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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?
Most cited
Posts that commenters keep linking to, ranked by how many different people have cited them in Hacker News comments. 21 posts.
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Why Explore Space? A 1970 Letter to a Nun in Africa.
Ernst Stuhlinger wrote this letter on May 6, 1970, to Sister Mary Jucunda, a nun who worked among the starving children of Kabwe, Zambia, in Africa, who questioned the value of space exploration. A…
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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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New study finds 45,000 deaths annually linked to lack of health coverage
Nearly 45,000 annual deaths are associated with lack of health insurance, according to a new study published online today by the American Journal of Public Health. That figure is about…
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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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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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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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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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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…
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Restoration of defocused and blurred images
Restoration of distorted images is one of the most interesting and important problems of image processing - from the theoretical, as well as from the practical point of view. There are especial cases: blurring due to incorrect focus and blurring due to movement - and these very defects, which each of you knows very…
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Look at yourself objectively
In the 1840s, hospitals were dangerous places. Mothers who went in to give birth often didn’t make it out. For example, at Vienna General Hospital’s First Obstetrical Clinic, as many as 10% of mothers died of puerperal fever after giving birth. But there was some good news: at the Second Clinic, the number was just…
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Your body wasn’t built to last: a lesson from human mortality rates
What do you think are the odds that you will die during the next year? Try to put a number to it — 1 in 100? 1 in 10,000? Whatever it is, it will be twice as large 8 years from now. This s…
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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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Why three prongs?
Why do AC cords need three prongs? If there is no positive or negative in AC systems, why do we have HOT and NEUTRAL? I attempt to shed light on some of these mysteries.
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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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Algernon's Law
Why most supplements fail: IQ improvement skepticism, Yudkowsky & Bostrom’s heuristics, nootropics
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Elon Musk and the Hyperloop
For a while now there have been tantalizing hints that Elon Musk is at it again. His usual way of approaching a problem is to look at an industry, find some fatal flaw in it, fix that flaw and then leave everybody else in the dust, wondering why they didn’t do what he did. He’s one of the most interesting people on…
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All Rational Approximations of Pi Are Useless
Investigation to find a better rational approximation for pi. Can we get out more digits than we put in? Chance to win a prize if you can do bette
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