I don’t remember where I found the link, but I was fascinated by what can happen (YouTube link to the same video) when you pour shampoo or other viscous liquids. The Wikipedia article states that “the surface suddenly spout[s] an upcoming jet of liquid which merge[s] with the downgoing one.” Arthur Kaye first described the phenomenon in 1963, but only a year ago, in April 2006, did a group of Dutch scientists (Michel Versluis et al.) manage to explain the effect. They also discovered a method to create a stable Kaye effect. You can download their article, “Leaping shampoo and the stable Kaye effect.” Michel Versluis et al, J. Stat. Mech. (2006) P07007, here at the IOP, or here.
Category Archives: Science
Lunar eclipse
A total lunar eclipse will be visible from almost everywhere on earth tomorrow night (March 3rd/4th, 2007). This site links to several webcasts and gives the beginning and ending times:
“The Moon encounters the penumbra, the Earth’s outermost shadow zone, at 20:18 Universal Time (UT). About thirty minutes later a slight dusky shading can be noticed on the leading edge of the Moon.
At 21:30 UT the Moon begins its entry into the innermost shadow zone, or umbra. For more than an hour a circular shadow creeps across the Moon’s face. At 22:44 UT, the Moon will lie completely within Earth’s dark shadow.[…]
Totality will end at 23:58 UT, when the moon’s leading edge exits the umbra. The moon will leave the umbra completely at 01:11 UT, and the eclipse will end at 02:23 UT when the moon makes its last contact with the penumbra.”
I just looked out of the window at the moon in an almost clear nightsky. If the weather is like this tomorrow, it’s going to be fun to watch the eclipse from the office without getting cold outside. ;-)
Did it ever occur to you that whenever a lunar eclipse occurs on earth, there’s a solar eclipse on moon at the same time because the earth blocks the sun? It never did to me even though I teach how eclipses work at least once every year, and my students usually come up with all sorts of interesting ideas and questions. Here’s a picture of what it would look like.
It’s a pity I only found out about the eclipse now, I would have liked to tell my students about it – I’m covering related topics in two of the three physics classes I teach at the moment (basic optics including lunar and solar eclipses in 8th grade, Kepler‘s laws of planetary motion in 11th grade).
Simulate your own solar system – and more!
Sometimes MetaFilter has links to sites right up my alley: Physics simulators. Lots of physics simulators.
“PhET – Physics Education Technology offers this astoundingly large library of online physics simulations.
Play orbital billiards. Land on a cheesy moon. Experiment with sound. Or try more advanced quantum physics simulators. Still bored? Try the “cutting edge” catagory. Here’s the complete index. (Warnings: Frames, Flash, Javascript, Java applets, graphics, sound, quantum timesuck.)“
I especially like the orbit simulator because I once had to program one in university. During my third semester (I was still aiming for a master in physics back then) I took a course on theoretical mechanics, and we had to write a program that simulated the paths of the moon relative to the earth and the sun. The masses and velocities of the objects were adjustable.
It took me weeks and weeks to finish because I had never programmed anything serious before, but it still didn’t calculate correct paths the day before the deadline, so I had to ask for some more time. Two frustrating afternoons later, I finally found the sign error in one of the formulas… Sigh.
I just realized that this must have been in February of 1996, so more than a decade has passed since then. I guess they do different programming tasks in theoretical mechanics now that you can just download applications like this from the web. Which is a good thing for me because now I can use these spiffy simulations in my lessons instead of my amateurish ones. I’m sure the students are going to appreciate it.
A small step for man…
Washington Post: The Saga Of the Lost Space – Tapes
NASA Is Stumped in Search For Videos of 1969 Moonwalk.
“As Neil Armstrong prepared to take his “one small step” onto the moon in July 1969, a specially hardened video camera tucked into the lander’s door clicked on to capture that first human contact with the lunar surface. […] Millions of television viewers around the world saw those fuzzy, moving images and were amazed, even mesmerized. What they didn’t know was that the Apollo 11 camera had actually sent back video far crisper and more dramatic — spectacular images that, remarkably, only a handful of people have ever seen. […]
The original, high-quality lunar tapes were soon stored and forgotten. Only in recent years was the agency reminded of what it once had — clean and crisp first-man-on-the-moon video images that could be especially valuable now that NASA is planning a return trip. About 36 years after the tapes went into storage, NASA was suddenly eager to have them. There was just one problem: The tapes were nowhere to be found.”
I think it would be really exciting if they manage to find the tapes after all, though the chances seem to be slim. I’d certainly like to watch the footage.
Link via Garret.
The Antikythera mechanism
Okay, the Antikythera mechanism seems to haunt me this week. First, I decide to re-read Richard Feynman‘s What Do You Care What Other People Think?, and from a trip to Greece Feynman writes to his family about a strange, ancient mechanism he saw at the Athens National Museum (more info). This rings a bell because I read an article about it in the most recent edition of Die Zeit (see link below). And today, there’s this at the Astronomy Picture of the Day: The Antikythera Mechanism, crediting the corresponding Wikipedia article on the Antikythera Mechanism. There are several articles about the mechanism, which was found in 1910 but is over 2,000 years old:
Science News: Crusty Old Computer: New imaging techniques reveal construction of ancient marvel.
“Scientists say that they have figured out the arrangement and functions of nearly all the parts of a mysterious mechanical gadget that was discovered a century ago in a 2,000-year-old shipwreck.”
Scientific American: An Ancient Greek Computer?
Der oben erwähnte Zeit-Artikel:
Wissen: Das Urwerk.
“Taucher bargen vor hundert Jahren ein undurchschaubares Räderwerk aus einem Schiffswrack. Erst heute entschlüsseln Forscher sein Geheimnis. Die Griechen waren die ersten Meister der Feinmechanik.”
Sehenswert ist auch die dazu gehörende Bildergalerie.