steuard: (lake)
Tuesday, January 17th, 2017 10:16 pm
[I’m making an effort to avoid serious spoilers, especially in the main body of these comments, but I’m sure there are little ones there and more in the list of specific thoughts that follows.]

A week or two ago, I finally finished reading The Three-Body Problem by Liu Cixin (as translated by Ken Liu). It was a fun story that touched on some neat science, and I quite appreciated the experience of reading fiction based on a rather different cultural background than my own. (The translator commented in his afterword that he had done his best to walk the fine line between an overly literal translation that failed to capture the author's sense and intent and an overly idiomatic translation that failed by purging everything that gave it its own sense of place and history. I think he was very successful.) I did have some issues with the structure of the tale itself, and over the course of the book I felt like the sci-fi elements went from “realistically plausible” to “well-done apart from some errors in the details” to “what the heck are you talking about?” So while I mostly enjoyed the book as a whole, a lot of its conclusion left me frustrated.

It was to some degree a humbling experience to read a story whose historical grounding and references (whether 50 years ago or 1500) were so, well, foreign to me. I had heard *of* some of the emperors mentioned, and about bits and pieces of the Cultural Revolution, but not remotely enough to feel oriented in the way that a person fluent in Chinese culture would. Would a Chinese reader have had the same "this is all madness" reaction to the various factions of Red Guards and others that I did, or did the author intend readers to feel sympathy toward some and not toward others? I was torn between feeling frustrated by those unclear moments and feeling excited by them (since I was learning something new, in just the right "organic" way). I'd estimate that about half of my moments of uncertainty along these lines were immediately addressed by a relevant translator's note filling in some cultural background. By and large, I really liked this aspect of the story.

As for the story itself, my impressions were mixed. I thought that a lot of the core conceptual premises were fresh and interesting: I haven’t read anything quite like it before. But there were also a lot of aspects that just didn’t work for me, for a variety of reasons. I’ve mused on some specifics down below, but the big issues for me were the main character’s lack of meaningful participation in the events of the story and a number of ways in which the behavior of characters or society seemed unrealistic or cliched.

I also had mixed impressions of the actual science/sci-fi elements of the story. One of Isaac Asimov's great strengths as a science fiction writer was his ability to build entire stories (or series of stories) around the consequences of a single, simple sci-fi premise: the Three Laws of Robotics, say, or the "Psychohistory" that shaped the Foundation. That same spirit of "let's really delve into the deep societal consequences of this sci-fi change" provides much of the richness and fascination of books by authors like Le Guin or Bujold, to name just a couple who leap to mind. Liu Cixin... does not work this way.

The early sci-fi elements (involving attempts to communicate at interstellar scales) were handled quite well with some clever, mostly plausible “new science” involved. A little later, the titular "three body" physics (and its in-story context) seemed well done on the whole, too. It's a really neat take on not just the dynamics involved, but how life might react to that. (I had minor to moderate issues with a handful of the details.) And then there’s the final reveal about “two protons” and their effects. I think there would be plenty of premises associated with those alone for about a dozen different sci-fi stories. Unfortunately, the science involved is nonsense even as a fictional new discovery, and the effects are so ridiculously overpowered that it seems to rip half a dozen gaping plot holes in the story in its attempt to explain earlier mysteries.

And with that, before I go on to chatter about specifics (which will tend to be more spoilery), I feel like I ought to close with a recommendation. Sadly, I’m torn on that. I suspect that some of my eye rolling near the end was just from being too close to the science involved, but some of the issues would likely grate on a lot of readers. The story and its structure are a bit spotty, too. Nevertheless, the novel premises and perspective are worthwhile and interesting. So I guess my final conclusion is, "Go not to the Elves for council, for they will say both no and yes."

A handful of random specifics about the story and its telling:

  • My biggest complaint about the story itself: much of the time, it felt like the main characters weren't really doing anything consequential. Rather, they were just on a roller coaster ride hearing about major historical events past and present, and scrambling to keep up. Even the main character's primary contribution to solving the climactic dilemma is saying "Oh, we've actually got a bunch of that back in my lab" after someone else proposes a strategy that would require a novel substance, and then watching others use it.

  • Maybe the description just didn't capture it for me, but the computer game in the story made no sense to me as a game. It sounded like an interestingly vivid simulation and teaching tool, and maybe a sort of participatory theater, but as presented within the story I just didn't buy it as something that players would be so drawn to (or more importantly, as something whose rules or goals they would understand, given the interface and explanation we were shown).

  • The secondary character who's "not a GOOD cop, but one heck of an effective one" and turns out to become a solid friend felt awfully close to a pure archetype, within his first few paragraphs on the page, and nothing ever happened to change that.

  • It was weird to me how we were introduced to the main character's wife and kid at one point and then he (and the author) proceed to show almost complete indifference to what they must be thinking or feeling at any future point (even as the main character practically has a mental breakdown, disappears overnight, and otherwise begins behaving very erratically).

  • There’s this weird assumption in the backstory that substantial fractions of the highly educated population of the world (and almost exclusively the intellectual elite) think humanity is hopeless and would be willing to basically sell out our entire species in one way or another. That just doesn’t fit with my experience at all. I can’t tell if this is a reflection of actual attitudes in Chinese society, or if it’s some sort of political statement by the author, or what.

  • The final confrontation with the most dangerous (human) faction felt almost perfunctory to me (gruesomely so). I guess that's exactly what they were aiming for, but I felt like they'd spent a fair bit of time developing a villain and a villainous organization, only to see the whole thing resolved completely tidily in a few paragraphs.

And a handful of specifics about the science:

  • As noted, I thought that the titular "three body" physics (and its in-story context) were generally well done. (Apart from the weird "invisible stellar outer atmosphere" thing that went with it, anyway.) It's a really neat take on not just the dynamics involved, but how life might react to that. Given the title and the physics I know, I guessed pretty quickly what was going on when it first came up, and even began to guess where it was going on. That said, some of the various "hot disaster" scenarios described felt just entirely "off" to me, on a "wait, that wouldn't happen, or at least not that way" level. (And I'm pretty sure that the most common fate of small bodies coupled to a 3+ body system like this is not "collided with something" but rather "hurled out of the system". Also, I don't think there's any way to deduce the past history of such a chaotic system in any detail, certainly not well enough to deduce all the details of its structure in the distant past.)

  • The final twist/explanation involving the four protons (or rather, "protons") just plain upset me. Not only was practically everything about the science of it nonsense, but the technology described was so insanely powerful that I'm pretty sure it could have solved all of the aliens' problems on its own, without any need to interact with the folks on Earth at all. (These last bits are especially spoilery.)

    • Nonsense: First, a proton is well established to be a composite particle, no matter what the ultimate theory of nature turns out to be, but every way I can try to make sense of the higher dimensional stuff can only sensibly apply to fundamental particles. Second, one of the essential properties of quantum systems like a proton is their indistinguishability: there is literally nothing you can do to a proton even in principle to make it different than any other proton: they are absolutely and unalterably identical. (This is a necessary ingredient for almost every system obeying "Fermi-Dirac statistics", a category including more or less half of all quantum systems.) That means that no matter what wacky extra dimensional extent it might have, is simply couldn't work to "paint on" even a serial number, much less to embed an entire functioning AI computer. Third, quantum entanglement doesn't work the way it's presented here: you can't use it for instantaneous communication at all, and I'm pretty sure that even if you didn't care about "instantaneous" two pairs of entangled protons could only carry two bits of information, total. This isn't an ongoing high-bandwidth communications channel! Fourth, even if they sent these "protons" to Earth somehow, it's clearly implied that the protons themselves have some sort of near-lightspeed propulsion to move them back and forth around the planet. What is it, and what's its energy source?

    • Solving problems: When the computer circuits are being etched(?) into the world-enveloping 2D-expanded protons, the surface blocks any and all light from reaching the planet below: the world was frozen as surely as in the long dark stretches of a Chaotic Era. It seemed pretty thoroughly impermeable! But... isn't that exactly what they would need to protect their world from close calls falling near a sun? (Heck, it might have even protected them from a close call with a solar atmosphere.) And the story provides evidence that these dimensionally altered protons can act as parabolic mirrors to focus sunlight, too: they might even be able to provide warmth during cold parts of Chaotic Eras, too! (Even if they can't reliably predict their planet's orbit decades in advance, they ought to be able to manage a few weeks or at least days: enough to be able to reconfigure their planet-sized superprotoncomputers for whatever protection is necessary. [But then, if they can reconstruct their solar system back to millions(?) of years earlier in enough detail to deduce that it once had many more planets, why can't they predict its future as successfully?]) Or as an offensive weapon, why worry about subtly tricking human scientists to keep our tech level down when they could just set the things to enclose our whole planet and cut off all sunlight for, say, a week or so? That would probably not do irreparable harm to the ecosystem, but it would probably devastate crop yields worldwide and lead to the total collapse of modern society, leaving our planet ripe for the picking. The short version is that these things are ridiculously overpowered, enough so to more or less break the plausibility of the rest of the story.

steuard: (physics)
Saturday, May 24th, 2014 04:19 am
We live in a remarkable era. If you brought an ancient Greek astronomer to the present day and dropped him off in a field somewhere, he would be awestruck, and maybe terrified. (Heck, it probably wouldn't even need to be an astronomer: I think that most people were quite familiar with the night sky until recent times.)

The meteor shower was pretty much a bust: I was outside for a decent stretch and only saw two for sure, plus a couple more "maybes" that were too brief and dim for me to judge whether they came from the expected radiant point. (To be fair, from where I was in our backyard I was seeing far less than the full sky.)

But in the same time, I saw at least half a dozen satellites, ranging from "almost too dim to see" to "easily the brightest object in the sky". It's obviously been too long since I just lay back to watch the stars: those things are now a near-constant presence. So I really do wonder how that Greek time traveler would react to the modern sky: what would those swift-moving, variable brightness points of light mean to him? What would Plato make of it? What stories would Homer tell?

For that matter, I'm sure that there are still plenty of societies and communities today that have little knowledge of high technology, from isolated tribes to rural villages. What do *they* make of the satellites that now pass constantly over their heads? This is a recent phenomenon: its origin is easily within living memory, and it has only gradually become as frequent as it is today. What stories do those people tell? Do they know or guess that these are the work of human beings? Do they fear that the newly mobile stars are an omen of some approaching doom?

And what stories might we tell about ourselves, as we alter the face of the heavens so deeply without ever pausing to think what an astounding achievement that is?
steuard: (physics)
Monday, March 17th, 2014 06:26 pm

So that physics announcement that I posted the rumors about happened, and it was indeed just as big of a deal as rumor had made it. Here are a few links I've found that summarize the results nicely:

This is really cool, and there are some neat, neat implications. (The data points to an energy scale for inflation that happens to be very close to the expected energy scale of grand unification of fundamental forces in simple supersymmetric models of particle physics, for instance.) It'll be great to see if this result holds up.

steuard: (physics)
Monday, March 17th, 2014 12:11 am
If you happen to be the sort to follow a few cosmologists on blogs or social media, you've probably seen rumors swirling around like mad for the past few days. I'm not sure if this was triggered by the Harvard press release promising that a "major discovery" in astrophysics would be announced Monday at noon, or whether that release was hurried out the door only after the rumors got out. But it sounds like it could be a Big Deal, so keep your eyes open tomorrow. (One rumor is that they've invited Guth and Linde, the first theorists to propose cosmic inflation, to attend the announcement.)

Probably the best description I've seen of what people think the press conference is going to be about came from my friend Sean Carroll at Caltech: it seems that an experimental group observing the Cosmic Microwave Background is going to announce that they have seen direct evidence of perturbations of that background caused by gravitational waves in the first instants of the Big Bang. (As Sean explains, today our direct experimental data on the early universe extends back to about one second after the start of the Big Bang. This observation would push that back to an astounding 10-35 seconds after the start.)

I won't try to explain the physics here, since it's really not my specialty. The intriguing thing is that, as far as I can tell, most people were not expecting to see any actual detection of this signal from the current generation of experiments: other data suggested that the current experiments would only be able to set "less than this threshold" sorts of limits. So this impending announcement would seem to imply one of four things: 1) The signal is much stronger than expected, which would be Very Exciting(TM) for physics, 2) The experiment turned out to be more sensitive than expected, which would presumably involve either really good luck or some neat improvements in data analysis algorithms, 3) The announcement is merely of strongly suggestive evidence rather than a true discovery-level result, which would make the "major discovery" press conference seem quite overblown, or 4) Someone messed up their analysis and/or got fooled by a statistical fluctuation, which after all this hoopla would probably wind up ending multiple careers. (I can guarantee that the experimental team here is painfully aware of all these possibilities. But then, so were the folks who claimed to have seen neutrinos moving faster than light a few years back.)

So yeah. It sounds like the actual science talk will begin at 10:45 (with papers and data going online at the same time). So watch the news, or at least the blogs! It should be exciting.
steuard: (physics)
Monday, September 2nd, 2013 10:02 pm
You've probably heard at some point that tides on Earth are mostly caused by the moon, along with some smaller but still noticeable effects from the sun. In other words, the two objects' tidal forces are comparably strong (rather than being many orders of magnitude different: Uranus doesn't appreciably affect our tides!). You've probably also heard (or seen, during an eclipse) that the moon and the sun appear to be about the same size in the sky, even though the sun is vastly larger (but farther away). Remarkably, it turns out that these two facts are directly related.

Here's the idea. Let's say that the distance from Earth to some distant object is D, the radius of that distant object is R, and its density is p (I won't bother typing the usual "rho"). Ignoring constant numerical factors that would be the same for every (spherical) object, the mass of that distant object is proportional to p R3. The gravitational acceleration due to that distant object is proportional to M/D2 = (p R3)/D2, but if you're experienced in the math of Netwon's gravity it's fairly straightforward to show that tidal forces are instead proportional to M/D3 = (p R3)/D3. (Tidal forces refer to the difference in gravitational force on opposite sides of the earth, and that extra power of 1/D essentially comes from a linear approximation of the changing force that's proportional to REarth/D.) Factoring that a little differently, that means that tidal forces are proportional to p (R/D)3. But using a little trig, R/D is just the tangent of (half of) the angular size of the object in the sky, and for small angles that equals the angular size.

In other words, the tidal force exerted on the Earth by a distant object is proportional to the density times the cube of its angular size. Since the moon and the sun have about the same angular size, it's only the sun's lower density that makes its effects on our tides less significant. And as expected, planets like Uranus have a much less significant effect, since their angular size is tiny by comparison (and their density is in the same ballpark).

Neat, huh?
steuard: (lake)
Saturday, April 6th, 2013 10:33 am
Every time I start teaching quantum mechanics in intro physics, I wind up feeling a little disappointed. To most students it's just another set of equations to memorize; they don't understand how much of a radical departure it is from everything we knew before. I suppose that's inevitable to some degree, since modern kids are raised on a diet of atoms and electrons and what seemed radical a century ago is familiar today. But I'd still like them to understand that this is something New, and Important.

So I spent entirely too much of the past week writing something akin to a live-action role playing game. In class on Friday (and continuing into at least part of this coming Monday), the students became world class scientists trying to figure out the "newly discovered" photoelectric effect. They're each a supporter of one of two competing theories of how light (classical electromagnetic waves) interacts with a metal surface to eject electrons and cause current to flow. On Friday, I welcomed them to the conference in the role of the physics department chair at the host institution:

[I stole this picture from a student's public Facebook post, by the way: thanks David T!] In their two big groups and then in six smaller lab groups, the students assembled a set of graphs illustrating their competing predictions, and then the leader of each main group presented their results to the conference.

And after that, the experimental data came in ("from the experimental conference down the hall"). Both groups got some things right, but fundamentally, everyone was wrong! So on Monday we reconvene to see if we can puzzle out the true story. I have absolutely no idea how that's going to go. I've tried to seed elements of the real (quantum!) explanation among them, and if anyone is particular clever or eager to get it right they might think to actually read the textbook. (On their own!) We'll find out! If nothing else, it was clear that they had a lot of fun with the activity, and they really were thinking hard about what their predictions should look like. I feel good about it.

In case you're curious, I'm including a glimpse of one character sheet here. I'll stick it behind a cut: The first page of Prof. Parma's character sheet. )
steuard: (Default)
Monday, August 20th, 2012 10:13 am
I was thinking about color this morning (yes, I do these things), and I was struck by a disturbing thought: when did I last see violet? Not purple, which I see all the time, but actual violet. [I'm not the first person to wonder this: here's a very thorough discussion.]

Purple, as you no doubt recall, is a compound color: it's what we perceive when we see a mixture of red and blue light. But violet is a pure color: light with wavelength somewhere a little over 400nm. (Side question: anyone have a clue as to why purple and violet are perceptually similar?) So what's the problem? RGB monitors, that's what. The shortest wavelength of light produced by an RGB monitor is blue, which is probably around 460nm or so. That means that your monitor is incapable of producing a violet color. Looking at a picture of a rainbow on your computer screen is inevitably a less vibrant experience than seeing one in person.

So, fine, look at a printed photograph. Well... not so fast. I don't know how all the different types of photo printing work, but a lot of printers are RGB or CMY themselves (and I think that CMY has the same problems as RGB in this regard, or worse). I have no idea what the process is (or was) for traditional photo printing from the analog era, but I'm willing to imagine that there are photo printers today who are capable of printing with actual violet dyes. But wait: what sort of camera took the photograph? Again, I don't know how good traditional film cameras were at capturing violet, but today's digital cameras are (as far as I know) also RGB.

So: when did you last see violet? Think back: what does it look like?
steuard: (Default)
Sunday, July 15th, 2012 11:31 am
Charged particles released after the big solar flare last week have been reaching the Earth all weekend, and there's a good chance of an impressive aurora tonight! (I probably ought to have said something yesterday...) There's a good Aurora Forecast page from the University of Alaska that will show you what to expect where. In fact, if it weren't sunny right now, their Short Term forecast map seems to imply that auroral activity would likely be happening right over Michigan (and Montana and Maine and possibly even farther south than that) and that it might even be visible on the horizon as far south as New Orleans. Who knows whether it will be anything like that tonight, but try to have a look!
steuard: (physics)
Sunday, July 8th, 2012 08:24 am
I've finally finished mucking with my poster of the solar system!

I made some last minor adjustments to the look of it (the black goes all the way to the edge, now, as does a "throwaway" portion of the Sun image), I clarified the license terms (with explicit permission to pay someone to print a copy of your own), and I put up a link to buy the poster on Zazzle. (I don't see much need to also list at CafePress... right?)

I still don't know for sure whether the college will actually decide to print a bunch of these for marketing in August or September. If they do, I might be able to buy a few from them at cost for anyone who'd like to have a copy, which would presumably be cheaper than what you'd get from Zazzle. But you're obviously welcome to just buy the things online, too, and that would give you more flexibility about the size you want. (If you do, let me know how Zazzle's quality is!) If you have any suggestions on making the interface at Zazzle a little easier to use, I'm all ears: it's a bit annoying that I can't specify a minimum size, for instance (and that the "this aspect ratio only" option is more trouble than it's worth).

This'll be my last post about the poster for a while, honest! (Kim will no doubt be glad to hear that.)
steuard: (physics)
Wednesday, July 4th, 2012 11:58 am
The rumors were true! Both experiments at the LHC that were searching for the Higgs announced discovery-level evidence early this morning. This is a Big Deal, even if we did pretty much expect that the LHC would produce a result like this eventually. There's a lot to say (and lots of good discussions out there at various technical levels), but for a nice layman's overview I might recommend Bad Astronomy's Higgs post. The quotes near the beginning of this post by Tommaso Dorigo are good, too.

The very short version is this: a new particle has most definitely been discovered, and CERN found it by looking in all the places that one would look for the Higgs. Its properties aren't nailed down very well yet, but they appear to be broadly consistent with the properties we expect for the Standard Model Higgs. But, enticingly, there are tentative hints of some differences from that expectation, too. Further data over the next few years will (we hope) show us whether those differences are just random noise in the detection system or whether they reflect entirely new physics. (Most of us really, really hope it's the latter.)

Edit: I've seen some folks linking to a nice video explaining the Higgs from PhD Comics a couple of months ago. Also, since the topic of Comic Sans came up in my blog last week, I'm sad to see that the things I grumbled about last December were still a problem for the real announcement.

Edit2: Strassler's post lists a few more specifics in a nice, clean way.
steuard: (physics)
Tuesday, July 3rd, 2012 11:04 pm
Wednesday may prove to be a very exciting day in physics: the two LHC teams searching for the Higgs boson are scheduled to give a seminar, and pretty much the entire particle physics community expects their announcement to amount to a discovery (though either experiment on its own may or may not pass the official threshold this time). This is a Big Deal: finding the Higgs was one of the primary goals of the LHC (perhaps the primary goal), and it's the very last piece of the Standard Model of particle physics whose existence has not yet been confirmed. These groups presented some very tantalizing evidence last December, but now that they've taken more data we may finally be there for real.

The really interesting thing to watch for in this announcement is whether the particle they're seeing seems to behave exactly as the Standard Model predicts, or whether its interactions are different in some subtle way. Most of us really, really hope that there are differences, because the behavior of the Higgs is sensitive to many types of "new physics": it could give us the first fundamentally new experimental evidence about the ultimate laws of nature that we've had in a decade (or maybe even three decades or more, depending on what you count as "new" and how narrowly you focus on particle physics). Nobody expects tomorrow's announcement to make solid claims about any of that: it will take years of data to really start to understand the details. But December's data seemed to have weak hints of something unexpected, so people will be watching carefully to see whether those hints get stronger or whether they fade away as the statistics improve.

I'll presumably post something all excited in the morning. But if you're interested, keep an eye on Cosmic Variance or your favorite particle physics blog for news. The seminar is at 9am in Geneva, so that's 3am Eastern. I expect to be envious of everyone on the west coast who gets to see the results live at midnight!
steuard: (Default)
Wednesday, June 20th, 2012 10:01 pm
When our college president sent out his monthly campus update, I was pleasantly surprised to see my picture: he was happy about the very successful public viewing event that another professor and I arranged for the transit of Venus on June 5. (I'm up for tenure this fall, so the recognition is good!) We got an article on the front page of the local paper that morning, and between that and a campus email we wound up sharing the event with something like 150-200 people over the course of the evening.

It was a lot of fun. We gave people three ways to view the transit. They could stand in line to look through our good telescope (with its solar filter). (That's what's pictured above, though this was just my attempt at a hasty, imperfectly-focused shot right before I had to leave. You can barely even make out the cool sunspots in my picture.) They could look at a fairly large image projected on the wall (pictured below), which wasn't as clear but allowed lots of people to look at once. And finally, they could use my Harvey Mudd solar viewing glasses (thanks, HMC!): it was just possible to make out the round black disk of Venus blocking the sun without magnification, but that was one of the coolest parts of the experience for me.

I won't clutter up everyone's friends pages with pictures... )

That last picture shows an impromptu scale model of the inner solar system that I set up on the football field (right next to the telescopes). I put a picture of the Sun on the 25 yard line, with the right scale to match Earth right on the goal line. Venus then wound up on the 7 yard line. If you click to zoom in on this photo, you might just be able to spot the tiny picture of Earth printed there (which is also to scale, along with the Moon and the distance between them). The solar system is big, and it's something of a miracle that these tiny little planets with their differently-tilted orbits ever manage to line up enough for transits at all. In fact, I got rather excited talking about all this to the crowd: a friend took a video of me giving my last "welcome chatter" of the night, after the crowd had thinned out a lot. (The college made its own video of the event, too. But it doesn't look like anyone thought to take pictures of the long line that we had for the first hour or so.)

Finally, the fun of the event and of tracking down pictures of the sun and planets for my scale model got me interested in making a poster of the planets to put up outside our planetarium. I spent a block of time hunting around NASA websites for big chunks of a weekend and a few evenings, and assembled this:

The full-resolution PDF will print 4'x3' with a resolution of at least 120dpi (and considerably more for many objects); I'll eventually be sharing it under a Creative Commons license. I'm pretty proud of it: you can't read them on this little picture, but each planet and moon comes with some interesting fact about the object. (There are very few posters like this based on real images, and too many of those obsess over dull numerical data instead of remarkable things like Mars's seasonal dry ice caps or Triton's probable geysers of liquid nitrogen.)
steuard: (Default)
Monday, June 4th, 2012 06:48 pm
Tomorrow (Tuesday, June 5) starting at about 6:04 Eastern time, the planet Venus will pass directly between the Earth and the Sun. This is a Rare Thing: the next time will be in 2117. There's been a lot of good science done using these transits in the past (like the first good estimates of the size of the solar system) and they still provide neat science opportunities today (like the plan to refine exoplanet detection by looking at the moon that I wrote about previously).

So look around locally for a chance to view the transit in person! Lots of observatories and planetariums and other groups will be organizing viewing events, which is probably your best bet. If you want to view it yourself, you can look at the official Transit of Venus site for some suggestions. (Don't look directly at the sun! Don't point an ordinary telescope at the sun!) Or look for some of the many webcasts out there: the Bad Astronomy site is planning what sounds like a good one, and there are others from NASA and other places. But you should really try to have a look: it won't look awe inspiring, but watching this sort of thing as it happens and thinking about the vast celestial objects in play can inspire great thoughts on astronomy and our place in the universe. Good stuff!
steuard: (physics)
Sunday, May 20th, 2012 10:54 pm
When we realized that our trip to see family in Los Angeles was going to line up with the (partial) solar eclipse, Kim and I made sure to bring a pair of the solar viewing glasses that Harvey Mudd sent out to alumni a few weeks ago. We were on our way to dinner when it started (after showing off the baby to a bunch of thrilled relatives all afternoon), and Kim's mom and I got to watch it begin from the car. (We politely declined to pass the glasses to Kim in the driver's seat when she asked for a turn.)

When we got to dinner, it was about halfway to maximum, and we all popped outside in turns occasionally to have a look. I was just about done with dinner when it reached maximum coverage (about 85% here), so I went outside to look. It was great, and when some people nearby looked at me curiously I got all excited and showed them, too. That drew more attention, and more and more people were drawn in by all the ooohs and ahhhs. (There were even a bunch of servers and staff from the restaurant.)

All in all, I probably shared the event with two or three dozen people. It was a fantastic science outreach experience, and I think Kim and her mom mostly forgave me for abandoning them in the restaurant with the baby for 15 minutes or so. (My only disappointment was that with the sun so low in the sky, there wasn't a good view of the crescent shadows under the tree leaves: that's one of the most awesome sights during an eclipse.) I hope Alma's public viewing of the transit of Venus in a few weeks goes as well!
steuard: (physics)
Sunday, May 6th, 2012 10:30 pm
One of the things that still blows my mind about our studies of planets around other stars (beyond the simple fact that we can see them at all) is that astronomers are actually able to figure out the composition of their atmospheres. That's possible when a planet passes between us and its star: it creates a tiny shadow that dims the star's light ever so slightly, and an even tinier fraction of that light passes through the planet's atmosphere. So if the spectral pattern of the star's light changes when the planet is in the way, we can analyze the changes to tell us what's its air is made of.

We think we understand the technique pretty well, but it would be great if we could test it out on a planet whose atmosphere we already understand. If only there were some known planet expected to pass between us and its star, we could point the Hubble at it and check this calculation against the known result. Well, hey! The planet Venus is going to transit across the sun on June 5th (the next time will be in 2117: watch it (carefully), and take your kids!). Only one problem: pointing the Hubble straight at the sun would destroy its sensitive optics (much like staring at it with unprotected eyes: be careful!).

So what are they going to do instead? Point the Hubble at the moon. The idea is that studying the much weaker reflected light of the sun (and briefly, of a tiny bit of the atmosphere of Venus) will be a decent test of those models. As long as they take a careful sample of the reflected spectrum for many hours before the transit, they can get an accurate baseline reading. Then by taking equally careful (and lengthy) measurements during the transit, they can measure the difference when Venus is present. If all goes well, the measurements will yield the same "no life on this planet!" signal that we've already established by looking straight at it.

Studying Venus by staring at the moon: crazy, but awesome. (Here's the original article: Hubble to Use Moon as Mirror to See Venus Transit.)
steuard: (physics)
Tuesday, April 24th, 2012 09:19 am
I am really excited by what I've heard about Planetary Resources, a private company that has just announced plans to mine near-earth asteroids for precious metals and other resources. Here's a write-up from the Bad Astronomy blog that goes into details: it sounds like these folks have a plausible business plan (as well as the necessary level of patience, and a dedication to the underlying cause of advancing humanity in space that will be an important complement to their profit motive).

Maybe it's just too much science fiction in my youth, but I've always felt that it will be important for humanity to Get Out: to avoid having all our eggs in this one basket called Earth. There are a whole lot of reasons for that (more of them than I had as a youthful sci-fi reader), and I won't go into them now. But it's been clear to me for a long time that while governments were the obvious choice to take the first steps into the solar system, we won't really be a spacefaring species until private industry and even private individuals are able to go there on their own. Asteroid mining seems like a really good stepping stone in that direction: small and close enough to be achievable, and with enough potential profit to make it appealing to investors. As soon as one of these ventures pays off, dozens more will spring up overnight, and space industry will go from being an epic project to a commodity. I don't know if we'll ever get out of our own solar system, but I look forward to the day when we can at least use more of it than we do today.

Meanwhile, in other news (only tangentially space related), it's possible that the Fermi gamma ray telescope satellite has seen a direct hint of the long-sought dark matter particle! There's a full write-up at the Résonaances blog, but the gist is that if you look straight at the galactic core (where dark matter should be most concentrated) the telescope sees an excess of photons with a very specific energy, as if there were some unknown source at that energy on top of the known gamma ray sources (which are all spread out over a range of energies). The only model in the literature that could explain such a pattern is the decay of a dark matter particle with that same energy (or something close to it). The most likely particle mass that would explain this data is about 130 GeV: that's 130 times the mass of an entire proton (and, by an odd coincidence that might not be a coincidence, just 5 GeV or so above the current best estimate of the Higgs boson mass).

This will be a big deal if it turns out to be true: the first direct evidence of particle physics beyond the 30-year-old "standard model" (and the first concrete reason to believe that particle physics won't be dead as a practical matter after the LHC). It's thrilling stuff. The one thing that's puzzling to me about this is that I saw this news a week ago on that one blog, and I haven't heard anything else about it since. (I talked to an Alma graduate who studies experimental cosmology while he was back for graduation, and he said he'd heard about it but didn't know enough to comment beyond that.) Is there some reason for skepticism that has kept all of my other physics/astronomy blogs silent on the story thus far? Only time will tell. But it will be a lot of fun to watch.
steuard: (Default)
Saturday, February 11th, 2012 04:04 pm
My "Physics of Video Games" talk at AlmaCon went beautifully. (The con as a whole seems to be going really well, too. Thank goodness!) Many thanks to those of you who suggested ideas: some of those confirmed the value of thoughts I'd already had and others filled exactly the gaps that I had been worried about finding good examples for. My turnout was surprisingly good. I got nods of familiarity and/or understanding for lots of my "good physics" examples, loads of laughter for some of my "bad physics" examples, and some great questions and discussion when talking about using games to teach the scientific method.

In case you're curious, here's a list of videos that I used (though I often showed only a relevant clip from each). I kinda wish that I'd videotaped it!

Good physics examples:
Angry Birds (as well as some graphs of bird motion).
World of Goo (another physics puzzle game)
Dwarf Fortress (fluid flow & melting points)
Myth: The Fallen Lords (an early example of a really complete physics environment)
Skyrim (lots of cheese) (this got a laugh, but illustrated the quality of modern physics engines)

Bad (or rather, unrealistic) physics examples, that might be either good or bad for game play:
Skyrim bug with a sabertooth tiger (this had them laughing louder and louder for about a minute straight)
Resonance (flash game where jumps have no momentum)
Grand Theft Auto: San Andreas (decent laugh here; I just had a short little clip on loop)
Grand Theft Auto IV (big laugh, but as I pointed out, in many cases this behavior probably makes the game more fun)
Portal (a fictional element in an otherwise realistic game)
Portal infinite fall (what happened to conservation of energy?)
Mario 3D Land (steering during a jump)
Mario 64 (kicks in midair push you higher)

Video games teaching the scientific method (with excerpts from the full paper)
steuard: (Default)
Tuesday, October 11th, 2011 03:05 pm
In a brief lull after lunch today, I happened upon a link to a cool-sounding science story: Giant Triassic Kraken Lair Discovered!. The gist of the story is that there's a fossil bed of ichthyosaurs in Nevada that's puzzling: nine bus-sized fossils were found in the same place, with no sign of how they all died. There's evidence that the location of the carcasses was in deep water when they were deposited: how did they all wind up in the same place?

Now paleontologist Mark McMenamin claims to have the answer. Based on some etching on the bones, he suggests that the icthyosaurs died elsewhere and were carried to this central location by some other creature. Modern-day octopuses collect bones in that way, so he suggests that there was a vast Triassic cephalopod (which he dubs a "kraken") that collected and indeed hunted these bus-sized aquatic reptiles (in the same way that a modern octopus may attack a shark). Why have we never found any trace of this kraken? Because cephalopods are made almost entirely of soft tissues that don't fossilize well.

But that's not all! Some of the bones in the fossil deposit are arranged in surprisingly regular patterns, with the disk-like vertebrae packed close together almost as if placed there intentionally... so McMenamin, looking at the huge patterns of close-packed circles, goes on to claim that the bones were knowingly arranged by the kraken as a self-portrait of the suckers on its arms! In words from his conference press release, the "vertebral disc 'pavement' seen at the state park may represent the earliest known self portrait," and the kraken "could have been the most intelligent invertebrate ever".

On the one hand, I'm tremendously intrigued: I've long wondered just how certain we can be that intelligent life has never arisen on Earth before. But it only takes a moment's thought to develop a lot of skepticism about this story. On the basis of a single moderately confusing reptile fossil site, McMenamin has hypothesized not just a race of ginormous killer octopuses (no trace of which has ever been found or previously suggested) but a race of intelligent, artistic ginormous killer octopuses. Cool though it may sound, the leaps of logic in that story are laughably vast.

Does this Geological Society of America conference by chance have a crackpot session? (And why are they issuing press releases about this sort of raw speculation?)
steuard: (strings)
Sunday, June 19th, 2011 12:11 pm
Just in time to avoid delays due to childbirth, I've finished and submitted a new paper for publication: The KK-Monopole/NS5-Brane in Doubled Geometry. I'm excited about this work; it's the same topic that I presented on a couple of months ago at the Great Lakes Strings conference in Chicago. Since the title is once again largely jargon, I've written up a summary of what it's all about for non-specialists. To be honest, I have no idea how much sense that summary will make anyway, so let me know if you think it's unreadable. I hope you at least like the pretty pictures there!

[Oh, and I've also replaced my user icon with something that looks a little more obviously like strings: strings interacting with D2-branes, to be exact. It's one of my more popular string images out in the wild, and hey, it's pretty, too.]
steuard: (physics)
Tuesday, May 31st, 2011 05:11 pm
It's been a long, long time since I wrote anything here: I've just finished teaching an intensive one month "Spring Term" class on Medical Physics that met two to three hours a day, five days a week. This might have been less stressful if I'd ever taught (or taken) a class on the subject before (or if I hadn't spent the whole week between my previous final exams and the class starting writing and giving a conference talk in Chicago). But it seems to have gone well, and I've now officially hit summer vacation! That means that I get to procrastinate on baby preparation and paper writing by sharing cool recent science tidbits.

The first is serious physics, and has the potential to be tremendously exciting if it pans out: the CDF experiment at Fermilab may have found the first direct evidence of physics beyond the Standard Model of particle physics! For a nice layman's summary, my friend Sean Carroll has a good writeup at Cosmic Variance; for some more detail, follow the links to posts at Résonaances. I won't try to repeat them here; I'll just show the exciting data:

and comment that the red line is the expected Standard Model result and the blue bump above would presumably correspond to an entirely new neutral particle about 150 times heavier than a proton. This result still isn't 100% solid: it's a "4.8 sigma" result, which is extraordinarily unlikely to happen by chance, but until it's reproduced by Fermilab's D0 experiment or by the LHC there's always the chance that someone forgot to carry a two during the data analysis.

The second thing to share is a beautiful time-lapse video of the Earth rotating under the stars that was recently adapted from an earlier video of stars rotating in the sky. It's a vivid demonstration of the Earth's motion through the heavens that makes you rethink your assumptions about what's really moving when you watch the sky. Here's the video; seriously consider watching it full-screen in HD!