May 16, 2010
Consider this not-so-difficult sum:
It consists of just a string of fractions up to whichever N you happen to choose. Add them up, and you certainly and unambiguously have a number. If you chose to stop at N = 10, you'd find that f(10) = 1627/2520, which is about 0.645635. If you chose to stop…
May 13, 2010
CNN has a headline up: Fate or Fluke: Air crash sole survivors. ON the homepage itself the banner reads "Fate or Physics?"
(CNN) -- Some will see it as divine intervention, others a simple quirk of fate, fortune or physics, but one boy's cheating of death in an air crash in Libya this week adds…
May 7, 2010
I recently learned about a great blog by S.C. Kavassalis of the University of Toronto called The Language of Bad Physics. She discusses, among other things, the way language is used in physics. She's got an interesting piece on the use of the word "theory". This is always a hot area of discussion,…
May 4, 2010
This semester I took a course on quantum optics. I'm an AMO guy and quantum optics is one of our department's particular strengths, so it was both a very useful class and a pleasure to take. One of the graded requirements of the class is to write a paper from a list of quantum optics with the…
May 2, 2010
It's been a while since we've done a Sunday Function, so let's get back into the swing of things with a weird one. This is Thomae's function, and using Wikipedia's conveniently typeset definition:
If you're new to the concept of rational and irrational numbers, it's pretty simple. A number is…
April 29, 2010
I'm not quite convinced Iron Man is entirely realistic.
"Proposterous!", you say, "Hollywood makes its superhero films to near-documentary accuracy!" No, hear me out. Iron Man can fly, using rockets in his hands and feet. We know from the commercials that the suit can in fact fit in a briefcase…
April 23, 2010
Back in the 1600s science was much less specialized. You didn't really have biology, chemistry, physics, and even mathematics for that matter as fully separate disciplines. If you did science, you were a "natural philosopher" and that was that. Now even physics by itself could be argued to be…
April 21, 2010
There's a really snazzy physics blog run out of Cornell called The Virtuosi. Sort of like this blog, they're big fans of looking at interesting scenarios through the equations of physics. Not long ago, they had an interesting post looking at whether or not laser guns would have recoil.
I'm not…
April 14, 2010
Here's an experiment to try. It's a thought experiment - it would be almost impossible to carry out in reality, though more delicate experiments roughly along these lines have been done.
You're in one of the space shuttles, or the Discovery One, or your favorite fictional but realistic spacecraft…
April 9, 2010
In every cop drama there's a scene where a suspect is being questioned in an interrogation room. The room contains a large mirror, and behind that mirror the detectives and district attorneys are observing and arguing about the progress of the case. The mirror is a two-way mirror.
These kinds of…
April 7, 2010
Ladies and gentlemen, I give you the worst physics news article I have ever seen:
Freaky Physics Proves Parallel Universes Exist
Every word in the title is wrong but "physics". It's not freaky, doesn't prove anything we didn't already know, and has nothing to do with parallel universes nor does…
April 4, 2010
Happy Easter, everyone!
This Sunday Function is going to be short and sweet, since unfortunately I've got a lot to do before Monday. Let's get down to business!
Here's a function I've made up out of thin air. It's pretty arbitrary - in fact, it's discontinuous at x = -1/2 and not differentiable…
April 2, 2010
There's a classic problem in physics textbooks which asks you about astrology. It's sometimes said - the problem will tell you - that the gravitational pull of the doctor delivering you is stronger than that of Jupiter, therefore it's unlikely that the planets are exerting a whole lot of influence…
March 31, 2010
So what exactly is light, anyway?
It's a tough question. Isaac Newton thought it was composed of streams of microscopic particles he called corpuscles. Really it wasn't a bad idea. Light rays travel in straight lines just like fast moving projectiles, light bounces off objects in a manner not…
March 26, 2010
If you happen to be in the Bryan/College Station area tomorrow, you might consider checking out the Texas A&M Physics Festival. It's sort of an open house with a ridiculous number of top-notch physics demonstrations as well as some very interesting talks. It's free! I'll be there helping out…
March 25, 2010
Somehow - and I don't know exactly how, you know how the internet is - I came across this odd but cute song by the ineffable Weird Al. It's an almost seven-minute(!) ode to the roadside attraction that is the titular biggest ball of twine. The twine ball actually exists, and lives in Darwin,…
March 21, 2010
This is the graph of the line y = x:
If you put your finger down on any point on that line, and then put another finger on another point on that line, you find that the total change in the y-coordinate divided by the total change in the x-coordinate between those two positions is 1. Move two…
March 19, 2010
GrrlScientist sends a link to this rather wild stunt from India:
How is it possible? What kind of friction is necessary, and is it any more difficult for the cars to do the stunt than it is for the motorcycles?
Before we do any math, I want to think about the problem qualitatively. Let's tally…
March 14, 2010
Sine, cosine, and tangent are of course the workhorse functions of trigonometry. You learn 'em in high school, and if you go on in math and science you never stop using them. Now on many occasions you might have the sine or cosine or tangent of some angle, and you want a way to invert those…
March 12, 2010
In the Stealth in Space post earlier this week, we discussed the problem of detecting the thermal emission from a spacecraft. If the interior isn't generating a lot of power, there's not much thermal radiation being emitted, making it a tough job to detect.
But it was pointed out in the comments…
March 10, 2010
While doing some poking around online, I came across a website called Project Rho, which tries to provide some science background for science fiction writers who want some degree of technical accuracy in their imaginative work. Generally it looks like they're on the right track.
In their section…
March 8, 2010
This Sunday I was at an event that involved a number of drawings for door prizes. There were perhaps 30 couples there - it was, not to beat around the bush, a wedding registry shindig at Bed, Bath, & Beyond. (Did I mention I'm recently engaged? I am. It's the main reason for the endemic…
March 4, 2010
If you read about science at all, you've heard of Heisenberg's uncertainty principle. It's the canonical example of quantum weirdness, the strange idea that you can't simultaneously know the position and momentum of a particle. Pack a particle into a small enough box and your accurate knowledge…
March 2, 2010
There's an interesting science puff piece that's been circulating around various media outlets about the length of the day after the earthquake in Chile. At random, here's the NY Daily News version:
The quake that rocked the South American nation may have also knocked the Earth off its axis.
The 8…
February 24, 2010
A reader writes in with a question about the speed of light. Since the meter and second are defined in terms of that speed, how would we be able to tell if the speed of light is changing or has changed throughout history?
It's a good question. According to the official standard, a meter is…
February 22, 2010
Here's a simple function that's not so often found in mathematical physics, but it's still a nice showpiece for exhibiting some interesting behavior:
I've only plotted it for positive real x, because for x less than zero it starts spitting out complex numbers in a very unfriendly way. We're only…
February 20, 2010
Unfortunately it's rarely on TV more than once every four years, but I have to say I've really gotten to curling. Not only is it interesting to watch, it looks like it's actually a sport that could be played for fun at the beginning level. Unfortunately there doesn't seem to be a whole lot of…
February 18, 2010
Grad school and a major (good) event in my personal life have been gobbling huge swaths of time, hence the comparative silence around here. I'm afraid we may be down to a few times a week for the next few months. I hope y'all'll bear with me. ("Y'all'll" is of course the standard contraction for…
February 15, 2010
Pretty much every high school student can quote the formula for the area of a circle: it's A = pi r^2, where r is the radius. Most of them can do the same thing for the volume of a sphere: V = 4/3 pi r^3.
You could, if you wanted, generalize the concept and call circles "2-spheres", because they'…
February 12, 2010
Recently I bought a plug-in power meter, along these lines:
It's a nice little invention to have. You can measure both instantaneous power consumption as well as total energy used. Given that and your power bill, you can see how much it costs to run a particular appliance in real time. The…
