Science
drorzel | August 27, 2010I'm pretty sure I've used this topic before, but not with PollDaddy. And while I really ought to do a ResearchBlogging post today to make it a clean sweep for the week, I just don't have the energy.
So here's a poll: what's your favorite fundamental force?
What's your favorite fundamental force?online surveys
Those of us with corporeal existence should restrict our answers to the low-energy condition of the present material universe, not any of the higher energy unification scales.
drorzel | August 26, 2010There's a minor scandal in fundamental physics that doesn't get talked about much, and it has to do with the very first fundamental force discovered, gravity. The scandal is the value of Newton's gravitational constant G, which is the least well known of the fundamental constants, with a value of 6.674 28(67) x 10-11 m3 kg-1 s-2. That may seem pretty precise, but the uncertainty (the two digits in parentheses) is scandalously large when compared to something like Planck's constant at 6.626 068 96(33) x 10-34 J s. (You can look up the official values of your favorite fundamental constants at…
drorzel | August 25, 2010New York Jets cornerback Antonio Cromartie is getting mocked for a clip where he takes some time to name all his children (the clip isn't as bad as the description makes it sound-- he's slow, but he doesn't struggle all that badly). Cromartie claims that HBO manipulated the footage to make him look bad.
Of course, there's an easy way to avoid this kind of mess: simply give all the kids the same name, thereby reducing it to a previously solved problem.
In discussion on a mailing list where this came up, someone wondered about how many children Wilt Chamberlain would've fathered, given his…
drorzel | August 25, 2010The Joerg Heber post that provided one of the two papers for yesterday's Hanbury Brown Twiss-travaganza also included a write-up of a new paper in Nature on Mott insulators, which was also written up in Physics World.
Most of the experimental details are quite similar to a paper by Markus Greiner's group I wrote up in June: They make a Bose-Einstein Condensate, load it into an optical lattice, and use a fancy lens system to detect individual atoms at sites of the lattice. This lattice can be prepared in a "Mott insulator" state, where each site is occupied by a definite number of atoms. As…
drorzel | August 24, 2010Two papers in one post this time out. One of these was brought to my attention by Joerg Heber, the other I was reminded of when checking some information for last week's mathematical post on photons. They fit extremely well together though, and both relate to the photon correlation stuff I was talking about last week.
OK, what's the deal with these? These are two papers, one recent Optics Express paper from a week or so ago, the other a Nature article from a few years back. The Nature paper includes the graph you see at right, which is a really nice dataset demonstrating the Hanbury Brown and…
stoat | August 23, 2010Yes, the review you've all been waiting for. Before I start, let me point out that this has been discussed by WE at WUWT, who has pointed out the obvious problem. It has also been mentioned by KK, though that appears to be more of a meta-discussion about the paper's reception rather than the paper itself.
[Note: follow-up here.]
To quote KK:
But back to the show. One commenter at WUWT, noting the negative reaction to Judith, gives her a backhanded compliment when he writes: I have to applaud Judith Curry on having the guts to present her paper in the boxing ring of climate blogs where the…
drorzel | August 23, 2010I'm a big fan of review articles. For those not in academic science, "review article" means a long (tens of pages) paper collecting together the important results of some field of science, and presenting an overview of the whole thing. These vary somewhat in just how specific they are-- some deal with both experiment and theory, others just theoretical approaches-- and some are more readable than others, but typically, they're written in a way that somebody from outside the field can understand.
These are a great boon to lazy authors, or authors facing tight page limits ("Ref. [1] and…
drorzel | August 22, 2010I was channel-surfing the other night, and stumbled across a History Channel program on paleoanthropology, talking about new-ish theories of how humans first populated the Americas. Coming off my recent read of 1491, this seemed like a good way to pass a little time.
After a little bit, it started to talk about some guy's theory that the Younger Dryas cooling and the mass extinctions at around that time were caused by an asteroid impact on one of the ice sheets. Which, you know, is a theory, I guess. The problem with this was, part of the evidence they were citing for the impact hypothesis…
drorzel | August 21, 2010I'm probably about the last person with an interest in such things to get around to watching Phil Plait's (in)famous "Don't Be a Dick" speech, but I finally got around to it, and it's really excellent:
Phil Plait - Don't Be A Dick from JREF on Vimeo.
Phil has posted about the speech itself, online reactions to it, and the in-person response after the talk. His thoughts are well worth reading, to put the whole thing it better context.
I really don't have anything to add, which is fine, because I should spend less time typing blog stuff anyway.
drorzel | August 20, 2010Johan Larson emails a suggestion for a post topic:
How many profs would it take to offer a good, but not necessarily excellent, undergraduate physics degree?
I can give you an empirical answer to this: Six.
I say that because in the course of my undergraduate physics degree at Williams, I took classes from only six different professors. Five-and-a-half, really, because one of those was half of a team-taught course. I had three-and-a-half classes with one professor, and two others for two classes each.
Of course, that's not a hard lower bound. Some have even suggested that the number could be…
drorzel | August 20, 2010It's nearly time for classes to resume, which means it's time for a zillion stories about Beloit College's annual Kids These Days List, listing off a bunch of things that this year's entering college class, who were mostly born in 1992, have always taken for granted. A sample:
1. Few in the class know how to write in cursive.
2. Email is just too slow, and they seldom if ever use snail mail.
3. "Go West, Young College Grad" has always implied "and don't stop until you get to Asia...and learn Chinese along the way."
4. Al Gore has always been animated.
5. Los Angelenos have always been trying…
drorzel | August 20, 2010In my post about how we know photons exist, I make reference to the famous Kimble, Dagenais, and Mandel experiment showing "anti-bunching" of photons emitted from an excited atom. They observed that the probability of recording a second detector "click" a very short time after the first was small. This is conclusive evidence that photons are real, and that light has discrete particle-like character. Or, as I said in that post:
This anti-bunching effect is something that cannot be explained using a classical picture of light as a wave. Using a wave model, in which light is emitted as a…
drorzel | August 19, 2010Everybody's favorite science-and-politics blogger has posted a video clip showing part of what's wrong in science communication. It's a clip from the BBC from last December, featuring one of those head-to-head quasi-debates about "Climategate" between Prof. Andrew Watson of the University of East Anglia and political consultant Marc Morano, who has made himself a nice little media niche as the go-to guy for climate change denial:
I don't think this is quite as damning as Chris says, but it's pretty bad. What you see here is a competition between a scientist and somebody who knows how the…
drorzel | August 19, 2010At the tail end of Tuesday's post about wind and temperature, I asked a "vaguely related fun bonus question:"
If the air molecules that surround us are moving at 500 m/s anyway, why isn't the speed of sound more like 500 m/s than 300 m/s?
This is another one that people are sometimes surprised by. The answer is simply that in a sound wave, the air molecules don't really go anywhere. When something creates a sound-- say a foolish dog barking at a perfectly harmless jogger going by outside, to choose an example completely at random-- there isn't any actual thing that travels from the noisy dog…
drorzel | August 18, 2010We picked up a used copy of Charles Mann's pop-archeology book 1491: New Revelations of the Americas Before Columbus a while back. I didn't read it at the time, because I was a little afraid that it would be rather polemical in what I think of as the Neil Young mode-- wildly overstating the awesomeness of pre-Columbian cultures, and exaggerating the evil of the European invaders (Neil's recorded some great stuff, but the lyrics to "Cortez the Killer" are pretty dopey). It came up several times recently in discussions elsewhere, though, and seemed like it would make a nice break from the…
drorzel | August 18, 2010Most of the time, when we talk about seeing quantum effects from light, we talk about extremely weak beams-- looking at intensities where one photon more or less represents a significant change in the intensity of the light. Last week, though, Physics Buzz wrote up a paper that goes in the other direction: they suggest a limit on the maximum strength of a laser pulse due to quantum effects, specifically the creation of particle-antiparticle pairs.
This is a little unusual, in that most of the time when people talk about really intense lasers, they end up discussing them as an oscillating…
drorzel | August 17, 2010I got forwarded a physics question last night asking about the connection between wind and temperature, which I'll paraphrase as:
Temperature is related to the motion of the atoms and molecules making a substance up, with faster motion corresponding to higher temperature. So why does it feel warmer when the air is still and why does wind make you feel cold?
This is a moderately common point of confusion, so while I responded to the question in email, I'll also appropriate it for a post topic. So, why doesn't "windy" equal "hot," given that wind consists of moving air molecules?
The full…
pharyngula | August 17, 2010I've never been a fan of SETI, the search for extraterrestrial intelligence. It's like playing the lottery obsessively, throwing down lots of money in hopes of a big payoff, and I don't play the lottery, either.
I'd really like to know if Seth Shostak is innumerate enough to play the lottery, though, because his recent claim that we stand a good chance of discovering extraterrrestrial intelligence within 25 years. All right, bring it: let's see your evidence for such a claim.
"I actually think the chances that we'll find ET are pretty good," said Seth Shostak, senior astronomer at the Search…
oracknows | August 16, 2010Over the years, I've written a lot about cell phones and the scientifically highly implausible claim that radio waves from cellular telephones can lead to brain cancer and other health problems. For example, two years ago, when the then director of the respected University of Pittsburgh Cancer Center, Dr. Ronald B. Herberman issued a warning to the faculty and staff of UPCC to limit their cell phone use because of the risk of cancer, I had a definite bone to pick with him. The evidence upon which Dr. Herberman based his hysterical warning, which was duly picked up by the press and spread…
drorzel | August 16, 2010A couple of "kids these days are bad at math" stories crossed my feed reader last week, first a New York Times blog post about remedial math, then a Cocktail Party Physics post on confusion about equals signs. The first was brought to my attention via a locked LiveJournal post taking the obligatory "Who cares if kids know how to factor polynomials, anyway?" tack, which was obvious bait for me, given that I have in the past held forth on the importance of algebra for science students (both of these are, at some level, about algebra).
Of course, these articles aren't about science students, so…