Science
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 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,…
pharyngula | December 29, 2011Geoffrey Pearce sent me this argument he uses with creationists, and I thought others might find it useful, too.
I am regularly approached by young Earth creationists (yes, even in the bedlam of sin that is Montreal...) both on the street and at home. If I have the time I try to engage them on the age of Earth, since Earth is something whose existence them and I agree upon. They will tell me that Earth is somewhere between 6,000 - 10,000 years old, and, when prompted, that the rest of the universe is the same age as well. I have taken the approach of responding to this assertion by pulling…
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…
pharyngula | December 21, 2011Menstruation is a peculiar phenomenon that women go through on a roughly monthly cycle, and it's not immediately obvious from an evolutionary standpoint why they do it. It's wasteful — they are throwing away a substantial amount of blood and tissue. It seems hazardous; ancestrally, in a world full of predators and disease, leaving a blood trail or filling a delicate orifice with dying tissue seems like a bad idea. And as many women can tell you, it's uncomfortable, awkward, and sometimes debilitating. So why, evolution, why?
One assumption some people might make is that that is just the way…
catdynamics | December 21, 2011Books, of course, but which books...?
One of these "be careful what you wish for" things, is that I now get a lot of requests to review books (and DVDs and online games etc), just as I reach the stage of my life where I spend most of my time doing reading reformatting paperwork instead of reading fun new things... which is a shame, because the books I get sent are pretty much generally exactly those I spent most of my very limited disposable income on when I was younger...
One day soon I'll catch up on the backlog.
In the meantime, here are three good looking physics books that any good…
oracknows | December 21, 2011I've made no secret of my opinion of the animal rights movement, in particular Jerry Vlasak, a trauma surgeon who has openly advocated the murder of researchers who use animals while--wink, wink, nudge, nudge--denying that he's advocating anything. Another animal rights activist who is equally despicable is Stephen Best, who is affiliated with the even more despicable Camille Marino of the odious Negotiation Is Over, which has recently taken to targeting for harassment students interested in biomedical research who have worked with animals. NIO put this strategy into action, too, by targeting…
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…
catdynamics | December 20, 2011Theorists think of observations and data a bit like businesses think of science and technology: it happens, apparently effortlessly, and is available for free as needed or on demand.
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…
pharyngula | December 19, 2011I've been guilty of teaching bean-bag genetics this semester. Bean-bag genetics treats individuals as a bag of irrelevant shape containing a collection of alleles (the "beans") that are sorted and disseminated by the rules of Mendel, and at its worst, assigns one trait to one allele; it's highly unrealistic. In my defense, it was necessary — first-year students struggle enough with the basic logic of elementary transmission genetics without adding great complications — and of course, in some contexts, such as population genetics, it is a useful simplification. It's just anathema to anyone…
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…
drorzel | December 16, 2011To end this week, we wrap up electricity and magnetism with the fourth and final of Maxwell's equations. this one includes Maxwell's own personal contribution to these:
This is sort of the mirror image of Faraday's Law from yesterday, with the curl of the magnetic field on the left, and stuff related to a change in the electric field on the right. There are two terms instead of just one on the right, though, because when you're dealing with electric fields, you can get a change in the field in two ways: by changing the field directly, or by moving charged particles around.
The first term…
drorzel | December 16, 2011Physics World has released its list of the top ten breakthroughs in physics for the year, and it doesn't include either fast neutrinos or the Higgs boson:
The two physics stories that dominated the news in 2011 were questions rather than solid scientific results, namely "Do neutrinos travel faster than light?" and "Has the Higgs boson been found?". However, there have also been some fantastic bona fide research discoveries over the last 12 months, which made it difficult to decide on the Physics World 2011 Breakthrough of the Year.
But after much debate among the Physics World editorial team…