Later On

A blog written for those whose interests more or less match mine.

Archive for February 2008

In the days of teaching

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I had a dream about this last night, so thought I’d blog the memory (of the actual events, not the dream).

About 35 years ago, I was teaching at a small private liberal-arts college and was asked to take over a Freshman Math Tutorial at the beginning of their second semester.

A word about class format: the college used the “Great Books Program”, and Freshman math was devoted for about the first two-thirds to the study of Euclid’s Elements (in translation) and then the Almagest of Ptolemy (also in translation). The tutorial consisted of the tutor (in this case, me) and 10-12 Freshmen (co-ed). The tutor’s job was to ask the right questions so that the students, in discussing the answers and thinking about the implications, would develop an understanding of the focus of study.

In studying Euclid’s Elements, there would occasionally be a general discussion, but mostly a student would go to the board and “demonstrate” one of the theorems or constructions: stating the proposition, setting out a diagram and stating what specifically is to be proved or constructed, doing any necessary construction, and then going through the proof. The student demonstrating could be asked questions by the other students (or the tutor): to clarify a step, to explain why something actually followed from what had been said, etc. Questions such as those were common.
Demonstrating the theorems led to a deeper understanding for all, and provided the student doing the demonstration with useful practice in presenting abstract material, answering questions, thinking on his/her feet, etc.

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Written by LeisureGuy

29 February 2008 at 4:22 pm

Posted in Daily life, Education

Solar thermal outpacing solar-voltaic

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Interesting article, which begins:

Investors and utilities intent on building solar power plants are increasingly turning to solar thermal power, a comparatively low-tech alternative to photovoltaic panels that convert sunlight directly into electricity. This month, in the latest in a string of recent deals, Spanish solar-plant developer Abengoa Solar and Phoenix-based utility Arizona Public Service announced a 280-megawatt solar thermal project in Arizona. By contrast, the world’s largest installations of photovoltaics generate only 20 megawatts of power.

In a solar thermal plant, mirrors concentrate sunlight onto some type of fluid that is used, in turn, to boil water for a steam turbine. Over the past year, developers of solar thermal technology such as Abengoa, Ausra, and Solel Solar Systems have picked up tens of millions of dollars in financing and power contracts from major utilities such as Pacific Gas and Electric and Florida Power and Light. By 2013, projects in development in just the United States and Spain promise to add just under 6,000 megawatts of solar thermal power generation to the barely 100 megawatts installed worldwide last year, says Cambridge, MA, consultancy Emerging Energy Research.

The appeal of solar thermal power is twofold. It is relatively low cost at a large scale: an economic analysis released last month by Severin Borenstein, director of the University of California’s Energy Institute, notes that solar thermal power will become cost competitive with other forms of power generation decades before photovoltaics will, even if greenhouse-gas emissions are not taxed aggressively.

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Written by LeisureGuy

29 February 2008 at 2:09 pm

Good article on transitional forms in evolution

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Excellent article in the current New Scientist on the variety and number of “transitional forms” in the fossil record. From the article:

When Charles Darwin published On the Origin of Species in 1859, there was relatively little evidence in the fossil record of evolutionary change. Darwin spent two chapters of his book apologising for the paucity of the fossil record, but predicted that it would eventually support his ideas.

What Darwin was bemoaning was the lack of “transitional” fossils – those with anatomical features intermediate between two major groups of organisms. At the time, such fossils were conceived as “missing links” in the “great chain of being” from lowly corals through higher organisms such as birds and mammals to humans (and ultimately to God).

We now know this is a misconception. Life does not progress up a hierarchical ladder from “low” to “high” but is a branching bush with numerous lineages splitting apart and coexisting simultaneously. For example, apes and humans split from a common ancestor 7 million years ago and both lineages are still around. Similarly, corals and sponges did not vanish when more advanced lineages of worms branched out 600 million years ago.

For this reason the concept of “missing link” is a misleading one. A transitional form does not need to be a perfect halfway house directly linking one group of organisms to another. It merely needs to record aspects of evolutionary change that occurred as one lineage split from another. They don’t even have to be fossils: many living lineages have transitional features.

Darwin’s 1859 prediction that transitional forms would be found was quickly confirmed. In 1861 the first specimen of Archaeopteryx – a classic transitional form between dinosaurs and birds – was discovered, and in the 1870s the iconic sequence of fossil horses was documented. By the time of Darwin’s death in 1882 there were numerous fossils and fossil sequences showing evolutionary change, especially among invertebrates.

Evidence of evolution in the fossil record has vastly increased since then. Yet the idea still persists that the fossil record is too patchy to provide good evidence of evolution. One reason for this is the influence of creationism. Foremost among their tactics is to distort or ignore the evidence for evolution; a favourite lie is “there are no transitional fossils”.

This is manifestly untrue. We now have abundant evidence for how all the major groups of animals are related, much of it in the form of excellent transitional fossils.

Recently palaeontologists have begun to strike back, pointing out the wealth of evidence for evolution in the fossil record and publicising their discoveries when they represent important transitional forms, something that perhaps was lacking in the past. Many examples are provided in my new book, Evolution: What the fossils say and why it matters (Columbia University Press). Just a few of these are given on the pages that follow.

He then reviews the evolutionary record for 10 different collections of species.

Written by LeisureGuy

29 February 2008 at 2:05 pm

Posted in Religion, Science

GOP governance: stall, stall, stall

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A consistent theme emerges from how the GOP approaches solving problems: stall. And keep stalling. Stall through protracted legal tactics. When the court orders action, don’t do it—keep stalling. Stall long enough, and perhaps the problem will go away, or can be dumped on the Democrats (cf. wars in Iraq and Afghanistan).

Also, while stalling, deny, deny, deny. Do whatever is necessary to keep from having to make those denials under oath with a transcript, and continue denying.

Deny and stall: the party’s basic strategy.

Written by LeisureGuy

29 February 2008 at 12:07 pm

EPA tries to explain

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EPA Administrator Stephen Johnson issued a long justification for his Dec. 19 refusal of California’s right to regulate tail-pipe greenhouse gas emissions. The gist of the 47-page explanation is this: because regulating greenhouse gases from vehicles in California won’t substantially affect climate change in California per se, it isn’t covered by the type of waiver that EPA in the past granted California each time it wanted to pass its own environmental regulations. That is, Johnson isn’t saying that greenhouse gases and climate change aren’t a serious problem. And he isn’t saying that California can’t justify its own regulation of other air pollutants—particulates, sulfur dioxide etc—because those California emissions cause harm in California. Whereas whatever harm comes from greenhouse gases harms globally, and thus shouldn’t be regulated locally.

There is some perverse logic to this thinking, but it seems pretty clearly to have been post hoc. The Bush administration has been trying to delay greenhouse gas regulation for seven years. The White House hasn’t cleared EPA’s own regulations, despite being ordered to do so by the Supreme Court last April. Johnson’s aides urged him to grant the waiver or resign, saying it would besmirch his reputation if he refused. But the die was cast long ago. A document released by Sen. Barbara Boxer (D-Ca) this week is particularly revealing. “I think we should assert the existence of preemption [i.e., the EPA’s right to preempt state regulators] and propose to deny the waiver based on absence of compelling and extraordinary conditions.” That was written by EPA political appointee Bill Wehrum—On March 15, 2006.

Written by LeisureGuy

29 February 2008 at 11:57 am

Public opinion on healthcare mandates

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When Medicare was being created in 1964, Ronald Reagan said, “I think we are against forcing all citizens, regardless of need, into a compulsory government program.”

To this day, conservatives continue to resist universal programs. In his 2008 State of the Union address, President Bush once again mentioned private health savings accounts, despite the fact that they may increase the number of uninsured Americans. Sen. John McCain (R-AZ) similarly touts private plans, saying he wants people to “go out and choose their insurer anywhere in America.”

A new poll from NPR, the Kaiser Family Foundation, and the Harvard School of Public Health, however, finds that most Americans reject conservatives’ approach to health care. In fact, the majority of the public supports mandates requiring Americans to purchase health insurance. NPR reports:

When asked whether they would support a broad proposal that would require everyone to get coverage, 59 percent said they would support it. Such a proposal would require employers to provide coverage or pay into a pool. The government would help low-income people get coverage, and insurance companies would be required to take anyone who applies. People who don’t get coverage through one of these channels or purchase it themselves would pay a fine.

Healthcare mandates

As Jonathan Cohn of The New Republic notes, “In a system based on private insurance, a lot of people won’t obtain even affordable insurance without some sort of requirement.” This point is backed up by prominent health care experts such as Columbia’s Sherry Glied and former Clinton administration adviser on Medicare Bruce Vladeck, who have criticized the tactic of scaring Americans into thinking mandates will force them to buy unaffordable health coverage.

For a practical approach to guaranteeing an American right to affordable, quality health coverage, the Center for American Progress has more here.

Written by LeisureGuy

29 February 2008 at 11:56 am

History of the Evolution vs. Creationism controversy

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The Missing Link – a monthly podcast on the history of science, medicine and technology – has just launched a three-episode series on the fascinating history behind the evolution-intelligent design controversy.

Episode 8, just posted at, begins the series with an investigation into how the nature of scientific method has changed over the centuries. Discover at just what point science invented rules that creationism could not follow.

Future episodes will consider topics like Jewish and Catholic responses to the evolution-ID controversy, why the creationism movement waned in the immediate postwar period in America, and how the very word “evolution” might be inadvertently fueling the controversy.

Find more information at

Written by LeisureGuy

29 February 2008 at 11:53 am

Posted in Religion, Science

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