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Dan Christensen
Works at University of Western Ontario, London, Canada
Attended Massachusetts Institute of Technology
Lives in London, Canada
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Dan Christensen

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While the linked post uses the typography of Bladerunner as motivation, it is full of interesting facts about the movie.
 
"The Immortal Game [that Tyrell and J.F. are playing in Blade Runner] is notable in that Anderssen defeated Kieseritzky despite sacrificing a bishop, both rooks, and his queen. By the time Batty meets Tyrell, he has already sacrificed Leon, Zhora, and two other Replicants in his quest to meet his maker."

The typographical exegesis at https://typesetinthefuture.com/2016/06/19/bladerunner/
of Blade Runner is amazing in its detail. Below is the relevant part of the game, in an animated gif. It took me a while to work out the chess set used. (via bb)
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Great news! LIGO has detected the gravitational waves from another binary black hole merger, just 48 days after the first.
Matt Strassler originally shared:
 
#LIGO detects a second merger of black holes #fb

There’s additional news from LIGO (the Laser Interferometry Gravitational Observatory) about gravitational waves today. What was a giant discovery just a few months ago will soon become almost routine… but for now it is still very exciting… LIGO got a…
There’s additional news from LIGO (the Laser Interferometry Gravitational Observatory) about gravitational waves today. What was a giant discovery just a few months ago will soon become almos…
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Live talks can be viewed as they happen. They will also be available for later viewing in about a week.
 
Live streaming for the Workshop on Homotopy Type Theory and Univalent Foundations at Fields Institute

Watch tomorrow! Or rather, starting 13 hours after this post.

http://www.fields.utoronto.ca/live

First up: +Michael Shulman , +Robert Harper , +Emily Riehl ,...
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It turns out that Monday's talks are already up!

http://www.fields.utoronto.ca/video-archive//event/2012/2016
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Only 9 days left if you want to apply for funding and/or to give a contributed talk at our upcoming workshop on Homotopy Type Theory!  The workshop is May 16-20, 2016, at the Fields Institute in Toronto.
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I'm not making this up:  the "Christensenella" gut bacterium is more prevalent in skinny people.  Maybe that explains something about me?

http://phenomena.nationalgeographic.com/2014/11/06/the-most-heritable-gut-bacterium-is-wait-what-is-that-2/
The twisting helices of DNA within our bodies influence everything from our height to our personality to risk of diseases. Now, it’s clear that our genes also shape our microbiomes—the trillions of…
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A plausible theory about how the NSA can decrypt most Internet traffic.
 
Probable answer: invest in building a machine that cracks one Diffie-Hellman 1024-bit prime at a cost of $1M*year.  Spending a million bucks each year to break the most popular primes used in industry standards is well within the NSA's budget.  The NSA itself recommends transitioning to ECDH.
There have been rumors for years that the NSA can decrypt a significant fraction of encrypted Internet traffic. In 2012, James Bamford published an article quoting anonymous former NSA officials stating that the agency had achieved a “computing breakthrough” that gave them “the ability to crack ...
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How i can chat with you?
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As another followup on the HoTT Toronto workshop, all the videos are now posted online! Given the amount of chalkboard work, the low resolution is a bit of a shame (though still readable). But nonethless, the sound quality is very clear and professional, as is the videography.

http://www.fields.utoronto.ca/video-archive/event/2012
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Thanks to Fields, AARMS, NSF, PIMS and The University of Western Ontario for supporting this workshop, and a special thanks to all of the speakers who did a wonderful job!
 
My flight is leaving soon, so no time for a big write-up, but here are some photos from this last day of the HoTT workshop in Toronto.

Benedikt's morning talk was very clarifying on the relationships between various categorical models of type theory, and Floris and Nikolai's talks made a very nice back-to-back pair regarding ways to think of "sequences" of truncation. In the guise of type theory, some very genuine homotopy-theoretical questions emerge. Later, talking to Nikolai, I came to appreciate how at least in a certain sense, HoTT makes talking about the idea of a fibrant replacement very pleasant.

And Paige North's talk, while a bit much for me to follow, ended by exhibiting a very nice construction -- a category entirely of topological spaces in which one obtains a model of a type theory.

Many thanks to +Chris Kapulkin +Dan Christensen and the other organizers of this workshop for such an educational and eventful week.
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A very impressive marble and magnet run.
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A nicely explained tutorial showing how to view and process the raw gravitational wave data using python.
 
+IPython notebook of the LIGO data analysis.
SIGNAL PROCESSING WITH GW150914 OPEN DATA¶. Welcome! This ipython notebook (or associated python script GW150914_tutorial.py ) will go through some typical signal processing tasks on strain time-series data associated with the LIGO GW150914 data release from the LIGO Open Science Center (LOSC): ...
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Finally, a way to get a free SSL certificate for a Web server, so you can host https pages! I set up my server using the Let's Encrypt certificate authority in just a few minutes.
 
As of today, Let's Encrypt is in public beta. If you're comfortable running beta software that may have a few bugs and rough edges, you can use it to instantly obtain and install certificates for any HTTPS website.
https://eff.org/deeplinks/2015/12/lets-encrypt-enters-public-beta
Today marks a major milestone for the encrypted Web. Let's Encrypt, the free and automated certificate authority, has entered Public Beta. That means it's easier than ever for websites to adopt HTTPS encryption. A huge percentage of the world's daily Internet usage currently takes place over unecrypted HTTP, exposing people to illegal surveillance and injection of unwanted ads, malware, and tracking headers into the websites they visit.
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My postdoc +Chris Kapulkin has a post on the n-category cafe which summarizes his recent paper about internal languages of higher categories:

https://golem.ph.utexas.edu/category/2015/07/internal_languages_of_higher_c.html

The paper is called "Locally cartesian closed quasicategories from type theory", and is available at:

http://arxiv.org/abs/1507.02648
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I should of course have put a plus sign before Chris' name in the original post!  I'll edit it to be so, but just to make sure I'll do it here:  +Chris Kapulkin 
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Tagline
Interested in math, physics, computation and more.
Introduction
Professor of Mathematics at the University of Western Ontario in London, Ontario, Canada.  Interested in mathematics, physics, computation, technology, the outdoors, the environment, and more.

Education
  • Massachusetts Institute of Technology
    PhD, Mathematics, 1992 - 1997
  • University of Waterloo
    BMath, Mathematics, 1987 - 1992
  • Malvern Collegiate Institute, Toronto
    1983 - 1987
Basic Information
Gender
Male
Work
Occupation
Mathematics Professor (Algebraic Topology, Representation Theory and Mathematical Physics)
Employment
  • University of Western Ontario, London, Canada
    Professor, 2000 - present
  • Johns Hopkins University, Baltimore
    Assistant Professor, 1997 - 1999
  • Institute for Advanced Study, Princeton
    Member, 1999 - 2000
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
London, Canada
Previously
Lisbon, Portugal - Princeton, NJ - Baltimore, MD - Boston, MA - Waterloo, Ontario - Montreal, Quebec - Zurich, Switzerland - Toronto, Ontario
Interesting menu, but food a little plain.
Public - a week ago
reviewed a week ago
A bit pricey, and the atmosphere was just so-so.
Public - 2 weeks ago
reviewed 2 weeks ago
Pleasant ruins of a castle, with good views and a nice tea room.
Public - 2 weeks ago
reviewed 2 weeks ago
They put pressure on us for unnecessary upgrades, and tried to make us pay for a smudge on the bumper. Also have not yet refunded the Hoppa shuttle fare, but they say the refund is on its way. If you rent from them, I highly recommend taking before and after photos of the vehicle in case they try to charge you for damage you didn't do.
Public - 2 weeks ago
reviewed 2 weeks ago
38 reviews
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Fun trampoline park with bouldering wall. Music too loud.
Public - 2 weeks ago
reviewed 2 weeks ago
We stayed one night, before flying out of Heathrow. The apartment had a well-equipped kitchen, including an oven and dishwasher, and the fold out couch produced two surprisingly comfortable single beds that could be pushed together. Our room was very quiet. The main negative thing for us was that the wifi was very unreliable. The parking garage (15£/night) was a bit awkward to enter. Next door to the hotel is a Tesco Express, with a good selection of groceries. The neighbourhood around the hotel isn't particularly nice.
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Public - 2 weeks ago
reviewed 2 weeks ago
This was a lot of fun for our whole family, and was very well organized. Highly recommended.
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reviewed 2 weeks ago