Physics
oracknows | January 6, 2012It's no secret that I've been highly critical of The Huffington Post, at least of its approach to science and medicine. In fact, it was a mere three weeks after Arianna Huffington launched her blog back in 2005 that I noticed something very distressing about it, namely that it had recruited someone who would later become and "old friend" (and punching bag) of the blog, Dr. Jay Gordon, as well as the mercury militia stalwart David Kirby, among others. As a result, antivaccination lunacy was running rampant on HuffPo, even in its infancy. Many, many, many more examples followed very quickly.…
drorzel | January 5, 2012Anybody who has taught introductory physics has noticed the tendency, particuarly among weaker students, to plug numbers into equations at the first opportunity, and spend the rest of the problem manipulating nine-digit decimal numbers (because, of course, you want to copy down all the digits the calculator gives you. Many faculty, myself included, find this kind of maddening, as it's pretty much the opposite of what professional physicists do-- we tend to work primarily with equations in abstract, symbolic form, and plug numbers in only at the very end of the problem.
Thus, very few people…
drorzel | January 4, 2012As mentioned a few times previously, the class I'm teaching this term is a "Scholars Research Seminar" on time and timekeeping. As this is an entirely new course, and will be consuming a lot of my mental energy, I plan to post occasional reports on what I'm doing to the blog.
Today was the first day of class, so a good chunk of the time was spent on introducing the basics of the course (my PowerPoint slides, for those who care), and going through one slightly silly example.
The stated learning goals for SRS courses (students should learn how to formulate a research question, find and evaluate…
drorzel | January 4, 2012It's the first day of class today (for me, anyway-- classes technically started yesterday, but I don't teach on Tuesdays this term). This, of course, means that something will go horribly wrong. The question is, what?
What will go wrong on the first day of class today?
This is a class for first-year students, so quantum superpositions of multiple answers are not allowed.
drorzel | January 3, 2012I'm a little late to the Most Popular Posts of the Year list party, partly because I wanted to wait until the year was actually over, and partly because Google Analytics was being Difficult, and I had to switch back to the "old" version to get actual numbers out. Having sorted that out, though, here are the top posts to this blog for the calendar year 2011:
Because 4% of the Energy Controls 100% of the Photons, 28607 pageviews
Links for 2011-09-04, 11470 pageviews
The Innumeracy of Educators; or Mark Twain Was Right, 9048 pageviews
Faster Than a Speeding Photon: "Measurement of the neutrino…
drorzel | January 2, 2012My class this term is a "Scholars Research Seminar" with the title "A Brief History of Timekeeping," looking at the science and technology of timekeeping from prehistory through modern atomic clocks. This is nominally an introduction to "research methods," though the class operates under a lot of constraints that fully justify the scare quotes, at least for scientists. As I am a scientist, though, I want the class to include at least one original measurement and the reporting thereof, so I've been thinking of really simple measurements that I can have them do independently and write up. I've…
drorzel | December 31, 2011A while back, a reader from Bulgaria sent me a photo of a highly topical bottle of local spirits:
You can either know where you are, or how much you've drunk, but not both...
Having spent my last day of 2011 taking SteelyKid to the mall for bouncy-bounce and midway games, and then having her help me bake apple pie (which she demanded to do out of nowhere, and wouldn't stop talking about), I could really use a shot of quantum liquor. Or even some classical beer.
Sadly, I'm fighting a wretched cold, so booze is out of the question. But if you're in a partying state, have a drink for me. And…
drorzel | December 30, 2011I will eventually do a "Year in Blog" post with a bunch of links to top posts and so on, but not until the year is actually over. At the moment, I'm too busy prepping next term's class to do all the link chasing.
That doesn't mean I can't engage in a little self-promotion, though. After all, my second book, How to Teach Relativity to Your Dog will be out at the end of February. And the first pre-publication review is in, from Publishers Weekly:
Physics professor Orzel follows his How to Teach Physics to Your Dog with a compact and instructive walk through Einstein's theory of relativity,…
esiegel | December 28, 2011"Don't cry because it's over. Smile because it happened." -Dr. Seuss
2011 has been an amazing year over here. After more than two hundred new posts this year here on Starts With A Bang, where we covered everything from the science of tiny snowflakes to the earliest, farthest and most spectacular galaxies in the Universe, I've finally gone through and compiled the top 10 posts of 2011! (And sadly, no, the BEST climate study and associated controversy did not make the cut.)
Feel free to take a look back -- or if you somehow missed one of these stories, a deep look for the first time -- at the…
esiegel | December 26, 2011"And you may find yourself in another part of the world.
And you may find yourself behind the wheel of a large automobile.
And you may find yourself in a beautiful house, with a beautiful wife.
And you may ask yourself, 'Well, how did I get here?'" -Talking Heads
What would you do if you woke up one day, and found yourself in completely unfamiliar surroundings? You don't know what day it is, what year it is, or even where you are.
Is there any way, without any other information, that you could figure out exactly where in the world you were?
Image credit: World Map from Theodora.com.
We…
drorzel | December 24, 2011As we started the last week of the advent calendar, I was trying to map out the final days, and was coming up one equation short. I was running through various possibilities-- the Dirac equation, Feynman's path integrals, the Standard Model Lagrangian, when I realized that the answer was staring me right in the face:
This is, of course, the Heisenberg Uncertainty Principle, saying that the product of the uncertainties in position and momentum has to be greater than some minimum value. Strictly speaking, this should've come before the Schrödinger equation, if we were holding to chronological…
drorzel | December 23, 2011A week and a half ago, when the advent calendar reached Newton's Law of Universal Gravitation, I said that it was the first equation we had seen that wasn't completely correct. Having done our quick swing through quantum physics, the time has come to correct that equation:
If you say "Einstein equation" to a random person on the street, odds are they'll immediatley think of "E=mc2." If you ask a physicist to think of the Einstein equation, though, this is the one they'll think of. This is the Einstein field equation from general relativity, and while it's not as well known as E=mc2, it's…
drorzel | December 22, 2011Newton's birthday (in the Julian calendar) is Sunday, so we're in the final days of the advent calendar. Which means it's time for the equations that are least like anything Newton did, such as today's:
This is the Schrödinger equation from non-relativistic quantum mechanics. If you want to determine the quantum state of an object that's moving relatively slowly, this is the equation you would use.
It also has probably the greatest origin story of any of the equations we've talked about. Or at least the most salacious origin story of any of the equations we've talked about...
Erwin…
drorzel | December 21, 2011Today's equation in our march to Newton's birthday is actually a tiny bit out of order, historically speaking:
This is the Rydberg formula for the wavelengths of the spectral lines in hydrogen (and hydrogen-like ions), with R a constant having the appropriate units, and the two n's being two dimensionless integers. This equation was developed in 1888 by the Swedish physicist Johannes Rydberg (who was generalizing from a formula for the visible lines of hydrogen that was worked out by a Swiss schoolteacher, Johann Balmer). As such, it pre-dates Einstein's equation from yesterday, but its…
drorzel | December 20, 2011Over at Backreaction, Bee is running an advent calendar of her own, with amusing anecdotes about famous physicists. Apparently, it's a good year for advent calendars.
A couple of days ago, her story was a famous one about Heisenberg nearly failing to get his Ph.D. because he disdained experiment:
Wien wanted to fail Heisenberg, but Sommerfeld, in whose exam on theoretical physics Heisenberg had excelled, put in a strong word for Heisenberg. Heisenberg passed the doctoral examination with the lowest possible grade
Between this, and my own advent calendar posts about historical physics, I got…
kcollins | December 20, 2011The world is buzzing from the latest news about the Higgs boson. Last Tuesday, scientists at CERN announced that they have made significant progress towards the search of the Higgs boson. Scientists are confident that the progress made will bring them much closer to the discovery by the end of next year.
At the Festival Expo, you will have the incredible opportunity to find out first hand from the experts about the details regarding this "God Particle". The Festival is honored to have The Atlas Experiment at the Large Hadron Collider (New York University), a research group that works at…
drorzel | December 20, 2011Yesterday's equation was the first real result of quantum theory, Max Planck's formula for the black-body spectrum. Planck never really liked the quantum basis of it, though, and preferred to think of it as just a calculational trick. It wasn't until 1905 that anybody took the idea really seriously, leading to today's equation:
From the year, you can probably guess the guy responsible: Albert Einstein. Einstein realized that if you took Planck's idea and ran with it, you could explain the photoelectric effect very neatly. Where Planck had viewed the quantized radiation as a fictitious…
drorzel | December 19, 2011Moving along in our countdown to Newton's birthday, we come to 1900, and one of the most revolutionary moment in the history of physics, represented in today's equation:
This is Max Planck's formula for the spectrum of the "black-body" radiation emitted by a hot object at temperature T. It's also the equation highlighted on what might be the most famous xkcd cartoon (albeit in different notation).
This is a fitting next step in the countdown not only for reasons of chronology, but also because it's a nice bridge from thermodynamics and statistical mechanics. After all, the red glow of a hot…
drorzel | December 18, 2011As I said yesterday, I'm going to blow through another entire subfield of physics in a single equation, as our march toward Newton's Birthday continues. Today, it's statistical mechanics, a very rich field of study that we're boiling down to a single equation:
This is Boltzmann's formula for the entropy of a macroscopic system of particles, which says that the entropy s is proportional to the logarithm of the number N of microscopic states consistent with that macroscopic state. The constant kB is there to get the units right.
Why does this get to stand in for the whole field of statistical…
drorzel | December 17, 2011Once again, the advent calendar is delayed until late at night by a busy day with SteelyKid-- soccer in the morning, playing with a trebuchet after lunch, then Arthur Christmas at the Colonie mall. We're running low on days to honor great milestones in physics, though, so I don't want to skip a day entirely.
I'm also trying to spread this around to cover a fairly representative set of subfields; having done classical mechanics and E&M at some length, I need to rush through a couple of other subfields quickly. One of these is classical thermodynamics, a field with a rich history and wide…