Fabry, Perot, and their wonderful interferometer (1897, 1899)

This is my entry for the fifth edition of The Giant’s Shoulders, to be held at Podblack Blog on November 15th.

By the late 1800s, physicists had begun a serious study of the structure of the atom.  The best tool for such studies, indeed pretty much the only tool in that pre-quantum era, was a spectroscopic analysis of the light emitted/absorbed by the atom.  Each species of atom radiates light at its own distinct, discrete set of frequencies (‘spectral lines’), and knowledge of these frequencies could be used, for instance, by astronomers to determine the chemical composition of distant stars.

Devices which could be used to analyze the spectral content of a light field in that era were, however, limited.  Like a far-sighted person trying unaided to read the fine print of a newspaper, the spectroscopes of the time were limited in how well they could distinguish (‘resolve’) very closely-spaced spectral lines.  Researchers needed a device which could outperform existing techniques, such as the use of a diffraction grating or a Michelson interferometer.

In 1897, Charles Fabry and Alfred Perot introduced a new interferometric device which would eventually bear their name: the Fabry-Perot interferometer.  The design of the interferometer is, in principle, simplicity itself: light is passed through a pair of parallel, highly reflecting mirrors.  Interference between components of the light undergoing multiple reflections result in extremely well-defined interference fringes emerging from the device, from which spectral properties of light can be deduced.

Fabry and Perot published a large number of papers on their interferometer, including 15 joint articles between 1896 and 1902.  The first of these articles dealt with the theory of the interferometer and applied it to the accurate measurement of very small distances, while the second described the apparatus in detail and applied it to spectroscopy.

In this post, we discuss the scientists, their interferometer, the results of their first few papers, and the impact the F-P interferometer has had on physics in general.

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Posted in History of science, Optics, Physics | 12 Comments

History of science at ScienceOnline ’09!

I should mention that I’ve been asked to help lead a discussion at ScienceOnline ’09 about the History of Science and blogging, along with the excellent bloggers Scicurious, Brian Switek, and John McKay.  ScienceOnline ’09 is the third-annual scienceblogging conference, to be held in January.  I’m delighted to be participating and sharing the session with such excellent bloggers!

A wiki page has been started to get the discussion going before the meeting.  Taking a cue from Brian, let me ask the readers here: is there anything in particular that you think should be covered in a History of Science and blogging discussion?  I can definitely give an impassioned argument as to why I think it is important, and also give oodles of tips about what I do to prepare a science history post, but I’d be interested to hear what other people might think are important topics to cover.

Posted in Science news | 3 Comments

A brief political observation

I went to Best Buy to buy my DVD copy of the fourth Indiana Jones movie, and I passed a major intersection where McCain supporters were standing with “Honk for McCain” signs.  On my way out and back, I was there for perhaps five minutes — and heard two honks.

Posted in Personal | 4 Comments

‘Ultima’ creator takes the ultimate ride!

This is quite cool: Richard Garriott, the millionaire creator of the Ultima series of fantasy role-playing videogames, is now in orbit!  Garriott is one of the board members of Space Adventures Ltd., the space tourism company which has been sending people up to the ISS since 2001.  He blasted off from Kazakhstan in a Soyuz TMA-13 capsule at 3:01 pm EDT today.

It’s no surprise that Garriott would do such a thing: he’s well-known for exceptional antics.  For years, he held elaborate haunted houses at his home, Brittania Manor.

He also deserves credit for making one of the first truly literary video games, in Ultima IV.  When I first played it years ago, I was incredibly surprised to find that the ‘quest’ was not the destruction of some ultimate evil, but rather the moral perfection of one’s own character!  Ultima IV was the first video game that really made me think about the consequences of one’s actions.

Anyway, best of luck to Garriott during his stay on the ISS and in his return journey!

Posted in Silliness | 1 Comment

Thomas M. Disch’s The M.D.: A Horror Story

My post-doc advisor once suggested that the ultimate sign of a good movie is whether or not it ‘stays’ with you after it’s over.  The same can also be said about good fiction, which will end up haunting the reader long after the last page is turned.

Since I’ve started blogging about horror fiction, I’ve been going back to some of the novels I read when I was much younger, some of which have stayed with me for quite some time.  Recently, I went back to read Thomas M. Disch’s The M.D.: A Horror Story (1991):

The M.D. is one of several novels Disch set in Minneapolis, including The Businessman: A Tale of Terror, The Priest: A Gothic Romance, and The Sub: A Study in Witchcraft. The story itself is one of the oddest you’ll find in horror fiction, containing dark humor, plenty of biting social commentary and, of course, scenes of incredibly nasty horror.  I give a description and some impressions of the novel below.

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Posted in Horror | 7 Comments

4 days until The Giant’s Shoulders #4!

The start of a new month means it’s time for a reminder that there’s 4 days until The Giant’s Shoulders #4, to be held on October 15th at Second Order Approximation.  Entries can be submitted, as always, through blogcarnival.com.  Let’s try and make it a big one!

Posted in General science, Science news | Leave a comment

h-index of 12 and 1,000 comments!

Today marked two milestones related to my scientific career.  First, according to the Web of Knowledge, my ‘h-index‘ finally hit 12!  The h-index (Hirsch number) is a rough measure of both the productivity of a scientist and the impact of his/her research.  It is defined as:

A scientist has index h if h of his Np papers have at least h citations each, and the other (Np – h) papers have at most h citations each.

In my case, an h-index of 12 means that I have 12 papers which have been cited 12 or more times by other scientists.

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Posted in Personal | 1 Comment

Valancourt Books continues its evil plot to free me of my money!

Anyone who’s been reading this blog for a while knows that I’m a big fan of Valancourt Books, especially their excellent reprints of classic works by Richard Marsh.  Well, I’ve been trying to cut back on my book buying recently, and what do they do?  They release a limited-edition volume of some of Richard Marsh’s rarest stories, just in time for Halloween!  Aaargh!

By the way, take a look at the cover of last year’s special edition — there’s something very odd about it — and then read the description!

Posted in Horror | Leave a comment

John McCain: Angry, anti-science miser

As the economic crisis has deepened, McCain’s biggest talking point about the economy has been the proliferation of “earmarks” in government, those state projects that legislators add to Federal budget requests for their home states.   For me, a discussion of earmarks during the current economic crisis has made McCain look incredibly out-of-touch, evenly dangerously so.  After all, as Obama pointed out, earmarks amount to $18 billion, and the current economic crisis will cost at least $700 billion.  McCain sounds very much like a man who, when he sees the wheels coming off his moving car, comments on how the cigarette lighter needs to be fixed.

One comment jumped out at me during the second debate, and I was reminded of it by a post on The Greenbelt; railing against earmarks again, McCain said,

He voted for nearly a billion dollars in pork barrel earmark projects, including, by the way, $3 million for an overhead projector at a planetarium in Chicago, Illinois. My friends, do we need to spend that kind of money?

The problem is, that “overhead projector” that McCain refers to is in fact the primary planetarium projector for the Adler Planetarium in Chicago, the country’s first planetarium, built in 1930.  The Planetarium issued the following statement in response:

To clarify, the Adler Planetarium requested federal support – which was not funded – to replace the projector in its historic Sky Theater, the first planetarium theater in the Western Hemisphere. The Adler’s Zeiss Mark VI projector – not an overhead projector – is the instrument that re-creates the night sky in a dome theater, the quintessential planetarium experience. The Adler’s projector is nearly 40 years old and is no longer supported with parts or service by the manufacturer. It is only the second planetarium projector in the Adler’s 78 years of operation.

Science literacy is an urgent issue in the United States. To remain competitive and ensure national security, it is vital that we educate and inspire the next generation of explorers to pursue careers in science, technology, engineering and math.

Senator McCain’s statements about the Adler Planetarium’s request for federal support do not accurately reflect the museum’s legislative history or relationship with Senator Obama.

So McCain apparently thinks that funding a building that promotes science education is something to be ridiculed.  His statement wasn’t accidental; he’s criticized planetarium funding as “foolish” before.

I couldn’t imagine my respect for McCain sinking any lower than it already had, but his stance that science education for kids is a waste of taxpayer money dropped him into the category of “vile, angry, anti-science miser.”

If I were the Obama camp, I would be hammering the McCain campaign about this:

McCain: science education is “foolish”

Posted in ... the Hell?, Politics, Science news | 4 Comments

Optical coherence tomography and the art world

ResearchBlogging.org
In recent years, scientific tools have been increasingly applied to the study of artwork, for numerous reasons: determination of authenticity, determination of provenance, analysis for restoration, or even for finding ‘hidden’ art buried behind or underneath existing masterworks.  Some time ago, Jennifer at Cocktail Party Physics wrote a fascinating post on the use of X-ray imaging for the latter application.

Around that same time, an entire issue of Applied Physics A was devoted to the “Science and Technology of Cultural Heritage Materials: Art Conservation and Restoration.”  The first paper in the issue is an overview of “Optical coherence tomography in art diagnostics and restoration,” by P. Targowski, B. Rouba, M. Góra, L. Tymińska-Widmer, J. Marczak and A. Kowalczyk.  Though it has been a few months since the paper’s release, I wanted to write a bit about optical coherence tomography and how it is being used in the analysis of artwork.

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Posted in Optics | 2 Comments