Physics
drorzel | January 25, 20102010 marks the 50th anniversary of the invention of the laser. To mark the occasion, the American Physical society has launched LaserFest, which will involve a large number of public events over the next year. The website includes a bunch of cool things explaining the physics of lasers, and a timeline of laser history with one glaring bug that you'll have to figure out for yourself. Over at Cocktail Party Physics, Jennifer Ouellette has an excellent historical survey of her own, saving me a lot of typing.
(Fun fact: Gordon Gould, who eventually won a lengthy patent fight, was a Union alumnus…
drorzel | January 24, 2010A few weeks back, I spoke on the phone with a freelance writer who was doing a piece for the Albany Times Union. She was putting together a joint article on How to Teach Physics to Your Dog and the Atomville book put together by Jill Linz and Cindy Schwarz (at Skidmore and Vassar, respectively). The piece was published today: "Physics without limits: Area writers explain quantum mechanics to adults, kids."
Unfortunately, the Times Union has a policy of reserving some stories for the print edition, and so there's no way to link to it. So, unless you have a way to get your hands on a paper…
drorzel | January 23, 2010Having seen other authors led into destruction by responding to customer reviews on Amazon, I tend to approach the customer reviews of How to Teach Physics to Your Dog with some trepidation.
It turns out, though, that they're really good. And I don't mean that in a Harriet Kalunser kind of way-- the positive reviews are thoughtful and positive, and the negative comments that have been made are for the most part legitimate criticisms of the book. And then there's this one:
My 11 year old son is nuts about physics, so I got this book to see how it would go over with him. It did, perfectly. The…
drorzel | January 23, 2010That's the bill for the time that I spent on deciphering his supposed falsification of decoherence. I don't want anyone to fall for his false argument, so here's the correct explanation of the scenario, to save other people the trouble.
The center of his so-called "proof" is this modified Mach-Zehnder Inteferometer:
Light enters at the lower left, is split by a beamsplitter (which I'm representing as a beamsplitter cube, because that's what I usually use, but it could be anything), redirected by two mirrors to a second beamsplitter where the beams A and B are recombined, then the recombined…
rallain | January 22, 2010Since my previous post on R2-D2 flying was so popular, I thought I would follow it up. I was going to add these two points in the comments, but a separate post seems to make more sense.
Point 1 - R2 flies at a constant speed
Well, he obviously doesn't always have to fly at a constant speed. However, in the clip I was looking at there are two important things in the analysis. What angle is R2's thrusters at? Is R2 flying at a constant speed? I found a much better quality version of the flying R2 from Billy Brook's site. That helped out a lot. So, on to Tracker Video Analysis (I always…
esiegel | January 22, 2010To most outsiders, modern mathematics is unknown territory. Its borders are protected by dense thickets of technical terms; its landscapes are a mass of indecipherable equations and incomprehensible concepts. Few realize that the world of modern mathematics is rich with vivid images and provocative ideas. -Ivars Peterson
Those of you who know me well know that I have little love for math for its own sake, but that I prize it as an incredible tool to help us understand and quantify physical systems. This has incredible applications, from figuring out what trajectory will succeed in a game of…
drorzel | January 22, 2010The NSF's Science and Engineering Indicators report came out not too long ago, and the bulk of it is, as usual, spent on quasi-quantitative measures of scientific productivity-- numbers of degrees granted, numbers of patent applications for various countries, etc. I find all of those things pretty deeply flawed, so I tend to skip past them and go straight to the stuff about public knowledge and understanding (chapter 7, available as a PDF at the link above).
This doesn't get much press, probably because the results are depressing. They've asked a bunch of factual knowledge questions of people…
drorzel | January 22, 2010We're once again in the "things are in the pipeline, but nothing has been posted recently" mode, which is a good excuse for some Amazon neepery.
Since the AP review came out, and was printed in 20-odd papers, the sales rank has climbed back into the four digits, and has spent the last few days hovering around 2,000. This is pretty respectable, and Amazon proudly touts it as being "#1 in Books > Science > Physics > Quantum Theory," which sounds nice.
Of course, what does that really mean?
If you click through to the "Quantum Theory" subcategory, you'll see that it's a weird…
drorzel | January 21, 2010I've mentioned before that I'm going to be giving an invited talk in the LaserFest session at the APS March Meeting. I finally got around to registering for the meeting, and booking my travel. $1,500 on the college credit card-- whee!
The March Meeting program is one of the more intimidating meeting programs I've ever seen-- there are 42 parallel sessions in every time block. Yikes. I thought DAMOP was getting to be a little too big to navigate, but this is ridiculous...
Speaking of DAMOP, I'll also be going to the 2010 DAMOP Meeting in Houston. I haven't booked my travel for that, yet,…
oracknows | January 20, 2010If you ever want to get a sense of the scale of the universe and how insignificant our little planet is compared to the scope of it all, here's something really cool to put things in perspective, courtesy of the American Museum of Natural History's Astronomy Picture of the Day:
It'd be really cool if it were physically possible to travel that fast and see what this video shows. It really is amazing, this universe of ours.
esiegel | January 20, 2010I'm always happy to receive questions from those of you interested enough to ask them, and every once in a while one of them feels just right to write up an article about it. Today's comes from Brad Walker, who asks about the inside of gas giants. Specifically,
The question pertains to the insides of gas giants like Jupiter... My question is, supposing Jupiter is made of Metallic Hydrogen, and it was dragged close enough to the sun that its atmosphere evaporated, what would be left? How would it go from a very strange non-terrestrial core to a rocky body like CoRoT-7b? Why wouldn't the…
drorzel | January 20, 2010The previous collection of things everyone should know about quantum physics is a little meta-- it's mostly talking up the importance and relevance of the theory, and not so much about the specifics of the theory. Here's a list of essential elements of quantum physics that everyone ought to know, at least in broad outlines:
1) Particles are waves, and vice versa. Quantum physics tells us that every object in the universe has both particle-like and wave-like properties. It's not that everything is really waves, and just sometimes looks like particles, or that everything is made of particles…
drorzel | January 20, 2010Derek Lowe has a post talking about things biologists should know about medicinal chemistry. It's a good idea for a post topic, so I'm going to steal it. Not to talk about medicinal chemistry, or biologists, of course, but to talk about my own field, and what everyone-- not just scientists-- should know about quantum physics. Not just humans, either-- even dogs should know this stuff.
1) Quantum physics is real. Probably the hardest quantum idea to accept is the notion of vacuum energy and "virtual particles"-- stuff appearing out of empty space, then disappearing again seems almost too weird…
drorzel | January 19, 2010Consider the air around you, which is hopefully at something like "room temperature"-- 290-300 K (60-80 F). That temeprature is a measure of the kinetic energy of the moving atoms and molecules making up the gas. At room temperature, the atoms and molecules in the air around you are moving at something close to the speed of sound-- around 300 m/s (give or take a bit, depending on the mass).
If you're a physicist or chemist looking to study the property of these atoms and molecules, that speed is kind of a nuisance. For one thing, the atoms and molecules tend not to stick around long enough to…
drorzel | January 19, 2010Consider the air around you, which is hopefully at something like "room temperature"-- 290-300 K (60-80 F). That temeprature is a measure of the kinetic energy of the moving atoms and molecules making up the gas. At room temperature, the atoms and molecules in the air around you are moving at something close to the speed of sound-- around 300 m/s (give or take a bit, depending on the mass).
If you're a physicist or chemist looking to study the property of these atoms and molecules, that speed is kind of a nuisance. For one thing, the atoms and molecules tend not to stick around long enough to…
rallain | January 19, 2010My dad and I had a disagreement. We were driving back from a trip and he let me take over the wheel for a while. His complaint was that I was driving too slow and it was driving him crazy. For me, I thought I was driving fast. My typical behavior is to drive 3 mph under the speed limit. That is just how I roll. In this case, I knew he wouldn't be able to handle this so I went the speed limit (70 mph).
Here is the problem. The speedometer said 70 mph. The gps thingy said the average speed was 69 mph. I think my dad feels that the gps is correct and that cars have speedometers that are…
esiegel | January 18, 2010There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.
There is another theory which states that this has already happened. -Douglas Adams
We started off our series on The Greatest Story Ever Told by talking about inflation, or a period when the Universe was expanding exponentially. We see plenty of evidence that inflation happened from looking at the geometry of the Universe (it looks like it was stretched flat),
at the fact that the…
drorzel | January 18, 2010A comment on the earlier poll asked about regular series of departmental talks, which the author called a department seminar. We have such a series of talks, bringing in roughly one outside speaker per week, but we call it a colloquium. This calls for a poll to settle the question:
An academic department has a talk by an outside speaker once a week. This is called:(surveys)
If you have a particular reason for preferring one or the other, please feel free to explain it in comments.
drorzel | January 18, 2010Before leaving Austin on Friday, I had lunch with a former student who is currently a graduate student at the University of Texas, working in an experimental AMO physics lab. I got the tour before lunch-- I'm a sucker for lab tours-- and things were pretty quiet, as they had recently suffered a catastrophic failure of a part of their apparatus.
Of course, there are catastrophic failures, and then there are catastrophic failures. Some dramatic equipment failures, like the incredible exploding MOSFET's when I was a post-doc, are just God's way of telling you to go home and get a good night's…
drorzel | January 17, 2010Of special interest to Ohio-type readers: I'm scheduled to do an interview tomorrow, Monday the 18th with Jim Scott of WLW AM in Cincinnati. I'm scheduled to call in at 9:50 am, which looks like it's after the regular show hours, and thus probably a taped interview. It says LIVE in the schedule I was sent by my publicist, though, so I'm not quite sure.
Anyway, if you're in the right area to pick this up, you might want to tune in to hear what I sound like on the radio. It looks like they have interviews archived on the web site, so I'll be spending a little time tonight listening to a few,…