Physics
drorzel | December 6, 2011For the sixth day of our advent countdown to Newton's birthday, we have the first equation that really departs from the usual notation. I've gotten to kind of like the way the Matter and Interactions curriculum handles this, though, so we'll use their notation:
This is what Chabay and Sherwood refer to as the Energy Principle, which is one of the three central principles of mechanics. The term on the left, ΔE represents the change in the total energy of a system, while the two terms on the right represent the work done on that system by its surroundings, and any heat energy flow into or out…
esiegel | December 5, 2011"Every time you look up at the sky, every one of those points of light is a reminder that fusion power is extractable from hydrogen and other light elements, and it is an everyday reality throughout the Milky Way Galaxy." -Carl Sagan
(This post is coauthored by Dr. Peter Thieberger, Senior Physicist at Brookhaven National Laboratory.)
A cheap, clean, efficient and virtually limitless source of energy would be just what our world needs right about now. The cheap sources -- coal, oil, and gas -- are dirty, destructive, and limited, while the clean sources -- wind and solar -- are expensive and…
gregladen | December 3, 2011
The The Manga Guide to Relativity might come in especially handy these days, what with faster than light neutrinos, Republican candidates and other science-defying entities zooming around. And, it is one of those Japanese anime things, which makes it cool. This is a story set in Tagai Academy summer's school session, where the "plucky" Miss Uraga teaches the kids relativity.
When you have finished reading this book you will be able to calculate the effects of time dilation, explain the Twin Paradox, understand Einsteinium famous E=mc2 and get a job at CERN.
Hideo Nitta, is in the…
drorzel | December 1, 2011It's that time of year again, when we count down the days to Isaac Newton's birthday (according to the Julian calendar, anyway), and how better to mark this than with mathematics? Thus, I'll post an equation a day until either Christmas Eve or I run out of ideas, and talk about what it means and why it's important for physics.
Since this is, after all, a celebration of Sir Isaac, let's kick things off with arguably his most famous equation:
OK, it might not look familiar in this form, but this is, in fact, the full and correct statement of Newton's Second Law (written in modern notation),…
drorzel | November 30, 2011Yesterday's physics education post kicked off a bit of discussion in a place I can't link to about the usefulness of lectures. Something in that reminded me of an anecdote from my grad school days, that I think is useful, so I'll post it here.
When we were working on the spin-polarized collision experiment, we expected that a certain effect ought to be pretty big, but when we did the experiment, it didn't show up at all. We mentioned this in a talk or poster, and a theorist said "Oh, that's not that surprising."
We had been pretty surprised, so I was sent off to talk to Paul Julienne, one of…
drorzel | November 29, 2011As I said last week, I recently wrapped up a term experimenting with "active learning" techniques in the two intro courses I was teaching. The diagnostic test results were a mixed bag-- one section showed really good improvement in their scores, the other was no better than the same class with traditional methods-- and the exam scores weren't really any different. There was probably some slight improvement in the multiple choice-- fewer students got trapped by the Newton's First Law questions than usual-- but in the free-response problems, they did about the same as usual.
So, having turned…
drorzel | November 28, 2011One of the many things I wish I had had time to blog about during the just-completed term was the big New York Times article on attrition in science majors. This generated enough commentary at the time that people are probably sick of it, but I haven't seen anything that exactly matches my take, so I'll belatedly throw this out there.
The big point of the article is that lots of students who enter college planning to major in Science, Technology, Engineering or Math (the "STEM" fields, in an awkward but now inescapable acronym) end up graduating with degrees in something else:
But, it turns…
esiegel | November 27, 2011"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat." -Albert Einstein
Long superseded by television and the internet, the radio perhaps is better seen today as a symbol of nostalgia than as one of paramount relevance to modern life. You can perhaps get a feel for this from Josh Ritter's live performance (from Dublin Castle) of his song,
Golden Age Of Radio.But…
esiegel | November 25, 2011"Between cold fusion and respectable science there is virtually no communication at all. ...because the Cold-Fusioners see themselves as a community under siege, there is little internal criticism. Experiments and theories tend to be accepted at face value, for fear of providing even more fuel for external critics, if anyone outside the group was bothering to listen. In these circumstances, crackpots flourish, making matters worse for those who believe that there is serious science going on here." -David Goodstein
I'm going to tell you a story that starts back in 1770, before not only the…
drorzel | November 22, 2011A few months back, I did a post about estimating the time required for the different routes I take to work, looking at the question of whether it's better to take a shorter route with a small number of slow traffic lights, or a longer route with a bunch of stop signs. This was primarily conceived as a way to frame a kinematics problem, but I got a bunch of comments of the form "Aren't you an experimentalist? Where's the data?"
Well, here it is:
This is a histogram plot showing the number of times my morning commute fell into a given ten-second bin over the last couple of months. The blue…
drorzel | November 21, 2011As noted in previous posts, I've been trying something radically different with this term's classes, working to minimize the time I spend lecturing, and replace it with in-class discussion and "clicker questions." I'm typing this while proctoring the final exam for the second of the two classes I'm teaching, so it's not exactly the end, but nearly everything is in but for the student evaluations, so here are some semi-final thoughts on this experiment:
-- On the whole, I think it went reasonably well, though things definitely flagged toward the end, particularly in the regular mechanics class…
jdupuis | November 21, 2011I like to think I'm developing a little niche here on Confessions of a Science Librarian, at least as far as some of my book reviews. And I like to think that niche is reviewing science-oriented graphic novels. And I've reviewed a few over the past couple of years. Logicomix (review), Evolution: The Story of Life on Earth (review) and The Stuff of Life: A Graphic Guide to Genetics and DNA (review).
And now the amazing new graphic novel Feynman, written by Jim Ottaviani and art by Leland Myrick. (Colours by Hilary Sycamore).
Now when I first heard about this new biography of Richard Feynman…
esiegel | November 18, 2011Q: "Why don't physicists shield themselves from neutrinos?"
A: "Because they never see them coming." #neutrinojokes
Over the past two months, we've talked more about neutrinos than ever before thanks to an extraordinary claim that neutrinos have been observed to move faster-than-light!
And as you well know, no particle is allowed to travel through spacetime faster than the speed of light in vacuum, no matter how much energy you put into it!
(Unless, that is, you count what happens in video games.)
Here's a brief refresher for you as to what's been going on. CERN, the home of the world's most…
drorzel | November 18, 2011One of the more reasonable criticisms of the OPERA result showing neutrinos apparently moving faster than light was that they were claiming 20-nanosecond resolution on the timing of a neutrino pulse that was 10000 nanoseconds long. They got their timing by doing fits to the shape of the whole pulse, as described in that link, and there's always a little bit of alchemy in that sort of process, but they had big long pulses because that's what the accelerator at CERN that served as the source of the neutrino beam provided.
After the original annoucnement, they got the neutrino beam reconfigured…
esiegel | November 16, 2011"She eyes me like a pisces when I am weak
I've been locked inside your Heart Shaped box for weeks
I've been drawn into your magnet tar pit trap
I wish I could eat your cancer when you turn black" -Nirvana, Heart-Shaped Box
By looking at the right combinations of wavelengths of light, one can literally find almost anything in the depths of space.
Image credit: Daniel Marquardt, of nebula IC 1805.
But back on Earth, we have some surprising natural features that have been captured from above with nothing more than a camera.
Image credit: NASA / STS-129 / Space Shuttle Atlantis, retrieved from…
esiegel | November 15, 2011"If there is anything that a man can do well, I say let him do it. Give him a chance." -Abraham Lincoln
It was nearly four years ago that I started blogging back at my old site, branching out from the hardcore research of physical cosmology and the teaching of physics and astronomy, and into what I think of as science communication.
Image credit: The cover of Paul Halpern's book.
And there have been a number of very curious things I've learned, some of which I expected and some of which caught me by surprise.
The least surprising: the entirety of our experience in this world is something…
esiegel | November 14, 2011"We don't understand how a single star forms, yet we want to understand how 10 billion stars form." -Carlos Frenck
When we look out into the distant Universe, we're also looking back into the Universe's past. The farther away an object is, the longer it's taken its light to travel from it to our eyes. And each time we observe something farther away than anything we've seen before, we're looking farther back into the past -- closer to the Big Bang -- than ever before.
Image credit: NASA, ESA and A. Felid (STScI).
The earliest thing we've ever been able to see -- of course -- is the Cosmic…
drorzel | November 10, 2011I've been incredibly busy this term, but not so busy I couldn't create more work for myself. Specifically, by writing an opinion piece for Physics World about the FTL neutrino business, that just went live on their web site:
The result quickly turned into one of the most covered physics stories of the year, with numerous articles in magazines, newspapers and on television asking whether "Einstein was wrong". Just as quickly came numerous physicists denouncing the media frenzy, with Lawrence Krauss from Arizona State University and Cambridge University cosmologist Martin Rees both calling the…
esiegel | November 9, 2011"A constant struggle, a ceaseless battle to bring success from inhospitable surroundings, is the price of all great achievements." -Orison Swett Marden
One of the greatest assumptions we make in our study of the laws of nature is, well, that they're laws of nature, not particularly special to where or when we happen to be looking at them.
Image credit: NASA & ESA.
Whether we look on our home planet, within our own galaxy, at a relatively nearby galaxy (like NGC 4522, above), or at galaxies extremely far away (faintly visible in the background), we always tend to assume that the…
esiegel | November 7, 2011"Mirth is like a flash of lightning, that breaks through a gloom of clouds, and glitters for a moment; cheerfulness keeps up a kind of daylight in the mind, and fills it with a steady and perpetual serenity." -Joseph Addison
One of the most brilliant phenomena found in our atmosphere is that of a lightning strike.
Shown below in breathtaking slow-motion, somewhere on the order of 100,000,000,000,000,000,000 electrons are exchanged in a single bolt between the clouds and the Earth's surface.
Video credit: Tom A. Warner from ZT Research; credit also WeatherVideoHD.TV, and retrieved from Jest.…