Physics

Last week, the blog Last Word On Nothing did a piece on the best and worst sciences to write about, and the two writers tapping physics as the worst said things that were really disappointing to hear from professional writers. I nearly wrote an angry rant here in response, but Jennifer Ouellette covered it more diplomatically than I would've, so I opted to try for a more positive response over at Forbes: Four Reasons to Not Fear Physics. Would've been better to get this out much earlier in the week, but it's the next-to-last week of the term, and I was buried in grading all this week, and it'…
The heat death of the Universe is the idea that increasing entropy will eventually cause the Universe to arrive at a uniformly, maximally disordered state. Every piece of evidence we have points towards our unfortunate, inevitable trending towards that end, with every burning star, every gravitational merger, and even every breath we, ourselves, take. Image credit: the Carnot Cycle, courtesy of NASA. Yet even while we head towards this fate, it may be possible for intelligence in an artificial form to continue in the Universe for an extraordinarily long time: possibly for as long as a…
“The crust, being so thin, must bend, if, over wide areas, it becomes loaded with glacial ice, ocean water or deposits of sand and mud. It must bend in the opposite sense if widely extended loads of such material be removed. This accounts for… the origin of chains of high mountains… and the rise of lava to the earth’s surface.” -Reginald Daly, 1932 When you think about volcanoes, you quite likely think about magma -- liquid rock -- accumulating and welling up beneath the Earth's surface. Every once in a while, this ultra-hot liquid seeps through the Earth's surface, resulting in a spectacular…
A few weeks ago, Amanda Peet gave a public lecture that we live-blogged here. In the Q&A part after the talk, she made a statement that I sort of glossed over: that the LHC was able to verify some of the predictions of String Theory. In my head, I thought, "yeah, all the predictions that the Standard Model itself made, and nothing more." And I let it go. Image credit: © WGBH Educational Foundation, via http://www.pbs.org/wgbh/nova/physics/conversation-with-brian-greene.html. But maybe it's time to ask that question for real: will the LHC be able to test String Theory? And if so, how?…
Last week, I did a post for Forbes on the surprisingly complicated physics of a light bulb. Incandescent light bulbs produce a spectrum that's basically blackbody radiation, but if you think about it, that's kind of amazing given that the atoms making up the filament have quantized states, and can absorb and emit only discrete frequencies of light. The transition from the line spectra characteristic of particular atoms to the broad and smooth spectrum of black-body radiation is kind of amazing. The way you get from the one to the other is through repeated off-resonant scattering. The…
It's one of the cardinal laws of physics and the underlying principle of Einstein's relativity itself: the fact that there's a universal speed limit to the motion of anything through space and time, the speed of light, or c. Light itself will always move at this speed (as well as certain other phenomena, like the force of gravity), while anything with mass -- like all known particles of matter and antimatter -- will always move slower than that. Image credit: Matt Howard. But if you want something to travel faster-than-light, you aren't, as you might think, relegated to the realm of…
“[I]f there were no light in the universe and therefore no creatures with eyes, we should never know it was dark. Dark would be without meaning.” -C.S. Lewis The Universe had two periods where light was abundant, separated by the cosmic dark ages. The first came at the moment of the hot Big Bang, as the Universe was flooded with, among the matter, antimatter and everything else imaginable, a sea of high-energy photons, including a large amount of visible light. As the Universe expanded and cooled, eventually the cosmic microwave background was emitted, leaving behind the barely visible,…
I was proctoring an exam yesterday in two different sections of the same class, so I had a lot of quite time. Which means I wrote not one but two new posts for Forbes... The first continues a loose series of posts about the exotic physics behind everyday objects (something I'm toying with as a possible theme for a new book...), looking at the surprisingly complicated physics of an incandescent light bulb. A light bulb filament emits (to a reasonable approximation) black-body radiation, which is historically important as the starting point for quantum physics. But when you think about it, it's…
One of the highlights of teaching introductory mechanics is always the "karate board" lab, which I start off by punching through a wooden board. That gets the class's attention, and then we have them hang weights on boards and measure the deflection in response to a known force. This confirms that the board behaves like a spring, and you can analyze the breaking in terms of energy, estimating the energy stored in the board, and the speed a fist must have to punch through the board. As a sort of empirical test, we can drop a half-kilogram mass from the appropriate height to match the…
“Journalists often ask me when I go to the field, ‘What do you expect to find?’ And my answer always is, ‘The unexpected,’ because we’re just looking at the tip of the iceberg; we’ve just scratched the surface.” -Donald Johanson Imagine you wanted to know what your acceleration was anywhere on Earth; imagine that simply saying "9.81 m/s^2" wasn't good enough. What would you need to account for? Image credit: © 1999–2014 Michael Pidwirny, via http://www.physicalgeography.net/fundamentals/10k.html. Sure, there are the obvious things: the Earth's rotation and its various altitudes and…
The big social media blow-up of the weekend was, at least on the science-y side of things, the whole "boys with toys" thing, stemming from this NPR interview, which prompted the #GirlsWithToys hashtag in response. I'm not sorry to have missed most of the original arguments while doing stuff with the kids, but the hashtag has some good stuff. The really unfortunate thing about this is that the point the guy was trying to make in the interview was a good one: there's an essentially playful component to science, even at the professional level. I took a stab at making this same point over at…
“One of the dreariest spots on life’s road is the point of conviction that nothing will ever again happen to you.” -Faith Baldwin Bet you thought you knew it all about the asteroid belt. These frozen, ice-and-rock worlds orbit farther out from Mars, closer in than Jupiter, and occasionally get hurled towards the inner Solar System by gravitational interactions. But the largest world, Ceres, at just about half the diameter of the Moon (or the size of Texas), exhibits an unusual surprise: a brilliant set of white spots at the bottom of one of its largest craters. Image credit: NASA/JPL-Caltech…
One of the points I make repeatedly in teaching introductory mechanics (as I'm doing this term) is that absolutely every problem students encounter can, in principle, be solved using just Newton's Laws or, in the terminology used by Matter and Interactions, the Momentum Principle. You don't strictly need any of the other stuff we talk about, like energy or angular momentum. Of course, just because you can solve any problem using the Momentum Principle doesn't mean that you want to solve those problems that way. As an example of a problem that's really annoying to solve with just the Momentum…
If you're not a theoretical physicist yourself, you might think that physics is physics -- we ask questions about the Universe, do experiments/make observations, and get the answers -- and math is just a tool that we use to help us get there. Image credit: © 2015 Shaper Helix — II Demo, via http://www.alevelsolutions.com/pure-mathematics. But that really sells the power of mathematics short. For a physical theory to be valid, there are a whole host of mathematical properties that theory needs to possess, including being free of logical inconsistencies, making predictions about observables…
A few things about the academic job market have caught my eye recently, but don't really add up to a big coherent argument. I'll note them here, though, to marginally increase the chance that I'll be able to find them later. -- First, this piece at the Guardian got a lot of play, thanks in part to the dramatic headline Science careers: doomed at the outset but even more thanks to the subhead "Has it become harder for graduate students to thrive, and are our best potential scientists giving up on academia?" Most of the people I saw re-sharing it used basically just that last clause, often…
I've been sort of falling down on my obligation to promote myself-- I've written two blog posts for Forbes this week, and forgotten to post about them here. The first is a thing about philosophy in physics, and how Einstein illustrates both the good and bad aspects of a philosophical approach. The second is a bit on the listicle side, looking at some types of diagrams that physicists draw when talking about physics. It's prompted by a ZapperZ post noting that scientists talking about science always draw pictures, but other subjects get by with just talking. These are both quickly-dashed-off…
This Nifty Fifty Podcast features, Dr. Loren Anderson, physicist from West Virginia University,  speaking to Tuscarora High School about the Milky Way Galaxy, astronomy, massive stars, and his career path to becoming a physics professor. Read the full blog here.
“Energy is liberated matter, matter is energy waiting to happen.” -Bill Bryson When it comes to the Universe, you might think that energy really is only limited by rarity: get enough particles accelerated by enough supermassive, super-energetic sources, and it's only a matter of time (and flux) before you get one that reaches any arbitrary energy threshold. After all, we've got no shortage of, say, supermassive black holes at the hearts of active galaxies. Image credit: NASA, ESA, Hubble Heritage (STScI/AURA). And yes, we do find cosmic rays hundreds, thousands or even millions of times…
“I just think too many nice things have happened in string theory for it to be all wrong. Humans do not understand it very well, but I just don’t believe there is a big cosmic conspiracy that created this incredible thing that has nothing to do with the real world.” -Ed Witten So the cat is out of the bag, and has been for a long time: as far as theoretical physics ideas go, I think String Theory is a blind alley, a dead end, an idea for whom the fat lady has sung. Image credit: Perimeter Institute’s Public Lecture series. But all it takes is one prediction -- a prediction that's unique…
A couple of weeks ago, after one of my Forbes posts, I got contacted by a publicist working for Makey Makey. They really wanted publicity in Forbes, but that's above my pay grade; I did, however, say that it sounded like the sort of thing my kids would get a kick out of, and I could mention it here... So, they sent me one. It's a small circuit board with a USB connector and a bunch of places for alligator-clip leads, and functions as an input device for the computer-- if you complete a circuit from one of the clip leads to ground, it records that as a mouse click, or a key press of some sort…