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The Ten Most Beautiful Experiments
 
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The Ten Most Beautiful Experiments [Format Kindle]

George Johnson

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chapter 1
Galileo
The Way Things Really Move
Galileo Galilei, by Ottavio Leoni

It is very unpleasant and annoying to see men, who claim to be peers of anyone in a certain field of study, take for granted certain conclusions which later are quickly and easily shown by another to be false.
—Salviati, in Galileo, Two New Sciences

When you throw a rock, catch a ball, or jump just hard enough to clear a hurdle, the older, unconscious part of the brain, the cerebellum, reveals an effortless grasp of the fundamental laws of motion. Force equals mass times acceleration. Every action results in an equal and opposite reaction. But this ingrained physics is sealed off from the newer, upper brain-the cerebrum, seat of intelligence and self-awareness. One can leap as gracefully as a cat but be just as powerless to explain the inverse square law of gravity.

Aristotle, in the fourth century BC, made the first ambitious attempt to articulate the rules of motion. An object falls in proportion to its weight-the heavier a rock, the sooner it will reach the ground. For other kinds of movement (pushing a book across a table or a plow across a field), a force must be constantly applied. The harder you push, the faster the object will go. Stop pushing and it will come to a halt.

It all sounds eminently sensible and obvious and, of course, is exactly wrong.

What if you place the book on a sheet of ice and give it a gentle shove? It will keep moving long after the impetus is removed. (Asked why an arrow keeps going after it leaves the bowstring, the Aristotelians said that it was pushed along by the incoming rush of air.) Now we know that something set in motion stays in motion until stopped by something else, or worn down by friction. And a one-pound weight and a five-pound weight, dropped at the same moment, will fall side by side to the ground. Galileo showed it was so.

It's entirely predictable that the great debunker of Aristotle-celebrated in a play by Bertolt Brecht, an opera by Philip Glass, and a pop song by the Indigo Girls-would come in for his own debunking. It is doubtful, historians tell us, that Galileo dropped two weights from the Leaning Tower of Pisa. Nor do they believe that he hit on his insight about pendulums-that each swing is of equal duration-while watching a certain chandelier in the cathedral of Pisa and timing it with his heartbeat.

His credentials as a cosmologist have also dimmed under scrutiny. Galileo was the most eloquent advocate of Copernicus's sun-centered solar system-his Dialogue Concerning the Two Chief World Systems is the first great piece of popular science writing-but he never accepted Kepler's crucial insight: that the planets move in ellipses. The orbits, Galileo assumed, had to be perfect circles. Here he was following Aristotle, who proclaimed that while motion on Earth (in the “sublunar” realm) must have a beginning and an end, celestial motion is necessarily circular.

For that to be true and match what was happening in the sky, the planets would have to move not just in circles but in circles within circles-the same old epicycles that had weighed down Ptolemy's geocentric universe. Galileo brushed off the problem. Most disappointing of all, he probably did not, as legend has it, follow his forced apology to the Inquisitors of Rome by muttering under his breath, Eppur si muove, “And yet it moves.” He was no martyr. Knowing he had been beaten, he retired to the solitude of Arcetri to lick his wounds.

Galileo's strongest claim to greatness lies in work he did long before his troubles with the Vatican. He was studying nothing so grand as stars or planets but the movement of simple, mundane objects-a subject far more perplexing than anyone had imagined.

Whether or not the research actually began at the Tower of Pisa hardly matters. He described a similar experiment in his other masterpiece, Discourses Concerning Two New Sciences, completed during his final years of exile. Like the earlier work it is cast as a long conversation among three Italian noblemen-Salviati, Sagredo, and Simplicio-who are try¬ing to understand how the world works.

Salviati is the stand-in for Galileo, and on the first day of the gathering he insists that, dropped simultaneously, a cannonball weighing 100 pounds and a musket ball weighing 1 pound will hit the ground at almost the same time. In an experiment, he concedes, the heavier one did in fact land “two finger-breadths” sooner, but Salviati recognized that other factors, like air resistance, muddied the results. The important point was that the impacts were almost in unison: when the cannonball hit the ground, the musket ball had not traveled just the distance-a single cubit-as common sense would have predicted. “Now you would not hide behind these two fingers the ninety-nine cubits of Aristotle,” he chided,“nor would you mention my small error and at the same time pass over in silence his very large one.” All other things being equal, the speed at which an object falls is independent of its weight.

A harder question was what happened between the time a ball was released and the time it struck the ground. It would pick up speed along the way-everybody knew that. But how? Was there a large spurt of motion at the beginning, or a lot of little spurts continuing all the way down?

With nothing like time-lapse photography or electronic sensors to clock a falling body, all you could do was speculate. What Galileo needed was an equivalent experiment, one in which the fall would be slower and easier to observe: a ball rolling down a smooth, gentle plane. What was true for its motion should be true for a steeper incline-and for the steep¬est: straight down. He had found a way to ask the question.

The year was probably 1604. Three decades later he, or rather Salviati, described the thrust of the experiment:

A piece of wooden moulding or scantling, about 12 cubits long, half a cubit wide, and three finger-breadths thick, was taken. On its edge was cut a channel a little more than one finger in breadth. Having made this groove very straight, smooth, and polished, and having lined it with parchment, also as smooth and polished as possible, we rolled along it a hard, smooth, and very round bronze ball.

A scantling is a piece of wood, and a Florentine cubit was twenty inches, so we can imagine Galileo with a twenty-foot long board, ten inches wide, propping it up at an angle.

Having placed this board in a sloping position, by lifting one end some one or two cubits above the other, we rolled the ball, as I was just saying, along the channel, noting, in a manner presently to be described, the time required to make the descent. We repeated this experiment more than once in order to measure the time with an accuracy such that the deviation between two observations never exceeded one-tenth of a pulse-beat.

Once they had perfected the technique, Salviati went on to explain, they timed how long it took the ball to traverse one-fourth of the track, then two-thirds, then three-fourths. They repeated the experiment with the board set at different slopes-100 measurements in all. These were taken with a simple device called a water clock, essentially an hourglass that parcels out seconds with liquid instead of sand:

We employed a large vessel of water placed in an elevated position. To the bottom of this vessel was soldered a pipe of small diameter giving a thin jet of water, which we collected in a small glass during the time of each descent, whether for the whole length of the channel or for a part of its length. The water thus collected was weighed, after each descent, on a very accurate balance. The differences and ratios of these weights gave us the differences and ratios of the times, and this with such accuracy that although the operation was repeated many, many times, there was no appreciable discrepancy in the results.

The weight of the water was equivalent to the passage of time. Ingenious. But maybe, some modern historians have concluded, a little too good to be true. Reading Galileo's words some three centuries later, Alexandre Koyré, a profes¬sor at the Sorbonne, could barely contain his scorn:

A bronze ball rolling in a “smooth and polished” wooden groove! A vessel of water with a small hole through which it runs out and which one collects in a small glass in order to weigh it afterwards and thus measure the times of descent...What an accumulation of sources of error and inexactitude! It is obvious that the Galilean experiments are completely worthless.

Koyré suspected that there had been no experiment-that Galileo was using an imaginary demonstration with rolling balls as a pedagogical device, an illustration of a law of physics that he had figured out mathematically, through pure deduction, the old-fashioned way. Galileo, it seemed, had been debunked again.

Koyré was writing in 1953. Twenty years later Stillman Drake, one of the leading experts on Galilean science, was sleuthing among the manuscripts in the Biblioteca Nazionale Centrale in Florence when he came across some unpublished pages-entries from Galileo's own notebook.

Galileo was something of a pack rat, and when his notebooks were published around the turn of the twentieth century, the editor, Antonio Favaro, had left out some pages that appeared to be no more than scribbles, a mess of calculations and diagrams that didn't make sense. The pages were apparently out of order, with little clue as to when they had been written or what their author was working on.

Drake was researching a new English translation of Two New Sciences. For three months at the beginning of 1972,he sat in Florence going through 160 pages of the seventy-second volume of Galileo's papers, comparing watermarks and styles of handwriting, restoring the pages to what seemed a sensible order. Among the earliest ...

From Publishers Weekly

Award-winning science writer Johnson (A Fire in the Mind; Strange Beauty) calls readers away from the industrialized mega-scale of modern science (which requires multimillion-dollar equipment and teams of scientists) to appreciate 10 historic experiments whose elegant simplicity revealed key features of our bodies and our world. Some of the experiments Johnson describes have a sense of whimsy, like Galileo measuring the speed of balls rolling down a ramp to the regular beat of a song, or Isaac Newton cutting holes in window shades and scrambling around with a prism to break light into its component colors. Other experiments—such as William Harvey's use of vivisected animals to demonstrate the circulation of blood, and the truncated frogs Luigi Galvani used in his study of the nervous system—remind us of changing attitudes toward animal research. Joule's effort to show that heat and work are related ways of converting energy into motion, Michelson's work to measure the speed of light, Millikan's sensitive apparatus for measuring the charge of an electron: these experiments toppled contemporary dogma with their logic and clear design as much as with their results. With these 10 entertaining histories, Johnson reminds us of a time when all research was hands-on and the most earthshaking science came from... a single mind confronting the unknown. 73 b&w illus. (Apr. 9)
Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.

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Amazon.com: 4.2 étoiles sur 5  31 commentaires
46 internautes sur 48 ont trouvé ce commentaire utile 
3.0 étoiles sur 5 Too brief... 14 juin 2008
Par BangorBill - Publié sur Amazon.com
Format:Relié
Scientists call an experiment beautiful or elegant if it is relatively simple and yields clear results, preferably involving a new discovery on an important topic. All of the experiments described by Johnson meet that criterion. We read brief descriptions of experiments by major scientists such as Galileo, Newton, Lavoisier, Faraday, Michelson, and Pavlov. The author, George Johnson, tells us a little bit about the personalities and the scientific-historical context of the experiments, including brief backgrounds on related work by other scientists. Though the described experiments were important, in some cases the meaning of the results was not fully understood at the time: for example, Galvani's work on animal electricity, where he demonstrated that nerve impulses could be electrically stimulated, but he did not understand that the impulse itself involved electrochemical activity. Seven of the ten chapters are on early experiments in physics. Only three topics are on biology topics, including those on William Harvey and the heart, Ivan Pavlov on conditioned responses, and Galvani on frog-leg twitches. One can always quibble over the selections. Why not make it a dozen beautiful experiments, and include Gregor Mendel on heredity, plus another one from biology or biochemistry?

Johnson's book is brief, with only 158 small pages of text before the notes and bibliography section. Unfortunately, it is too brief. The problem is that several of the experiments are not explained in sufficient detail to enable the non-expert to understand exactly how they were done, and/or why they were done the way they were done, and/or why the results demonstrated what they were claimed to demonstrate. For example, I still don't fully understand how an electromagnet or a cathode-ray tube or Michelson's interferometer work. Nor do I fully understand how Millikan used a cloud chamber to demonstrate the existence of electrons and to measure their electric charge. Johnson includes many drawings of experimental apparatuses, most of them taken from the original published sources. Unfortunately, most of the drawings are not labeled or described well enough to enable the non-expert to understand how the apparatus worked. In some cases it would have been better to create entirely new drawings, similar to those found in most modern introductory physics textbooks.

I like the basic idea of Johnson's book very much. Parts of it were interesting and informative, and I enjoyed learning some personal information about the researchers, such as the fact that Ivan Pavlov was very fond of his research dogs and treated them as humanely as possible. But the author could have done a better job of science education if he had extended the text to, say, only 199 pages, and included better illustrations, in order to make the explanations of the experiments clearer.
39 internautes sur 40 ont trouvé ce commentaire utile 
5.0 étoiles sur 5 A Wonderful Book 22 avril 2008
Par G. Poirier - Publié sur Amazon.com
Format:Relié
In this little book, the author, a seasoned science writer, takes the reader on ten fascinating adventures into the world of science. Each adventure focuses on an important experiment that has provided humanity with a certain insight into the way in which nature works. The author's selection of these ten particular experiments appears to be a bit arbitrary, since he freely admits that others could have been included; however, in his view, these stand out the most. But that's not all: not only are the experiments described (with plenty of illustrations), but mini-biographical sketches of the scientists themselves are included, as are snapshots of the times in which they lived. The writing style is very accessible, friendly and quite engaging. This book can be enjoyed by anyone - especially those fascinated by how science works.
43 internautes sur 46 ont trouvé ce commentaire utile 
5.0 étoiles sur 5 Beautiful dreamers 27 avril 2008
Par Julie Neal - Publié sur Amazon.com
Format:Relié|Achat vérifié
Here's a surprisingly compelling read, a lively blend of history and science filled with interesting true tidbits about the people involved. Author George Johnson's mission is to list and describe the top 10 most "beautiful" experiments that have explored the mysteries of science. By "beautiful," he means an experiment that has a straightforward elegance, where "confusion and ambiguity are momentarily swept aside and something new about nature leaps into view."

Each chapter covers one experiment or series of experiments. It explains the back story, the theory, the procedures the scientist used and any conclusion he or she drew. Included is a drawing or photograph of the scientist, quotes, diagrams and drawings.

The most unforgettable chapter for me concerned how Ivan Pavlov trained dogs to salivate to different stimuli. Pavlov loved his animals, and gave them names such as Buddy and Gypsy and Spot. He tried to spare his dogs pain, unlike many other animal researchers. The author describes an ornate fountain topped by a large dog that graces the grounds of Pavlov's institute still today, complete with busts of eight canines around the top, "water pouring from their mouths as they salute in salivation."

Here's the chapter list:
1. Galileo: The way things really move
2. William Harvey: Mysteries of the heart
3. Isaac Newton: What a color is
4. Antoine-Laurent Lavoisier: The farmer's daughter
5. Luigi Galvani: Animal electricity
6. Michael Faraday: Something deeply hidden
7. James Joule: How the world works
8. A.A. Michelson: Lost in space
9. Ivan Pavlov: Measuring the immeasurable
10. Robert Millikan: In the borderland
Afterword: The eleventh most beautiful experiment
8 internautes sur 8 ont trouvé ce commentaire utile 
5.0 étoiles sur 5 A guiltless pleasure 23 juin 2008
Par Susan Golob - Publié sur Amazon.com
Format:Relié
The book is a delightful surprise. I bought it mostly because I enjoy the author's unpaid appearances on bloggingheads.tv, and thought I'd show my appreciation. I've enjoyed the book more than expected. While I agree with Johnson's assessments that the experiments are truly beautiful, the book captures another important notion. By reliving the "ah ha" moments revealed by these beautiful experiments, I was continuously amazed that the simple ideas we take for granted today could be hidden from so many great minds for so long. That is, while the book is primarily a testimony to the creativity of these scientists, it is also a reminder of human limitations, of how great insights can lie so close to the surface of what we think we know.
8 internautes sur 8 ont trouvé ce commentaire utile 
5.0 étoiles sur 5 Entertaining and Inspiring 15 juin 2008
Par J. McBride - Publié sur Amazon.com
Format:Relié
I thoroughly enjoyed this book. I found myself wishing I could have been a part of some of the discoveries Johnson discusses.

Another reviewer commented that the book was too short. It was a fairly short book, and it didn't go into great detail about all of the science behind each experiment, but for me that was a plus. It was short enough to read quickly (I finished it on one plane trip) and keep your interest. If you are looking to dig into the details of any of the experiments, there are plenty of more appropriate books available for that. He provided enough information so that it didn't feel superfluous, but didn't include so much that it was a chore to work through it all. I liked the fact that he included some original notes and drawings from the experimenters. I definitely suggest this to anybody with any interest in the history of science!
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