Built on Facts

Archives for December, 2008

Sex and Simultaneity

From the inimitable xkcd, a comic about relativity in sex: This rather clever piece of humor is referring to the relativity of simultaneity. According to relativity, time and space are different for observers in different reference frames. Events which are simultaneous in one frame are not necessarily going to be simultaneous in a different frame…

The Physical Mob

So Tony Soprano pitches ties a concrete block to Salvatore Bonpensiero and pitches him into the ocean, where he will inform the police no more. Being a big guy, Bonpensiero has a fairly low density compared to your average human being – say, 0.96 grams per cubic centimeter. That’s less than water and so he’d…

Where’s the hydrogen?

A mysterious gap in posting? Must be finals time! As of now I’m done. We’ll see how they went. One of them went well for sure, the other sort of depends. My own students are having their own exams as well, and I’ve got my fingers crossed for them. One of the things that’s going…

Sunday Function

This rather striking image is the imaginary part of the Airy function. Rather than a lot of words today, I’d like to just present this mathematical function as art. I’ve always disagreed with Whitman in his assessment of science, but it is nonetheless a good thing to occasionally look up in silence at the stars…

Weekend Update

Yesterday I posed a famous trick question, and we had the shortcut answer, the long “standard” answer, and a particularly elegant solution by commenter meichenl. Turns out he has his own blog called Arcsecond, and it’s really fantastic. He focuses mostly on examining interesting mathematical situations. Check it out! Some physics news: the perils of…

Bouncing Birds

Challenge question! It’s either very easy or somewhat difficult depending on how clever you are at approaching it. No fair answering if you’ve already seen the problem before, though if no one’s managed it in a few hours I’d say it’s fair game to post the solution if you already know it. Two trains are…

Vandalizing Big Brother

Seed’s editorial policy is unusually generous in the latitude we ScienceBloggers get. Let’s hope it’s generous enough for this! Linked via Instapundit, I saw this interesting article about theft of and damage to speed cameras. As an strong supporter of civil liberties, this warms my heart. If a flesh-and-blood police officer catches me speeding, fair…

Gas in a (very small) box.

Before the physics, I want to point out one of the most interesting ScienceBlogs posts I’ve seen in a long time: Not Exactly Rocket Science discussing the body-swapping illusion. You should read it. Now, here’s a quiz I gave my Physics 201 students. Easy as usual, but I’m a sucker for these order-of-magnitude problems where…

Microwaves and Money

If you go to Capital One’s website and type in the appropriate login information, you’ll see a “Welcome Matthew Springer” message and two accounts. One’s a checking account and one’s a money market account where I’m endeavoring to accumulate some savings. (I need to get that moved to a CD or something, the interest rate…

Horribly Cold Lasers

Well, my Thanksgiving posting break lasted longer than I thought. Real life is a more fun place than the internet though, and I hope you were having lots of fun and food and were not on the internet to notice my absence. Among the things I did this Thanksgiving was watch Dr. Horrible’s Sing-Along Blog…