Sam Roweis died unexpectedly on January 12, 2010.

He was a truly wonderful person; a beloved son, husband and father; and a treasured friend and colleague.

This is a place for all of us who were lucky enough to know Sam to share our memories and to help celebrate his life.
If you would like to add an article to this blog please contact Or you may leave a comment on any article. (Comments are moderated: please bear in mind that this is a place to remember Sam and to help celebrate his life.)

There is also an album of photographs for which contributions are welcome. Instructions on how to contribute appear next to album.

Sunday, 7 February 2010

from Haris Jabbar

I am an avid listener of Professor Roweis' lectures posted on It is such a good experience listening to him and watching his effortless style to explain stuff in such an interesting manner. It was one such lecture that I was watching about half an hour back that prompted me to write to him and congratulate him on his wonderful lecture. When I googled "Sam Toronto" as he had so fondly put on many of his title slides and clicked on the NYU link that appeared, I could not believe my eyes that he had passed away. I really couldn't! I searched about a dozen or so articles/news before I realized that it is true, that such a remarkable person is no more amongst us. I had almost looked forward to meet him one day when I visit Canada or USA, but I guess that's not to be and to be honest, the news has probably not sunk in till now.

I don't know what happened there but I want to convey to Meredith that he will be missed, not only by his family and friends but by this one person from Pakistan and by all those people whose lives he had touched through his talks and through his demeanor.

Regards to Meredith and love to Aya and Orli.

Friday, 5 February 2010

from the NYU obituary

This obituary was written for the NYU webpages. The version that appeared there was modified.

Sam Roweis (1972-2010)
Scientist and Engineer

The Department of Computer Science, the Courant Institute, and New York University mourn the untimely death of Professor Sam T. Roweis, who took his own life on January 12, 2010. Sam was a brilliant scientist and engineer whose work deeply influenced the fields of artificial intelligence, machine learning, applied mathematics, neural computation, and observational science. He was also a strong advocate for the use of machine learning and computational statistics for scientific data analysis and discovery.

Sam T. Roweis was born on April 27, 1972. He graduated from secondary school as valedictorian of the University of Toronto Schools in 1990, and obtained a bachelor's degree with honours from the University of Toronto Engineering Science Program four years later. His first exposure to AI and neural computation occured when--as an exceptional undergraduate--he took the graduate-level Neural Network course taught by Geoffrey Hinton. Here Sam discovered what would become his lifelong interest: unlocking the mysteries of intelligence; motivating all his work was a dream to understand human intelligence, and to build intelligent machines.

In 1994 he joined the Computation and Neural Systems PhD program at the California Institute of Technology, working under the supervision of John J. Hopfield. Sam made several contributions to the then-nascent field of molecular and DNA computing. With his contemporary Erik Winfree and others, he made a proposal for a sticker-based model of computation. But the main topic of his thesis was speech recognition, time-series analysis, and dynamical systems modeling. A central theme of his research was the systematic use of probabilistic frameworks to formulate and analyze learning algorithms. He realized that non-linear dynamical systems could be learned using the Expectation-Maximization (EM) algorithm. He proposed a variation of the well-established Hidden Markov Model (HMM) method for speech recognition, and he showed how a new form of Independent Component Analysis (ICA) could be used to separate multiple audio sources from a single microphone signal. He also realized that Principal Components Analysis (PCA) could be re-interpreted as the limit of a probabilistic model. His PhD research culminated with the publication of a landmark 1999 article, co-authored with Zoubin Ghahramani, that demonstrated that HMM, ICA, PCA, and Kalman Filters can all be seen as variations on a single linear Gaussian model.

After earning his PhD in 1999, Sam took a postdoctoral position in London with the Gatsby Computational Neuroscience Unit founded by Geoff Hinton. Sam's enthusiasm and creativity played an important role in making the Gatsby Unit one of the top labs in computational neuroscience. At Gatsby, Sam started an incredibly fruitful long-distance collaboration with Lawrence Saul (then at AT&T Labs in New Jersey), which led to the Locally Linear Embedding algorithm (LLE). The LLE paper, published in Science in 2000, revolutionized the field of dimensionality reduction, and gathered over 2700 citations in less than 10 years. It spurred an entire new sub-field of machine learning, called manifold learning, and gathered a considerable amount of interest from other technical fields, including applied mathematics. With LLE, Sam and Lawrence taught us to "think globally and fit locally": Given points in a high-dimensional space, local geometric relations among groups of nearby data points capture both local and global structure in the whole data set. This permits organization, visualization, and search for large, complex data collections. The method has had numerous applications in data visualization for biology, neuroscience, and the social sciences.

After his postdoc, some time at MIT, and a stint with the startup company WhizBang! Labs, Sam took a faculty job at the University of Toronto, to which Geoff Hinton had returned. In making this choice Sam rejected several extremely prestigious offers for the unparalleled intellectual atmosphere he found at Toronto surrounding his mentor, Geoff.

In this period, two new unsupervised methods he developed were Stochastic Neighborhood Embedding (SNE) and Neighborhood Component Analysis (NCA). Both methods use the idea of learning a function that maps datapoints into a space in which semantically similar objects are nearby, while semantically dissimilar objects are far apart. SNE has become a popular method for visualizing and organizing high-dimensional data, while NCA has spurred a resurgence of interest in methods that learn similarity metrics from data. Sam published a set of papers on speech and signal analysis, particularly using factorial HMM and hierarchical models. He was appointed to a Canadian Research Chair in statistical machine learning, and received a Sloan research followship in 2004.

In 2005 Sam spent a semester at MIT. Capitalizing on his work on blind source separation, he co-authored a landmark 2006 SIGGRAPH paper with Rob Fergus and others on removing camera shake from a single photograph. It was during his stay in Cambridge, MA that he met his wife, Meredith Goldwasser.

While at MIT and upon his return to Toronto, he focused on using machine learning and statistical methods to contribute to other sciences, such as astronomy and biology. He started an extremely fruitful collaboration with NYU astronomer and secondary-school friend David W. Hogg. Their most visible success together was a kind of search engine for the sky, called The system can take any picture of the sky from any source, and instantly identify the location, orientation, and magnification of the image, as well as name each object (star, galaxy, nebula) it contains. Sam and David introduced astronomers to a number of large-scale statistical methods that enabled increasingly automated and precise data analysis. One of their methods can even estimate the year at which an image was taken by measuring tiny variations in stellar positions.

In 2006 he was named a fellow of the Canadian Institute for Advanced Research (CIfAR) and received tenure at Toronto. Sam was not just a scientist, however, he was also an engineer. When Meredith took a job at Genentech in San Francisco, Sam took an opportunity to have a more direct impact on the world by joining Google's research labs in San Francisco and Mountain View in 2007. He was fond of saying that Google's search engine is one of the closest things we have to an intelligent computer.

In the summer of 2008, Sam and Meredith's twin daughters, Aya and Orli, were born in San Francisco. They were born very prematurely and had to be kept in intensive care unit for many weeks. Sam took an extended paternity leave from Google to take care of the twins.

Sam's stay at Google, and the success of his computational astronomy work, had renewed his interest in academic research. He decided to join the Computer Science Department at NYU's Courant Institute as an Associate Professor, and moved the family to New York City in September 2009. At NYU, his collaboration with David Hogg redoubled, as did his ongoing collaborations with Rob Fergus and Yann LeCun. His passing leaves many open threads, and many projects unfinished; at the time of his death he was working on beautiful, simple, but game-changing ideas for astronomical data analysis and remote sensing.

Sam had a singular gift: to him, any complex concept was naturally reduced to a simple set of ideas, each of which had clear analogies in other (often very distant) realms. This gift allowed him to explain the key idea behind anything in just a few minutes. Combined with contagious enthusiasm, this made him an unusually gifted teacher and speaker. His talks and discussions were clear and highly entertaining. His tutorial lectures on graphical models and metric learning, available on video at, have been viewed over 25,000 times. He would often begin group meetings by giving a puzzle, the solution of which was always beautiful, enlightening, or hilarious.

Many members of the research community became friends with Sam, because of his warm and friendly personality, his communicative smile, and his natural inclination to engagement and enthusiasm. Sam inspired many students to pursue a career in research, and to focus their research on machine learning and artificial intelligence. Already in his short time at NYU, Sam had become a key member of the computer science department, thanks to his broad interests, his clear-sightedness, his sense of humor, his warmth and his infectious enthusiasm. He was also a loving and devoted father to the twins and husband to Meredith.

In the last year of his life, he was battling hopelessness and pessimism about his life and career. His wonderful professional demeanor concealed these problems from most his friends and colleagues. He is greatly mourned by his colleagues and students at NYU, who extend their sympathy to his many friends in the broader research community, especially at the University of Toronto, the Gatsby Neuroscience Unit, and Google Research. Most of all, we express our deepest sympathy to his wife Meredith, his twin baby daughters Aya and Orli, and his father Shoukry.

-- Yann LeCun, David Hogg, Zoubin Ghahramani, Geoffrey Hinton.

Sam Roweis's home page and publications

from Sarah Elson

Like so many others, I was deeply saddened to hear of Sam’s passing. I had known Meredith a little before she and Sam moved to San Francisco, and was lucky to become friends with them while they were in the Bay Area. Spending time with the two of them was always uplifting. I knew Sam as a delightful, warm, caring, and energetic friend. He was the kind of person who asked questions and listened, who could be interested in whatever you were interested in. His warmth and passion were infectious. We ran into each other several times on our ways to work, and his exuberant greetings always brightened my morning. On the occasions we went rock-climbing together, Sam was an encouraging and inspiring partner. I did not know him through professional circles, and my surprise at learning the extent of his accomplishments speaks also to his humble nature. The last time I saw Meredith and Sam was a little over a year ago, and I was touched to see the father he had become and the love he had to share with Orli and Aya. The world has lost a truly remarkable individual.

Wednesday, 3 February 2010

from David Karger

I only shared time with Sam on a few occasions but they generated wonderful memories. The first was during his job search---boy did I want to hire him at MIT! I was so impressed by his work and the tremendous clarity with which he presented it to people outside his area. We had occasional conversations later, but my singular memory is of day during his time at MIT, when we spent a few hours walking along the river as he described an we worked on a problem. At this point I don't really remember the details---something about improving Viterbi for HMMs, where we worked out a pretty nice solution but got scooped a couple of months later---but what hasn't faded at all is the feeling of warmth, friendliness, and freewheeling intellectual enthusiasm that I got from Sam during that conversation. It's going to make a treasured memory.

Monday, 1 February 2010

from Mark Bedworth

I met Sam a few times around the turn of the millennium. I particularly remember attending one of his lectures at UCL on HMMs and their generalisations; despite having worked with them myself for 15 years or more by then. I expected to learn nothing and attended just to say “hi”. How wrong I was! His enthusiasm for teaching and his joy of knowledge shone through the whole lecture and reminded me why we all liked the subject, why we all liked the intellectual challenge, and why we all liked Sam. A decade later and I still recommend his papers as a model of explanation: how to make something complicated and impenetrable seem simple and enjoyable – a rare quality indeed. I only learnt of Sam’s untimely death today and feel so sad that his family and our community have lost such a special guy. Remembered always.