Ice Storm (II): Most of the city looks like this. The ice should melt off over the weekend, but some people may not have electricity for 7 days.
Mail It Home? Over on InstaPundit, Reynolds quotes a suggestion from the esteemed Eugene Volokh (esteemed by me, that is, as one of the truly sane voices from the glory days of Libernet, ca 1994):
Here's a way for airlines to make a cheap gesture to help customers *and* minimize delays caused by debates with the security guards: Get the USPS to set up a mailbox and a stamped-envelope machine in front of every security checkpoint. If need be, they can even pay the USPS some modest extra amount in case the side trip for the mail carrier would otherwise be non-cost-justified.
Then, if you have a congressional medal of honor or a pair of nail-clippers or a hairpin or whatever else that you want to get home, you won't need to spend everyone's time arguing with the security guards. You'd just step out of line and take a minute to mail the item to yourself.
I think you might have mentioned the mail as a possible solution in an earlier post, but the trick -- as anyone who focuses on customer convenience knows -- is to make it *easy*, and then maybe even take the credit for making it easy.
Well, mailing your stuff home is certainly preferable to having it confiscated, but there's still a world of difference between getting it the next day (or three days later) and having it with you half an hour after you get off the plane. See my earlier comments on "schedule risk."
If I were running things (perhaps a frightening thought), I'd set up a mechanism for quickly repacking forbidden items in a small box, labeled with the customer's name, which would simply be added to checked luggage. That way the only inconvenience would be that of not having access to those items while in flight.
As Glenn noted, however, "I have to say, so far I don't see any great interest in making life easier for passengers."
Politics and the English Language
Politics and the English Language: Thanks to Bjørn Stærk and Glenn Reynolds for pointing to an online version of this magnificent essay by George Orwell. Stærk contends that "1984 ... is always quoted foolishly," and I think this may be yet another symptom of the gap between the technical and the non-technical, or the mathematical and the non-mathematical. Here are a couple of excerpts from Politics and the English Language; as you read them, consider who would be more vulnerable to indulging in the evasiveness Orwell describes: the technophile or the technophobe?
The great enemy of clear language is insincerity. When there is a gap between one's real and one's declared aims, one turns as it were instinctively to long words and exhausted idioms, like a cuttlefish spurting out ink. In our age there is no such thing as "keeping out of politics." All issues are political issues, and politics itself is a mass of lies, evasions, folly, hatred, and schizophrenia.
Defenseless villages are bombarded from the air, the inhabitants driven out into the countryside, the cattle machine-gunned, the huts set on fire with incendiary bullets: this is called pacification. Millions of peasants are robbed of their farms and sent trudging along the roads with no more than they can carry: this is called transfer of population or rectification of frontiers. People are imprisoned for years without trial, or shot in the back of the neck or sent to die of scurvy in Arctic lumber camps: this is called elimination of unreliable elements.
Ice Storm: See this story for an explanation of why I didn't post anything yesterday. It's being called either the worst ice storm since the mid-'80s or the worst one ever, depending on what is being measured. It's the worst I've seen since March of '84, when some people, my parents among them, had no electricity for 8 days, and over half my co-workers could not commute to work because of tree limbs blocking driveways and streets (I got off easy then by virtue of living in an apartment building in midtown -- buried power lines, and on a boulevard which was kept clear of debris).
Roughly half the metro area is without electricity, including the Manifold residence. I got up at 5 this morning and could see no lights anywhere in our neighborhood, and we live on a hillside with a good view (in winter) for some distance to the north and east, so we appear to be located in a large area without power. To answer the obvious question, I'm posting this from the day job, to which I was ferried by She Who Must Be Obeyed.
The freezing rain started Tuesday afternoon, and residential streets were largely impassable (by rear-wheel-drive vehicles, at any rate) by Wednesday morning, but the real damage did not begin until early Wednesday evening. The precipitation, which had turned to sleet, turned back to rain, and the temperature at ground level was still at or below freezing. Tree limbs and power lines built up an enormous coating of ice. The big oak tree in our front yard looks like a willow, but it had not lost any limbs as of this morning. We have quite a few limbs down from various trees in the back yard, but nothing vital was hit.
Last night was a distant cacophony, not conducive to sleep, of crashing tree limbs and exploding transformers -- great flashes of blue-green light, followed shortly by varyingly muffled booms -- and steadily increasing darkness, until sometime after 1 AM every light directly visible from our house was extinguished.
It will be interesting to see how long the recovery takes. We may go so far as to purchase a generator to keep our furnace fan, thermostat, refrigerator, and a few outlets running when the inevitable "next time" happens.
Terrific War Stats: Thanks to Reynolds for pointing to some phenomenal stats over on Flit. The most telling? Fatalities per weapon: Gulf, 0.01; Kosovo, 0.02; Afghanistan, 0.08. We will see this value reach (if not exceed) unity within a generation. Pull a trigger, push a button, and somebody dies, every time.
I've Upgraded: To Blogger Pro™. It's worth it.
Talkin' 'bout My Radiation: I'm still getting feedback from this piece, which got mentioned over on JunkScience.com (search on "Manifold"). R.D. "Donny" Dicharry, President of Source Production & Equipment Co., Inc. in St. Rose, LA (hey, that's in Alex delCastillo's back yard!) sent me a note, from which the following is quoted with his kind permission:
We are the company in Louisiana to whom Studsvik shipped the radioactive material package that you mentioned in your article ...
You are correct; it could not be iridium-172. In fact, it was iridium-192. The NY Times article got every detail of the story wrong.
You are also correct about certain politicians churning up public anxiety to suit their agenda. Congressman Ed Markey ( D - Mass) is leading the way. He is a long time anti-nuclear activist who will seek any opportunity to demonize anything connected with radiation. Now he wants Americans to worry about terrorists shipping radioactive material to make "dirty bombs".
I am not a terrorist expert, but it seems to me that if a terrorist has radioactive material in his possession the last thing he would want to do is willingly let it out of his possession - such as by shipping it somewhere thus risking detection. Indeed, the best way for a shipment to get detected is if the package is marked "radioactive" and is leaking radiation, like the Studsvik shipment to us. Nevertheless, watch the anti-nuke faction use this incident to try to ban shipping radioactive material.
Need A Little Help With Those Phrases? Look no further than this.
Roundabouts (II): After my earlier comments, Iain Murray, proprietor of The Edge of England's Sword, sent me a kind note and a really scary picture of a huge pentagram-shaped roundabout somewhere in the UK, captioned in French by somebody who, as near as I can tell, was as frightened by the looks of the thing as I am. Here are some excerpts from the note:
The roundabouts critique is interesting. I have a dim memory of sitting in a meeting at the Dept of Transport with a traffic engineer and a safety statistician in which they proved to each other mathematically that roundabouts were incredibly safe things. I'd love to see what they said about your analysis.
One of these days I'd like to see a fixed effects model of road traffic deaths. I think safety features like roundabouts will come in as much less influential than seatbelts (the number one killer in Britain, and, I suspect, the US), alcohol, priorite a droite (where it's practiced), age speed and size differential, as well as distance from hospital. Of course, so many of these are interconnected; rural crashes are more likely, I understand, to involve a young driver, drunk, not wearing a seatbelt and in a pick-up that crashes head-on into something much bigger. Is any of those factors the most important in causing the fatality? Danged if I know.
Murray was responding, in part, to something I should have said on Arcturus the first time around, but thought of only in time to e-mail it to him (when I finally figured out how to): "... the real thing that American fatal motor accident stats should be corrected for is the phenomenally low population density here. Some years back, SciAm printed two maps of the US, with each county color-coded: one was deaths per 100,000 population by motor vehicle accident, the other was population density. They were photographic negatives. The closer you are to a hospital, the better your chances (I believe the expression among trauma specialists is 'the golden hour'); some rural counties in this country have a higher death rate from car wrecks than the worst neighborhoods of the biggest cities do from homicide."
I want to avoid raising trivial questions, defined as those which could be immediately answered by anyone in the insurance business. My hypotheses, such as they are, are these:
So is anyone out there reading this aware of a "fixed effects model" like the one Murray wishes for? Or definitive responses to my hypotheses?
Rewards for Readers: After reporting on some correspondence from Clayton J. Bradt, CHP, Principal Radiophysicist of the NYS Dept. of Labor Radiological Health Unit, and dubbing him "Dr Bradt," (see this post), I received another e-mail from him thanking me for the "honorary doctorate." Having gotten one or two honorary doctorates of this type myself, I know the feeling.
Well, there ought to be something in it for people who read Arcturus and send me comments, so I hereby dub Clayton Bradt the first recipient of an honorary Doctorate of the Order of Arcturus, which entitles him to put "D.O.A." after his name. ;)
A Quart Low: I gave blood this morning and am accordingly having a bit of difficulty concentrating, so some things I meant to post today might not make it. I am, however, nowhere near as wiped out as I was after donating blood one fine day in August 1993 and then staying out that night until 3 AM watching the Perseid meteor shower, after which I had to chair a teleconference at 8:30 AM. Not recommended.
Once More Into the Breach: Let's look at that travel math again. Conceptually, intercity travel breaks down into five phases:
For air travel, typical values of each of the above are:
For train travel, typical values are:
For car travel, typical values are:
This is enough info to do a spreadsheet and figure the breakeven points associated with the different values, especially of phase #2. A purely quantitative approach would indicate that most trips of 400 miles or less can be done faster by car than by plane.
There are, however, intangibles to consider. Driving a car eats up a lot more mental bandwidth than sitting on a plane. Six hours of driving is almost certain to wear you out more than one hour of driving at each end and four hours of waiting and sitting in a coach seat in between. This may be quantifiable, perhaps as simply as by comparing calories burned while driving vs just sitting around, but I'm not prepared even to guess at this point. Advantage: airplanes.
But the killer intangible is uncertainty. Will it take one hour or three to get through security? Will my plane be on time or an hour late? Will I miss my connection? Will things be even worse in six months?
And this may apply to trains as well. After my earlier post, Virginia Postrel wrote me: "If trains get popular, they’ll also get two-hour security checks. They already have airline-style delays." I thought, that's stupid; what for? But the Feds have a notable tendency toward overkill in this area, and the Office of Homeland Security can't be allowed to appear superfluous. And not three days later, I went to the Nelson with She Who Must Be Obeyed and had a rather unpleasant encounter with a security guard; all purses must be hand-searched, and patrons must either wear coats or check them. In an art gallery, for God's sake.
This is what will kill the airlines and turn the clock back to something like the pre-de-reg ('78) days, except with ludicrous inconveniences rather than high prices keeping most of us out of the air. And the technological back door the American people will use instead?
Smart cars and smart highways.
Stay tuned ...
Get Your (Telescope) Motor Running: I got on the bike again today and headed out to find the new ASKC dark-sky observing site. It's located between West Line and Freeman, MO, approximately 11 miles ESE of Powell Observatory and 34 miles S of downtown KC MO.
Here's an area map, and here's a detailed map.
The written directions, kindly provided by Gary Pittman of the ASKC, and slightly edited by me, are:
Ch-Ch-Ch-Ch-Changes (II): Upon further feedback from a reader who bluntly informed me that "you've got about the least legible type imaginable," I made a few tweaks. Hope this helps.
Carpe Noctem: I'm fresh back from 1) a terrific ride on my bike -- it was sunny and 64° F. here today; I wandered south into Cass County and worked my way back home on country roads in Jackson County that probably got paved when Harry Truman was Presiding Judge -- and 2) the monthly meeting of the Astronomical Society of Kansas City and am accordingly looking forward to this event (the "Dec 20" in the diagrams is a typo) and lusting after this telescope, or perhaps its replacement, or perhaps this related model. My existing telescope is one of these, a 13.1" f/4.5 Newtonian reflector on a Dobsonian mount. It's been all over the country, including both coasts, over the border into Canada, and on numerous trips to West Texas, so it's looking a bit worse for wear these days. In the real world, it will not be replaced any time soon, as we have a basement and a couple of bathrooms to finish.
Locals, watch for an e-mail invite from me to an "occultation party" next month!
Fly Baggage Separately? Glenn Reynolds extols a NYTimes letter to the editor which suggests that airlines "... eliminate the need for baggage screening by sending all baggage on cargo-only flights."
I will now follow the emerging "Arcturian" pattern of discussing a tranportation issue (not necessarily what I had in mind when I started this thing) by looking at it in terms of processes and throwing some high-school-level math at it to see if the proposal stands up. This one looks problematic.
Here are the process issues I can think of right off the top of my head:
The proposal is not without its merits, but it looks to me like they mostly accrue to the airlines at the expense (literally) of their customers:
Now for some supporting math:
Grazing (midwesterners don't surf) over here, we find that some nice fast C4 (8092 ± 26 m/s) has a density of 1.63 g/cm3. A fist-sized lump of this would weigh at least 1 lb -- compare that to the 10-14 oz of Semtex hidden in a "ghetto blaster" (hey, it really was a boom box!) that brought down Pan Am 103. Ladies, time to check your purses.
OK, let's pick a medium-sized, relatively mature jet to work out the ratio of passenger planes to cargo planes. I found this spec sheet for the MD-80 (actually the MD-83 variant), which tells us that the maximum payload for this type of aircraft is 41,272 lbs. Then this article about the MD-83 tells us that it seats 142 passengers. So it allows 290 lbs per passenger, with luggage. So one baggage flight for every 5 passenger flights would allow each passenger to ship almost 60 pounds of belongings. This is generous -- the ratio in practice might be even higher. Schedules vary widely, but in all but the busiest hubs, waiting for 5 more planes to arrive from your departure city would mean the loss of a business day, and frequently the loss of a calendar day.
I conclude that the overall effect of this proposal would be to increase the "breakeven distance" (alluded to in this earlier post) of plane vs car or train travel to at least 1,000 miles, and perhaps to transcontinental distances. But I'll take another whack at the math for that later.
Why Guys Make Conflicted Peace Activists: A typically delightful (and in this case, merely PG-rated) article from The Onion.
For Those of You Pouring In: I made the big time on InstaPundit, so there will be lots of traffic here today. Recommended reading: my attempt at self-explanation. Other than that, please poke around; you're very welcome. Do be aware that I am not prompt about answering e-mail, but I love getting it and nearly all my correspondents get mentioned and followed up with eventually.
Ch-Ch-Ch-Ch-Changes: As you can see, I caved in and got another template (for those just tuning in, the old look was this really cool color-changing thing that pretty much didn't work except on IE v5.5). The final push came from Reynolds, but others had been chiding me about this for some time.
Now that I've actually got a readable blog, I need to write something worth reading. One thing at a time.
Trains, Planes, and ...
Thanks toInstaPundit for pointing to a piece from the LATimes written by John Balzar and entitled Flying in the Face of Countless Indignities. After a wretched series of preliminaries, he is finally allowed aboard a flight from Las Vegas to Los Angeles:
"After almost six hours, we're in the air for the one-hour flight home. The pilot tells us to look down at the traffic on the I-15 Freeway, as if we should be consoled.
"I'm imagining a billboard that reads, 'If you were down here, you would have been home an hour ago.'"
Six hours?! (Actually seven, plus the airport-to-home drive.) According toMapQuest, driving it takes only 4½!
This calls for some algebra. Call them the travel-industry human-endurance equations:
All times are in hours and distances in miles. The equations assume that planes average 500 mph, trains average 50 mph, and car travel averages 60 mph -- that is, on limited-access highways, with occasional brief stops. Typical values for some of the variables are:
Tairport = 1 hour (drive from home to airport)
Twait = 3 hours (wait at airport, including all security checks)
Tdest = 1 hour (drive from airport to destination)
Ttrain = 0.5 hour (drive from home to train station)
TTwait = 0.5 hour (wait at train station)
TTdest = 0.5 hour (travel from train station to destination)
Tgas = 0.25 hour (time to gas up the car)
At these values, distances of 195 miles or less are quicker by train than by plane. Distances of 325 miles or less are quicker by car than by plane.
But increase Twait to 6 hours, as in Balzar's experience, and traveling up to 360 miles is quicker by train than by plane. The car-plane breakeven distance is 530 miles!
What this means for Kansas Citians is that air travel to St Louis, Springfield, Tulsa, Wichita, Omaha, Des Moines, and (on a good day) Oklahoma City now makes almost no sense. You'll get there faster in your own car. If the delays at KCI get as bad as they are at Las Vegas, it will be faster to drive to the Twin Cities or Chicago than it is to fly. Not a lot of trains in these parts, but it may become economical to take the train to St Louis or Chicago.
Of course, in more densely-populated regions, things are different. I'll leave it to my readers in the Northeast to figure out how much abuse they're willing to take from the airlines and Federal "security."
As for what will happen ifinexpensive personal air transportation becomes a reality, let's just say that the airlines' troubles have barely begun.
Actual Word: "Megabats"
It's all inStories of modern science... from UPI. Also "microbats," but I think "megabats" is much cooler.
A Google search led me tothis site, which offers the comma-spliced but fun question: "Take a look at some different types of megabats, which one do you like the most?" (I prefer #4.)
Don't Just Do Something, Sit There
Over onUniSci, there's a nicely counterintuitive story about how, at least sometimes, "... people should try to avoid mitigating [droughts or other environmental] disturbances."
In England's Green and Pleasant Land
Somebody I think that CS Lewis would have liked a whole lot is profiledhere. Thanks to Iain Murray for the lead.
Falsifiable Prediction Followup
A while back, I noted what appeared to be aparticularly silly falsifiable prediction by Pat Robertson, whose Bible appears to lack, for example, Genesis 18:23-32. Subsequently, Bill Walker reminded me that "as usual he doesn't give a time or even say that SF, Detroit, or Dallas is the NEXT target," implicitly raising the question: how do we expose this pathetic little fraud?
Not a trivial project, I readily admit; look what it took to exposeGary North. We all should have learned something from Y2K (or perhaps by reading WorldNetDaily). For a terrific compilation -- though these are from people much less well-known -- see The Doomsday List.
So, anyway, here's some ideas for backing Robertson into a corner:
Feel free to contribute ideas on this one, but be warned that it may lead to another contest of sorts, in which you pass along your own failed predictions. I've got an old Y2K one stashed somewhere -- about the best I can say is that I wasn't trying to sell people generators or survival rations.
I’ll Be the Roundabout
Over on The Edge of England's Sword, which I link to partly because of my own anglophilic and "anglospheric" tendencies but also because it is, hands down, the coolest blog name yet, Iain Murray, for whom I have despaired of finding an e-mail address, has a post calledTransports of Fright in which he chides American drivers for their troubles with roundabouts.
Murray concludes: "US traffic accidents are therefore essentially a cultural phenomenon. I wonder how many foreign road traffic engineers appreciate that?"
Treading cautiously -- Murray is a statistician, after all -- I perused theInternational Road Traffic and Accident Database, where I found that the US death rate from motor vehicle accidents is 9.6 persons per 1 billion vehicle-kilometers. This is slightly higher than Finland (9.4), the Netherlands (9.3), Norway (9.5), Sweden (8.3), and the UK (8.1), and lower than everybody else (cancel that driving vacation in Turkey). If it were corrected for age, by which I mean the relative prevalence of testosterone-addled young men behind the wheel, Americans (who usually begin driving at 16) might well be the safest driving population anywhere.
Those idiots we like to yell at every day are some of the best drivers in the world. So is the roundabout problem "culture" -- or engineering?
A technology is mature insofar as it vanishes into the consciousness of the user, as somebody or other a whole lot smarter than me once said. Limited-access highways were an advance precisely insofar as they do not (usually) require sharp turns and decelerations. As a motorcyclist, I am all too aware that anything with intersections is more dangerous than anything without intersections.
So roundabouts would seem, at first inspection, to be safer than traffic signals, but they're not; the reason is the abrupt lane change required to make a (left) turn, which can (and often does) place the vehicle making the turn directly in front of a vehicle not making a turn; result, T-bone, as we say in the heartland. This is avoidable only if the roundabout is only one lane wide, that is, something like what you get if you plop a decorative traffic island at the intersection of a couple of residential streets. Not applicable to major arteries.
Non-locals may wonder what attracted my attention to this in the first place. Locals will realize that I'm leading up to a mention ofMeyer Circle, location of one of KC's more attractive public fountains, and the only full-scale roundabout within several hundred miles. It is an aesthetic delight, an urban treasure that almost no one who lives here would want to see removed -- and a complete pain in the neck if you're trying to turn left from Meyer Boulevard onto Ward Parkway, or vice versa.
Roundabouts are lovely, as long as there aren't too many of them. And if anybody can send this to Murray, please do; I hate doing this behind his back.
Why Baseline Selection is Important
Friend of Arcturus (whether he knows it or not)Rod Martin sends along the following, as part of The Lighthouse; you can read the whole thing at "Violence in the Twentieth Century: A Closer Look." The summary:
IS GLOBAL VIOLENCE ACCELERATING?
Did the world become more violent in the twentieth century? Contrary to popular opinion, according to James Payne, historians have not proven that the last century was history's bloodiest.
"The world, we say, is being consumed by an increasing and increasingly dangerous wave of violence," writes Payne in the winter 2002 issue of THE INDEPENDENT REVIEW. "The facts, easily seen if we step back a little, point in the opposite direction, however. They reveal a broad and highly encouraging decline in world violence."
True, Mao, Stalin, Hitler, and the two World Wars, killed many, many people. (About 189 million died in genocide, war or civil unrest in the 20th century, according to one leading authority, scholar R. J. Rummel.) But history has had plenty of lesser known tyrants and wars. During the Nanking revolt of 1853-64, for example, the population of that province fell by 70 percent.
And isn't branding the 20th century, "history's most violent" because of deaths that occurred half a century ago as misplaced as calling the 20th century history's most economically depressed because of a Great Depression that ended more than 50 years ago? Payne asks.
Among Payne's other observations:
* No major powers have fought each other since World War Two.
* Central and South America saw only four armed conflicts between countries in the 20th century, and they were much less destructive that the two dozen wars of the 19th century fought in that region.
* The relative size of the military in 63 nations that existed before World War Two fell from about 8.5% to 5.25% from 1960 to 1997, while the average length of conscription fell from 17.4 months in 1970 to 8.6 months in 2000. In many countries the draft has been ended.
* From 1975 to 2000, death from genocide, war and civil strife as a percentage of world population fell to less than one-tenth the level of 1925 to 1950. Just as the Industrial Revolution made the poverty that carried over from pre-industrial times a scandal, so contemporary attitudes to some degree have made armed conflict scandalous, rather than acceptable behavior.
"In proceeding along the path of patient muddling in disputes around the world, the diplomats and the public in general ought to take heart. The lesson of the 20th century, clearly borne out in the statistics of war and peace, indicate that history appears to be on the side of peace."
"War and Democracy: Reply and Rejoinder"
"Autocratic Ghosts and Chinese Hunger"
"Freedom, Terror, and Falsehoods"
A working building block of cell-repair nanobots andmicroscopic sensors is described here.
Speaking of Body Counts
Yet another recurring topic around here will bewhat's killing us. We should also give some attention to what's killing everybody else, and it's mostly things like "World's fresh water faces growing threats," the most important passage of which is:
"... water-related diseases ... annually claim 5 million to 10 million lives, mostly of children, and ... two-thirds of the world's population -- some 4 billion individuals -- are at risk. Diarrheal disorders leave millions of youngsters underweight, mentally and physically handicapped and vulnerable to other diseases. Cholera is endemic in most of Africa. Dengue fever, having taken a firm hold in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, Southeast Asia and the Western Pacific, threatens 2.8 million people. Malaria, endemic in 101 countries, affects 2 billion humans, with 300 million to 500 million cases and 1 million deaths reported each year, the vast majority among young children in remote regions of Africa ..."
(See alsothis related item.)
The report was authored by thePacific Institute for Studies in Development, Environment and Security in Oakland.
You can download it as a 1.1 MB *.pdfhere. No warranty expressed or implied; the news story contains the puzzling sentence: "The scientists call for a 'new water ethic' that places more importance on equity and the needs of the poor, the health of the aquatic environment and the welfare of future generations than on economic and agricultural development." And without economic and agricultural development, what happens to the poor -- and future generations?
Double-Peaked Solar Cycle?
That's the import ofthis item, which I grabbed off JunkScience.com. See my earlier post on "radical contingency" for why this sort of thing is important. Heliogenic (is that a word?) climate change will affect humanity far more than anthropogenic climate change, even assuming that the latter is occurring.
Four years ago, I wroteBeth Elliott: "It seems to me that when judging a sociopolitical system, we should select a small number of simple, objective criteria. The most concise method I can think of is: what's the body count?"
Today, friends, there's abody count, and the sociopolitical system to judge is that of the "Democratic Republic" of Congo, but the charity to judge is our own.
Geophys links arehere. Relief agencies are here.
My Favorite Ex-President
Gets more counterintuitive accolades,here and here.
Last Saturday morning, we cruised out toHutch, a 3½-hour drive out I-435, I-35, and US-50, and toured this astonishing facility, which advertises itself as second only to the National Air & Space Museum. Based on what we saw, this is not an exaggeration. Locals, take note, as this is (just) within range as a day trip from KC; non-locals, about the best I can say is that once you make it out to the middle of nowhere, admission is cheap.
TheV-2 exhibit is probably the best that will ever be created anywhere, and the chronological arrangement of exhibits generally imparts an excellent sense of the origins and progressive development of rocketry. The Cosmosphere has lots of smaller items of space hardware, like working backup models of the Explorer I and Vanguard I satellites and actual spacesuits worn on Apollo missions. It is renowned for its restoration work, which takes place in a glass-walled room viewable by the public. All in all, highly recommended.
We then headed forLindsborg to continue our ongoing investigation of Swedish- (and especially Carl Larsson-) style home furnishings and decoration. We stayed here and visited this museum -- which includes the (reasonably intact) Swedish pavilion from the 1904 World's Fair in St Louis -- and this gallery in addition to hitting the shops, most of which were open on Sunday afternoon for something called "King Knut's Day." There were, in the event, relatively few visitors besides ourselves, so we spent much of the day walking the nearly-deserted streets of a charming 19th-century Swedish-American village. The weather was simply incredible: sunny, windless, and in the mid-60s Fahrenheit. Many of the houses in Lindsborg are magnificent Victorian structures, helping lend an atmosphere of peace and refuge to the town, and everyone was polite and kind in that inimitably taciturn Midwestern way. Very stress-reducing.
This weekend we aren't going anywhere, and KC finally got a decent snowfall, about 4" overnight, just enough for that winter-wonderland look. It's already melting fast and will probably be gone by Monday afternoon.
What Can You Say?
In yesterday's "Best of the Web" (subscribehere), James Taranto crows over a factually-incorrect item in The Nation, to wit:
"What can you say about a magazine that publishes a major factual error in the very first sentence of an article? Here's how Matt Bivens's piece in The Nation begins: 'When George W. Bush co-owned the Houston Astros and construction began on a new stadium, Kenneth Lay agreed to spend $100 million over thirty years for rights to name the park after Enron.' Of course, it was the Texas Rangers, not the Astros, that Bush co-owned. The Rangers' stadium,the Ballpark at Arlington, is one of the few holdouts from the trend toward corporate sponsorship."
Bivens's opener is wretchedly inaccurate, and if Democrats are going to base their campaign to regain the House of Representatives, and ultimately the Presidency, from the Republicans based on things like this, they'll be running a huge risk. Faced with the choice between voting for a crook and voting for an idiot, Americans will vote for a crook, as those of us old enough to remember '72 know all too well.
But Taranto's characterization of the unimaginatively named (but quite attractive) ballpark in question is simply bizarre. The Ballpark at Arlington doesn't need corporate sponsorship because it's already "sponsored" by North Texas taxpayers. The citizenry of Arlington was stampeded into approving a ½-cent sales tax to build the thing back in the mid-'90s after the Rangers began threatening to depart. Not one Republican officeholder or activist in Arlington would oppose the tax. The Rangers ownership, which just happened to include our President-to-be, leaked stories about talking to Irving, Dallas, and even Plano about moving the team there. After the sales-tax election, it was learned that no such discussions ever took place. Construction of the ballpark with taxpayer money caused GWBush's share in the Rangers to increase in value by tens of millions of dollars.
What can you say about Republicans who do things like that and then claim to be rescuing us from Democrat perfidy?
The Moral Compass of Science Fiction
-- and related literature, is magnificently defended against PoMo lit-crit types by Bjørn Stærk in his "warblog,"The World After WTC. Excerpts:
"What you will find in nerd culture, though, is rationalism and a belief in Good and Evil. And I'll bet you can find more and better discussions of philosophy, psychology, sociology and history in science fiction, fantasy and horror than in anything they call serious literature these days. In mathematics, impossible concepts like complex numbers and eternity can be used to prove statements that are true, and so it is with fantastic literature."
"One of the advantages of growing up a nerd is that our subculture, with the apocalyptic battles of Fantasy and the galactic perspective of SciFi, has a moral compass branded so firmly into it the relativism of people like [Naomi] Klein stand out like a suit at a hacker convention."
It's high time somebody made this point. Consider the following list, drawn from thescifan 162 Classics List and from my own reading experience:
Every one of the above (with the possible exception of Rogue Moon, which I include mostly out of romantic sentiment) is an absolutely towering epic of individual moral struggle and responsibility. Tolkien, White, and Herbert, in particular, have profoundly influenced my generation throughout the English-speaking world. Our culture would be impoverished without them.
The KCI Solution?
Thanks toThe Scene for mentioning this possible solution to long airport lines. For non-locals, the problem at KCI is the "drive-to-the-gate" design, which used to be phenomenally convenient but now means that once you've gone through security, you can't go to the bathroom.
Postrel vs Reynolds (II)
A follow-up on my earlierawkwardly-formatted post.
Glenn gets too much e-mail. Virginia probably does too, but answered me anyway, with the all-too-evident: "You forgot 'audience of millions' (mass media) vs. 'audience of thousands' (blogs)."
Well, that's what I meant by efficient/inefficient, he says, backpedaling furiously. Which raises a few more questions, like what did all the cryptic entries in that table mean? Let's take it from the top ...
decentralized/centralized: Hundreds of thousands of bloggers, including a few hundred capable of hosting substantial memes, soon (I believe) to grow by a couple of orders of magnitude; tens, at most, of major media outlets, actually a single-digit number considering the characteristics of the subculture involved. Picture an ocean liner on the one hand, and all the passengers of the ocean liner out on jet-skis on the other.
chaotic/orderly: Large numbers of self-edited bloggers publishing new material whenever they feel like it; a small number of newspapers, magazines, and network TV news programs which are rigorously edited and publish or broadcast according to an unvarying schedule. Maybe I should have saved that ocean liner/jet ski line for this paragraph. You see, the ocean liner makes only scheduled visits to specific ports of call, and ... [remainder of nauseatingly simplistic analogy deleted].
creative/unimaginative: Partly because they're under no deadline pressure, partly because they edit themselves, bloggers can both develop and get away with things the major media can't.
rapid evolution of memes/continue to espouse failed memes: The example du jour is, if I may say so, libertarian bloggers learning, post 9/11, that a selectively interventionist foreign policy might be a good idea after all; while mainstream journalists just keep on predicting disaster in Afghanistan and generally missing the significance of the technological and tactical improvements in the US military over the past quarter century. A more enduring example is the relentless attraction of mainstream journalists to interventionist domestic policy, notwithstanding the historic and continuing failure of State action to, for example, control prices, control narcotics, control firearms, control the Internet, etc.
Couple more points on that before I go on to the next one: First of all, I pulled the "libertarian bloggers learning" out of my own rather unsettled experience of last autumn. It of course remains to be seen how adaptable bloggers will be on many issues; if blogging becomes just another closed subculture, its ability to apply selective pressures to memes will diminish drastically. Second, optimistically assuming bloggers will not just talk to each other like a bunch of, well, politically-correct academics, there is no telling where this will all go. It is a phenomenally open-ended process. And just in case you don't know what a meme is, readthis.
inefficient/efficient: OK, now we get to the heart of Virginia's argument, and it's a slam-dunk. All but a handful of blogs have only a handful of readers, most of whom are other bloggers and in any case lack influence upon major media. In other words, the total number of people reading every blog in existence is probably a low multiple of the total number of blogs. And there is no obvious way to "broadcast" a blog. One possible mitigating factor is thesurprisingly small "width" of the Web, but the hard fact is that the major media in the US alone have millions of daily readers and tens of millions of daily viewers. No blog can begin to approach this. Segue to ...
conceptual/visual: Blogs are text, and are (at their best) about ideas. Major media are far more generally visual, and are often filled with out-and-out eye candy. This partly accounts for the difference in audience sizes; people enamored of the written word are far outnumbered by people who are not. But the important thing about this contrast is that reading a thoughtful commentary and watching even relatively cerebral TV are two very different experiences.
changeable, oscillating elements / "frozen" elements, "canalized" functions: Uh, this one's complicated. It -- and several of the other contrasts here -- are based on "Antichaos and Adaptation," my favorite Scientific American article of all time. I believe the model explained in the article has profound implications for all organizations and the processes taking place within them. It is why I perceive weblogs and the major media as being components together of a larger system.
infant technology/mature technology: I actually managed to explain this one the first time.
Hoping all this helps my tiny handful of readers, I remain, etc.
The Science of Global Warming
OK, the headline was a teaser. Nothing's easier than starting a fight over climate change -- or challenging the technically illiterate PC-types who want to use it as an excuse for authoritarianism. So I'm not going to do either one. Rather, this post is to raise the point that scientific debate and political debate are not the same.
This is not an original idea. I first heard it articulated byBob Nelson of JPL at last year's Lunar & Planetary Science Conference during a session called "Societal Connection of Planetary Exploration and the Search for Life Elsewhere," which led me to found the SCoPE-L discussion group.
But to get an idea of the consequences, readthis story and ponder the effects of subtleties like this:
"In April 1963, for instance, a weather observing station in Athens, Ala., was moved about 20 feet. This led to an almost instant 0.44 degrees C (about 0.8 degrees F) "warming" at that site, affecting data recorded over the next 31 years.
"'In the climate record it would show up as a spurious warming, but it was probably that the earlier temperature readings were too cool,' Christy said. 'I've seen a map of that site and it looks like it was close to the shade of a tree in the afternoon. I'm guessing it was well shaded. But that's all it takes. Move the thermometer 20 feet and you’ve got a new climate trend.'"
Why Human Civilization Exists
File this one underradical contingency: "If confirmed, this mechanism may help to explain why the Ice Age climate was so much less stable compared to that of the past 10,000 years, in which human civilization was able to thrive."
Wait 'til PETA Sees This!
Here's abreak (scroll down a bit) from my usual techno-jive. Thanks to "Orchid" over at The Daily Dose.
Postrel vs Reynolds
It's like being a little kid when your parents are in a fight. What do you do?
My "'blog parents," Glenn and Virginia, are having a (good-natured) dispute about the influence of 'blogging.Glenn says it's a huge phenom, comparable to the Reformation, which I hereby casually reinterpret as a reference to the introduction of the printing press. Virginia says the major media are still far more important and likely to remain so.
If you think this post is going to be one of those thesis-antithesis-synthesis things, you're absolutely right.
Let's compare and contrast weblogs with major media, in their aspect asparallel-processing Boolean networks. I contend that cultural transmission of information by the two methods looks like this (apologies for the huge blank space below; my lack of HTML skills again):
rapid evolution of memes
continue to espouse failed memes
"frozen" elements/"canalized" functions
In terms of memetic engineering, these are obviously complementary, or at worst orthogonal, processes. The system as a whole may be quite robust.
We should not overlook the obvious question: what happens next? As noted above, the technology of weblogging is in its infancy. One must still learn HTML -- and I've evidently still got some learning to do -- and not infrequently FTP, to participate in it. Until the technology "vanishes into our consciousness," to borrow a phrase, weblogging will be the province of the dedicated, in many ways analogous to being a sysop back in the days of BBSing.
I don't expect the removal of this barrier to entry to take long. In 2-3 years, at most -- and quite possibly within a few months -- the interface will require nothing more than e-mail, or even instant messaging. If there are hundreds of thousands of weblogs now, there will be tens of millions then.
So in terms ofgame theory, for weblogs to have influence, the "discount parameter" must be sufficiently low, which is a fancy way of saying that they'll have to hang around long enough for people -- especially major media people -- to expect to continue to see them in the future.
Since nearly all weblogs will be quite ephemeral, a strategy for building influence consists largely of adroit networking combined with sticking it out.
Selective DNA Activation -- by RF!
Thisflabbergasting development provides yet another avenue toward detailed understanding of the nanomachinery that keeps us alive. "Exquisitely fine electronic control of biology also will likely become more and more important in dissecting intricate molecular interactions and formations in great detail. There is currently no way to achieve this fine control over one molecule without disturbing its neighbors."
Ten Years and Counting
Unisci has a story about agrant to fund working nanodevices which contains the following provocative quote:
"[USC professor of computer science Ari] Requicha estimates that it will be a decade before the researchers can build and deploy nanoscale robots in the ocean capable of the kind of instant and specific test like [professor of biological sciences David] Caron's for Brown Tide."
This strongly implies that routine diagnoses of all types of medical conditions, to a degree of precision impossible today, and without using macroscopic or invasive instruments, will be widely available sometime in the 2010s. Treatments and cures for everything should arrive shortly thereafter.
Hot on the heels of the useless, wretchedly overhyped "Segway" (aka IT, Ginger, etc) comessomething that might actually have some utility, namely the SoloTrekTM XFV® Exo-Skeletor Flying Vehicle.
Methinksthis variant has more potential, though. If it performs as predicted, it could roughly triple routine commute distances and increase the area reachable on a given trip by one order of magnitude (10x) relative to present-day automobiles. Fuel costs may be a bit high, though. See also my earlier extended rant on the subject.
FromChristianity Today, a comparison of globalization with a certain ongoing memetic-engineering project. Thanks to Glenn Reynolds for pointing to this one.
Journalists vs Technologists -- and (Good) Managers
An oldie-but-goodie fromVirginia Postrel:
"On the day of the  California primary, an all-but-meaningless election with record-low turnout, two famous men died, both in their early 80s. One was Edmund Muskie, former senator, briefly secretary of state, and the candidate wistful Democrats like to imagine might have been their 1972 nominee if not for a dirty trick and tears in the snow. (They forget, conveniently, that McGovernites had engineered the delegate-selection rules.) Muskie's obituary took 82 column inches in The Washington Post, 84 in The New York Times.
"The other man—eulogized in a mere 28 inches by the Post (eight devoted to his two years as deputy secretary of defense), 40 by the Times—was David Packard. On the day he died, the only American politician who could rival him in real-world importance was Ronald Reagan. But the papers didn't see it that way."
The Good, the Bad, and the Ugly
Good: I sendan earlier post off to JunkScience.com -- and they hotlinked to Arcturus!
So the site probably got more traffic yesterday morning than in the entire previous four weeks of its existence. I don't really know, because I don't have a counter. Maybe Blogger includes one somehow that I don't know about, but I am presently, as the expression goes, in a clue-free environment. It doesn't help that I don't feel right about counting visitors; there is something of1 Chronicles 21:1 about it.
Also good was the mail I got: several kind and encouraging messages to which I hope to respond Real Soon Now. If you sent one of these, know that I appreciate it.
Bad: I screwed up. Looked at in a certain way, that is. Here's Clayton J. Bradt, CHP, Principal Radiophysicist of the NYS Dept. of Labor Radiological Health Unit: "Iridium-192 decays by electron capture (4.69%) and by beta decay (95.31%) with a half-life of 74.02 days (Kocher, D., Radioactive Decay Data Tables). The cascade of gammas that follows each beta decay occurs so quickly that in practice these are attributed to the iridium decay even though they are really coming from daughter products. The overall rate of decay is determined by the 74 day half-life of iridium. So it is indeed possible that the source shipped from Sweden was very hot. Radiography sources are typically 100 curies (100 X 3.7 x 10^10 decays per second) or more, and the exposure rate at the package surface could easily exceed 10 R/hr."
Well, since I was talking about 172Ir, not 192Ir, how did I screw up? By 1) not spending a few more minutes in the isotope table and figuring out what the NYT's typo was and 2) spending rather longer verifying that 10 rad hr-1 is reasonable for the mass and activity of the correct isotope. Dr Bradt continues: "The story wasn't junk science in this case, though they did get the atomic mass wrong (172 instead of 192). The incident does reveal an inexcusable lapse in monitoring procedures, which contrary to FedEx's assertion, does have security implications."
Actually, Dr Bradt's message to me didn't include that last passage. The version he sent to Barry Hearn, who edits the JunkScience.com webpage, who forwarded it to me, was a bit more, shall we say, direct. So now I know that Dr Bradt is discreet as well as meticulous -- surely the best kind of reader to have.
Ugly: This site. The color-shifting thing is not getting rave reviews, and after one of my new fans complained that it prevented him from cutting and pasting something he admired, I decided to do something about it. So I dug into Eric Costello's marvelous code and found that he included a way to turn it off for the banner, centercontent, and rightcontent divs. Done.
Also ugly are the security implications, getting back to Dr Bradt's message, of radioactive shipments. Ten rads per hour is several orders of magnitude more than a nuclear warhead would emit. This is exactly the kind of "process gap" so skilfully exploited on 9/11. We need to identify these and close them ASAP. Notwithstanding that a planted nuke might actuallykill relatively few people, I neither 1) want to be one of them nor 2) want to experience the effects of a public or governmental panic.
We Will Have Our Quagmire
With apologies in advance for a more-political-than-usual post ...
The endangeredquagmire, beloved of journalists, having been driven out of Afghanistan, may find sanctuary in DC. The latest on the Enron mess reads: "Enron's bankruptcy, already the subject of criminal, civil and congressional investigations, threatens to pull the White House into a political quagmire even as Bush's approval ratings reach near-record levels because of the war against terror."
The same article contains the puzzling remark of Rep. Henry Waxman, D-Calif.: "It is now clear the White House had knowledge that Enron was likely to collapse but did nothing to try to protect innocent employees and shareholders who ultimately lost their life savings." And if the Administration had arranged a bailout in response to Enron's generous campaign contributions to Bush and Ashcroft, Enron's half-dozen meetings with the vice-president, and Enron's chairman's phone calls to Greenspan and sundry other contacts with Cabinet secretaries, I'm sure that would have been just dandy with Waxman.
Even the wire stories admit that this is revenge for Whitewater -- which was itself at least partly revenge for Clinton's election in '92. A congressional election is less than 10 months away, and the Democrats only need to pick up, what, 6 seats to take over all the committees? The prize is great, and the time is near; consistency begone! Quagmire to the rescue!
Dedicated readers of Arcturus will infer that:
Please note that I did not code the template for this weblog. All praise to the actual author, Eric Costello (whom I have never met). You may view the original codehere.
Finally, if you'vesent me a comment about anything on Arcturus recently, I probably haven't gotten around to responding. Don't give up. I love getting notes about this thing and hope to answer them all. Keep sending me stuff and you're sure to get mentioned here eventually.
Liberal-Arts Types Strike Again
Continuing to browse the NYTimes, we findFedEx Shipped a High Radiation Package Without Knowledge. Well, FedEx isn't the only entity lacking knowledge, as it turns out. Key excerpts:
"The recipient, the Source Production and Equipment Company, notified FedEx of the radiation after a FedEx truck delivered the 300-pound package to the company's factory in St. Rose, La.
"The company told FedEx in an initial estimate that the dose at the surface was 10 rem per hour. If that is correct, a person exposed to the radiation would exceed the annual limit for exposure in half an hour, and within a few hours would show effects from radiation poisoning ....
"The package contained Iridium- 172, which is used for industrial radiography. The radioactive material is put behind a heavy piece of metal, and by measuring what comes through the other side, technicians can look for cracks or other flaws.
"The shipper was a Swedish manufacturer, Studsvik."
So far, so good. Ten rem hr-1 is bad news. A couple of days of that would kill just about anybody. Even a few hours of it would drive someone's lifetime probability of cancer way up. This is not a "junk science" story hyping an insignificant danger.
Providing that 10 rem hr-1 figure is correct, that is. The problem is that the average duration of the decay cascade of 172Ir -- the sum of the half-lives of 172Ir and all its "daughter" products down to 152Ba, which is stable -- is about 13 seconds (you can look this up at theBerkeley Laboratory Isotopes Project). There are over 270 such durations in 1 hour, so an initial population of over 2270=1081 atoms of 172Ir would emit all its radioactivity and be completely converted to stable barium in less than an hour. The total number of atoms (of all the elements) in the Milky Way galaxy is ~1053. So ~1028 galaxies' worth of 172Ir would disappear in an hour.
We may therefore safely assume that not a single atom of 172Ir could possibly be shipped from Sweden to Louisiana, even by Concorde. In which case it wasn't "Iridium- 172," or it wasn't 10 rem hr-1, or both. Which makes it both highly likely that the crucial elements of the story are widely at variance with the truth and completely impossible to assess the actual danger -- or mitigate it.
None of which keeps "policymakers" from telling the rest of us what we can and can't do on the basis of such scientific semiliteracy, or environmentalist pressure groups from trumpeting stories like these to panic the public.
How to Retract a Falsifiable Prediction
An article in today's NYTimes entitledThe Internet's Invisible Hand contains a delightful account of atonement for a failed prediction and a fine description of the virtues of decentralization. Excerpts:
"In December 1995, Robert Metcalfe, who invented the office network technology known as Ethernet, wrote in his column in the industry weekly Infoworld that the Internet was in danger of a vast meltdown.
"More specifically, Dr. Metcalfe predicted what he called a gigalapse, or one billion lost user hours resulting from a severed link -- for instance, a ruptured connection between a service provider and the rest of the Internet, a backhoe's cutting a cable by mistake or the failure of a router.
"The disaster would come by the end of 1996, he said, or he would eat his words.
"The gigalapse did not occur, and while delivering the keynote address at an industry conference in 1997, Dr. Metcalfe literally ate his column. 'I reached under the podium and pulled out a blender, poured a glass of water, and blended it with the column, poured it into a bowl and ate it with a spoon,' he recalled recently.
"The failure of Dr. Metcalfe's prediction apparently stemmed from the success of the Net's basic architecture. It was designed as a distributed network rather than a centralized one, with data taking any number of different paths to its destination.
"That deceptively simple principle has, time and again, saved the network from failure. When a communications line important to the network's operation goes down, as one did last summer when a freight-train fire in Baltimore damaged a fiber-optic loop, data works its way around the trouble."
And the Winner Is ...
A frequentHendersonian complaint is that the Nobel Peace Prize frequently goes to persons of dubious merit. This is difficult to argue with.
Well, at least we can take heart that Glenn Reynoldstried to do something about it. We'd have to be living in a much better world for his nominee to have a chance, but hey, I can dream, can't I?
Supernova Zapped Ozone Layer?
A fascinating interdisciplinary hypothesis, combining paleontology, geology, and astronomy, is featured onUniSci.
"Asteroid 2001 YB5, estimated to be 1,000 feet across, was traveling about 68,000 mph relative to the Earth when it zipped past," saysthis AP story.
OK, let's run those numbers again. Mass is still 4 * 1010 kg, but velocity is now (again with acceleration due to Earth's gravity added) 41,500 m sec-1. So KE becomes 6.9 * 1019 J = 1.6 * 1019 kg TNT, ie 16,000 megatons. Our 5-psi overpressure radius is now 107 km, and the seriously flattened area is somewhat larger than Massachusetts. Isn't this fun?
-- is the designation of the asteroid that missed us by 830,000 kilometers (0.0055 AU, or twice the distance from Earth to the Moon) yesterday.
TheBBC says 2001 YB5 is "a rocky body about 300 metres across." Assuming that it is not a rubble pile, but rather a solid rock, we assign it a density of 2.8 g cm-3, the same as the Earth's crust. Mass is density multiplied by volume. Assuming 2001 YB5 to be a sphere, we have V = 4/3 * pi * r3, with r = 150 m. This works out to just under 40 million metric tons.
Perusing theNEODyS Object List, we find that at 0.03 AU distance, 2001 YB5's apparent motion is 6.157 degrees per day. Assuming nearly all of this to be transverse velocity, it works out to a relative velocity of 5.2 km sec-1. Had 2001 YB5 hit us, it would have been accelerated by an additional 11.2 km sec-1 by Earth's gravity in the final hours of its course, for a total impact velocity of 16.4 km sec-1.
Recall that KE = ½mv2. Plugging in the figures determined above, we get an impact energy of 5.4 * 1018 joules. Since 1 kg TNT = 4.2 MJ, this equals nearly 1,300 megatons. Applying the inverse-cube relationship noted inThinking About the Unthinkable, we find a 5-psi overpressure radius of 46 km. The BBC's estimate of "total devastation for 150 km and severe destruction for a further 800 km" from the point of impact suggests either that my velocity figure is low or that they were working from a different definition of "devastation." Going with the larger figures, in American terms, the area of total devastation would be the size of West Virginia, and the area of severe destruction would be four times the size of Texas.
An ocean strike would be considerably worse, potentially devastating the coastlines of entire continents.
Notice, however, that the area of a circle 830,000 km in radius is nearly 2.2 * 1012 km2, of which Earth's cross-section (radius = 6,378 km) occupies less than 130 million km2, or about 1/17,000. Think of us as a bullseye the size of a quarter in the middle of a target 11 feet across.
Now suppose that an event like this occurs once per decade. Generously estimating the focusing effect of Earth's gravity to increase our capture cross-section to 1/10,000, we would be struck by an object of this size once every 100,000 years. This is consistent with information available atthis FAQ. Graze on over to Calvin J. Hamilton's Terrestrial Impact Craters page for some actual examples, or browse David Morrison's Asteroid and Comet Impact Hazards page.
Smaller objects are much more common than large ones, of course, but below a certain size they are unlikely to penetrate Earth's atmosphere. Penetration also varies by composition; sizeable fragments of comets vaporize at high altitude (~30 km) several times each year. Many of these explosions are in the kiloton range, and some are as large as 100 kT, but the only effect on Earth's surface is a tremendous flash of light.This paper gives the following effects for a 300-meter object, which it describes as capable of creating a "regional disaster": Localized fire at ground zero; stratospheric dust below catastrophic levels; local ground shaking; flooding of historic proportions along shores of proximate ocean; crater zone ~5-10 km across.
Perhaps more significantly, it notes: "Impacts that are even smaller and more frequent impacts ... like the 15 Megaton impact in Tunguska, Siberia, in 1908 -- may have major consequences near ground zero. But other natural disasters, like earthquakes and floods, having the same damage potential (e.g. human fatalities), happen at least a hundred times more frequently than small impacts. Perhaps the most serious consequences of impacts similar to and smaller than Tunguska, which happen on timescales comparable to or shorter than a human lifetime, are unpredictable reactions by observers. A bolide ten times brighter than the Sun occurred in the Yukon in January 2000, yielding some meteorites. Such an event in an unstable location in the world could be misinterpreted as an enemy attack and precipitate war."
The danger then becomes a second-order one of public or "official" panic rather than the direct physical effects of the event itself. Which pretty much describes the risks facing Americans in the wake of 9/11.