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Income inequality, as seen from space
Last week, I wrote about how urban trees—or the lack thereof—can reveal income inequality. After writing that article, I was curious, could I actually see
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Bill Thurston has died
Bill Thurston, who made fundamental contributions to our understanding of low-dimensional manifolds and related structures, died on Tuesday, aged 65. Perhaps Thurston’s best known achievement…
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Feynman's Clock
You, dead, are so much better than anyone else alive. – Richard Feynman, to his wife, Arlene Richard Feynman is famous for his ceaseless questioning of life and the universe, to a degree unexpected even for being a Nobel Prize quantum physicist. His dogged investigation of the Challenger explosion is the most…
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Parrondo's Paradox: How two ugly parents can make a beautiful baby
"How two ugly parents (mathematically) can make a beautiful baby"
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Urban trees reveal income inequality
Wealthy cities seem to have it all. Expansive, well-manicured parks. Fine dining. Renowned orchestras and theaters. More trees. Wait, trees? I’m afraid
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How to leave academia (for science PhDs)
So you've decided to leave academia, or are perhaps just thinking about doing so. Welcome to the dark side. I made the transition a few years ago, and since then I've gotten a number of questions about how to do it. Hence, this article. First of all, I'm going to …
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Pascal's Apology, or why computer science is complicated
Blaise Pascal once famously ended a letter with an apology : I'm sorry that this was such a long letter, but I didn't have time to write you a short one. Computer science has pretty much the same problem. It's a young field, and young fields are, by their nature, messy. As we race to generate new knowledge, we also…
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Gödel's Incompleteness Theorem explained
This theorem is one of the most important proven in the twentieth century. Here are a few brief selections that will help you start to understand it. Gödel’s original paper “On Formally Undecidable Propositions” is available in a modernized translation . It’s also in print from Dover in a nice, inexpensive edition …
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Who Expected That? Extreme close-ups create a Klein Bottle.
Suppose you go around taking extremely close-up black-and-white pictures of randomly chosen natural and unnatural objects (rocks, trees, streams, buildings, etc.). What do they look like? Well, eac…
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What comes next: π/2, π/2, π/2, π/2, π/2, π/2, π/2, ...?
I’m eager to summarize the (largely excellent) discussion of last week’s nightmares and to talk about what it all means. I’ll surely get to that in the next few days. But meanwhil…
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How we gave colors names
“Who in the rainbow can draw the line where the violet tint ends and the orange tint begins? Distinctly we see the difference of the colors, but where exactly does the one first blendingly enter in…
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The Science of Serif vs Sans Serif Type
Update March 2012 See my expanded critique of Colin Wheildon’s legibility research .
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What happens when a basebal goes at nearly the speed of light (what-if.XKCD)
What would happen if you tried to hit a baseball pitched at 90% the speed of light?
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Droppings
If you went outside and lay down on your back with your mouth open, how long would you have to wait until a bird pooped in it?
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Everybody Jump
What would happen if everyone on earth stood as close to each other as they could and jumped, everyone landing on the ground at the same instant?
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Time-Nuts -- Precise Time and Frequency for Amateurs
Time-Nuts ™ is a mailing list for amateurs who are interested in precise Time & Frequency. Topics include stability of quartz oscillators, measurements of rubidium and cesium atomic clocks, using WWVB, Loran-C, and GPS for long-term comparisons.
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A Mole of Moles
What would happen if you were to gather a mole (unit of measurement) of moles (the small furry critter) in one place?
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Rosser’s Theorem via Turing machines
(Thanks to Amit Sahai for spurring me to write this post!) The Background We all remember Gödel’s First Incompleteness Theorem from kindergarten. This is the thing that, given a formal syste…
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Pump Up the Storage
If we adopt solar and wind as major components of our energy infrastructure as we are weaned from fossil fuels, we have to solve the energy storage problem in a big way. An earlier post demonstrated that we do not likely possess enough materials in the world to simply build giant lead-acid (or nickel-based or…
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Galactic-Scale Energy
[ An updated treatment of this material appears in Chapter 1 of the Energy and Human Ambitions on a Finite Planet (free) textbook , and also appears as part of an article in Nature Physics in 2022.]
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My visit to D-Wave: Beyond the roast-beef sandwich
Last week I was in Vancouver, to give talks at the University of British Columbia and at the American Association for the Advancement of Science annual meeting. As part of that visit, on Friday af…