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I'm a scientist. I helped pioneer quantum computing and the modern open science movement. I also have a strong side interest in artificial intelligence. All are part of a broader interest in ideas and tools that help people think and create, both individually and collectively. [bio, cv] I work as a Research Fellow at the Astera Institute. My online notebook, including links to many of my recent an
Many thousands of articles have been written purporting to explain Bitcoin, the online, peer-to-peer currency. Most of those articles give a hand-wavy account of the underlying cryptographic protocol, omitting many details. Even those articles which delve deeper often gloss over crucial points. My aim in this post is to explain the major ideas behind the Bitcoin protocol in a clear, easily compreh
Unless listed below, all the above bounds were produced by the Polymath8 project. [BI]: R. C. Baker, A. J. Irving, Bounded intervals containing many primes [M]: J. Maynard, Small gaps between primes We have been working on improving a number of other quantities, including the quantity [math]\displaystyle{ H_m }[/math] mentioned above: [math]\displaystyle{ H = H_1 }[/math] is a quantity such that t
Today I get back into my post series about the Google Technology Stack, with a more detailed look at distributed dictionaries, AKA distributed key-value stores, AKA distributed hash tables. What we’d like to do is store a dictionary of key-value pairs [tex](k_1,v_1),(k_2,v_2),\ldots[/tex] across a cluster of computers, preferably in a way that makes it easy to manipulate the dictionary without hav
Imagine you’re a programmer who is developing a new web browser. There are many malicious sites on the web, and you want your browser to warn users when they attempt to access dangerous sites. For example, suppose the user attempts to access http://domain/etc. You’d like a way of checking whether domain is known to be a malicious site. What’s a good way of doing this? An obvious naive way is for y
More precisely, I crawled 250,113,669 pages for just under 580 dollars in 39 hours and 25 minutes, using 20 Amazon EC2 machine instances. I carried out this project because (among several other reasons) I wanted to understand what resources are required to crawl a small but non-trivial fraction of the web. In this post I describe some details of what I did. Of course, there’s nothing especially ne
On my first day of physics graduate school, the professor in my class on electromagnetism began by stepping to the board, and wordlessly writing four equations: He stepped back, turned around, and said something like [1]: “These are Maxwell’s equations. Just four compact equations. With a little work it’s easy to understand the basic elements of the equations – what all the symbols mean, how we ca
I’ve posted to YouTube a series of 22 short videos giving an introduction to quantum computing. Here’s the first video: Below I list the remaining 21 videos, which cover subjects including the basic model of quantum computing, entanglement, superdense coding, and quantum teleportation. To work through the videos you need to be comfortable with basic linear algebra, and with assimilating new mathem
This is a clearinghouse wiki page for aggregating the following types of items: Analysis of Vinay Deolalikar's recent preprint claiming to prove that P != NP; News and information about this preprint; Background material for the various concepts used in the preprint; and Evaluation of the feasibility and limitations of the general strategies used to attack P != NP, including those in the preprint.
Part I: How Industries Fail Until three years ago, the oldest company in the world was the construction company Kongo Gumi, headquartered in Osaka, Japan. Kongo Gumi was founded in 578 CE when the then-regent of Japan, Prince Shotoku, brought a member of the Kongo family from Korea to Japan to help construct the first Buddhist temple in Japan, the Shitenno-ji. The Kongo Gumi continued in the const
In this post I explain how to compute PageRank using the MapReduce approach to parallelization. This gives us a way of computing PageRank that can in principle be automatically parallelized, and so potentially scaled up to very large link graphs, i.e., to very large collections of webpages. In this post I describe a single-machine implementation which easily handles a million or so pages. In futur
Posts PageRank and MapReduce Introduction to PageRank (video) Building our PageRank intuition (video) The PageRank distribution for the web (no video, short supplement extending the last post) Using your laptop to compute PageRank for millions of webpages Write your first MapReduce program in 20 minutes Using MapReduce to compute PageRank Consistent Hashing A Number-Theoretic Approach to Consisten
The slow revolution Some revolutions are marked by a single, spectacular event: the storming of the Bastille during the French Revolution, or the destruction of the towers of the World Trade Center on September 11, 2001, which so changed the US’s relationship with the rest of the world. But often the most important revolutions aren’t announced with the blare of trumpets. They occur softly, too slo
Building a better collective memory In your High School science classes you may have learnt Hooke’s law, the law of physics which relates a spring’s length to how hard you pull on it. What your High School science teacher probably didn’t tell you is that when Robert Hooke discovered his law in 1676, he published it as an anagram, “ceiiinossssttuv”, which he revealed two years later as the Latin “u
On Twitter, I’ve been chatting with my friend Julia Galef about tensions between thinking creatively and thinking in a way that reduces error. Of course, all other things being equal, I’m in favour of reducing error in our thinking! However, all other things are not always equal. In particular, I believe “there’s a tension, too, between behaviours which maximize accuracy & which maximize creativit
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