Thursday, December 28, 2006

Advanced astronomy, Mayan-style

There was a time when astronomy was not publically viewed as an abstract intellectual endeavor or a hobby, but was instead one of the bedrocks upon which the greater ancient civilizations relied. Without astronomy, there could be no calendar or accurate time-keeping. Without a calendar, agriculture was much less efficient. Inefficient agriculture lead to slow population growth and vulnerability to famine or conquest, as any player of 4X-style computer games like Civilization know all to well.

The image is of a Mayan calendar, with eighteen 2-day months plus a 5-day extra month, comprising a 365-day year (no leap year). Today is 3 Men 8 Kankin, by the way.

Indeed, Mayan astronomy was very advanced for that period in time, even compared to the middle-eastern civilizations we commonly consider to be the "Great Ancient Civilizations", as was their civilization.

To give you more of a taste for their sophistication, I reproduce below an excerpt from an article at Orcinus - the link to the full article "Bringers of Light and Death" is here (the article discusses the extremely misleading and racist treatment of Mayan civilization portrayed in Mel Gibson's latest film Apocalypto).

Mayan culture featured a complex and fascinating cosmology. Their art was both sublime and beautiful. And their language -- which was so complex and unusual in structure that it only has been deciphered generally in the past 20 years or so, and is still not completely so -- produced a massive literature that included poetic, religious and philosophical works.

However, we only are able to obtain a slight glimpse of this body of work today because those Spanish "saviors," in the two centuries following their arrival, successfully eradicated, through forced burning, nearly the entirety of it. As Michael D. Coe observed in his 1987 book The Maya:
"[O]ur knowledge of ancient Maya thought must represent only a tiny fraction of the whole picture, for of the thousands of books in which the full extent of their learning and ritual was recorded, only four have survived to modern times (as though all that posterity knew of ourselves were to be based upon three prayer books and 'Pilgrim's Progress')."

Their scientific and agricultural achievements were also substantial. Their astronomical observations in particular were extremely accurate; modern scientists note that their lunar and planetary charts are at least the equal of, if not superior to, those produced by any civilization working from the naked eye. And their astronomical achievements also played a role in their architecture; as David E. Stannard explains in American Holocaust: The Conquest of the New World [p. 38]:
... [I]t is important at least to point out how little we still know of these people. Their involved writing system, combining elements of both phonetic and ideographic script, for example, appears to have been fully expressive of the most intricate and abstract thinking and has been compared favorably to Japanese, Sumerian, and Egyptian -- but it continues to defy complete translation.

Similarly, for many years the absence of a gridwork layout to streets, plazas, and buildings in Maya cities puzzled scholars. Right angles weren't where they logically should have been, buildings skewed off oddly and failed to line up in the expected cardinal directions; everything seemed to twist away from an otherwise northward presentation. Apparently, said some archaeologists, Maya builders were incompetent and couldn't construct simple right angles. Given the exquisite and precise alignment of every other aspect of Maya architecture, however, others thought this to be at best a hasty criticism. And now it is beginning to become evident that these seeming eccentricities of engineering had nothing to do with incompetence.

On the contrary, a complicated and original architectural pattern had always been present -- the same pattern, some began to notice, in city after city after city -- but its conceptual framework was so foreign to conventional Western perception and thought that it remained effectively invisible. Recently the "code," as it were, of Maya engineering and construction has begun to be deciphered, and the story it reveals is mind-boggling. So precise were the Maya calendrical measurements and astronomical observations -- and so central were these cosmic environmental calculations to their ritual and everyday lives -- that the Maya constructed their cities in such a way that everything lined up exactly with specific celestial movements and patterns, particularly as they concerned the appearance and disappearance of the planet Venus in the evening sky.

Wednesday, December 27, 2006

COROT launches today

COROT, a small European astronomical satellite designed to perform stellar seismology and detect tell uric (i.e. rocky) planets by the micro-occultations they produce, should be launched today. has the story. COROT is unlikely to find Earth-like planets, but between 10 to 40 larger rocky planets are expected to be discovered during the mission's 2.5 year lifetime.

As of today 182 extra-Solar planets are known, the majority of which are massive gas giants orbit ting much closer to their parent star than the gas giants in our own Solar system do. This class of gas giant are often called hot Jupiters.

Tuesday, December 26, 2006

Windows Vista "Content" protection and the cost for all computing

Modern astrophysics, if not most sciences, ultimately rely on modern advances in computing power and in the continued growth of cheap computing power (e.g. the Large Synoptic Survey Telescope will obtain [and have to process] 30 terabytes of data each and every night [30 TB = 30 000 Gigabytes]). Anything that interferes with current trends in computer speed, cost, reliability or accuracy thus threatens to interfere with the global pace of scientific research.

Unfortunately it appears that the requirements that Microsoft is now asking of software and hardware makers in order to "protect" "premium content" in their new Vista operating system will negatively impact the entire computer industry and all those using computers (and whether or nor you use any of Microsoft's products).

Peter Gutmann, a computer security analyst in New Zealand, provides a particularly clear description of the requirements Microsoft is placing on computer hardware manufacturers for Vista-compatibility and their implications.

The important thing to note is that this will affect you even if you use a different operating system on your PC or server. Yes, even if you only buy Apple Macs! Your hardware will be more expensive, and the software to run on you new hardware more prone to bugs. Worse still, there will be the genuine dangers to human health (e.g. this cartoon) and general safety. Ironically, these changes, while made in the name of "security" ignore genuine issues the public would think important (such as protecting your bank records) and focus ultimately on controlling the way you view the "entertainment" provided by the US movie and TV industry.

It is a long article, but worth reading in its entirety.

Thursday, December 14, 2006

Emperors of the US, and elephant-killing lions

As I just got back from 8 days in Honduras (our honeymoon, very nice, thank-you for asking) I'm in the process of catching up with work etc, but here are two interesting things I've learnt in the last 24 hours.

First of all - adult elephants are not free from predation (as is often stated in wildlife programs). The ever-interesting Darren Naish has a post on this over at Tetrapod Zoology. Go read. He also discusses the self-censorship most wildlife programs practice with respect to showing popular animals killing and eating other popular animals.

Secondly. Bet you didn't know that there was an Emperor of the US (and I don't mean GW)?

I'm Joshua Abraham Norton, the first and only Emperor of the United States of America!
Which Historical Lunatic Are You?
From the fecund loins of Rum and Monkey.

Thursday, November 30, 2006

Did a starburst in the Milky Way 2.4 billion years ago have affect life on Earth?

2.4 billion years ago a storm of Cosmic Rays produced by an increase in the star formation rate of our home galaxy (the Milky Way) ionized the Earth's atmosphere to such an extent it changed the climate, triggering spurts of growth and die-backs in the primitive life on the Earth at that time.

That is the sure-to-be-highly-controversial suggestion in a new paper by Danish scientists (H. Svensmark, 2006, Astronomische Nachrichten, 27, 871) reported on by When I get back from the honeymoon I'll have to check out the full paper and write a more detailed follow up of this.

As a starburst guy I've love for this to be true, but right now it is best to be skeptical. That Cosmic Rays (CR) strongly affect the Earth climate appears to be by no means well established, and has often been used by climate-change deniers (e.g. see this older post of mine about CR-driven climate change claims made by [strangely enough!] the exact same Danish group).

Also there are issues about the significance, duration, and effect any upturn in Galactic star formation at that time may have been - even if there were a major burst in the MW its by no means clear how the CR flux at Earth would have been altered.

I'll look into these and other issues later...

[update 14/12/06 (1) I still haven't got around to reading the paper in full. (2) Typo in title has been corrected]

Tuesday, November 28, 2006

So apparently I look like some guy called Adam Brody

But who are these people?

Thursday, November 09, 2006

Holy Moley - even more Ehrlich/Steele and general GOPer naughtyness!

Hidden in another WaPo article about the Ehrlich/Steele attempt to trick African Americans into voting for them is this gem:

A mailer, produced by a Bowie woman, urged support for Steele and declared: "Ben Cardin Promises to Attack Jesus Christ, Pastors, Churches and Christians and to Take Away Blacks' Freedom If He Is Elected. [emphasis mine]" The Washington-based National Jewish Democratic Council called the flier "despicable" and "thinly-veiled anti-Semitism" aimed at Cardin, who is Jewish.
Note that unlike the Ehrlich/Steele Democrats flier case there doesn't (yet) seem to be any evidence that this mysterious Bowie woman worked for the Ehrlich/Steele campaign directly.

Ehrlich and Steele had tried something similar in 2002

TPMmuckraker is still on the case! Following on from my last post about the dirty tricks Ehrlich and Steele tried last Tuesday to trick African American voters into voting for them by trucking-in unsuspecting and hungry homeless people to hand out deceptive voters guides/ example ballots, it now turns out that Ehrlich/Steele had tried similar trickery in 2002.

The image of Steele is from his great advert "Steele loves puppies and cheating". Cute Boston Terrier though, might have to call Animal Cops to rescue it.

He may like puppies, but he's into disenfranchising voters from both MD and PA.

The folks at TPMmuckraker must be feeling particularly Herculean after all the mud-slinging associated with the 2006 midterm, but additional commendations are due to them for this follow-up about Ehrlich (R-ex governor) and Steele's (R-loser) attempt to trick pro-Democratic African-American voters into thing Ehrlich and Steele were democrats (see the original story from Nov 07th here first for some context if you want).

Let us present the Sordid history of Maryland Republican's latest attempt to mislead and disenfranchise the African American voter:

  • Oct 31st 2006: Five African American County Council members from Prince Georges county and a former county executive (Wayne K. Curry) endorse Steele (R-lying liar). Of the images of African American democrats presented on the cover of the Ehrlich Steele Democrats flier only Curry endorses Steele (even Curry does NOT support Ehrlich). Mfume is shown, and as a former congressman and former leader of the NAACP and recently a candidate for Democratic MD Senate primary Stelle is running for) certainly doesn't endorse Steele in any if you need any proof that this is not a genuine "democrats for Reagan" cross-party endorsement.
  • Nov 07th 2006: Washington Post reports on the misleading sample ballots handed out at voting places in Maryland. Note an important part of the article:
Erik Markle, one of the [trucked-in PA homeless] people handing out literature for Ehrlich ... said he was recruited at a homeless shelter in Philadelphia. After a two-hour bus ride to Maryland, Markle said the workers were greeted early this morning by first lady Kendel Ehrlich, who thanked them as they were outfitted in T-shirts and hats with the logo for Ehrlich's reelection campaign
  • Nov 07th 2006: Jesse Signal's personal experience with one of the trucked-in leafleteers.
  • Nov 07th 2006: Maryland Community Papers Online (aka the Gazette) reports on how homeless people from Philadelphia were trucked down to Baltimore to hand out Ehrlich-Steele Democrats example ballots.
  • Nov 07th 2006: The brown shirts at FreeRepublic cross-post an image (the one shown above, originally from Dailykos. Shows where the freepers really go to find of what's really happening in the US!) of the offending sample ballot and twitter on about how its obvious that this was produced by Democrats who support Steele and whats the big fuss [I'm not going to even vaguely endorse freeperism with link to them].
  • Nov 9th 2006: David Harrington, one of the huge total of five PG county Councilmen who had actually endorsed Steele is pissed off at this blatant cheating. From an article in the Washington Post blog: 'The ugly, last-ditch efforts by Republicans Bob Ehrlich and Michael Steele to win over black voters in Prince George's County were "over the top," "foolish," "counterproductive," and "an unnecessary attempt to confuse voters,"' Nevertheless, Harrington expresses no regrets, so potentially Steele dishonesty has also killed another African American's political career.
  • Nov 09th 2006: The Philadelphia Enquirer posts a length story about the how the homeless Philadelphians were premised a $100 and breakfast lunch and dinner for distributing the fliers, how they were NOT returned to PA in time for them to vote themselves, and how used they feel now that they know they were part of a dirty tricks campaign.
    Yesterday's Washington Post reported that neither Ehrlich nor Steele was personally aware of the Philly hires [dks: so Ehrlich's wife is part of the group who does this, and Ehrlich was somehow was not aware of it? How stupid do you think we are Ehrlich?]- who knows which group loosely connected to the camps got the bus caravans rolling? Though Ehrlich told the Post, "If folks are here from out of town, that's fine with me. That's what the Democrats have always done. [So he doesn't even admit its wrong, who ever did it, and btw the Democrats are the real cheaters. Note the post article lets that unsupported allegation stand rather than following it up to check its veracity. What a wonderful liberal media we have!]"
    "I am so angry and upset, I don't know what to do," said El-Bedawi, who's particularly shattered that he and at least 200 other Philadelphians didn't get home from Maryland in time to vote here. "These people think we're too stupid to understand the magnitude of what we did." What they did, said El-Bedawi, was cheat an entire community of unsuspecting voters. And just because they didn't know they were doing it doesn't mean it doesn't feel awful. [Note to Ehrlich: El-Bedawi may not have many possesions or a home, but he has this thing called integrity that you don't have, so without a doubt he'd make a better Governor than you ever will. He's a better man than you are, Gunga Din]

Tuesday, November 07, 2006

How Telemarketing Dirty Tricks work (not science)

I've been meaning to post about winds from galaxies, specifically the standard idea of winds being most likely to escape from dwarf galaxies. But... its election day and I have a lot of other work to do so I'll just post something else very quickly and get back to real work.

Those of you with your ears to the ground will already know about the news (from the internet, the so-called media isn't mentioning it much. I wonder why? ;> See here for info and links to more about misleading robocalls) that the RNCC has been repeatedly ringing people up pretending to be democrats by messing with the Caller ID, so as to generate anger against the democrats. Quite apart from the politics (I wont rant about how this is so typical of the modern Republican criminal mentality) I was interested in the more technical sense about how this Caller ID faking is done and why it doesn't seem to be illegal.

Since the national No-Call-List was put into place and we signed up for it, we now often receive telemarketing calls with confusing, misleading or even absent Caller IDs. Its illegal for telemarketers (*) to call you if you are on the NCL. But filing a complaint is not exactly a piece of cake, as when you fill the in the complaint form on the web you need to give the offending telemarketers number and ID... and if they're sending out fake ones you have little hope of having the true offenders punished for selfish, inconsiderate and parasitic ways.

So how is it done? Well, G2geek (a telecommunications engineer) over at Daily Kos has a informative post all about how companies manipulate their Caller ID entries. So GO READ IT.

(*) Illegal except for politicians and businesses you are already a customer of.

Friday, November 03, 2006

Venus: no catastrophic volcanic resurfacing?

It used to be thought that the relative absence of
craters on our planetary (evil) twin Venus's surface (as radar-mapped by the NASA mission Magellan) implied recent (about 500 Myr-ago) catastrophic volcanic resurfacing (lava covering a large fraction of the planet to a depth of about 3 km is pretty catastrophic).

A new reanalysis of the original data is casting doubt on that old interpretation - the lava might be only (!) 1 km or so deep, and may date from billions of years ago.

Read the full article here on the New Scientist "Space" web page.

The false color radar image of a part of Venus's surface is credit NASA/JPL.

Tuesday, October 31, 2006

Usra Major: The oldest constellation?

Two quick but fascinating pieces regarding the constellation Ursa Major (aka the Big Dipper, aka the Great Bear, aka the Plow, aka the Wagon) came to my attention this month.

(1) Scientific American had an article by the archaeo-astronomer Bradley E. Schaefer regarding the origin of the Greek Constellations (note: only a preview is available online unless you are a SciAm Digital subscriber). The majority of the constellations are not that old - the official constellations used today date back to an IAU resolution of 1922, and archaeological evidence shows that very few constellations were named by 1300 BC, with a big burst of constellation-naming occurring at ~ 1100 BC.

But what I found really interesting is that one of the constellations, the Great Bear, might be many times older than that.

"The wagon name must, of course, have come after the invention of the wheel (roughly the fourth millennium B.C.), but the bear name is undoubtedly much older. Early societies throughout Eurasia recognized the Great Bear stars and myth. The most common version was the the four stars in the bowl of the dipper were the bear, which was perpetually chased by the three stars in the handle, which represented three hunters. The Greeks, Basques, Hebrews and many tribes in Siberia had this basic star/myth combination. Surprisingly, the same bear stars and stories surfaced throughout North America. With some variations, many tribes of the new world - including the Cherokee, Algonquin, Zuni, Tinglit and Iroquois - share the interpretation of the bear followed by three hunters... [he discusses various ways of interpreting this synchronicity, before concluding] ... The Bear is unlikely to be an independent invention, because the stars do not look like a bear... The most logical [remaining] explanation to connect the traditions holds that the first settlers of the New World carried the basic myth across the Bering Straight [i.e. about 14000 years ago]."

(2) Space.Com has an interesting article about a powerful optical illusion where the Great Bear appears to shrink as it rises away from its winter position (near the horizon).

Hubble repair mission gets the go-ahead from NASA

NASA has officially announced that the shuttle will be used to repair and upgrade the Hubble Space Telescope, in mission STS-125 set for 2008. Hopefully Hubble will survive until then...

From the BBC article:

Dr Griffin's decision reverses that of his predecessor, Sean O'Keefe, who cancelled the planned visit in the wake of the Columbia shuttle disaster in 2003.

This is certainly the correct decision - both benefiting science and making sense economically. The indefinite delays arising from the last Shuttle disaster have cost NASA a huge amount of money that would otherwise have been spent on doing other astrophysics, and has caused real funding problems for US astronomers (in particular those not associated with HST-based science).

No doubt Maryland's hard working and influential (democratic) Senator Barbara Mikulski has had a large part to play in making this repair/servicing mission a reality.

Sunday, October 22, 2006

Failure in the self-correcting system? Maybe not.

The NYT magazine has a fascinating article by Janeen Interlandi on the case of Eric Poehlman, a medical researcher at UVM who was discovered faking his data by a student at his lab. Eventually he was sentenced to 1 year and 1 days jail time for scientific fraud, but he'd been getting away with it for years - indeed he was hired to UVM based on work he'd faked and seemed never to have stopped faking data until he was investigated.

The scientific process is meant to be self-correcting. Peer review of scientific journals and the ability of scientists to replicate one another’s results are supposed to weed out erroneous conclusions and preserve the integrity of the scientific record over time. But the Poehlman case shows how a committed cheater can elude detection for years by playing on the trust — and the self-interest — of his or her junior colleagues.

... Not only does any research touched by tainted data have to be re-examined, but high-profile cases of misconduct can also shake public confidence. “We already have a large subculture in society of people who don’t trust science to begin with,” says John Dahlberg, one of the Office of Research Integrity investigators who oversaw Poehlman’s case. “This doesn’t help at all.”

Peer review and repeatability in science are self correcting, but deliberate fraud is harder to guard against. If you get a result that disagrees with a colleagues you don't immediately think "fraud" - you check your analysis, try to see how they might have analyzed or interpreted the data differently. It might even be a typo in their manuscript, or put in the journal. And thats if you're using the same data, often you're not. Deliberate fraud of the "making up data" variety is probably rare, but this case shows that it is caught... eventually. The self-correcting part of science is necessarily speedy.

Another interesting part of the article is when it asks how did he get away with it for so long?

The length of time that Poehlman perpetrated his fraud — 10 years — and its scope make his case unique, even among the most egregious examples of scientific misconduct. Some scientists believe that his ability to beat the system for so long had as much to do with the research topics he chose as with his aggressive tactics. His work was prominent, but none of his studies broke new scientific ground. (This may also be why no other scientists working in the field have retracted papers as a result of Poehlman’s fraud.) By testing undisputed assumptions on popular topics, Poehlman attracted enough attention to maintain his status but not enough to invite suspicion. Moreover, replicating his longitudinal data would be expensive and difficult to do [emphasis mine].

“Eric excelled at telling us what we wanted to hear,” Matthews, Poehlman’s former colleague, told me.“ He published results that confirmed our predisposed hypotheses.” Steven Heymsfield, an obesity researcher at Merck Pharmaceuticals in New Jersey, echoed Matthews’s sentiments and added that Poehlman’s success owed more to his business sense and charisma than to his aptitude as a scientist.

Friday, October 20, 2006

Friday Catastrophysics: Battered Galaxies part 1

Our cosmic neighborhood is not as quiet and suburban as you might imagine. New research using the Spitzer Space Telescope suggests that the nearest giant spiral galaxy (i.e. similar in type and size to our own Milky Way galaxy) took a direct hit from another galaxy, triggering an ripple of star formation that has now propagated 30 000 light years outward.

The image to the left is an optical image of M31 and its satellite galaxies: M32 (the bright white dot at center left) and M110 (the fuzzy blob toward the bottom right hand side), taken by Robert Gendler.

Block et al (2006, Nature; also see astro-ph/0610543) base this interpretation on mid-infrared imaging at a wavelength of 8 micron, which is sensitive to warm dust (and starlight, but they can remove the starlight using 3 micron imaging which is only sensitive to starlight). The resulting image of M31 is shown in red here, along with a the optical image rotated and scaled (by eye) to match the orientation of the Spitzer image.

Although there is something of a weak distorted spiral arm pattern to M31, the 8 micron image shows closed ring-like structures. The outer red ring is a region of hot dust, heated by the young massive stars that have recently formed there. This star-forming ring has been know about for some time, but it is the inner dust ring that is the new discovery.

Star-forming rings can be produced by two mechanisms. The more standard one is for a stellar bar to create inner and outer rings, but M31's bar is relatively weak and not as large as the 10-kiloparsec radius (30 000 light year) outer ring, nor is it aligned with the inner dust ring. The other way to get a large-radius ring of gas and dust in a spiral galaxy is for another galaxy to pass through the disk on a polar orbit. Here the culprit is suspected to be M32, the smaller of the dwarf galaxies visible in the image of M31.

This form of galaxy collision has been seen before, and in the more extreme cases (where the colliding objects are closer in size and mass) the disruption of the impacted galaxy can be severe, as can be seen below in the image of the Cartwheel Galaxy. These objects are typically called ring galaxies. Another example worth a look at is NGC 4650A.

An an aside, Astroprof had a blog post about our (the Milky Way) not-so-imminent collision with M31 just the day before the Block et al results were released.

Wednesday, October 18, 2006

Fascinating Fungi

The ever interesting Carl Zimmer has a fascinating post up about Fungi. Go read.

[Update: picture from a hike we did in Pennsylvania back in 2003.]

Monday, October 16, 2006

Cosmic Rays and Climate Change: RealClimate's analysis

The always interesting RealClimate blog has an interesting analysis of a paper by Svensmark et al [Svensmark, H., et al, 2006, Proc. Royal. Soc. A., xx, 1364] investigating whether Cosmic Rays can promote low altitude cloud formation, a paper with the snappy title "Experimental evidence for the role of ions in particle nucleation under atmospheric conditions"

The paper itself (go read it) is pretty innocuous and hardly applies their results to anything, but the press release isn't shy about explaining the (supposed) implications:

"A team at the Danish National Space Center has discovered how cosmic rays from exploding stars can help to make clouds in the atmosphere. The results support the theory that cosmic rays influence Earth’s climate."

Here are some more choice bits from the press release:

The experimental results lend strong empirical support to the theory proposed a decade ago by Henrik Svensmark and Eigil Friis-Christensen that cosmic rays influence Earth’s climate through their effect on cloud formation. The original theory rested on data showing a strong correlation between variation in the intensity of cosmic radiation penetrating the atmosphere and the amount of low-altitude clouds. Cloud cover increases when the intensity of cosmic rays grows and decreases when the intensity declines.

It is known that low-altitude clouds have an overall cooling effect on the Earth’s surface. Hence, variations in cloud cover caused by cosmic rays can change the surface temperature. The existence of such a cosmic connection to Earth’s climate might thus help to explain past and present variations in Earth’s climate.

Interestingly, during the 20th Century, the Sun’s magnetic field which shields Earth from cosmic rays more than doubled, thereby reducing the average influx of cosmic rays. The resulting reduction in cloudiness, especially of low-altitude clouds, may be a significant factor in the global warming Earth has undergone during the last century. However, until now, there has been no experimental evidence of how the causal mechanism linking cosmic rays and cloud formation may work.

Its not quite claiming that ALL climate change is due to changes in the Cosmic Ray irradiance, but its not making any attempt to say this might only be a small effect.

If you're interested in a discussion of the physics, and why Gavin at RealClimate isn't buying the PR spin, then go over to RC.

What I'd like to know is who chose to put the emphasis in the press release on climate change? It certainly sounds like it was written by someone who doesn't believe that human activity is responsible for the unprecedented climate change in the 20th century.

Buts its not clear to me as yet that we know who put this spin into the press release.

Within the last year we've seen the case of a unqualified political hack who somehow got a job in the NASA press office editing scientific press releases to reflect his personal beliefs, and attempting to cut of press access to a prominent climate scientist. Perhaps something similar has happened in this case?

Saturday, October 14, 2006

Debate or Denial? What constitutes a valid argument?

I was not going to discuss the Hopkins/Iraqi mortality study recently published in the Lancet (as its methodology is outside my experience in statistics, and there are already a lot of good analyses of the fallacies in the naysayers arguments), but I saw an interesting comment by Zeyad of Healing Iraq (that This ModernWorld had picked up on) that is actually quite a nice explanation of what makes for a real scientific debate verse simple (unscientific) denial:

One problem is that the people dismissing – or in some cases, rabidly attacking – the results of this study, including governmental officials who, arguably, have an interest in doing so, have offered no other alternative or not even a counter estimate. This is called denial. When you have no hard facts to discredit a scientific study, or worse, if you are forced to resort to absurd arguments, such as “the Iraqis are lying,” or “they interviewed insurgents,” or “the timing to publish this study was to affect American elections,” or "I don't like the results and they don't fit into my world view, therefore they have to be false," it is better for you to just shut up.

This is just as true in the physical sciences, e.g. astrophysics, as it is in the medical/social sciences. In astronomy, much of it an observational science, there are as many claims made based on human interpretation of images ("by eye" as we'd say) as there are based on quantitative measurements based on the data.

I've just been mulling over one such issue, which I'll present part of just for fun as to get some real superwind stuff into this blog (and as an antidote to all the complaining about the woes of the space program).

For me the issue is whether the soft X-ray emission in superwinds (which are galaxy sized winds of gas flowing out of star-forming galaxies, I'll do a better into some time later) comes from the stuff drivin the wind itself, or is just a tracer of its interaction with the ambient medium. By way of analogy, think of a dust devil or tornado. What you see in a tornado is only a tracer of the actual thing powering it, you see debris (dust, water vapor, leaves, bits of houses etc) carried along by the motion of the wind - you don't actully see the air molecules themselves.

This image is of a dust devil. Notice how there seems to be more dust a the left and right-hand edges of the devil than in the center? In astronomy we would call this limb-brightened (limb as in edge, not as in arm or leg). If you imagine looking down on the devil from above you might seem an approximately circular structure, with a central circle of nearly clear air (little dust) surrounded by an annulus of dusty air.

Now that was an interpretation based purely on a qualitative argument - I looked at the image and interpreted it based on my scientific experience and came up with an hypothesis based on the dust devil looking (by my eye) to be limb brightened.

But could I test this hypothesis rather more quantitatively? Well, I could construct a mathematical model of the 3-dimensional geometry and distribution of dust, calculate how that would look projected into 2-dimensions (i.e. an image) and compare that to the data (the image).

What if someone said that the dust devil didn't look limb brightened to them? Say they though it was pretty uniformly dusty from left to right and that they though this meant it was uniformly filled with dust. Well, rather than a meaningless he said/she said argument what we'd have to do is measure the amount of dust from left to right [Note: A uniformly filled cylinder would actually appear to have more dust in the center when seen in projection].

Just for fun I've rotated the dust devil image by 5 degrees (to make the dust devil more nearly vertical) and written it out as a FITS file using the gimp, so I can use some standard astrophysical software (the wonderful fv) to probe the image quantitatively. Then I've just taken a horizontal cut accross the evil and plotted the brightness in a X-Y graph. As the dust is brighter than the sky then the image brightness is roughly a measure of the amount of dust.

As you can see the edges are brighter (have more dust) than the center, so this is evidence for limb-brightening. One side is slightly brighter than the other, which tells us there are assymetries in the dust distribution, but to first order its OK just to say its limb-brightened.

In astronomy we often have to compare data taken with difference telescopes at different times, which makes things a bit more complicated. The different telescopes often will differ in sensitivity, in the wavelengths of light they're most sensitive too, and in their spatial resolution (how sharp the images are), not to mention that the astronomical source itself might have actually changed its state in the time between the different observations.

Imagine if we'd taken a picture of the dust devil with a rather blurry camera. Then it would be harder to see evidence for limb-brightening.

Just for fun, here is that image again, now blurred so as to represent a lower spatial resolution observation (I haven't added the noise you'd actually get in a new observation). You can see the same general shape as before, but note that the evidence for limb-brightening is weaker - the peak to trough amplitude (dust devils edges to center) in the profile on the right hand side is much less than the earlier full-resolution image. If I'd blurred the image even more you wouldn't see any evidence for limb brightening. But it doesn't mean it isn't there - in this case by blurring the image we're using an effective spatial resolution too low to be able to test the hypothesis of limb-brightening.

Could we use data from the second camera to argue against the limb brightening seen in the first camera? The answer, which might surprise you, is a qualified yes. Sure the instrument itself might be not as well suited to the question we're trying to anser, but nonetheless if we got really good data we could try to quantitatively compare the two images, if we make sure to accounht for the difference in instrument capability. But you would need to work harder to prove it, you couldn't just say "well, doesn't look limb brightened in our lower resolution data, therefor the interpretation using the better camera is wrong".

Of course, no practising professional scientist would be so lazy as try a flat-out unsubstantiated denial, would they?

Friday, October 13, 2006

Seeing through dust

The Hubble Space Telescope is the public face of astronomy, but despite the beautiful pictures it produces it alone can only show use a tiny fraction of the Universe - specifically those parts that can be seen in the visible part of the electromagnetic spectrum (although its vision does extend into the near ultra-violet and near infra-red, unlike human vision).

But even a small change in the wavelength of light can make a big difference - what appears opaque to the human eye can be completely transparent to IR or X-ray radiation.

Astronomers need telescopes covering the full range of the EM spectrum. Without that coverage, even with a Hubble or JWST, we're really handicapped. Try to image medicine without X-rays, CAT scans, PET, MRIs and just relying on one technique, say ultrasound.

A native Hawaiian was leading a tourist trip up Mauna Kea that I was on last year asked "Why do these astronomers need all these telescopes? Why can't they all just get together and share one?" Its a fair question [particularly if it is your sacred mountain that is being built on] - one answer is one type of instrument can only detect a limited range of wavelengths, and hence you need multiple observatories to be able to cover as much of the spectrum as possible.

If we astronomers were limited to just the optical it wouldn't really save money, it actually be a waste of money as we could not fully understand and make use of the limited data we'd get. Unfortunately the public, and politicians, don't understand this. They tend to think that if they scrap a billion dollar mission they've saved a billion dollars (which can then be spent on a pork-barrel bribes to the public), but in fact they've just reduced the bang-for-buck of the remaining observatories.

As an example of what a small change in wavelength does, compare the picture at the top (the Hubble optical image of the Eagle Nebula) to this one here: a near IR image taken with the VLT ISAAC. I've tried to scale and rotate the VLT image to match the HST image (as closely as is possible by eye).

Seen in the near-IR the once imposing "Pillars of Creation" have half vanished. Look at the left-hand-most pillar, for example. Background stars are visible through the region that appeared almost black in the Hubble image. Only the densest conglomerations of dust and gas still block the background star (IR) light near the tips of the pillars.

In fact it is these dense clumps that create the pillar-like structures by shielding the less-dense gas in their shadow from the destructive UV radiation of the young massive stars in the cluster (they're outside the field of view to the upper right). In between the dense clumps the atomic gas has been photo-dissociated and effectively evaporated away.

Cosmic Chesire Cats in M16

Given the tradition of Friday cat-blogging I thought I should start presenting some astronomical cats. The most famous of which is the one lurking in M16, aka the Eagle Nebula, aka the Pillars of Creation.

The cat visible in the image to the left has an angular size of about 15 arcseconds (lengthwise). M16 is about 2.0+/-0.1 kpc distance from us (about 6500 light years), so the physical size of the structure that looks like a cat is (15/3600) * (pi/180) * 2000 = 0.145 pc long, or very roughly about 2.8e12 miles (say three thousand billion miles) long.

I was reminded about the Eagle Nebula by Gagne et al's (2006) preprint on regarding a Chandra observation of M16. Unfortunately the Chandra X-ray image is rather dull looking (to me) as you don't see the nebula (its only a HII region/PDR, so the temperatures in the gas are too low for X-ray emission) but only the young stars.

The cat's ears are actually tipped by EGGs (Evaporating Gaseous Globules), which either are the same thing as Proplyds, or will evolve into them (there seems to be some argument about this). Proplyds are thought to be young solar systems (maybe with planets, but mainly they're comprised of a very young star still in the process of forming), and M16 is covered in EGGs/proplyds (hence the Pillars of Creation moniker).

Thursday, October 12, 2006

Earth's orbit and extinction patterns in spanish rodents

In a study that is bound to get tons of press, a paper by van Dam et al (published in Nature, I'll add the exact reference later) claims that long-term periodic changes in Earth's oribital tilt "offers a plausible explanation for the characteristic duration of more or less 2.5 million years of the mean species life span in mammals.” They were looking at rodent species, which is odd as naively you'd assume rodents are pretty much impossible to exterminate!

I shall remain skeptical for now. There have been many claims of periodicity in extinction rates over the years, and for pretty much any time scale you can find a similar astronomical timescale, or make one up (e.g. the orbital period of Nemesis, the hypothesized stellar companion of the Sun).

David Raup even wrote a very convincing (but probably wrong) book exploring whether ALL extinctions might be due to astronomical causes.

Correlation does not imply causation, and at present van Dam et al's results are intriguing but not compelling. Much more evidence will be required to prove such a link between orbital variations and species extinction. Still, this will spur more work by people eager to disprove this hypothesis.

Wednesday, October 11, 2006

The Iraqification of Space?

Although it has received little press the US now has a new National Space Policy, replacing one dating back to 1996. Secrecy News has an informative write up that compares the old Clinton and (the non-secret parts of the) new Bush policies.

The new parts of the policy appear to be mix of grandiose objectives ("extending human presence across the solar system") and dangerous unilateralism ("The United States will oppose the development of new legal regimes or other restrictions that seek to prohibit or limit U.S. access to or use of space").

Tuesday, October 10, 2006

Michael Steele may like puppies, but he isn't into the truth

If you live in Maryland you'll probably have seen Ben Cardin's amusing attack ad "Its nice that Michael Steele likes puppies" whether you want to or not. Its taken a while for Steele to respond (perhaps too long for someone who continues to trail Cardin by about ten points in the polls), but tonight I got to see Steele's response... about 3 times in the same ad break.

It contained a rather stunning claim:

"First….Ben Cardin's team hacks into my credit report…steals my Social Security number. Oh yeah: they pled guilty in federal court." These exact lines come from Steele press release about his new ad.

Wow - that sounds bad! Illegal behaviour is definitely not acceptable to me as a liberal, whether or not the person involved shares my political beliefs or not. But is what Steele claims the truth?

The substantive claims in Steele's ad are that:
  1. Operatives working for Ben Cardin obtained Steele's credit report by hacking;
  2. Said operatives stole (i.e. obtained illegally) Steele Social Security number;
  3. and that they plead guilty in federal court to the above deeds.
Steele's press release quotes the Washington Times, which as Sun Myung Moon's propaganda organ is hardly a trustworthy source of information.

Of these three claims it turns out that none of them are actually true. Yes, there is (or was) a scrap of truth in there originally, but its been as heavily distorted as Bush's claims about Iraq. The Washington Post's John Wagner covered the case back in March 2006.

  1. Yes, Steele's credit report was obtained fraudulently, but not by any one on Ben Cardin's campaign. It was instead a researcher working for the Democratic Senatorial Campaign Committee in DC who obtained Steele' credit report without authorization (presumably by using an online service like I presume, the reports don't say how). No nefarious computer "hacking" involved. So charge number one is false.
  2. But what about the stolen (identity theft!) Social Security number? From Wagner's article we find this: "Personal finances were considered fertile territory for researchers looking into Steele, who acknowledged financial difficulties when he ran for statewide office in 2002. Sources familiar with the episode said Steele's credit report was obtained with the use of his Social Security number, which was found on a public court document. [emphasis mine]". So no theft.
  3. OK, but they plead guilty right? Well... the researcher involved plead guilty to a misdemeanor, and the charge will be dismissed in a year. They certainly didn't plead guilty to hacking and theft, as Steele's ad implicitly implies. Neither the DSCC's director of research (who along with the researcher had resigned, in deed the resignations drew the FBI's attention in the first place) nor the DSCC itself were charged.
So Steele's big come-back ad against Cardin is based on total distortions of events that are not tied to Cardin in any way! Great work there you Steele staffers - nothing like incompetence to help your candidate along. You are really helping the GOP lose one of the few seats they stood a vague chance of taking from the Democrats...

But it gets better... Cardin's ad strategy is simply to make Steele look (a) ineffectual (which Steele's puppy ads only help solidify) and (b) like another rubber-stamp republican toadying up to Bush.

So what is Steele's great rejoinder against attacks of this type? What proof will he show of his resolve and independence?

Now he says I'm in the President's hip pocket.

Listen to me Mr. Cardin: I think for myself.

Wow - that was convincing! Remember, Steele is the guy who was happy to criticize Bush when he thought it was off the record, but didn't have the guts (or sense) to stand by it after his comments were released and attributed to him in the press.

[I've just discovered Oliver Willis' excellent blog on Maryland politics, lots of great stuff to read through if you're interested.]

Friday, October 06, 2006

Those old computer monitors were good cat beds

Final Friday cat blogging as a batchelor. This is a 2003-era picture of Macio keeping himself warm on my viewsonic monitor.

Future Airport Hell due to NASA funding woes?

DailyTech has an interesting article on how NASA's current funding problems impact aviation research, such as the next generation of air traffic control (note that NASA itself says there isn't a funding problem).

You might end up stuck in horrendous airport delays in a few years time thanks to Shuttle cost overruns and the Moon/Mars program. Not the kind of social impact we'd like the space program to have eh?

[update - fixed typos]

Tuesday, October 03, 2006

COBE team get Nobel in Physics for verifying the Big Bang

The Nobel Prize committee have made an excellent choice in awarding the 2006 Nobel Prize in Physics to John Mather and George Smoot for their work leading to the NASA COBE (Cosmic Background Explorer) satellite. SciAm has a nice summary of Mather and Smoot's work.

COBE was an Explorer-class NASA mission (*) (i.e. pretty small and low cost compared to HST or Cassini) launched in 1989 that measured the microwave background radiation reaching Earth. This link will take you to a NASA page with more info on COBE.

This radiation arises from warm dust in the Milky Way and also the left over glow of the Big Bang itself, now cooled by the expansion of the Universe to a temperature of about 3 degrees above absolute zero. Detecting this background and showing that it has an almost perfect black body spectrum is pretty much inescapable proof of the Big Bang.

The picture shown here is comes from the COBE data, and shows the separate components to the detected microwave emission:

  • The horizontal structure (top two panels) is emission from the disk of our Milky Way galaxy. Filaments and spurs are also Galactic emission.
  • The blue-ish curvy structure seen in the top image is microwave emission from inter-planetary dust within our Solar system - the curve actually marks the (physically flat) plane of the ecliptic within which the planets orbit (Pluto's orbit is rather inclined away from the ecliptic, which shows you that its formation or history are significantly different from the other planets).
  • The isotropic extra-galactic emission left behind when you remove the previous two components is the T=2.7 Kelvin microwave background left over from the Big Bang, as seen in the bottom panel. The minute variations in the temperature of the background from different parts of the sky also carry cosmologically-important information regarding the shape of space, the mass density of the Universe, and the formation of the first galaxies... stuff WMAP is doing in greater detail now (maybe Chuck Bennett will eventually get a Nobel for his work on WMAP?).
It is good to see astrophysics recognized by the Nobel Prize committee. Historically astronomers have received a much smaller fraction of Nobel prizes in Physics than they probably should have given the contribution of astronomy to our understanding of the Universe.

(*) There are several types of Explorer class missions, e.g small (SMEX), medium (MIDEX) and so on. There have been significant changes to the classes of space mission NASA funds since the new Moon/Mars push was imposed, but I'll have to look up the details.

Monday, October 02, 2006

The speed of sound in an ideal gas

Reading through today's astronomy preprints on astro-ph I couldn't help but notice one of my pet peeves: the wrong speed of sound!

For an ideal gas, assuming adiabatic compression, a sound wave travels at a speed c_s = sqrt(gamma*pressure/density), where gamma is the ratio os specific heats at constant pressure and constant volume (gamma=5/3 for a monatomic gas).

So for a typical astrophysical plasma with a temperature of T=1,1604,500 Kelvin (kT=1 keV) the sound speed is 511 km/s (the speed of sound in air at STP is about 0.3 km/s). Yet its not uncommon to see the speed of sound for this temperature given as being around 300 km/s. Why the big difference?

Its because many astronomers simply insist on using the isothermal speed of sound, c_s_iso = sqrt(Pressure/density), i.e. ignoring the gamma.

What exactly is the difference?

The isothermal speed of sound is valid in conditions where the period of the distance (i.e. 1/frequency) is long compared to the cooling time of the plasma. You compress the plasma, it heats up adiabatically, but radiation carries the heat away and the plasma cools back the ambient temperature before the next pulse of the sound comes along. Another way of looking at it is that the ratio of specific heats is now ~1.

Basically in any situation where the temperature of the plasma is independent of the density you should use the isothermal sound speed. A good example is an HII region, where the plasma temperature is set by photoionization from the embedded stars.

But if the plasma temperature is not set by an external process and the cooling time is long then then gamma = 5/3 and the isothermal sound speed IS NOT VALID. Yet time after time I see papers always applying the one formula they learnt at grad school (which is typically the isothermal version) irrespective of the actual physical conditions in the plasma. Doesn't anyone actually pay attention to what Spitzer says instead of just using the formulae? Here is Wolfram on the case as well.

OK, I know using the wrong sound speed is not quite as bad a thing as ignoring warnings about increasing terrorist activity and then keeping that information from the 9/11 commission (yes Condi, I mean you), but its still wrong.

[Update] Forgot to add labels to the post.

Cat Astrophysics? Late cat blogging...

Argh! --- I just realized that catastrophysics (catastrophy/astrophysics, get it?) could also be interpreted as cat (as in feline) astrophysics. No wonder I liked the word...

This catastrophy is Karma, sadly still losing badly on kittenwars, rather strangely as she was extra cute as a kitten (I think). Must be Dielbold running the voting...

Thursday, September 28, 2006

Dry Neptunes and Dusty Galaxies's preprint server delivers a bumper crop of interesting papers this morning:

Star-forming galaxies:

  • Murphy et al combine the Spitzer Infrared Nearby Galaxies Survey (SINGS) and the Westerbork Synthesis Radio Telescope to study the nature and origin of Radio-Far Infrared correlation within the galaxies. They find that in the galaxies with the hifger star formation rates the radio emission is dominated by cosmic ray electrons that have diffused less far from their natal star forming regions (i.e. are presumably younger).
  • Hirashita and Hunt find that the the average radio energy emitted per SNR over its radiative lifetime is very different in the active and passive blue compact galaxies SBS 0335-052 and I Zw 18, being roughly tens times higher in SBS 0335052 than in I Zw 18. I would have expected the opposite (as total energy losses per SN should be less for higher supernova rates per unit volume), so I'll have to read this one a bit more carefully...
  • Buat et al compare galaxies selected from far-infra red (FIR) and far-ultraviolet (FUV) surveys (IRAS and GALEX respectively). The luminosity functions of the two samples differ, even in bolometric luminosity, but the bulk of the bolometric luminosity from FUV or FIR-selected galaxies in the local universe is emitted by galaxies with log10 (Lbol/Lsun) ~ 10. They also have specific star formation rates (total star formation rate/galaxy mass) significantly higher than the average SSFR from the optically-selected SDSS sample.

  • Wiktorowicz and Ingersoll consider whether liquid water oceans exist at any level within ice giants like Neptune or Uranus. The answer: probably not (sorry SciFi authors) now (but maybe in the future as it cools. Hot extra-solar neptunes also won't have water oceans unless the lose a lot of their hydrogen and/or helium.
  • Marley et al point out that existing models of gas giant thermal evolution (i.e. how hot they are with time, which translates into how bright they'd be) start off with initial conditions NOT based on modern planet formation models. Correcting this leads to young Jupiters that are fainter than the older predictions.
  • Lecavelier des Etangs (that must be an interesting family history!) considers the evaporation of extra-solar planets by their parent stars. Interestingly the prediction is that the Neptune-mass planets recently found must contain a significant amount of rock (or water, I wonder?) if they're to have survived evaporation for long.
  • Last but not least: X-rays from Jupiter! Branduardi-Raymont et al analyze an XMM-Newton observation of Jupiter. They conclude "The XMM-Newton observations lend further support to the theory that Jupiter's disk X-ray emission is controlled by the Sun, and may be produced in large part by scattering, elastic and fluorescent, of solar X-rays in the upper atmosphere of the planet." What gives me cause for concern (about my science, not theirs) is that the spectra are pretty much indistinguishable from the thermal hot plasma models I fit to the diffuse X-ray emission from star forming galaxies and superwinds.

Friday, September 22, 2006

Torture: not effective

Hidden from view by the superficial media arguments over what how much ill-treatment to allow in the interrogation of suspected terrorists and the sophistry of those "ticking time bomb" arguments is an issue as important as the oft-discussed moral dilemma: is torture effective?

Talking Points Memo points to an old (Dec 2005) Op-Ed in the Washington Post by a former Soviet dissident, Vladimir Bukovsky.

Here is a quick history lesson for John Yoo and other neocons: Before the "Axis of Evil" there was the "Evil Empire." This empire collapsed because of the waste and inefficiency inherent in a totalitarian state (frankly it was doomed from the start, so forget about that BS about the blessed Gipper's being responsible for bringing down Communism). The good reasons for the West opposing the old Soviet Union were because it tortured, killed and oppressed its own people, and frankly wanted to export that brand of inhumanity to other countries.

Back to Bukovsky. As a Soviet dissident who spent over a decade in Soviet prison camps he might just know a thing or two about state-implemented torture, and his argument (one echoed by many western intelligence experts) is that torture simply isn't effective. Worse than that: Its not going to save lives, if anything its going to exacerbate problems within the US intelligence gathering apparatus.

[What has this got to do with astrophysics? Nothing. But even purely as exercise of reason this dimension of the issue is something that should be asked and answered. Not to mention that this is probably the most pressing moral issue facing the Western world, so it deserves at least one post in this blog]

Friday cat blogging: Piper

20 lbs of pure male catness: Piper, aka Pooper, when he is being bad.

Too much emphasis on manned space flight (?)

The current WH-ordered emphasis on manned space flight is not capturing the (liberal) public imagination, at least in terms of DailyKos readers. As of 11am EST (with 203 votes) 54% think more emphasis should be placed on unmanned missions (you know, the ones that actually produce useful results and also cost vastly less than manned mission).

This is from DarkSyde's science friday article, which is is pretty damn clear as to the cost/benefit outcomes of manned missions (the shuttle, the international space station) and unmanned missions (e.g. Hubble, Cassini).

What is a little disturbing (at least to me) is that despite his rather clear discussion 16% believe the current balance (i.e. running NASA's science capability into the ground) is acceptable, and 26% believe more manned space flight should be done.

Just for fun lets basically recap the facts, the numbers are rough but are qualitatively correct:

International Space Station:

  • Reason for construction: Congress, after deciding GHWB's Mar's plan was too expensive.
  • Total cost: $100 billion dollars?
  • Unique science accomplished: None. Microgravity experiments can be done on planes.
  • Unique advances/development of space technology: ?

Space-based (unmanned) observatories: example, the Hubble Space Telescope
  • Reason for construction: Scientific need to determine the expansion rate of the Universe (the Hubble Constant) by detecting Cepheid variables in galaxies further away than possible with any ground-based observatory.
  • Total cost: At about $5 billion HST is one of the most expensive science missions of the last 2 decades.
  • Unique science accomplished: Determined Hubble constant, distant SNe show Universe is expanding, presence of Dark Energy, deepest observations of the Universe to date, etc etc.
  • Unique advances/development of space technology: Multiple successful upgrades performed in space by astronauts.
The problem, and the cause of wasted tax-payer money, is not manned space flight itself, it is any form of space mission driven by narrow political or financial reasons. NASA does (did?) science well because missions were chosen based on apolitical scientific need as prioritized by the entire scientific community.

Thursday, September 21, 2006

A planet burnt beyond recognition

The two bright stars right at the center of this image form the binary star system ADS 16402. Binary star systems are common, maybe even to the extent that the majority of stars are part of a binary.

What makes ADS 16402 particularly interesting is a discovery announced only a few days ago. ADS 16402 b (the star on the left of the two) has a planet. What is even more astounding is that it was discovered using a network of telescopes little bigger than a SLR camera: HATnet.

Extra-solar planets (planets outside of our own Solar system) are nothing new. Starting with the first robust discovery a decade ago there are now 206 extra-solar planets known to astronomy (as of today, visit the Exoplanets Encyclopedia to find the latest details). Most are Jupiter-like gas giants.

This planet, named HAT-P-1b, is nevertheless something special. It weighs in at about half of Jupiter's mass, but its radius is approximately 40% larger than Jupiter's. Put those two things together and you have a planet with a density of ~0.4 g/cc, i.e. its less dense than water.

So what you might say? Well, this is an unusually low density for a planet, in fact standard planetary structure theory would say you can't have a gas giant planet with such a low density.

The figure on the right comes from the discovery paper of HAT-P-1b (Bakos et al 2006, E-print: astro-ph/0609369). Its a plot of the mass vs radius for the known exo-planets, and its clear that HAT-P-1b and the similarly weird HD 209458b are well outside the norm.

Why is HAT-P-1b so weird? Well, it orbits very close to its parent star. Its average distance from its star is only 5% of the distance between the Earth and the Sun, and about 1% of the distance between Jupiter and the Sun. This itself is not that unusual: many giant exo-planets, in particular the first ones to be found, orbit close to their stars despite having almost certainly formed much further out (which is a fascinating topic in its own right).

One possibility to explain the bloated puffed up nature of HAT-P-1b is that its being cooked by its parent star. IF some fraction of the stellar energy falling on the planet gets transported deep down in the atmosphere then the atmosphere could be puffed up. Its not enough just to heat the very surface layers though. This is a cool-sounding idea, and I liked the idea enough to title this post along those lines (paraphrasing from a Mentallo & the Fixer album). However the problem is that other close-in exo-planets aren't puffed up.
What are the other options? Tidal heating, either from an eccentric orbit, or from a Cassini State (its rotation axis lying close to its orbital plane, unlike the Earth where they're about 90 degree apart), might heat the planets interior sufficiently to alter the atmosphere drastically enough. But these hypotheses, as Bakos et al write, are "ad hoc; they require unusual circumstances for which there is no independent evidence." Ad hoc solutions are bad form in science, as they so often turn out ot be wrong.

So the mystery of HAT-P-1b remains, for now.

Wednesday, September 20, 2006

SciAm review of Owen Gingerich's book

The September 2006 issue of Scientific American has a review of Prof. Owen Gingerich's new book: "God's Universe". Owen Gingerich is or was an Astrophysicist and still is a noted Historian of Science at Harvard - previously mentioned in this blog regarding the Pluto redefinition furore.

Scientists write popular books all the time, but this one is likely to have a different readership from the average popular science book, and get a bit more press too. Why? Well, Prof Gingerich is one of the approximately 40% of scientists who manage to reconcile holding spiritual beliefs while still practicing the methodological/philosophical naturalism required for science. He is part of the smaller (sub)set holding theistic religious beliefs (i.e. believes in God).

Shame on him for violating the stereotype of souless atheistic scientists fiendishly plotting the moral and metaphysical downfall of the West, or whatever it is we're supposed to be doing. I forget now, must have deleted the last memo from SASFPTMAMDOTW from my inbox.

This kind of thing, the apparent oxy-moron of a religous scientist, really gets the media excited. NPR happily interviews Francis Collins (human genome project, whose book is also reviewed in the same SciAm article), in fact just about anyone who appears to break the science vs. religion theme perpetuated by the media seems to be of great interest to the same media. What is annoying is the implicit appeal to authority inherent in such attention: "Tell us about your religious beliefs o wise one. How tolerant and open minded you must be compared to your non-religious fellow scientists."

Why should we view a scientist Joe OverEductated reasons for believing supernatural thing X any more seriously than Joe Redneck's reasons for believing supernatural thing X?

And is Joe OverEducated's vision of what God is anything like Joe Rednecks. Deism, probably the most common form of religious belief by scientists, is so far from your average Southern Baptist's view of Christianity as to be irreconcilable. Yet all these cases of religious scientists are inevitably portrayed as support for Christianity (yes, some fraction are Xtian, but they're can hardly be a majority). I feel that if these interviewers did their job properly and actually probed these issues maybe we'd see less enthusiam for this sort of religious apologetics.

Hopefully our library will get a copy so I'll be able to read Gingerich's book myself, but in the mean time I'll content myself with a few choice quotes from George Johnson's review in SciAm.

... its premise survives: that there are two ways to think about science. You can be a theist, believing that behind the veil of randomness lurks an active, loving, manipulative God, or you can be a materialist, for whom everything is matter and energy interacting within space and time. Whichever metaphysical club you belong to, the science comes out the same.

In the hands of as fine a writer as Gingerich, the idea almost sounds convincing. "One can believe that some of the evolutionary pathways are so intricate and so complex as to be hopelessly improbable by the rules of random chance," he writes, "but if you do not believe in divine action, then you will simply have to say that random chance was extremely lucky, because the outcome is there to see. Either way, the scientist with theistic metaphysics will approach laboratory problems in much the same way as his atheistic colleague across the hall."

Mmmh, thats not promissing - sounds like the standard "materialism is just as much a matter of faith as religion" argument.

The reviewer, moving onto Francis Collin's book which employs a very similar rhetorical devices, remains firmly grounded in reason:

But what sounds like a harmless metaphor can restrict the intellectual bravado that is essential to science. ... Whether they are right or wrong is not a matter of belief but a question to be approached scientifically. The idea of an apartheid of two separate but equal metaphysics may work as a psychological coping mechanism, a way for a believer to get through a day at the lab. But theism and materialism don't stand on equal footings. The assumption of materialism is fundamental to science.