Built on Facts
Everything in Pi… maybe.
Posted by Matt Springer on April 12, 2013 George Takei posted the following thing to Facebook recently: It got reposted by a bunch of people and provoked a tremendous amount of discussion (for a math topic, anyway), much of which was somewhere in the continuum between merely wrong and psychedelically incoherent. It’s not a new subject – a version of the image got…
Why are clouds white?
Posted by Matt Springer on April 1, 2013 Why is the sky blue? It’s a classic question – probably the classic question of the genre of explanatory popular physics. The famous short version of the answer is that Rayleigh scattering by air molecules affects short-waveength light more than long-wavelength light, and so blue light tends to get scattered in random directions to create…
Light from a Hairbrush
Posted by Matt Springer on March 15, 2013 Question from a reader: Pick up a comb, rub it with your hair and you have got some electric charge. Now shake it and you are generating an electromagnetic wave. Am I right? Yes indeed. So why don’t we see light emitted when we brush our hair? Let’s run some numbers. If you wiggle around…
Quick, hit the brakes!
Posted by Matt Springer on February 27, 2013 A reader emailed me a fun question from a physics exam he took, along these lines: A car driver going at some speed v suddenly finds a wide wall at a distance r. Should he apply brakes or turn the car in a circle of radius r to avoid hitting the wall? My first thought…
The Theoretical Minimum, by Susskind & Hrabovsky
Posted by Matt Springer on February 12, 2013 A review of an odd but beautiful pop-physics book.
The Human Eye, Optimized For Sunlight. Maybe.
Posted by Matt Springer on January 29, 2013 The human eye is sensitive to a portion of the electromagnetic spectrum that we call visible light, which extends from around 400 to 700 nanometer wavelength, peaking in the general vicinity of greenish light at 560 nanometers: Here’s the intensity (formally: power per area per unit solid angle per unit wavelength – whew!) of the…
Gun Control Debate with Mark, Pt. 2
Posted by Matt Springer on January 28, 2013 Gun violence is bad. Gun laws have very little to do with it.
The Physics of the Ponytail
Posted by Matt Springer on January 22, 2013 The first major computer-animated film was Toy Story. It had a few human characters, most prominently Andy (who spends most of the film wearing a hat) and Sid (who sports a buzz cut). The focus of the film is on the plastic toys. One of the major reasons for this is the fact that toys…
The Mathematics of Reddit Rankings, or, How Upvotes Are Time Travel
Posted by Matt Springer on January 16, 2013 Ok, so this isn’t really physics as such, but it’s pretty fascinating. There’s a very large online community called Reddit in which users submit links which interest them. These links come with two little arrows beside them, and the users can vote the link up or down. Here’s a screenshot of how the website looks…
Gun Control Debate with Mark Hoofnagle, pt. 1
Posted by Matt Springer on January 14, 2013 In which I argue against gun control.