers in terms of the computing resources needed to reproduce it.

Simple or complex? Ask Kolmogorov

A computer program can generate a seemingly complicated image, such as

this portion of the Mandelbrot set fractal, relatively easily. Rather than

storing information about every pixel required, it simply uses the definition of

the Mandelbrot set to produce it.

Credit: Reguiieee, Wikimedia Commons

But Yanofsky isn’t just interested in strings; he has a wider vision of determining the information content of structures across mathematics, computer science and physics. So he will generalise Kolmogorov complexity to find the information content of the categorical descriptions of these structures. He has created a programming language to generate the categorical descriptions, so the information content of each structure will be the length of the most succinct computer program that generates it.

If “simple” is taken to mean “contains the least information,” then quantifying the information content of different theories and comparing them should give insights into why Occam’s Razor seems to work. “If Yanofsky can describe the information content of a mathematical or scientific theory, then we can begin to think about these philosophical questions, like Occam’s Razor, in a more precise way,” says Jim Cox, a close colleague of Yanofsky’s at Brooklyn College.

”It’s a very innovative and exciting idea,” agrees Caramello. “The notion of “simplicity” of a scientific theory does not have a precise meaning unless it is formalized in some way. Because of its broad range of applicability, the general notion of categorical complexity developed by Yanofsky should eventually significantly clarify these issues, and help us detect when a certain theory should be preferable to another.”

P versus NP

Yanofsky also has his eye on a problem that many consider the main open problem in computer science. Known as the P versus NP problem, it concerns a whole set of problems called NP-Complete problems. There are billions of dollars at stake in being able to solve these hard problems because they crop up in scheduling, shipping routes, and even gene sequencing. Although NP-Complete problems were first defined in the 1970s, no one has yet managed to prove whether or not they can be solved in a reasonable timescale—even with proposed

The difficulty with these hard problems is that a computer has to do a lot of searching to find the possible solutions. For example, the only way for a computer to work out the shortest route between ten cities is to go through all the possible combinations of routes, as there is no structure to point the way to the solution. But easy problems have a structured solution space, for example, if you are finding three times three, you could count up in threes, making it quicker to get to the answer.

”Computer scientists want to know what’s a hard problem and what’s an easy problem so that they know whether they should carry on searching for

Cox agrees that Yanofsky’s categoric approach could shed light on the question, but cautions that the most difficult part of the project will be in the interpretation of the results, rather than in the technical details. Nevertheless Cox is optimistic that something philosophically interesting will come out of the work: “He’s thought deeply about the philosophical issues, so he’ll probably come up with a reasonable interpretation that we can argue about over coffee.”

Comment on this Article

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!

function ValidatePostText_main () {
form = document.addPostForm_main;
var recaptcha = $("#g-recaptcha-response").val();
if (recaptcha === "") {
event.preventDefault();
alert("The reCaptcha Box below must be checked before you submit the form");
}
else if (form.postText_main.value == '') {
alert ("The post contains no text");
return false;
}
else {
return true;
}
}

**Your name:**
(optional)

Recent Comments

read all article comments

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!

Please enter the text of your post, then click the "Submit New Post" button below. You may also optionally add file attachments below before submitting your edits.

HTML tags are not permitted in posts, and will automatically be stripped out. Links to other web sites are permitted. For instructions on how to add links, please read the link help page.

You may use superscript (10

^{100}) and subscript (A_{2}) using [sup]...[/sup] and [sub]...[/sub] tags.You may use bold (

**important**) and italics (*emphasize*) using [b]...[/b] and [i]...[/i] tags.You may also include LateX equations into your post.

Insert LaTeX Equation
[hide]

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview

preview equation

clear equation

insert equation into post at cursor

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview

preview equation

clear equation

insert equation into post at cursor

Attachments
[hide]

You may optionally attach up to two documents to your post. To add an attachment, use the following feature to browse your computer and select the file to attach. The maximum file size for attachments is 1MB.

Once you're done adding file attachments, click the "Submit New Post" button to add your post.

You may optionally attach up to two documents to your post. To add an attachment, use the following feature to browse your computer and select the file to attach. The maximum file size for attachments is 1MB.

Once you're done adding file attachments, click the "Submit New Post" button to add your post.

HERB WIGGINS wrote on September 16, 2014

First, Occam's Razor is very likely a kind of least energy principle. That is, it suggests the least energy solution to a problem, viz., that the best solution to a problem creates the fewest new terms, hypotheses, etc., in explaining a phenomenon. In this case, it's thermodynamically efficient when compared to the other hypotheses which purport to explain a phenomenon. It's a process comparing the energy cost outcomes of the other hypotheses.

But what does it mean to "explain"? That is...

First, Occam's Razor is very likely a kind of least energy principle. That is, it suggests the least energy solution to a problem, viz., that the best solution to a problem creates the fewest new terms, hypotheses, etc., in explaining a phenomenon. In this case, it's thermodynamically efficient when compared to the other hypotheses which purport to explain a phenomenon. It's a process comparing the energy cost outcomes of the other hypotheses.

But what does it mean to "explain"? That is...

ECKARD BLUMSCHEIN wrote on September 11, 2014

"whether questions exist whose answer can be quickly checked, but which require an impossibly long time to solve by any direct procedure."

The question how large is the sum 1/2 + 1/4 + 1/8 + ... can be quickly and plausibly answered by means of common sense but definitely not by direct procedure.

While Kolgomorov's idea is convincing to me, I did not yet grasp its promised application.

Let me reiterate a seemingly quite different statement of mine: Addition of redundancy,...

"whether questions exist whose answer can be quickly checked, but which require an impossibly long time to solve by any direct procedure."

The question how large is the sum 1/2 + 1/4 + 1/8 + ... can be quickly and plausibly answered by means of common sense but definitely not by direct procedure.

While Kolgomorov's idea is convincing to me, I did not yet grasp its promised application.

Let me reiterate a seemingly quite different statement of mine: Addition of redundancy,...

ELLIOT MARTIN PINES wrote on August 28, 2014

Still the thought nags.

Is not Occum's Razor--be it Kolmogorov complexity/(Chaitin's) algorithmic information--merely the approximation of a rapidly decaying tail of an infinite distribution of possibilities.

In the greater scheme of things, will assuming such a decaying tail still prove valid?

Still the thought nags.

Is not Occum's Razor--be it Kolmogorov complexity/(Chaitin's) algorithmic information--merely the approximation of a rapidly decaying tail of an infinite distribution of possibilities.

In the greater scheme of things, will assuming such a decaying tail still prove valid?

read all article comments