Physics
drorzel | January 27, 2011I probably ought to get a start on the big pile of grading I have waiting for me, but I just finished a draft of the problematic Chapter 7, on E=mc2, so I'm going to celebrate a little by blogging about that.
One thing that caught my eye in the not-entirely-successful chapter on momentum and energy in An Illustrated Guide to Relativity was a slightly rant-y paragraph on how it's misleading to talk about the energy released in nuclear reactions as being the conversion of mass into energy, because what's really involved is just the release of energy due to the strong force. It struck me as…
drorzel | January 27, 2011Subtitled "Understanding Einstein's Relativity," David Mermin's It's About Time is another book (like An Illustrated Guide to Relativity) that grew out of a non-majors course on physics that Mermin offers at Cornell. It's also an almost-forty-years-later update of an earlier book he wrote on the same subject. And it's been a really good resource for writing the book-in-progress, which I ought to repay by reviewing it here.
Like the Illustrated Guide, this is a book that aims to teach students something about how relativistic kinematics actually works. Unlike the Illustrated Guide though, this…
drorzel | January 25, 2011Over in locked LiveJournal land, I read a post talking about computer science education, and how it's biased against people who aren't already tech geeks coming into college:
Taking an intro CS course if you don't already know how to program is like taking intro Spanish without ever having taken it in high school - 90% of the people in that class are ahead of you, possibly way ahead of you, on day one, and you're working from the back.
That is a brutal situation to be in, honestly, and it does nobody any favours. The people who don't already know how to program are dealt a crushing blow to…
esiegel | January 20, 2011"What do we mean by setting a man free? You cannot free a man who dwells in a desert and is an unfeeling brute. There is no liberty except the liberty of some one making his way towards something. Such a man can be set free if you will teach him the meaning of thirst, and how to trace a path to a well. Only then will he embark upon a course of action that will not be without significance. You could not liberate a stone if there were no law of gravity -- for where will the stone go, once it is quarried?" -Antoine de Saint-Exupery
Gravity, on the largest scales, rules everything in the Universe…
drorzel | January 20, 2011A pretty straightforward question: Which prime number do you like the best?
What's your favorite prime number?online surveys
This is a purely classical poll, so you only get to choose one favorite, not a superposition of multiple numbers. Your selection is legally binding, so choose wisely!
(There's actually a point to putting this up today, beyond providing some cheap and easy blog traffic... I'll explain later.)
drorzel | January 19, 2011I'm giving a talk at the AAAS meeting next month on international physics tests, and they have asked me to provide information that they will duplicate and distribute to the media. Items requested include:
-- A one-paragraph biographical sketch (not a C.V.)
-- A lay-language summary of your talk, beyond the abstract.
-- The full text of your talk or a related (ideally recent) technical
paper, either as a Word file or a PDF. PowerPoint presentations are
acceptable, but a full text will better serve reporters' needs.
The first two are no big deal, but the third is kind of weird. I don't…
drorzel | January 19, 2011We did a lab yesterday that asked students to measure the speed of a ball leaving a spring-loaded launcher in a few different ways. this is a great way to talk about the difference between systematic and random errors and how those are dealt with. As a way of starting that discussion, I asked the students to calculate the speeds last night, and then enter their values in an Excel sheet when they came to class this morning. Since generating a sensible plot in Excel 2007 is such a gigantic pain in the ass, I used an older data set to set up a template, and made a graph of the quantities we were…
drorzel | January 18, 2011The latest snowstorm is wreaking some havoc on my plans for the day, which means I'm going to lift another question and answer from the Physics Stack Exchange, with some modification. This one is a question about thermal radiation:
What are the quantum mechanisms behind the emission and absorption of thermal radiation at and below room temperature? If the relevant quantum state transitions are molecular (stretching, flexing and spin changes) how come the thermal spectrum is continuous? What about substances (such as noble gases) which don't form molecules, how do they emit or absorb thermal…
drorzel | January 17, 2011Part of this past weekend's meeting of the Committee on Informing the Public was to evaluate 100+ proposals for "mini-grants" of up to $10,000 for new outreach activities. It wouldn't be appropriate to go into detail about any of the proposals or what we decided (the PI's of the proposals we decided to fund will be notified soon), but there was one issue that came up again and again that I think is appropriate for the blog, which is what should be considered as a successful effort, particularly in the online world.
A large number of the proposals we were considering had "new media" components…
drorzel | January 16, 2011I was at a meeting of the Committee on Informing the Public of the American Physical Society at the tail end of last week, so it seems appropriate to post a couple of APS-related announcements here on my return:
1) The APS has just created a Forum on Outreach and Engaging the Public. You may have read about this in the monthly APS News, but in case you missed it, there is a new organization with APS to bring people interested in outreach together:
"The forum provides a venue for people to congregate, provide best practice manuals...and disseminate things that work so people don't have to…
gboustead | January 14, 2011
Yesterday, I went on Facebook. Not an unusual activity for someone my age. Or for someone my parents’ age, which I still haven’t gotten used to. But that’s not the point of this.
Several of my “friends” had statuses mentioning "Ophiuchus", whatever that is. One girl’s panicked reaction to this unpronounceable phenomenon had received enough attention to elicit ten of my peers to "comment" on it.
So, I did what any self-respecting person would do. I decided if nineteen-year-old girls were fascinated by it, it was probably just as important as Justin Beiber and Twilight.
But when I went on…
drorzel | January 14, 2011The physics book generating the most bloggy buzz in the latter part of 2010 would have to be Ian Sample's Massive: The Missing Particle that Sparked the Greatest Hunt in Science, about the as yet undetected particle known as the Higgs boson. Detecting the Hiigs is the most immediate goal of the Large Hadron Collider, so it's a topic that's in the air at the moment, so this book was inevitable-- in fact, the publisher sent me not one but two review copies. I gave one away, but that makes me feel even more guilty for taking months to get around to reviewing it.
This is, basically, a concise…
drorzel | January 13, 2011I am in Florida for a meeting this week, having flown from Albany to Ft. Lauderdale. Due to the vagaries of the air travel system, though, this required a change of planes in Orlando. The Orlando-Ft. Lauderdale flight is sufficiently short that I like to think of it as a ballistic route-- you're not cruising at altitude for any significant time, but start going down practically as soon as you're finished going up.
Let's imagine that we have a commercial enterprise-- let's call it Angry Birds Airlines-- that wants to fling objects from Orlando to Ft. Lauderdale. What would that require? That…
drorzel | January 12, 2011Another response copied/adapted from the Physics Stack Exchange. The question was:
What are the main practical applications that a Bose-Einstein condensate can have?
Bose Einstein Condensation, for those who aren't familiar with it, is a phenomenon where a gas of particles with the right spin properties cooled to a very low temeprature will suddenly "condense" into a state where all of the atoms in the sample occupy the same quantum wavefunction. This is not the same as cooling everything to absolute zero, where you would also have everything in the lowest energy state-- at the temperatures…
drorzel | January 10, 2011I'm always a little hesitant to post reviews of books that I'm using as reference sources when I'm writing something, because it feels a little like recommending that you skip past my book and go to my sources instead. This is, of course, completely irrational, because however much I my use a given book as a resource, what I'm writing is going to cover a different set of topics, with a slightly different slant. And since the folks at Cambridge University Press were kind enough to send me a review copy of Tatsu Takeuchi's An Illustrated Guide to Relativity, I really kind of owe it to them to,…
drorzel | January 10, 2011A seasonally appropriate poll, brought to you by this morning's frigid dog walk (15F/ -9C), and the memory of a newscast back when I was in Maryland that referred to an overnight low temperature of 22F/-6C as "Bitter, bitter cold":
The maximum (daytime high) temperature I would characterize as "bitter cold" would be:survey software
For the purposes of this poll, assume a still day with no significant "wind chill." All of these temperatures are too high for quantum effects to be significant, so you may only choose one answer at a time, not a superposition of multiple answers.
drorzel | January 9, 2011A reader from the UK, James Cownie, was kind enough to send this picture of the "New and Bestselling" shelf at a WH Smiths " at one of the service stations on the M20." You might not recognize the cover immediately, but in the #11 spot on that list is occupied by How to Teach Quantum Physics to Your Dog, the UK version of my book. Or, given how well it's doing there, perhaps I should start referring to the cover pictured in the left column of the blog as "the American edition..."
Anyway: Woo-hoo!
drorzel | January 6, 2011I've reached a point in the book-in-progress where I find myself needing to talk a little about particle physics. As this is very much not my field, this quickly led to a situation where the dog asked a question I can't answer. But, hey, that's why I have a blog with lots of smart readers...
The question is this:
What are all these extra particles for?
Or, to put it in slightly more physics-y terms: The Standard Model contains twelve material particles: six leptons (the electron, muon, and tau, plus associated neutrinos) and six quarks (up-down, strange-charm, top-bottom). The observable…
drorzel | January 6, 2011Not an exhaustive list, but since I'm noodling around with my calendar, I might as well note some of the stuff I'll be doing this year:
I'll be on a panel about international science testing at the AAAS Annual Meeting in February. This will be a different experience-- not only have I never been to a AAAS meeting before, the whole thing appears to be organized in a different manner than any meeting I have been to. I'm doing a bit of a drive-by for this-- coming in Friday afternoon, leaving Sunday evening-- but I have classes to teach.
I've been invited to give a Saturday Morning Science…
esiegel | January 5, 2011"The size of the universe is no more depressing than the size of a cow." -David Deutsch
But it is bizarre, I'll give you that. The most common scientific question I get asked is how, if the Universe is 13.7 billion years old, and the speed limit of the Universe is the speed of light, why do I say the observable Universe is 93 billion light years across?
In other words, why is this picture of the Universe wrong?
I've tried to answer this before, and so have others, but perhaps it's time for another -- more conceptual -- attempt. This is one of the most mind-boggling things about relativity.…