Blowing the wind.
May 27, 1931: Wind Tunnel Lets Airplanes ‘Fly’ on Ground
In a massive building covering more than two acres, the wind tunnel used a pair of 35-foot propellers connected to 4,000-horsepower electric motors. Air was sucked through large funnel-like structures that directed a smooth flow of air past the staging area where airplanes, helicopters, race cars and even a Navy SEAL submarine were tested.
Foucault’s pendulum is sent crashing to Earth
The original pendulum, which was used by French scientist Leon Foucault to demonstrate the rotation of the Earth and which forms an integral part of Eco’s novel’s labyrinthine plot, has been irreparably damaged in an accident in Paris.
The pendulum’s cable snapped last month and its sphere crashed to the marble floor of the Musee des Arts et Metiers.
In 1851, Foucault used the pendulum to perform a sensational demonstration in the Paris Pantheon, proving to Napoleon III and the Parisian elite that the Earth revolved around its axis. Such was its success that the experiment was replicated throughout Europe.
13 Things That Saved Apollo 13
If the explosion happened earlier (and assuming it would have occurred after Apollo 13 left Earth orbit), the distance and time to get back to Earth would have been so great that there wouldn’t have been sufficient power, water and oxygen for the crew to survive. Had it happened much later, perhaps after astronauts Jim Lovell and Fred Haise had already descended to the lunar surface, there would not have been the opportunity to use the lunar lander as a lifeboat.
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But this was not the first time the crew had been ordered to stir the tank. It was the fifth time during the mission.
Links to the other 12 things are in the post.
Instruments for Natural Philosophy
In February 1975, Deborah Jean Warner, a Curator of Physical Science at the National Museum of American History, called me to ask if Kenyon had any historical physics teaching apparatus. I looked around my office, and reeled off the names of four or five good pieces of apparatus that I was using in my lectures. The next month I was at the Smithsonian, exploring the collection and photographing some of it in black and white and in color. Since then, I have visited and photographed nearly seventy collections of early physics apparatus. This web site displays pictures of about 1850 pieces of apparatus, along with text and references.
“Are spies really of any value?” investigated (mostly) in the context of Operation Mincemeat, a deception to make Germany think an invasion in the Mediterranean would come through Greece, instead of Sicily.
A body that washes up onshore is either the real thing or a plant. The story told by the ambassador’s valet is either true or too good to be true. Mincemeat seems extraordinary proof of the cleverness of the British Secret Intelligence Service, until you remember that just a few years later the Secret Intelligence Service was staggered by the discovery that one of its most senior officials, Kim Philby, had been a Soviet spy for years. The deceivers ended up as the deceived.
But, if you cannot know what is true and what is not, how on earth do you run a spy agency? In the nineteen-sixties, Angleton turned the C.I.A. upside down in search of K.G.B. moles that he was sure were there. As a result of his mole hunt, the agency was paralyzed at the height of the Cold War. American intelligence officers who were entirely innocent were subjected to unfair accusations and scrutiny. By the end, Angleton himself came under suspicion of being a Soviet mole, on the ground that the damage he inflicted on the C.I.A. in the pursuit of his imagined Soviet moles was the sort of damage that a real mole would have sought to inflict on the C.I.A. in the pursuit of Soviet interests.
50 historical speeches available online
You hope that your professors will be good speakers who can keep your interest for at least the length of a class period, but more often than not, you’ll have a teacher or two each semester who drones on and on and doesn’t make you feel passionate about the subject. They could take tips from these speakers who have inspired thousands or even millions of people around the world, some even long after they’ve died. Here are 50 incredible, historical speeches you should watch online.
Uncertain Principles: Measuring the Angular Momentum of Light
Being a formal and mathematical book, it pretty much leaves the subject there, but my immediate reaction is to look for an experiment that proves the angular momentum is real. So I did a little Googling, and turned up a paper from 1936(!) that does just that. And I talked about it in class, because I think experiments are way cool, and like to bring them in whenever possible. Having looked this up and read it carefully, I figure I might as well write it up for ResearchBlogging while I’m at it.
The “Ghost Army” was a unit that used deception to imitate or cover the actions of real units during WWII. There is a documentary being made.
Mason’s platoon was attached to General Joe Collins’ VII Corps as an experiment in deception. Their assignment was to set up dummy artillery emplacements, about a mile forward of the 980th artillery, to draw enemy fire. I was kind of scary says Mason. Task Force Mason stayed with the 980th Artillery for 28 days. Their efforts to draw fire succeeded as they were attacked by both German artillery and aircraft. Luckily, there were no casualties. The experiment was judged a success. There would be bigger operations–and more danger–in the Ghost Army’s future.
Built of Facts: A Brief History of Light
A nit (nit being the quanta of disagreement or concern):
Water waves and sound waves need something material to “wave”. Physicists assumed there was a thin and invisible medium called luminiferous aether permeating the universe, and that light waves were oscillations of this substance. But in 1887, Albert Michelson and Edward Morley were able to do a very careful experiment to measure the speed of light as the earth moved through the aether as it orbited in space. Their experiment came up negative. There just wasn’t any aether.
M&M were attempting to ultimately confirm the speed of the earth moving through the ether, via changes in the speed of light, and the reason they knew they had to do this measurement is that way back in 1725, James Bradley had measured stellar aberration — the apparent shift in position of a star due to the motion of the earth, which manifests itself in measurements taken at different times of the year. If the earth were somehow at rest with respect to the ether, there should be no aberration, so this option was already eliminated when the models of electromagnetic wave propagation were being hammered out. The M-M experiment was the experiment that showed we weren’t moving with respect to it, because being at rest wasn’t an option for explaining the null result.
Not everybody gets to do tightly controlled experiments in the lab. It’s still science, though (provided you do it right). Can you apply it to the study of history? Jared Diamond and James A. Robinson think you can.
Natural experiments: Working in the history lab
In Snow’s case the difficulty was not that manipulative controlled experiments were impossible or illegal, but that they were immoral. In other sciences, manipulative controlled experiments are impossible, so, for example, astronomy, evolutionary biology, epidemiology and historical geology all use natural experiments. If you are studying planets, volcanoes or glaciers, you cannot manipulate them. The same goes for dinosaurs or other things that existed or happened in the past, so manipulative experiments are ruled out in such historical sciences as palaeontology, too. In social sciences such as economics, political science and sociology, manipulative, controlled experiments are ruled out on all three grounds – they are either impossible, or they are immoral or illegal. Investigators have no choice but to test hypotheses using naturally occurring experiment-like variations.
Yet there is one field where natural experiments could be used but seldom are: most historians resist them. That is odd because, after all, many of the sciences that use natural experiments are deeply historical.