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Moon
Interactive article about the Moon
Top posts
Every blog post that took off on Hacker News, ranked by the votes of its best submission. 179 posts.
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Airfoil
Interactive article explaining the physics of an airfoil and what makes airplanes fly
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Why is Chile so long?
Chile is so long, it's curved. How long is it? Why not longer? Why is no other country as thin? How does that make Chileans incomprehensible?
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How I got my laser eye injury
It has been brought to my attention that I have never actually written this story down before, merely told it in person to many students for valuable lessons and also for laughs over cocktails. It is a litany of bad ideas from several people that all came together at once to reach out and zap … Continue reading "How I…
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How French Drains Work
[Note that this article is a transcript of the video embedded above.] In February of 2017, one of the largest spillways in the world, the one at Oroville Dam in northern California, was severely damaged during releases from heavy rain. You might remember this. I made a video about it, and then ano
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The Lunacy of Artemis
Introduction A Note on Apollo I. The Rocket II. The Capsule III. The Orbit IV. Gateway V. The Lander VI. Refueling VII. Conclusion Notes
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Did Sandia use a thermonuclear secondary in a product logo?
I happened to look at a slide deck from Sandia National Laboratories from 2007 that someone had posted on Reddit late last night (you know, as one does,...
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Radios, how do they work?
A brief introduction to antennas, superheterodyne receivers, and signal modulation schemes.
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Phased Array Microphone (2023)
A 192-channel phased array microphone, with FPGA data acquisition and beamforming/visualization on the GPU. Phased arrays allow for applications not possible with traditional directional microphones, as the directionality can be changed instantly, after the recording is made, or even be focused at hundreds of…
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An intuitive guide to Maxwell's equations (2020)
An Intuitive and Visual Guide to Maxwell's Equations
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How many bathrooms have Neanderthals in the tile?
A Reddit poster finds an ancient jaw in his parents' new travertine. It may be more common than most people imagine.
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The Engineering of Landfills
[Note that this article is a transcript of the video embedded above.] This is the Puente Hills Landfill outside of Los Angeles, California. The first truckload of trash was dumped here in 1957, and the trucks just kept coming. For more than five decades, if you threw something away in LA County, t
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Is the world really running out of sand?
[Note that this article is a transcript of the video embedded above.] If you have to know the answer right away, it’s no; or at least, my goal with this video is to convince you that the world is not running out of sand. But if it were that simple, I wouldn’t be here (right?) and you probably woul
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The baffling intelligence of a single cell: The story of E. coli chemotaxis
I want to tell the story of a beautiful phenomenon in biology. In some sense it’s the prototype of much of the activity of life. The phenomenon is the way in which an individual cell of E. coli forages for nutrients. This process, known as “chemotaxis”—the “chemo-” for chemical and the “taxis” from the Greek τάξις…
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How photos were transmitted by wire in the 1930s
I didn’t know what to expect from this 1937 video explanation of how wire photos were transmitted to newspapers, but a double stunt sequence featuring an airpla
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Sir, there's a cat in your mirror dimension
Pets do the darndest things, especially if you teach them a bit of math.
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Testing the F-35C Tailhook
Welcome to the blog. As a way to kick things off, here’s a single-page version of my thread on the F-35C tailhook.
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Visualizing World War II
If you’ve been reading this blog for any length of time, you’ll know that maps and history are two of my favorite things. I love history because I love learning about the vast panoply of the human …
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Homemade 6 GHz pulse compression radar
Designing a modern pulse compression radar that uses digital signal processing.
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What does the cerebellum do?
Hint: It's Not Just Balance
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Why time seems to pass faster as we age
1/ I’ve been mega-obsessed with this feeling. A year as a 36-year-old seems so much shorter as compared to when I was a kid or even as a teen. It seems cosmically unfair – we have fewer years to live, and each year flies by faster. 2/ But, why is that happening? My tentative conclusion is that… Read More
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Can solar costs keep shrinking?
The costs of some parts of solar farms will drop to near zero. But some obstacles remain to make this energy cheaply available everywhere. As a result, the entire energy industry will change. What are those obstacles? How will the industry change?
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The magic of DC-DC voltage conversion (2023)
Resistor-based dividers, linear regulators, buck converters, and other ways to adjust voltages.
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What happens when you touch a pickle to an AM radio tower
A few months ago, our AM radio hot dog experiment went mildly viral. That was a result of me asking my Dad 'what would happen if you ground a hot dog to one of your AM radio towers?' He didn't know, so one night on the way to my son's volleyball practice, we tested it. And it was awesome. There's a video and some…
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On the Nature of Time
Stephen Wolfram takes a computational view of time, defining it abstractly, and the implications from computational irreducibility.
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Why Bridges Don't Sink
[Note that this article is a transcript of the video embedded above.] The essence of a bridge is not just that it goes over something, but that there’s clear space underneath for a river, railway, or road. Maybe this is already obvious to you, but bridges present a unique structural challenge. In
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Ultrasonic investigations in shopping centres
Many public address systems emit a continuous near-ultrasonic sound that is used for system health monitoring.
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What Is Entropy?
I wrote a little book about entropy; here’s the current draft: • What is Entropy? If you see typos and other mistakes, or have trouble understanding things, please let me know! An altern…