Physics
rallain | May 13, 2010Yes, I am going to talk about the MythBusters latest duct tape episode. A couple of pre-post points:
They call it "duct" tape. I call it duck tape. It doesn't work very well with ducts. Also, it is good for water proofing stuff - you know like a duck. For the rest of this post, I am calling it duck tape. (Wikipedia agrees there is some naming problem)
You know I love the MythBusters - right? I hope you don't think I sit around waiting for them to make a mistake so I can pounce on them (I save that for ESPN Sport Science). In this case, they just made a small mistake. A mistake that…
drorzel | May 13, 2010Spinning off a blog at Inside Higher Ed, the Dean Dad has a post on deciding what classes are essential:
My personal sense of it is that the distinction between core and periphery is largely a function of purpose. If your goal in life is to be an exhibited artist, then you might well decide that art is essential and history a frill. If your goal is to be an engineer, I could understand valuing a math class over a psych class. Since different students have different purposes, I wouldn't be surprised to discover that one student's frill is another student's priority.
But the questions go deeper…
drorzel | May 12, 2010Via Jennifer Ouellette on Twitter, I ran across a Discovery News story touting a recent arxiv preprint claiming to see variation in the fine-structure constant. It's a basically OK story, but garbles a few details, so I thought it would be worth giving it the ResearchBlogging treatment, in the now-traditional Q&A format.
What did they do? The paper looks at some spectral lines in radio emission from a moderately distant galaxy with the poetic name "PKS1413+135." These lines are produced by OH molecules in interstellar gas clouds, and the frequencies they see suggest that there may have…
drorzel | May 11, 2010I should note up front that I'm kind of jealous of Marcus Chown regarding this book. Subtitled "What Everyday Things Tell Us About the Universe," The Matchbox That Ate a Forty-Ton Truck is a book that uses trivial everyday observations-- the fact that you don't fall through the floor, the fact that the sky is dark at night-- as a jumping-off point for discussions about deep and fundamental scientific ideas like Pauli exclusion and inflationary cosmology. It's a fantastic idea for a pop-science book, and I wish I'd thought of it first.
The range of topics here is pretty big, covering most of…
esiegel | May 10, 2010"Music is perpetual, and only the hearing is intermittent." -Thoreau
A couple of weeks ago, my wife and I went to the circus together. Someday, I vowed, I'll be strong, flexible, and stable enough to do the amazing hand-balancing tricks we saw.
And all the while, the six-year-old girl behind us screamed her piercing, high-pitched scream, cheering the performers on.
(This is totally appropriate behavior, IMO, and no children reading this should be discouraged from screaming at the circus.)
Now, one of us has better hearing than the other. And while one of us found the high pitched screaming…
drorzel | May 10, 2010I've written before about the problem of having in-between views on controversial subjects in blogdom. This is something that also comes up in Jessica's excellent entry on online culture, and has been scientifically demonstrated in political contexts.
I'm somewhat bemused, then, to see the same thing happen in a physics context. A while back, I got an email asking about quantum foundations that read in part:
I'm very keen to understand why you and Andrew Thomas reject [the Many-Worlds Interpretation of QM].
I'd be very happy if you'd take a few minutes to try to describe why you think MWI is…
drorzel | May 9, 2010When I was writing about the seemingly contradictory meanings of "adiabatic" the other day, I almost gave "theory" as an example of a word with nearly opposite meanings. After all, as anyone who has even glanced at the evolution-creation "debate" has heard, a "Theory" in science is something more exalted than a mere guess-- it's a guess that has been confirmed by observations and experiments, and can thus be regarded as true with a high degree of confidence (and assigned a capital letter in this post, to set it apart). (Also, in physical science at least, it makes quantitative predictions.).…
drorzel | May 8, 2010While it's not aprt of the official LaserFest package of stuff, Physics World is marking the 50th anniversary of the laser with a couple of really nice pieces on lasers in science and popular culture:
Where next for the laser interviews six laser experts-- Claire Max of UCSC, Bill Phillips of NIST, Steven Block of Stanford, science writer Jeff Hecht, John Madey of Hawaii's FEL lab, and Eric Gustafson of Caltech and LIGO.-- about the current status of lasers in their areas of science, and the future prospects.
From ray-gun to Blu-Ray is a very nice survey of lasers and laser-like devices in…
esiegel | May 7, 2010"What is art but life upon the larger scale, the higher. When, graduating up in a spiral line of still expanding and ascending gyres, it pushes toward the intense significance of all things, hungry for the infinite?" -Elizabeth Barrett Browning
I don't mean to ask why the Milky Way is a spiral in an existential sort of way. You see, many galaxies, like our own, and also like Andromeda and the Triangulum Galaxy (below) -- our nearest galactic neighbors -- are spiral galaxies.
They're what I think of when I think of galaxies, and they're probably the first thing that pops into your head, too.…
drorzel | May 7, 2010The Steinmetz Symposium is today at Union, as mentioned in yesterday's silly poll about fears (I love the fact that "Wavefunction Collapse" leads "Monsters from the Id" by one vote at the time of this writing-- my readers are awesome). As a more serious follow-up, there were two presentation options offered to the students, and this year's physics majors overwhelmingly chose one over the other. I'm curious as to how many people would make the same choice, so here's a poll:
You have to give a presentation about a research project you have done. Which of these presentation types would you…
rallain | May 6, 2010I already mentioned the MythBusters' crashing two cars episode where they correctly doubled the speed of a pendulum type object. Overall, this was a very visual (although expensive) demo. There was one part that left a sour taste in my mouth - the final explanation from the narrator. First, they showed this.
And then they had an explanation that went something very similar to to this (after restating what the sign above said)
"Although the two-car crash doubles the speed, the energy the crash is transferred to twice the mass resulting in a crash that looks like just one car hitting a wall…
drorzel | May 6, 2010There's a minor kerfuffle at the moment over the XENON experiment's early data (arxiv paper) which did not detect any dark matter in 11 days of data acquisition. This conflicts with earlier claims by the DAMA experiment and recent maybe-kinda-sorta detections by the CoGeNT and CDMA experiments.
As a result, a couple of members of other collaborations have posted a response on the arxiv saying, basically, that they don't believe the sensitivity claimed for the XENON detector in the energy range in question, and that their result can't really be said to rule out the possibility of dark matter…
rallain | May 6, 2010In the last episode of MythBusters, Adam and Jamie wanted to test something that Jamie had said earlier:
"Two cars crashing head on at 50 mph is the same as one car crashing into a wall at 100 mph"
Jamie was wrong, but that is not what I am going to talk about. Instead, I am going to talk about Adam's small scale test of this situation. Really, it was a nice set up. Basically, he wanted to collide something into a wall at one speed and then double that speed. Then he was going to collide two things together at the lower speed. He had a cool way of measuring the collision. He put a piece…
drorzel | May 6, 2010My publisher would like to include a Teacher's Guide with the paperback edition of How to Teach Physics to Your Dog. which means that, well, I need to put together a Teacher's Guide for How to Teach Physics to Your Dog. The problem is, I'm not exactly sure what should go in that sort of thing.
So, if you have any opinions on the subject of Teacher's Guides for pop-science books in general, or can point to examples of Teacher's Guides that you particularly like, or have suggestions for what ought to be in a Teacher's Guide for How to Teach Physics to Your Dog. If you were a teacher planning to…
rallain | May 5, 2010I was going to make this as a video tutorial, but it just didn't work out right. So, here it is in blog post form.
How do you deal with a video that zoom and pans at the same time? You could keep on adjusting the coordinate axis AND adjust the scale for each frame - but sometimes that is not possible. Tracker Video has a great tool to handle these types of videos - the calibration point pair. The basic idea is that you identify two points in a scene that should be stationary (part of the background) and track those two points. Tracker will then adjust the coordinates and scale to make…
drorzel | May 5, 2010Over at the Virtuosi, there's a nice discussion of the physics of letting air out of tires. Jesse opens the explanation with:
Have you ever noticed how when you let air out of a bike tire (or, I suppose, a car tire) it feels rather cold? Today we're going to explore why that is, and just how cold it is. Many people consider the air escaping from a tire as a classic example of an adiabatic process. What is an adiabatic process? It is a process that happens so quickly there is no time for heat flow to occur. For our air in the bike tire this means we're letting it out of the tire so…
drorzel | May 5, 2010It's been a couple of weeks since I did an update on How to Teach Physics to Your Dog, but that's been as much laziness as a lack of news. Some developments, mostly relating to foreign lands:
The US paperback edition is slated for December release. I'm working on a Teacher's Guide to go with it-- suggestions on what ought to be in there are welcome, as I have no idea
If you do the right search, you'll also find a forthcoming UK edition which will be out this fall with a slightly different title. There's a production schedule for this, and everything-- more information as things become…
rallain | May 4, 2010So you have seen these color filters (or gels as they are also called). When you look through a red filter, everything looks red. What do they do to the light? I am not going to tell you the answer. However, I will show you some examples so that you can figure out the answer yourself.
In this video, I am going to use a red and a green laser pointer. The nice thing about laser pointers is that they essentially create only one color of light.
rallain | May 4, 2010It is my duty as a blogger to mention lasers in this time of international laser celebration. This May is the 50th anniversary of the first lasers. Everyone knows a laser that they love, right? We all use them. So, instead of talking about lasers, I am going to post some great links to other laser stuff (including some of my stuff).
the history of the first lasers (AIP)
The above is the American Institute of Physics's presentation of the history of the laser. Really, this does a great job of giving all the details you would want. I highly recommend it.
Uncertain Principle's Laser…
esiegel | May 3, 2010"An educational system isn't worth a great deal if it teaches young people how to make a living but doesn't teach them how to make a life." -Unknown
Every now and again, people with all sorts of backgrounds -- from some graduate school all the way to having not finished high school -- ask me about getting involved in Astronomy and Astrophysics. Often, people's interest simply come from looking up at night.
I'm not going to lie, this is a huge question, with many different answers. First off, let's start off assuming that you have no background in math, no background in physics, and that you'…