Astronomy
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 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…
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…
drorzel | May 3, 2010While I missed the controversial episode with comments about aliens, I figured I should at least take a look at the Discovery Channel's Into the Universe with Stephen Hawking, so I put it on last night after putting SteelyKid to bed. This was the big two-hour "Story of Everything" episode, starting with the Big Bang and describing the whole history of the universe.
I made it through about half an hour, before I gave up and went to bed. This was partly due to it being a really long day (I took SteelyKid shopping and to a playground, did some yard work, and went to a meeting on campus), so I…
drorzel | May 3, 2010Voting has closed on the Laser Smackdown poll, with 772 people recording their opinion on the most amazing of the many things that have been done with lasers in the fifty years since the invention of the first working laser (see the Laserfest web site for more on the history and applications of lasers). The candidates in the traditional suspense-building reverse order:
Lunar laser ranging 22 votes
Cat toy/ dog toy/ laser light show 41 votes
Laser guide stars/ adaptive optics 46 votes
Holography 47 votes
Laser eye surgery 53 votes
Optical storage media (CD/DVD/Blu-Ray) 60 votes
Laser…
drorzel | April 28, 2010I'm a little surprised at the vehemence of some of the negative reactions to Stephen Hawking's comments about aliens. Not so much in blogdom-- Ethan's response is pretty reasonable, for example-- but there was a flurry of Twitter traffic yesterday of the form "Where does Stephen Hawking get off pontificating about aliens?" which strikes me as kind of silly.
As all the news stories point out, Hawking's comments were made in the context of a Discovery channel series based on filming Stephen Hawking pontificating about stuff. And, really, if the Discovery Channel called me up and offered to film…
drorzel | April 26, 2010As of 1:45 Monday, 217 people have cast votes in the Laser Smackdown poll. That's not bad, but it's currently being handily beaten by the 271 people who have voted for a favorite system of units.
The nice thing about using actual poll services for this sort of thing, though, is that I can re-post the poll to boost signal a little. So, here it is again, a list of the twelve most amazing laser applications suggested by my wise and worldly readers, with links to short explanations of the pros and cons of each:
Which of the following is the most amazing application of a laser?Market Research…
drorzel | April 23, 2010In 1960, the first working laser was demonstrated, and promptly dubbed "a solution looking for a problem." In the ensuing fifty years, lasers have found lots of problems to solve, but there has been no consensus about which of the many amazing applications of lasers is the most amazing.
Now, in 2010, as we celebrate the anniversary of the laser, we finally have the technology to definitively answer the question: radio-button polls on the Internet!
Which of the following is the most amazing application of a laser?Market Research
Each of the choices above links to a post I wrote here giving…
drorzel | April 22, 2010What's the application? Producing artificial "stars" to serve as a reference for telescopes using adaptive optics to correct for atmospheric turbulence. This allows ground-based telescopes to produce images that are as good as those from the Hubble Space Telescope.
What problem(s) is it the solution to? "How can I make this giant telescope produce even more impressive pictures?"
How does it work?The basic problem with ground-based telescopes, as anyone who has ever looked at the stars or listened to nursery rhymes can tell you, is that stars "twinkle." They appear to fluctuate in brightness…
drorzel | April 21, 2010What's the application? An optical frequency comb is a short-duration pulsed laser whose output can be viewed as a regularly spaced series of different frequencies. If the pulses are short enough, this can span the entire visible spectrum, giving a "comb" of colored lines on a traditional spectrometer. This can be used for a wide variety of applications, from precision time standards to molecular spectroscopy to astronomy.
What problem(s) is it the solution to? 1) "How do I compare this optical frequency standard to a microwave frequency standard?" 2) "How do I calibrate my spectrometer well…
drorzel | April 12, 2010What's the application? LIGO stands for Laser Interferometer Graviitational Wave Observatory, because (astro)physicists feel free to drop inconvenient words when making up cute acronyms. This is an experiment to look for disturbances in space-time caused by massive objects, which would manifest as a slight stretching and compression of space itself.
What problem(s) is it the solution to? 1) "Can we directly observe the gravitational waves that are predicted by the equations of General Relativity?" 2) "Can we detect things like colliding black holes, because that would be awesome!"
How does it…
drorzel | April 8, 2010Back when I was in grad school, and paper copies of journals were delivered to the lab by a happy mailman riding a brontosaurus, I used to play a little game when the new copy of Physical Review Letters arrived: I would flip through the papers in the high energy and nuclear physics sections, and see if I could find one where the author list included at least one surname for every letter of the alphabet. There wasn't one every week, but it wasn't that hard (particularly with large numbers of physicists from China, where family names beginning with "X" are more common).
Every so often, somebody…
drorzel | March 26, 2010Somebody at Houghton Mifflin Harcourt has a really high opinion of this blog, as they not only sent me an Advance Reading Copy of Paul Davies's forthcoming book about SETI, The Eerie Silence: Renewing Our Search for Alien Intelligence, they followed it up with a finished hardcover. I read the ARC on the plane on the way back from the March Meeting, and put the hardcover in the mailbox of a colleague who just finished co-teaching a course on astrobiology.
This book is being released in 2010, which Davies cites as the 50th anniversary of an active Search for Extra-Terrestrial Intelligence (SETI…
drorzel | February 11, 2010What's the application? Measuring the distance from the Earth to the Moon by bouncing a laser off one of the retro-reflector arrays left there by the Apollo missions.
What problem(s) is it the solution to? 1) "How does the distance from the Earth to the Moon vary over time due to things like tidal drag?" 2) "Does the strength of gravity change over time?" 3) "What can we do with a laser to really cheese off people who think the Moon landings were fake?"
How does it work? This concept is simplicity itself. You simply point a laser at the Moon, fire off a short pulse of light, and wait for it…
drorzel | December 21, 2009How to Teach Physics to Your Dog goes on sale in fine bookstores everywhere tomorrow. But maybe the four previous posts explaining why dogs should care about quantum physics haven't yet convinced you to go buy a copy. So here's another reason, one appropriate to this solstice season, when dogs in the Northern Hemisphere will start to enjoy longer days again: Sunlight.
You like sunlight, right? Of course you do, unless you're a vampire. And what dog doesn't like a sunny day? Well, you have quantum physics to thank for sunlight, because as hot as the Sun is, it's not nearly hot enough to burn…
drorzel | December 18, 2009As a physicist with a blog, I am contractually obligated to do a post on the CDMS almost-a-result. This is that post.
The short version: they expected at most 0.8 events (that's total events, not events per day, or anything-- this is a whole community built on detecting nothing at all), and got 2, with maybe a third that was close to making the cut, but didn't. I think Joe Fitzsimons on Twitter summed it up best, writing:
Isn't that the least informative number of events possible?
It's more events than expected, but not enough to really be meaningful. The probability of this level of signal…
drorzel | December 6, 2009I'm kind of fried from all the recent driving, and I've got some stuff to catch up on. So we'll ease back into regular blogging, by posting a clip from last week's Colbert Report with everybody's favorite Jesuit, Brother Guy Consolmagno, talking about how alien life would affect Christianity:
The Colbert Report
Mon - Thurs 11:30pm / 10:30c
Gold, Frankincense and Mars - Guy Consolmagno
www.colbertnation.com
Colbert Report Full Episodes
Political Humor
U.S. Speedskating
There's your "science and religion are compatible" item for this month, as well.
drorzel | October 15, 2009I gave a guest lecture this morning in a colleague's sophomore seminar class about time. She's having them look at time from a variety of perspectives, and they just finished reading Longitude, so she asked me to talk about the physics of clocks and the measurement of time.
I've long considered using "A Brief History of Timekeeping" as the theme for a general education course-- there's a ton of interesting science in the notion of time and timekeeping. This was just a single class, though, so I didn't go into too much detail:
A Brief History of Timekeeping
View more presentations from Chad…
drorzel | October 11, 2009Over at Physics and Physicists, ZapperZ notes a fairly useless interview with Guy Consolmagno, and suggests some alternative questions:
1. How old do you estimate the universe to be based not only on your observation, but also the consensus among astronomers? Would this be contrary to the biblical interpretation on the age of the universe? What about the Young Earth's interpretation of the age of the universe?
2. What is your view of the treatment received by Galileo by the church? {Oh c'mon, you knew that one was coming, didn't you?}
These would be better questions than what was asked in…
drorzel | October 8, 2009A couple of days ago, I answered a question from a donor to the Uncertain Principles challenge page in this year's Social Media Challenge (we've raised $1,807 thus far-- thank you all). If you'd like a question of your own answered on the blog, all you need to do is send me the confirmation email for a donation of at least $20, and your question.
The donor from the other day, Lauren Uroff, had a second question as well, also on behalf of her teenager:
He's an avid Discworld fan (where the speed of light seems to be variable) and wants to know what would happen in our real world if the speed…