Having once relegated Pat Robertson to the status of a supermarket-tabloid psychic -- and his time's about up, by the way -- perhaps I should issue a few predictions of my own. Unlike Pat, I will not fob my prognostications off on someone else (in Robertson's case, the prophet Isaiah); and unlike Hal, I will be specific in my timeframe: 2003.
Of course, some of these are negatives -- things that won't happen:
Positives -- things that will happen:
Contingent predictions -- things that might happen:
I'll check these a year from today. For my non-terroristic readers, have a healthy and prosperous New Year!
(The headline is a riff on the NYTimes "most boring headline" contest.) Powell Observatory's status as the preeminent amateur facility in the central US may be in for a challenge. While strolling through downtown Clifton, Texas, on Saturday, I noticed a flyer posted in the window of an insurance office detailing the progress of the Paul J. Meyer Observatory, under construction near Turnersville, in northern Coryell County, Texas (this is less than 20 miles NW of Crawford, which is frequently in the news thanks to you-know-who).
The news release announcing construction, issued last March, noted: "Of great current importance: [the 24" telescope will allow] observers [to] search for and discover near earth-crossing asteroids." Readers in central Texas are hereby encouraged to look up this fine organization for more details and involvement, if they are so inclined.
Cyberspatially speaking, that is. Glenn Reynolds points to Newspapers Run Half Of Top News Sites, the relevant statistic within which is: "The top news [site] in terms of audience for November [was] MSNBC.com" -- 17,702,000 people at 23m37s each. This is good news for me, since roughly half of my ~1,000 visitors per day are grazing in via Alan Boyle's Cosmic Log.
Not to overlook the obvious, the second-largest segment of my traffic, about an eighth, is coming from Glenn.
New readers since mid-August are referred to Good Question on Organ Donation and Cloning for an explanation of my position. I also strongly recommend Virginia Postrel's Making Medical Progress A Crime.
But for those with the time and inclination, ReasonOnline's Criminalizing Science is a truly exceptional compilation of commentary from the dynamist side of the issue.
Nothing like moving a little farther down Maslow's hierarchy of needs to get reader response -- maybe I should change the focus of this blog. ;)
Regarding Did Someone Say BBQ?, Scott Cole, who reads this blog from Japan, wrote to reminisce:
A couple of years ago I was sent to train some Naval reserves at the old airbase south of KC [Richards-Gebaur].
I've sampled a lot of the BBQ joints, and though I didn't make it to the city and eat at your picks there was a good steak house and a chain type (claimed that Clinton ate there) that was really good.
One interesting thing. I live in Japan and the school girls here are fashion conscious and stylish. Close to the old air base was a small BBQ joint called Odin's BBQ. It was not as good as the others I ate at but the portions were big. I remember a time that a bunch of young school girls went to eat there and they chowed down! I think most Japanese school girls would not be caught there (though a good value place like Odin's BBQ would be crowded out by adult customers).
Sounds like a market niche just waiting to be exploited ...
Following up, more or less, on this earlier post, I again consulted subject-matter expert Maureen Duffy with regard to Eyes in the Back of Your Mouth, which sounds like something from HPLovecraft but is in fact a discussion of using non-optic-nerve inputs for visual data.
Maureen kindly solicited several of her graduate students for their reactions, which I have sorted into categories:
Clearly, there is a wide array of risks to be managed in the introduction of this technology. Many of them fall into -- for the layman, at least -- the "what you don't know that you don't know" category, making them that much more challenging. In particular, one's economic resources aside, it might make perfect sense for a blind person to wait until something better, eg brand-new eyeballs grown from stem cells, or regenerated optic nerves, comes along in another decade or two.
Blind people are capable of near-miraculous feats of adaptation, as the story of Erik Weihenmayer illustrates.
I am informed by the Society of Arcturian Technologists' Ancillary Network Interchange Committee (SATANIC) that the servers containing the graphics normally present in the left sidebar have suffered a catastrophic failure. This is being worked on, but the ETR is later today at best. You'll know it's fixed when everything looks normal again (you may wish to reacquaint yourself with the definition of "normal," as opposed to "normative" -- JDM).
This may be the first time in history that a blog on Blogspot was affected by a non-Blogspot system problem. Another distinction for me!
Reynolds set off a flurry of correspondence with an absurd claim of preeminence in this sacred field of endeavor.
Well, since I just happen to live in the barbecue capital of the world, I feel a moral obligation to impart the truth to the untutored barbarians residing beyond the KC MSA:
The Carolinas can rightfully claim to be the cradle of American barbecue and Texas is by far the brisket capital of the world. But Kansas City brings it all together with more than 90 barbecue joints - from little bitty eateries to full-blown, nothing-but-barbecue restaurants.
A barbecue match made in heaven occurred when the abundance of skill and wood came together with the ready supply and variety of meat from the Kansas City stockyards. Where the Carolinas concentrate on pork and Texas tends to beef, "here, if it moves, we cook it," according to Carolyn Wells, Executive Director of the Kansas City Barbeque Society ...
My personal favorite is this one (the original "Martin City" location), but I can also highly recommend Rosedale Barbeque in KCK, and have many fond memories of Lil' Jake's, where I often ate (at its former location on Baltimore Av) when I worked downtown in the early '80s. Ironically, I have never eaten at LC's (the original location, on Blue Pkwy), though I live nearby. Hmmm ...
(Judging by the frequency of responses so far, I'll be updating this as more stuff comes in -- JDM.)
Canadian reader Andy Ferris is taking a wait-and-see attitude about the clone; he points to this article for some history on the Raelians, and notes: "While the Raelians are as goofy as ever, I still think that the various religious organizations and anti-science luddites having a canary over this news are the big story ..."
Meanwhile, blurb-writer (see left sidebar, under the logo) and occasional contributor Maureen Duffy writes to note the resemblance between Claude Vorilhon and Zippy the Pinhead.
And David Appell, who actually makes a living writing about science, has an entry over on Quark Soup, which I think could use the traffic anyway (look for "this neat star map" a couple of posts down).
UPDATE: Well, duh -- Glenn Reynolds linked to me. OK, newcomers, here's the routine: while you're here, be sure to read my most recent entry which actually required thought, which happens to be the "Boniface in Blogdom" thing from the 26th. I also encourage reading of the "Important Stuff" entries (see left sidebar), and just for fun, check out the contest results.
Vinteuil gives us some spoilers (and page down to read a somewhat inadvertent argument for gender-segregated classrooms -- but I digress). Having just seen the movie last night, I am in general agreement. Those of you who haven't seen it are encouraged to regard it as a mechanism for getting lots more people to read the book, which it only tangentially resembles.
What I Liked Best: the destruction of Isengard (well, not the tower itself, of course). Spectacular. If I see the movie again, it will be for that scene.
What I Liked Least: weakening of Faramir's character -- he is depicted as only slightly less menacing than Boromir, with very little of the contrast between their personalities as given in the book.
What I Least Expected: T T T, the movie, ends several chapters short of the end of T T T, the book. Frodo and Sam don't make it to Cirith Ungol in the movie, nor has Rohan been mustered to ride to the relief of Minas Tirith.
What I'm Wondering About: what they left out that will be in the DVD version, eg the gift-giving scene in Lothlorien in the first movie.
Glenn Reynolds points to this terrific game-theory analysis of Bush v Hussein in Julian Sanchez's Notes from the Lounge. This is the sort of analysis that never appears in conventional media, since few people who go into journalism are sufficiently mathematically-minded. Read the whole thing.
While I would not be as blunt as Tim Blair, this story, the headline of which mysteriously fails to put quotes around Scientist, is almost certainly junk science. To his credit, the AP's Malcolm Ritter opens with
A chemist who belongs to a sect that believes life on Earth was created by extraterrestrials claimed Friday to have produced the world's first human clone, a baby girl.
and notes that
Clonaid was founded in the Bahamas in 1997 by Claude Vorilhon, a former French journalist and leader of a group called the Raelians. Vorilhon and his followers claim aliens visiting him in the 1970s revealed they had created all life on Earth through genetic engineering.
This is the biggest howler since cold fusion.
Way back in February, I referred to this:
... a Technology Timeline from British Telecom which, albeit something of a grab bag of not-particularly-internally-consistent predictions, many of which will be obviated by nanotech, has its interesting moments. One such occurs on page 5: "People have some virtual friends but don't know which ones - 2007."
I think there will be a virtual blogger well before 2007 -- quite possibly by the end of 2002. A blog that does nothing but create hyperlinks to various news items and say things on the level of "this is cool" need be no more complex, conceptually, than Eliza. A blog more articulate than 90% of the blogs in existence wouldn't take much more coding than that.
(See also You Read It Here First and The Turing Blog.) A couple weeks back I awoke from an afternoon nap with the following, which I was unsure about blogging. Well, now the phenomenal John J. Reilly has written an entry about The Turing Test; things seem to be moving quickly toward what I have envisioned.
What I now foresee is the potential for subcultures to be hacked in a manner analogous to Winfrid/Boniface chopping down the Oak of Donar at Geismar. (I'll let my readers do their own searching on this story; Googling "Boniface sacred oak" [without the quotation marks, of course] works well.)
Imagine a Turing blog infiltrating a subculture. I'll pick on the Pagans here (nothing personal). It scans websites, other blogs, and message boards for events and composes postings about observances, ceremonies, holidays, etc. It selects a geographic location and pretends to be written by a member of a local Pagan group, creating chatty posts about recent goings-on. This goes on for a year or so, during which time the Pagan "mystery blogger" amasses quite a reputation. I need hardly discuss why pseudonymous blogging would be the norm for this subculture.
At this point, the human who launched the blog publishes a post announcing that the whole thing is nothing but a gigantic hack, and also posts the source code to prove it.
Taking his courage in his hands (for a great crowd of pagans stood by watching and bitterly cursing in their hearts the enemy of the gods), he cut the first notch.
But when he had made a superficial cut, suddenly the oak's vast bulk, shaken by a mighty blast of wind from above, crashed to the ground shivering its topmost branches into fragments in its fall.
-- The Life of St. Boniface by Willibald, written between 754 and 768
What happens to the subculture getting this treatment?
I don't know. Maybe some people quit in disgust. Probably others become resentful. A running technological battle to detect future hacks, and evade detection of hacks, begins. Not so much a war of memes as a war of meme-supporting infrastructures. And even successful hackers can have second thoughts:
Boniface was encouraged and relieved by the positive reaction and continued on in the same vein, destroying temples and shrines and smashing sacred stones into bits. Gradually he began to question the validity of this aggressive approach. He confided his doubts to another bishop, who advised him that such forceful methods were unwise and that a more meaningful and lasting approach was to "ask them questions about their gods, to enquire about their origins, their seemingly human attributes, their relationship with the beginning of the world, and in so doing elicit such contradictions and absurdities from their answers that they would become confused and ashamed."
Destruction, or moral suasion? Which should it be? Which will it be? If the axe of Boniface were offered to you, what would you do?
OK, now I really am going to take a break from blogging for a day or two. I wish you all ... well, I hope that everything I write here shows what I wish for you. Gratitude for what we all have, fellow-feeling for everyone we share the world with, but most of all, hope.
Following up on Rodney Kendrick's question, I found an introductory article on space weathering by none other than Beth Clark, whom I met briefly in 1995. It implies that most of the effects are optical, as does this source, which states that for Europa: "Due to the bombardment of the surface by charged particles from the plasma sheet ... crater rays are expected to be removed by sputtering erosion over time scales as short as a few million years."
This paper about Jupiter's rings says:
Lifetimes for 1-mm particles have been estimated as 102 to 104 years for erosion by sputtering and 104 to 106 years for catastrophic fragmentation after micrometeoroid bombardment.
... we find that each square centimeter of target produces 10-15 kg s-1 or erodes at 10-5 cm year-1. Despite this bombardment, all ring moons have erosional lifetimes that exceed the solar system’s age. Over the ring’s ... lifetime, impacts into Amalthea and Thebe easily generate the mass visible in the rings.
A 100-km body losing 1 mm of its surface every hundred years would last for 5 trillion years. The short answer, then, is that Amalthea, while being a principal source of the particles making up Jupiter's rings, isn't going to be eroded away to nothing.
(Now blogging from the not-so-undisclosed location. Drove through atrocious weather yesterday, taking 12 hours for what is normally a 9-hour trip.)
Anyway, Micro-machines can get boost from UV rays, says UPI's Charles Choi:
"You could even wind up chains and store energy like that," researcher David Leigh, an organic chemist at the University of Edinburgh in Scotland, told United Press International.
Most nanotech energy-storage work has been devoted to getting hydrogen in and out of carbon nanotubes for fuel cells; this is quite a bit more exotic. This source mentions the development of batteries delivering 250 wh/kg, a significant improvement; this table shows that most present batteries have an energy density of < 100 Wh/kg, and around 100 Wh/l.
But Drexler's Nanosystems forecasts "mechanochemical power conversion at >109 W/m3" and "electromechanical power conversion at >1015 W/m3" -- which would give us thousand-horsepower motors less than one liter in volume, and batteries with energy densities ten orders of magnitude higher than at present. This should result in, among many other things, incredibly cheap, fast, quiet cars driving on heated roads kept permanently free of snow and ice. That is, for those who don't simply take to the skies in their personal aircraft.
UPI's Wes Stewart nicely debunks it here. I recently received a piece of spam from "email@example.com," which of course turned out to be a fake address, touting the Global Star Registry. Incredibly, they even have a FAQ which openly admits that you're paying $70 for absolutely nothing:
Will my star name be used by astronomers?
No. Scientists use astronomical coordinates to identify and locate stars. It is not possible to actually own a stellar object as nobody (or everybody, depending on your way of looking at it) has ownership. A star is essentially a ball of boiling gas trillions of miles away, so ownership is hardly a viable option anyway!
Some years back, the fianceé of a friend of mine "bought" him Saiph. The things I could do if I didn't have any scruples ...
Ironically, there is a way to get your name attached, officially and permanently, to a celestial piece of real estate -- and one whose distance is measured in AU rather than light-years. Start by grazing over here, here, and here. Warning: requires getting out from behind computer keyboard. Also, persons living within easy driving distance from KC are at a relative advantage, as the ASKC now leads the world in asteroid discoveries by amateurs.
Methane Clouds Discovered at the South Pole of Titan, says ScienceBlog; the news release has pictures, and points to this Cassini-Huygens page about Titan, which informs us that "Titan's atmospheric pressure is about 60 percent greater than Earth's -- roughly the same pressure found at the bottom of a swimming pool." (A somewhat misleading image, as the atmosphere would not feel more viscuous than air.)
Titan's mass is 1.346 × 1023 kg, and its solid-body radius is 2,575 km (source). Applying g µ M/R2, we find that Titan's surface gravity is 13.8%, or 1/7¼, of Earth's.
Result: you could fly. This source notes: "Light, low speed aircraft will generally have wing loadings [of] 10-15 pounds per square foot." In MKS units, that's 480-720 pascals (N m-2, or kg m sec-2). Suppose that you and your ornithopter had a combined mass of 100 kg; on Titan, this would weigh only 135 newtons (30 pounds). Less than one square meter of wing area would provide plenty of lift.
You'd need good thermal protection -- the ambient temperature is about 95°K (-178°C; -288°F) -- and your suit would need to be airtight, because there's some hydrogen cyanide in the air. But it would not need to be pressurized.
The scenery is potentially spectacular. Titan is believed to be covered by an ocean of liquid ethane (C2H6), with at least one large continent of water ice. Which might not sound very substantial, but at these temperatures, water ice has the consistency of concrete. And now we know there's weather; from the news release:
"These clouds appear to be similar to summer thunderstorms on Earth, but formed of methane rather than water. This is the first time we have found such a close analogy to the Earth's atmospheric water cycle in the solar system," said Antonin Bouchez, a Caltech researcher.
Of course, visualizing it requires factoring in Saturn's ~9½ AU distance from the Sun, meaning that a landscape or seascape on Titan would receive, at most, 1/90 the amount of sunlight we're used to on Earth. Turning again to the Observer's Handbook, we find that solar illuminance outside Earth's atmosphere at 1 AU is 1.27 × 105 lx; this source states: "Outside noontime direct sunlight intensity is about 100,000 Lux. Atmospheric changes will reduce this to about 50,000 Lux. When twilight, impingement mode, incidence angle and attenuation factors are included; intensity is brought to about 10,000 Lux." So what we're looking for is 100 - 600 lx.
This is much brighter than Full moonlight (< 0.3 lx), and is comparable to typical indoor illumination levels. But what would it look like? Turning to this unlikely source, we find:
The following illuminance figures for the above three stages of twilight have been reported by Muneer (1997). For a horizontal surface under a cloudless sky,
sun at zenith
sun at horizon
end of civil twilight
end of astronomical twilight
full moon at zenith
The light level, then, would closely resemble that on Earth at the moment of sunrise or sunset. The predominant sky color, judging by this, would be a sort of peachy-orange. A whole bunch of Cassini-Huygens artwork, including a somewhat fanciful image of the Huygens descent onto Titan, is here.
If it's clear where you are, and you've got a pair of binoculars or a small telescope, you can spot Titan; An Observing Guide to Saturn says: "A 2-inch scope will show Titan," and indeed its visual magnitude is only +8.4, bringing it within binocular range. A pair of 10×50s (which will allow the observer to spot 11th-magnitude objects from a dark-sky site) with a field of view of 6.5° will make Titan's average separation from Saturn look about the same as the diameter of Full Moon does to the naked eye. Graze over here and page down to "This Week's Planet Roundup" for instructions on how to find Saturn in the sky. Or use the handy Sky Chart.
For the solstice, three tales of human folly.
Accident lands pair in jail after drugs are discovered in bag has to be read to be believed. The moral of the story: "It's a bad idea to ask rescuers to hand you a bag full of illegal drugs while police are milling around."
The KCStar story cited above ends with (emphasis added):
By Friday afternoon, Johnson County prosecutors had charged John Mark Hicks, 44, of Roeland Park and Dalayna Lynn Jennings, 32, of Kansas City, Kan., with numerous counts of possessing drugs and drug paraphernalia, and with not having Kansas drug tax stamps.
You can look it up:
Who is liable for the drug tax?
An individual is classified as a drug dealer and is liable for the payment of drug taxes if he/she manufactures, produces, ships, transports, or imports into Kansas or possesses:
Davis' budget-adviser pick gets mixed reviews, politely notes the OCRegister:
[Steve] Peace will replace outgoing Finance Director Tim Gage, who leaves with California facing a $34.8 billion budget shortfall over the next 18 months - the worst in the state's history and in the nation.
Peace .... is famous for producing the cult movie classic "Attack of the Killer Tomatoes" in his youth.
Without wishing to offend any of my Californian readership, I must say that this strikes me as in an altogether different league from Kansas' attempt to tax drug dealers. Midwestern looniness is strictly an amateur effort; you guys are the professionals.
Previously encountered reader Rodney Kendrick wrote again to pass along his own calculations regarding the ability of Jupiter's moon Amalthea to hold together in spite of the significant tidal forces acting on it. He concludes: "A rock sitting on the surface of Amalthea at the pole away from Jupiter would experience a force 1/3,398 g holding it to Amalthea. [but] You would think that the rain of high energy dust over the eons would cause Amalthea to evaporate."
As this source notes, however, Amalthea is "overtaken by the faster corotating charged particles," so they are not causing its orbit to decay. And since Amalthea has low bulk density but is nonetheless comprised (at least mostly) of rock, it is less subject to being directly eroded by charged-particle bombardment. How much less, though, is another great question and I'll be looking into it.
But not in the next few days, as I'll be at an undisclosed location -- well, actually, here -- for the next week or so. Blogging is almost certain to be light, and may be nonexistent, but I'll try to come up with something. So do check back.
Finally, see Man Bites Dog at Grauniad for an update.
The Administration has shown great strategic ability so far. Events are on track for a 2-7 day conquest of Iraq within a month if Saddam is not assassinated first. The big question is possible use of Iraq's WMD by somebody.
If the operations described in the Holsinger column are critically dependent on illumination, or the lack thereof, then we'll hit them in another couple of weeks: next New Moon is Thu 2 Jan at 20:23 UT (14:23 CST, 23:23 Baghdad time). I don't think this is the case, though it should be noted that, as per this earlier post, even first- or third-quarter moonlight is about 100 times brighter than all the stars in the night sky combined.
Turning to Latitude-Longitude of World Cities, we find Baghdad at 33°20' N, 44°26' E, which we plug into this handy application. Results for Baghdad:
Civil twilight ends at 17:34 local time on Thursday the 2nd, and begins at 06:39 on Friday the 3rd, for 13 hours of darkness. Were the attack to wait until 3 AM local time (midnight UT), as was the case in 1991, it would still have well over 3 hours of darkness. The night of Thu/Fri 2/3 Jan will be entirely moonless in Iraq. The Moon sets as seen from Baghdad at 16:36 local time on Thursday the 2nd, and does not rise until 07:42 on Friday the 3rd.
The Holsinger column notes: "Knowledge of military details is critical. One of the most important is the 120 mile combat radius of action of the Army's standard UH-60 Blackhawk helicopter in the assault transport role." This source states: "The Black Hawk ... has a speed of 163 mph (142 knots)." It could therefore fly a 240-mile round trip in 1½ hours. Each aircraft, carrying "an entire 11-man fully-equipped infantry squad," could conduct two such flights between midnight UT (0300 local time) and the beginning of civil twilight on the morning of Friday the 3rd. The UH-60L variant is faster and can carry more.
The coalition had nearly 2,000 helicopters on hand during the Gulf War. Our current deployment is much smaller; assuming 500 Black Hawks, some 11,000 infantry could be inserted into Baghdad in 3 hours. The built-up area of modern Baghdad is well under 400 km2; a force of this size, evenly distributed, could have 3 squads of infantry roaming each square kilometer!
It is difficult to imagine the battle of Baghdad lasting more than one day under such circumstances, especially given the incentives of Iraqi forces to surrender.
Analysis: 'Deployed' defense misnamed, reports Scott Burnell of UPI, after interviewing Charles Peña of the Cato Institute, whose written statements appear in the Cato Daily Dispatch under Bush Announces Missile Defense Plan, and elsewhere as Missile Defense Program Will Provide No Real Protection.
Since I don't often disagree with Cato, and I'm fascinated by risk management, I'm going to explain myself carefully. The UPI piece identifies several problems, which I categorize, according to section 18.104.22.168.3 of the PMBOK, as follows:
Peña concludes with an analogy:
"This is the equivalent of someone asking you to buy a very expensive car, and they're telling you it won't work ... but don't worry, we will fix all the problems after you've bought it," Pena told UPI. "You don't even know if you turn the key on, if the motor's going to turn over; that's what we seem to be doing here with this rush to deployment."
The first thing to note is that Peña is not directly opposed to the idea of NMD; his statements at Cato carefully include this endorsement of it: "If such a system can be demonstrated, a truly national limited land-based missile defense designed to protect the U.S. homeland is the appropriate system against the potential limited threat of rogue states armed with ballistic missiles."
My disagreements fall into two categories: first, I think all the risks are manageable -- given time.
Secondly, Peña's analogy need not mean that the NMD project has no value, even if its initial deployment has significant performance issues. In project management parlance, planned value, earned value, and actual costs are all different things, and all three of them typically have nonzero values the moment a project is underway. In the real world of geopolitics, demonstration of, or merely general belief in, even a limited NMD capability will result in substantial uncertainty on the part of any attacker. Whatever the "cost performance index" and "schedule performance index" of the project might appear to be to Americans, any ability to disable an incoming nuclear missile is far better than none.
Got together with fellow Friday-lunch-bunch member Steve Potratz this evening for a bit of observing. I provided the 'scope, he provided the patio/backyard of his house, plus additional observers (wife and children, sons ages 3½ and 5½, and a cat, who observed us). Steve has now been bitten by the astrophotography bug; here are his first-ever pictures taken through a telescope -- using eyepiece projection!
The Saturn picture does not clearly show the Cassini Division but does show a difference between the "A" and "B" rings, and between the darker clouds at the pole and the lighter clouds at lower latitudes. Resolution on the lunar pictures is better than 10 km, possibly as good as 5 km, which is pretty good considering how dirty and badly collimated my telescope's optics are.
Alert readers will notice changes to the left sidebar. Permalink list is now current, for the first time in several months, and I've done a bit of cleanup, including adding to the "Important Stuff" list (posts which all new readers are encouraged to go through -- if they don't run you off, you've got what it takes to stick around). The blatantly fake picture of Virginia Postrel reading this blog in nonexistent book form is used with her permission.
Something I should have explained a long time ago is that the Arcturus logo, such as it is, is actually a Chesley Bonestell painting of the variable star Mira Ceti (o Ceti). Graze on over here and look around until you find it. Hey, if you've seen one big orange star, you've seen them all. ;)
Graze on over and check out Lunar Crash of 1953: Impact Crater Identified. It's a 1.5-km crater resulting from a 0.5-MT impact of a body 20 m across.
Half a megaton is 2.1 × 1015 J. Assuming an impact velocity in the middle of the possible range -- 36 km sec-1 -- and rearranging KE = ½mv2 as m = 2KE/v2, we get 3.2 million kg. A spherical body 10 m in radius has a volume of about 4,200 m3. Resulting density r = 0.76 g cm-3, implying loosely packed water ice -- essentially a snowball.
Cutting the impact velocity in half, to 18 km sec-1, drives the mass of the impactor up to 13 million kg and its density to 3.1 g cm-3, slightly greater than that of the Moon (and of Earth's crust).
Whole lotta linkin' goin' on to Technical Difficulties, a well-crafted template which happens to be full of, well, dubious assertions -- and to rely on a scanty knowledge of history on the part of its viewers. Whatever "technical difficulties" we're experiencing now ain't a patch on General Order #11.
While that sinks in, let's assess our current troubles more realistically than the folks at "Technical Difficulties" by reviewing the fourth paragraph of Jefferson's First Inaugural, which I have reformatted for greater readability:
About to enter, fellow-citizens, on the exercise of duties which comprehend everything dear and valuable to you, it is proper you should understand what I deem the essential principles of our Government, and consequently those which ought to shape its Administration. I will compress them within the narrowest compass they will bear, stating the general principle, but not all its limitations.
These principles form the bright constellation which has gone before us and guided our steps through an age of revolution and reformation. The wisdom of our sages and blood of our heroes have been devoted to their attainment. They should be the creed of our political faith, the text of civic instruction, the touchstone by which to try the services of those we trust; and should we wander from them in moments of error or of alarm, let us hasten to retrace our steps and to regain the road which alone leads to peace, liberty, and safety.
Let's run through the list:
Of the sixteen "essential principles," I count -- tentatively -- one as specifically threatened by brand-new, post-9/11/01 policies. Most of the rest are either relatively secure or continually hampered by the (domestically) interventionist policies going back nearly a century. Few, if any, of these threats are opposed by the anti-Bush set. And all too few of them are opposed by the pro-Bush set.
(New readers may wish to graze through parts I, II, and III before continuing.) Previously unknown reader (the best kind) Rodney Kendrick of Bellevue, Washington, points to Featherweight Jupiter moon is likely a jumble of pieces and asks: "Amalthea is so close to its primary that I would have thought that tidal shear would pull a 'pile of rubble' apart. What are your thoughts on the matter?"
This turns out to be a great question, and I was wanting to figure the tidal stresses anyway. This source informs us that (emphases added)
With the exception of Amalthea, little was known about the small inner satellites of Jupiter prior to Galileo's arrival other than their orbits. The innermost pair, Metis and Adrastea, both orbit at the edge of Jupiter's brightest main ring at distances of 1.79 and 1.81 Jupiter radii (RJ) respectively from the center of the planet. Both lie within the Roche limit and would [therefore] be disrupted by tidal forces if they had no internal strength. Their orbital periods are shorter (~7 hours) than the period of Jupiter's rotation (~10 hours), hence their orbits will gradually decay and they will ultimately fall into Jupiter. Unlike the other satellites, Metis and Adrastea orbit faster than Jupiter's plasma sheet, the dense swarm of trapped charged particles that corotates with the jovian magnetic field. In contrast, Amalthea at 2.54 RJ and Thebe at 3.11 RJ have periods of about 12 and 16 hours, respectively, and so they are overtaken by the faster corotating charged particles. All of the inner satellites are thought to be in synchronous rotation, having spin periods the same as their orbital periods so that they keep the same face pointed towards Jupiter at all times. Their densities and bulk compositions are unknown.
Well, we know Amalthea's density now, and can make inferences about its bulk composition. (I note that Amalthea is the closest thing to a "jovisynchronous" satellite among Jupiter's moons; its orbital period of 11h 57m 23s is only a couple of hours longer than the Jovian day.)
Notwithstanding the above, Amalthea is strongly affected by tides. It is far from spherical -- this source states: "Amalthea is irregular and neither a triaxial ellipsoid nor an equilibrium body. It has a volume of about 2.4 × 106 km3, and its best-fit ellipsoid has dimensions 131 × 73 × 67 km" -- and its orientation is not random. The invaluable Phil Stooke, whom I have had the pleasure of meeting several times at the annual Lunar & Planetary Science Conference in Houston, has produced a map of Amalthea, which has the effect of showing that its longest axis points through Jupiter. Picture an American (or a rugby) football, being swung in a circle by a long cord attached to one end.
But what, quantitatively, are the forces involved? Turning to this source, we find that
RL = 2.44 3Ö(rP/rS) RP ,
FD = 2 (G MP RS / r3) ,
Fg = G MS / RS2 ,
In MKS units, for the Jupiter/Amalthea system,
The upshot of all this is the expected result: Amalthea is not a rigid body, being inside the Roche limit; but its gravity is more than adequate to hold it together, being 6 times stronger than the forces pulling it apart. Its component boulders, however, have been stretched into an ellipsoid with its longest axis pointing at Jupiter.
The Spaceflight Now article quotes Galileo project scientist Dr Torrence Johnson: "This finding supports the idea that the inner moons of Jupiter have undergone intense bombardment and breakup. Amalthea may have formed originally as one piece, but then was busted to bits by collisions." The implication is that if Amalthea once were rigid, it could not have formed as close to Jupiter as it is now, though it would have had to be less than 20,000 km farther out, just over 10% farther than at present.
More information on the general topic of tides, moons, and rings is here.
I founded A Voyage To Arcturus one year ago today, so I guess I'm supposed to reflect, recapitulate, reiterate, and re- a few other things besides.
The trivial option would be to repent and shut it down, but I'm having way too much fun to do that. So let's go with the obligatory what-I've-learned list.
But first, some advice for my fellow bloggers:
And now for everyone else's edification:
Once again, send 'em if you got 'em. I was at Blue & Gray Park from 2:15 to 3:45, and would have stayed longer had it been a few degrees warmer or had I been wearing long johns and electric socks.
It was a beautiful night; sky transparency was excellent and seeing was at least decent -- the Beehive Cluster was clearly visible to the naked eye. Temperature around 30°F and a light breeze from the west; also humid enough for frost. The winter Milky Way is less prominent than the portion of it we see in summer, but thanks to the relative proximity of the Orion Arm (note especially the "Orion Association"), has more bright stars, arranged in a large polygon -- running clockwise from the northernmost point, they are Capella, Aldebaran, Rigel, Sirius, Procyon, Pollux, and Castor -- with Betelgeuse near the center.
With all this, plus Saturn near z Tauri and Jupiter just west of the Sickle of Leo, I immediately decided to set up the telescope. Besides, there was one other observer out there, a guy from Oak Grove, who hadn't brought anything but binoculars.
The first thing we looked at, of course, was Saturn. Due to its axial tilt, the rings are at their widest this year (they will now gradually begin closing up, and will be edge on about 7 years from now), so it appears that much more breathtaking (a recent shot from the Cassini-Huygens spacecraft is here). At 60x, the Cassini Division was clearly visible, as was the contrast between the polar clouds and those closer to the equator. Of the moons, Titan, Tethys, Dione, and Rhea were obvious.
On to the Orion Nebula, always the second most spectacular thing in the sky after Saturn. My telescope gathers about 2,000 times as much light as the unaided eye, enough to activate the cone cells in the human retina, so some color appears. Last night, it was faint tinges of red and blue from H-a and H-b (it doesn't always look the same; I've seen it glowing emerald green from the O-II spectral line).
Then on to Jupiter, blazing at magnitude -2.5, with the north and south equatorial belts prominent and all four Galilean moons visible -- but no shadow transits in progress. Back to the Beehive for a quick look -- it wouldn't all fit in the field of view but was quite impressive nonetheless. In between all this I was sitting back to watch for meteors, and was seeing two or three a minute, at least; I'd guess the ZHR was 200 or more, which would make this among the best Geminid showers ever. Plenty of bright ones but not a lot with persistent trails, or much color, though some did appear slightly green.
My fellow observer had expressed a wish to see the Andromeda Galaxy, but it was low in the northwest and obscured by city lights, so I decided to go after M65/66, a pair of obliquely-angled spiral galaxies in Leo. I first tried this without star maps and spent a comical fifteen minutes or so thrashing around somewhere in the vicinity of a = 11h, d = +10°, before giving up and digging the Tirion out of the van. They turn out to be halfway between q and i Leonis, 3rd- and 4th-magnitude stars, respectively.
After that, I wimped out due to the cold, packed everything up, and drove back home. Hit the sack about 4:30 and slept for five hours. I'll be recovering from this for a couple of days ...
Weather is looking good in KC; I plan to be at my observing site at 2 AM. CNN has a story, Meteor shower from the 'Twilight Zone', which points out that the Geminids are associated with 3200 Phaethon, an unusual source: "Astronomers theorize that 3200 Phaethon is the remnant of a comet that gradually lost its ice supply after repeated brushes with the sizzling heat of the sun."
In Asteroid moons pulled in by gravity, Lidia Wasowicz of UPI reports that binary Kuiper Belt objects are the result of capture, not collision.
Unlike binary asteroids in the main belt, such as Ida/Dactyl, which are only about 100 kilometers apart, "the separation in Kuiper belt binaries is hundreds or even thousands of diameters [said lead study author Re'em Sari]." Since all known KBOs are at least 10 km in diameter, and many are over 100 km in diameter, the absolute separations are 103 - 105 km.
Just for fun, let's figure the orbital period of a hypothetical binary KBO. Suppose the primary is 100 km in diameter, the secondary ("moon") is 10 km in diameter, they're both reasonably spherical, and both have density r = 1.0 g cm-3. Separation is 100,000 km.
Referring back to this exercise, in which we found that the appropriate version of the equation for Kepler's Third Law is MP2 = D3, we first solve for P = Ö(D3/M).
If D is expressed in AU (1.496 ´ 108 km) and M is expressed in solar masses (1.9891 ´ 1030 kg), then P will be expressed in years. Ignoring the secondary, which is only 1/1000 the volume, and therefore the mass, of the primary, M works out to 5.2 ´ 1017 kg, or 2.6 ´ 10-13 MSun. D = 6.7 ´ 10-4 AU.
Result: 34 years; the orbital velocity of the secondary would be only six-tenths of a meter per second! Now, a KBO 50 AU from the Sun would revolve about it once in 354 years (at a velocity of 4.2 km sec-1). So if it had such a "moon," it would have about 10.4 "months" per "year." Rather like the Earth/Moon system, with everything slowed down by a factor of about 300.
UPDATE: Further visualization ... assume both primary and secondary have an albedo of 10% (David Jewitt of U Hawaii explains albedo measurement here). Consulting Conversion of Absolute Magnitude to Diameter, we find that the primary would have H = 8.0 and the secondary would have H = 13.0 (definition).
So an observer standing on the surface of the primary, if the secondary were "full," would see it as a point (since it would subtend only 21 seconds of arc) shining at magnitude +5.6, comparable to the faintest stars ordinarily visible on Earth. An observer standing on the secondary observing a "full" primary would see it as a tiny disk, 3.4 arc-minutes across, one-ninth the size of the Full Moon as seen from Earth, shining at magnitude +0.6, comparable to Betelgeuse (a Ori) or Altair.
Surface gravity on the primary would be 1/700 of Earth's; on the secondary it would be only 1/7,000. From the viewpoint of either the primary or the secondary, the other body would take 34½ Earth days to move through 1 degree of sky. Not to overlook the obvious, the Sun would shine at magnitude -18.2, 160 times as bright as a Full Moon. -- Which wouldn't warm things up much: the surface temperature would be perhaps 40°K (-233°C; -387°F).
This time it's for Vinteuil, the Proust-derived pseudonym of a new blogger who teaches at a public school in Virginia.
"Vinteuil" is, without exaggeration, among the most remarkable individuals I have ever known. We briefly attended the University of Chicago together in the late 1970s. I will not erode his pseudonymity by describing his subsequent journey in detail, but mine -- from aimless dropout to ... well, OK, I'm an unemployed loser just now, but I've had my moments, trust me -- pales in comparison. The kids in his classrooms have no idea how staggeringly fortunate they are. I expect his blog, which is already a worthwhile read, to become one of the best.
Close on the heels of the Brookings Institution report comes Study: Mo., Kan. above average for 'economic freedom', says KC Bus J, referring to a study from the National Center for Policy Analysis (news release). Missouri ranks 17th, thereby edging into the top third, and Kansas 21st, among the 50 states.
The study, Economic Freedom of North America (warning: 68-page *.pdf; very large file), has some bad news for the Great White North: almost every Canadian province ranks below every American state in economic freedom, and the largest province in Canada would be the fourth poorest state:
All provinces, except Alberta, are clustered at the bottom of the rankings of both the all-government and the subnational economic freedom indexes and also have low levels of prosperity. Ontario is the only other province that is freer than some states in some years. Yet, its level of prosperity in 2000 is ahead of only the three poorest states, West Virginia, Mississippi, and Montana, states that also suffer weak economic-freedom scores.
Locals, here's the word:
Kansas is another state in which economic freedom is neither enshrined nor defeated. It ranked 26th in all-government overall and 21st in state and local. Its best showing was in size of government, state and local, where it rated 14th (all-government was 24th), after which there was almost no diversion between the two measurements. Takings and taxation finished 32nd in all-government and 31st in subnational, and labor market freedom 22nd by both measurements. Kansas ranks 21st in effective state and local tax burden and 23rd in total tax burden.
Missouri ranks 15th overall in the all-government rankings and 7th in state and local, with respectable scores in both takings and discriminatory taxation (12th and 7th, respectively) and labor market freedom (17th and 16th). It fairs [sic] worse in the all-government measurement for size of government, coming in 32nd, although in the state and local rankings it placed 11th. It has a relative [sic] low general sales and use tax, among the states that charge one, at 4.225% and tipplers enjoy the nation’s second-lowest tax on beer (6¢) and one of the lowest table wine taxes (30¢). In the rankings where citizens want their state to finish far down the line, effective state and local tax burden, Missouri is 38th at 9.7%.
About time I plugged one of the more interesting locals. But first, the setup:
Via Glenn Reynolds, Ted Barlow on market research -- and resulting biases; also via Glenn, Ron Bailey on media bias.
Which leads me to Rhetorica, Andy Cline's blog about journalistic theory:
The press ... is often thought of as a unified voice with a distinct bias (right or left depending on the critic). This simplistic thinking fits the needs of ideological struggle, but is hardly useful in coming to a better understanding of what is happening in the world. I believe journalism is an under-theorized practice. In other words, journalists often do what they do without reflecting upon the meaning of the premises and assumptions that support their practice. I say this as a former journalist. I think we may begin to reflect upon journalistic practice by noticing that the press applies a narrative structure to ambiguous events in order to create a coherent and causal sense of events. Rhetoric is the engine of this project.
His piece on media/political bias, especially the list of 7 structural biases, is a must-read. "Narrative bias," in particular, affects news reporting far more than most people realize. I urge my readers to take 10 minutes to carefully browse this page, and consider bookmarking Rhetorica for regular visits.
I got to thinking some more about Amalthea's packing fraction and decided to take a stab at calculating some of the forces involved. Specifically, for a given boulder somewhere beneath Amalthea's surface, how much weight might be pressing on it from above?
Amalthea is, more or less, an ellipsoid 270 ´ 170 ´ 150 km. Its volume V = 4/3 p a ´ b ´ c, where a, b, and c are the semi-axes, is therefore approximately 3.6 million km3, and its mass (with r = 0.9 g cm-3) is around 3.2 ´ 1018 kg.
Earth's mass is 5.974 ´ 1024 kg, and its mean radius is 6,371 km (source). Since g µ M / R2, dividing Amalthea's values (assume mean radius = 100 km) into Earth's and working the equation establishes that mean surface gravity on Amalthea is approximately 0.002 g.
The technical term for the value I want is the lithostatic stress, and it's calculated by sv = rgz. We know that r = 0.9 g cm-3, but z may be anywhere between 0 and 100 km -- and g actually varies with z.
I'm not going to slog through the derivation, but the pull of gravity inside a planet or moon is less than that on its surface, proportional to the amount of mass closer to the center. Go halfway into a body of uniform density, and you would experience only one-eighth the pull of gravity on the surface. (The exact center of the Earth is a microgravity environment!) So let's imagine a point inside Amalthea at one-half "Amalthea gee," or 0.001 Earth g, which would actually be 1/3Ö2 of the distance from the surface to the center, typically about 21 km below the surface. Plugging these values into the equation (using MKS units) yields a result of just under 200,000 newtons -- about 43,000 pounds.
For comparison, the same value occurs in Earth's crust (r = 2.8 g cm-3) at a depth of about 23 feet. So the internal forces of Amalthea are those of a pile of boulders on Earth a few tens of feet high.
UPDATE: Readers are invited to use the better figures for Amalthea's mass and volume in part IV of this series to recalculate the depth in Earth's crust which is the equivalent of the half-gee depth inside Amalthea.
In yet another attempt to provide a perspective which is at least faintly tinged with uniqueness, I again ask my readers to indulge me for a few paragraphs -- there's actually a sci/tech touch to this at the end.
I contend here that Trent Lott's ad lib assertion that the domestic problems of the second half of the 20th century could have been avoided had Strom Thurmond been elected President of the United States in 1948 was only incidentally racist; it would be truly astonishing, to a degree of which Trent Lott is almost certainly incapable, if he were to be revealed as a secret advocate of segregation.
Nor was it merely stupid. Politicians say stupid things every day, usually under the pressure of being required to know a small number of things about a great variety of topics, sometimes out of intellectual and moral rudderlessness, and occasionally out of sheer viciousness.
Nor was it even merely ahistoric, though this gets closer to the matter. Few living Americans in 2002 were old enough to vote in 1948 (no one under age 75 today). Trent Lott himself was all of 7 years old then. That eye-popping Dixiecrat sample ballot is simply unimaginable to baby boomers and younger generations.
No, it was arcadian, that is, reverse-Utopian; we are declining from an ideal past. The nation was untroubled until Bad People sullied it with Bad Ideas and Bad Behavior. Now things are Out of Control and Getting Worse. The End is Near.
Alert readers will recognize arcadian elements in many political beliefs, including, perhaps, their own. My own comrades often indulge in questionable assertions of the form "the US prospered under limited government until [insert arbitrary date here], but now is much worse off under the oppression of [insert interventionist public policy here]." That this country is at the peak of its power and prosperity sometimes slips the minds of those gripped by arcadian memes. It certainly appears to have slipped Trent Lott's, at least briefly.
Other popular examples of this sort of thing are: native Americans lived in harmony with the Earth, but now the environment is being ravaged by rapacious corporations; our forefathers were godly men who founded a Christian nation, but liberals in the government now mandate official atheism; there used to be many competing newspapers and broadcasters, but lax regulation is allowing corporate consolidation and eroding choice and cultural diversity; mad scientists are commodifying human life with cloning and stem-cell research.
That last example is most deliberate. Arcadianism eventually collides with dynamism. People who genuinely believe, and act on their belief, that this country was a better place 50 or 200 or 500 years ago (in that case, meaning that it was a better place without us altogether), will struggle to deal with many things, and technological advance is one of them. Perhaps such people ought not to be in positions of power. Or, as I rhetorically asked a while back: How long can the equilibrium of technically incompetent rulers lording it over technologically advanced societies be maintained?
Trent Lott must go.
According to Anderson, Amalthea's average density is close to that of water ice. However, he and other scientists do not think the moon is largely composed of ice. Instead, they suspect the moon contains chunks of rock, and perhaps some ice, with a lot of gaps in between.
"It's probably boulder-size or larger pieces just touching each other, not pressing hard together," [John D.] Anderson [of JPL] says. Planetary scientists suspect many other small moons and asteroids of being similar "rubble piles."
Water ice is r = 0.9 g cm-3; for comparison, the innermost Galilean moon of Jupiter, Io, has r = 3.57 g cm-3. If Amalthea is composed of materials similar to those of Io, nearly three-quarters of its volume must be empty spaces between chunks of rock!
In technical terms, Amalthea's packing fraction h may be as low as 0.25. Another prominent example of this phenomenon (with h = 0.5) is asteroid 216 Kleopatra, a New Jersey-size bundle of metallic shards.