On Reading Potter’s You Are Here

Another book I read and enjoyed recently was by Christopher Potter: You Are Here : A Portable History of the Universe (New York : HarperCollinsPublishers, 2009; 194 pages). Here is my book note.

Potter said he wanted to write the book he wanted to read but no one had ever written. Great idea! His saying that made me think that it was not a book I would have (or could have) written, but that’s a good thing. The book is appealing and the ideas presented very thoughtfully, so I think it could certainly reach an audience that other books don’t speak to. How to tell? I don’t know whether there’s any alternative to reading some of it to see whether it works for you.

Anyway, there were, as usual, a couple of left-over excerpts. This first one is a very telling point that doesn’t much get discussed.

Einstein’s famous theory, the one known as the special theory of relativity, first appeared in 1905 in a paper entitled ‘On the Electrodynamics of Moving Bodies’. It was the German physicist Max Planck (1858—1947) who renamed the theory, though Einstein thought the word relativity was misleading and would have preferred the word invariance instead, a word that has the opposite meaning. [p. 87]

I don’t know that I would exactly say it has the “opposite meaning”, and even if it does have an opposite meaning, it doesn’t refer to the same concept that “relativity” does. However, calling it “invariant” would have been a good, if inscrutable, idea.

“Invariant” means just what it sounds like it means in physics as well as English, something unchanging. But it is used in physics and math to refer to things that don’t change specifically when other things are changed, or transformed.

Special relativity provides one of the best examples of something that it physically invariant, too: the speed of light. If all the laws of physics were to “look the same” in various inertial reference frames (see the film “Inertial Reference Frames“), or under transformation to different inertial reference frames, then the speed of light must be the same, or invariant, in all of those frames. The invariance of the speed of light is the central concept of Einstein’s 1905 theory “On the Electrodynamics of Moving Bodies”. “Electrodynamics” because that is the “classical” theory of moving charged particles, which, as we saw in the most recent “Beard of the Week“, is identical with Maxwell’s theory of electromagnetic radiation / light.

This next excerpt I thought was a fair and concise summary of Bishop James Ussher’s contribution to the idea stream about the age of the Earth, and as the darling of young-Earth creationists.

In his Annals of the Old Testament, published in 1650, the Archbishop of Armagh, James Ussher (1581—1656), had worked out a chronology of Creation. In a supplement to this work published in 1654 he calculated that Creation had occurred on the evening before Sunday 23 October 4004 BC, a date that does not differ much from the attempts of others, from at least the time of the Venerable Bede (c.672—735), to set a date for Creation. Ussher is today often taken for a fool, but he was a greatly respected scholar of his time, known throughout Europe. According to some biblical scholars, the reign of man was meant to last no more than 6,000 years, taking as evidence a line from the Book of Peter: ‘One day is with the Lord as a thousand years, and a thousand years as one day’ (2 Peter 3:8). Creation, which began around the year 4000 BC, was set to end 6,000 years later. today, we believe that in 4000 BC the wheel was being discovered in Mesopotamia. Ussher’s date was inserted into the margins of editions of the King James Bible from 1701. It is to this version of the bible that fundamentalists have their curious relationship. [p. 212]

Magnets & Relativity

This^* is Scottish physicist James Clerk Maxwell (1831–1879). He did significant work in several fields (including statistical physics and thermodynamics, in which I used to research) but his fame is associated with his electromagnetic theory. Electromagnetism combined the phenomena of electricity and magnetism into one, unified field theory. Unified field theories are still all the rage. It was a monumental achievement, but there was also a hidden bonus in the equations. We’ll get to that.

He published his equations in the second volume of his A Treatise on Electricity & Magnetism, in 1873. I think we should look at them because they’re pretty; I suspect they’re even kind of pretty regardless of whether the math symbols convey significant meaning to you. There are four (which you may not see in Bloglines, which doesn’t render tables properly for me):

	;
	;

I don’t want to explain much detail at all because it’s not necessary for what we’re talking about, but there are a few fun things to point out. The E is the electric field; the B is the magnetic field.

The two equations on the top say that electric fields are caused by electric charges, but magnetic fields don’t have “magnetic charges” (aka “magnetic monopoles”) as their source. The top right equation gets changed if a magnetic monopole is ever found.

The two equations on the bottom say that electric fields can be caused by magnetic fields that vary in time; likewise, magnetic fields can be caused by electric fields that vary in time. These are the equations that unify electricity and magnetism since, as you can easily see, the behavior of each depends on the other.

There’s one more equation to look at. A few simple manipulations with some of the equations above lead to this result:

This equation has the form of a wave equation, so called because propagating waves are solutions to the equation. Maxwell obtained this result and then made a key identification. Just from its form the mathematician can see that the waves that solve this equation travel with a speed given by , which is related to the product of the physical constants and that appeared in the earlier equations.

The values of these were known at the time and Maxwell made the thrilling discovery that this speed

was remarkably close to the measured value of the speed of light. He concluded that light was a propagating electromagnetic wave. He was right.

That’s fine for the electromagnetism part. What’s the relationship with relativity? Let’s keep it simple and suggestive. You know from the popular lore that Einstein came up with the ideas of special relativity from thinking about traveling at the speed of light, and that the speed of light (in vacuum) is a “universal speed limit”. Only light — electromagnetic waves or photons depending on how your experiment is measuring it/them — travels at the speed of light.^†

In fact, Einstein’s relativity paper (published as “Zur Elektrodynamik bewegter Körper”, in Annalen der Physik. 17:891, 1905) was titled “On the Electrodynamics of Moving Bodies”. (Read an English version here; there are no equations at the start, so read the beginning and be surprised how familiar it sounds.) That’s suggestive, don’t you think?

Speaking of special relativity, you’ve no doubt heard of the idea of an “inertial reference frame”, a concept that is central to special relativity. But, what exactly is an “inertial reference frame”?

I’m so glad you asked, since that was half the point of this post anyway. You surely realized by this time that Maxwell was partly a pretext. For our entertainment and enlightenment today we have educational films.

First, a quick introduction to the “PSSC Physics” course. From the MIT Archives:

In 1956 a group of university physics professors and high school physics teachers, led by MIT’s Jerrold Zacharias and Francis Friedman, formed the Physical Science Study Committee (PSSC) to consider ways of reforming the teaching of introductory courses in physics. Educators had come to realize that textbooks in physics did little to stimulate students’ interest in the subject, failed to teach them to think like physicists, and afforded few opportunities for them to approach problems in the way that a physicist should. In 1957, after the Soviet Union successfully orbited Sputnik , fear spread in the United States that American schools lagged dangerously behind in science. As one response to the perceived Soviet threat the U.S. government increased National Science Foundation funding in support of PSSC objectives.

The result was a textbook and a host of supplemental materials, including a series of films. In a discussion I was reading on the Phys-L mailing list recently, the PSSC course was discussed and my attention was drawn to two PSSC films that are available from the Internet Archive: “Frames of Reference” (1960) and “Magnet Laboratory” (1959). (Use these links if the embedded players below don’t render properly.) Both are very instructive and highly entertaining. Each lasts about 25 minutes.

Let’s look first at the film on magnets; it’s quite a hoot. First, the background: when I was turning into a physicist I knew some people who went to work at the “Francis Bitter National Magnet Lab” (as it was known at the time) at MIT. This was the place for high-field magnet work.

Well, this film is filmed there when it was just Francis Bitter’s magnet lab, and we’re given demonstrations by Bitter himself, along with a colleague, not to mention a tech who runs a huge electrical generation and is called either “Beans” or “Beams”–I couldn’t quite make it out. These guys have a lot of fun doing their demonstrations.

At one point in the film we hear the phone ringing. Beans calls out: “EB [?], you’re wanted on the telephone.” Bitter replies, without losing the momentum on his current demonstration, “Well, tell ‘em to call me back later, I’m busy.” Evidently multiple takes were not in the plan.

This is great stuff for people who like big machinery and big electricity and big magnets. Watch copper rods smoke while they put an incredible 5,000 amps of current through them. I laughed when Bitter started a demonstration: “All right, Beans, let’s have a little juice here. Let’s start gently. Let’s have about a thousand amps to begin with.” Watch as they melt and then almost ignite one of their experiments. It evidently happened often enough, because they have a fire extinguisher handy.

This next film on “Frames of Reference” is a little less dramatic, but the presenters perform some lovely simple but clever and illustrative experiments, demonstrations that would almost certainly be done today with computer animations so it’s wonderful to see them done with real physical objects. After they make clear what inertial frames of reference are they take a look at non-inertial frames and really clarify some issues about the fictitious “centrifugal force” that appears in rotating frames.

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^* The photograph comes from the collection of the James Clerk Maxwell foundation.

^† Duh.

On Reading The Age of Entanglement

Reading proceeds apace, but writing about the books seems to happen in big clumps. For instance, my book note on Louisa Gilder’s The Age of Entanglement : When Quantum Physics was Reborn (New York : Alfred A. Knopf, 2008. xvi + 443 pages). Perhaps if I wrote less I could write sooner.

Oddly, I didn’t realize how much I had enjoyed the book until I wrote about. I found it quite engaging and, despite the author’s defensiveness about writing narrative nonfiction (and her queasiness cause me a bit of queasiness at first), I thought it was not only engaging but high in scienticity. She’s done a very careful and thorough job with keeping her science precise, and I thought she showed quite a depth of understanding in what is described as her first book.

From my collection of quotations noted but unused in the book note, this one about the distinction between a theoretical physicist and an experimental physicist. It’s pretty much true, but a bit of reflection makes it unsurprising.

“How do you tell an experimental physicist from a theorist?” asks [experimental physicist John] Clauser more than thirty years later, in his northern California desert home encrusted with sailing trophies and plaques. Running his finger along the thick spines of schoolbooks, he beings to answer his question: “A ”theorist” will have: lots of textbooks (the experimentalist will have some engineering ones, too).” He taps these with his finger. “Lots and lots of ”Phys. Rev. Letters.”” In fact, a bookshelf taking up a whole wall is crowded with the pale green journals. “Biographies of the great, and books written by them.” Clauser gestures through the door of his wood-paneled office. “But the ”experimentalist” will have”—he turns: here, in the hallway beside the kitchen door, is another floor-to-ceiling bookshelf, packed with rows and rows of narrow, shiny softcover book spines in garish fluorescent colors—””catalogues.”” He grins. “Anything I need to make, if I don’t have the pieces already, I look for it here. I can make anything.” [pp. 260—261]

Up, Up, Up and Away

These are Les Frères Tissandier,^* the brothers Albert Tissandier (1839-1906) on the left, and Gaston Tissandier (1843-1899). Albert was the artist, known as an illustrator, and Gaston was the scientist and aviator.^†

The Tissandier Brothers were pioneering adventurers (only Gaston did the flying) in high-altitude balloon ascensions. From the U.S. Centennial of Flight Commission’s “The Race to the Stratosphere“:

During the nineteenth century, balloonists had blazed a trail into the upper air, sometimes with tragic results. In 1862 Henry Coxwell and James Glaisher almost died at 30,000 feet (9,144 meters). Sivel and Croc.-Spinelli, who ascended in the balloon Zénith in April 1875 with balloonist Gaston Tissandier, died from oxygen deprivation. The last men of the era of the nineteenth century to dare altitudes over 30,000 feet (9,144 meters) were Herr Berson and Professor Süring of the Prussian Meteorological Institute, who ascended to 35,500 feet (10,820 meters) in 1901, a record that stood until 1931.

The first men to reach 30,000 feet (9,144 meters) did not know what they were facing. It is now known that at an altitude of only 10,000 feet (3,048 meters), the brain loses 10 percent of the oxygen it needs and judgment begins to falter. At 18,000 feet (5,486 feet), there is a 30 percent decrease in oxygen to the brain, and a person can lose consciousness in 30 minutes. At 30,000 feet (9,144 meters), loss of consciousness occurs in less than a minute without extra oxygen.

About that harrowing experience, here is Gaston’s account from his autobiography: Histoire de mes ascensions: recit de vingt-quatre voyage aériens (1868-1877).^‡

I now come to the fateful moments when we were overcome by the terrible action of reduced pressure (lack of oxygen). At 22,900 feet torpor had seized me. I wrote nevertheless, though I have no clear recollection of writing. We are rising. Croce is panting. Sivel shuts his eyes. Croce also shuts his eyes. At 24,600 feet the condition of torpor that overcomes one is extraordinary. Body and mind become feebler. There is no suffering. On the contrary one feels an inward joy. There is no thought of the dangerous position; one rises and is glad to be rising. I soon felt myself so weak that I could not even turn my head to look at my companions. I wished to call out that we were now at 26,000, but my tongue was paralyzed. All at once I shut my eyes and fell down powerless and lost all further memory.

He lost consciousness and their balloon ultimately descended while he was unconscious. When he awoke it was to find his two companions dead.

Gaston wrote quite a number of books, over 17 according to his Wikipedia entry. The majority are about ballooning, but it seems that he also had a passion for photography, which was then in its infancy. In fact, several of his titles appear to be in print, including A History and Handbook of Photography.

From Project Gutenberg, two books by Gaston Tissandier are available:

• En ballon! Pendant le siege de Paris (link)
• La Navigation Aérienne L’aviation Et La Direction Des Aérostats Dans Les Temps Anciens Et Modernes (link)

For photographic entertainment, visit this site at the Library of Congress Tissandier Collection of 975 photographs, etchings, and other images emphasizing the early history of ballooning in France; about half of the images are digitized and online.

Finally, because I love research librarians, here is the Library of Congress’ Tracer Bullet on “Balloons and Airships“.
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^* Crédit photo: Ministère de la Culture (France), Médiathèque de l’architecture et du patrimoine (archives photographiques) diffusion RMN / Référence: APNADAR022912 / Photograph by the studio of Nadar / source link.

^† You may have detected the buoyant-flight theme that has preoccupied BoW for a couple of weeks. It’s because I recently read the very enjoyable Lighter than Air : An Illustrated History of Balloons and Airships, by Tom D. Crouch (Baltimore : Johns Hopkins University Press, in association with the Smithsonian National Air and Space Museum, 2009; 191 pages). My book note is here.

^‡ From Indiana University’s Lilly Library, an online exhibit called “Conquest of the Skies: A History of Ballooning“, provides a chance to see images from Gaston Tissandier’s book Histoire de mes ascensions: recit de vingt-quatre voyage aériens (1868-1877) (“History of my [balloon] ascensions : accounts of 24 aerial trips”).

Zeppeliner

This is Ludwig Dürr (1878–1955), remembered as the chief engineer who built the successful Zeppelin airships.

After an unsatisfactory one-year period in the navy, Dürr was hired, on 15 January 1899, as an engineer at Luftschiffbau Zeppelin GmbH, the company that had been formed by Count Ferdinand Graf von Zeppelin to build rigid, hydrogen-filled airships. While working at their design offices in Stuttgart he completed his last semester of the Royal School of Mechanical Engineering, took his final exams, then Immediately went back to work for Count Zeppelin, moving to the company’s new location in Friedrichshafen, in southwest Germany on the north shore of Lake Constance (“Bodensee” ).

Zeppelin’s company, in the beginning, was beset with difficulties raising money and avoiding disaster. The first dirigible, known as LZ 1 (LZ = “Luftschiff Zeppelin” or “Zeppelin Airship”), at 420 feet long and 32.8 feet in diameter (the largest thing ever built to fly at that time), the airship proved underpowered and hard to manage in strong winds. Bad publicity meant no hoped-for government funding. LZ 1 was broken up for scrap and the company dissolved.

However, Zeppelin kept Dürr around. A few years later King Karl of Württemberg lent his support and Zeppelin, with Dürr as his chief engineer, set out to build LZ 2. This new ship was the same size as LZ 1 but had more power engines (provided by Daimler, as before). It was launched in January1906 from its floating hanger on Lake Constance, as seen in this photograph.

Unfortunately, LZ 2 was also difficult to maneuver in strong winds, but Zeppelin and his crew managed an emergency landing when an engine failed. While they celebrated their safe landing, LZ 2 was destroyed by a storm.

LZ 3, launched that October, flew several flights successfully, but the government wasn’t terribly impressed yet. They gave him money to continue some work, promising to buy LZ3 and LZ 4, provided the latter could stay in the air for 24 hours.

In August 1908 the new airship was taken for a flight up the Rhine Valley. Again, engine failure forced the dirigible down. A storm came along, blew the nose of the ship into a stand of trees, and a hole tore in the gas bags. Rubberized material, flapping the wind, generated a spark that ignited escaping hydrogen and LZ 4 went up in flames.

Now the indefatigable Zeppelin finally felt like the time had come to give up. But then, what happened?

Prepared at last to accept defeat, the seventy-year old Count was stunned by the public outpouring of support that would be remembered as “the miracle of Echterdingen.” Almost without his noticing it, the Count, who had persevered in the face of overwhelming disappointments, emerged as a revered public figure. The old man and his airships decorated a wide range of consumer items, from children’s candies to ladies’ purses, hair brushes, cigarettes and jewelry cases. Copies of the soft white yachting cap that was the Count’s sartorial trademark were sold in stores across Germany, along with an assortment of items from toys to harmonicas bearing Zeppelin’s image. Schools, streets and town squares were renamed in his honor. And now, in his time of greatest need, the German people came to the support of the Count.

In an age of rampant nationalism, Germans looked to the Zeppelin airship as a symbol of national pride. From the Kaiser to the youngest schoolchild, Germans dispatched money to the Count, the sum eventually reaching 6.25 million marks. Those who could not afford to make a cash contribution sent farm products, home-made clothing, anything they thought might help. The ill-fated flight of LZ 4 up the Rhine, Zeppelin would later remark, had been his “luckiest unlucky trip”.

[Tom D. Crouch, Lighter Than Air: An Illustrated History of Balloons and Airships (Baltimore : The Johns Hopkins University Press, 2009), p. 83.]

Zeppelin reformed his company, still with the loyal Dürr as chief engineer, and this time success was theirs and Zeppelin’s name is etched in popular history.

Dürr’s name is not quite so well known as Zeppelin’s, but he’s not forgotten. I was delighted to discover that there is a school in Friedrichshafen named in his honor — the Ludwig-Dürr-Schule — where they are justifiably quite proud of their namesake. Here is the google translation of the page “How has our school its name?” that I’ve enjoyed reading. Visit the welcome page and you can also see the staff plus the menus for lunch.

On the subject of zeppelins, here is a nice, short history by the US Centennial of Flight commission.

There is a Zeppelin Museum in Friedrichshafen. Among many interesting exhibits there is a reconstruction of the passenger areas of the LZ 129 Hindenburg, which famously burst into flames and crashed during landing in Lakehurst, New Jersey on 6 May 1937, killing 35 of the 97 passengers and crewmen aboard. The tragedy brought an end to the practice of filling lighter-than-air ships with highly flammable hydrogen.

Luftschiffbau Zeppelin GmbH is now known as Zeppelin Luftschifftechnik GmbH (in English), and they still build zeppelins. I read that, in conjunction with Airship Ventures, Inc., one of their new zeppelins is making commercial, mostly sightseeing, flights near San Francisco.

Finally, some visual dessert.

• This page has a nice collection of images of zeppelins in world stamps.
• This page, thanks to the generosity of the grandmother of one Charlie Grant, offers a collection of newspaper clippings about the Hindenburg and its tragic end.