Have you ever wondered why one side of the moon always faces us? The reason for the moon's orbital period matching its rotational period is a phenomenon called "tidal locking" or "tidal despinning": http://www.aas.org/publications/baas/v30n3/dps98/320.htm
Google Answers has some good write-ups:
The mass of the Earth tugs on the Moon in the same way the moon pulls on the Earth. Since the Earth is so much greater in size it is able to distort the sphere of the moon. The Earth draws mass from the Moon towards it. This elongation of the Moon reduces its rotational velocity and converts it to heat. Eventually the spin is nearly nullified. The elongation is drawn along an axis pointing to the Earth. It results in permanent tidal bulges which makes it dynamically most stable if one end of the bulge is always pointed towards the Earth.
Here is an interesting article about how DNA dissipates the energy from UV radiation. Apparently UV doesn't damage DNA by breaking the base pairs, but instead travels up the helical edges fo the DNA molecular strand and disrupts the electronic bonds between successive base pairs. Also interesting is this:
The Nature paper builds on work from five years ago, when the associate professor of chemistry and his team first discovered that single DNA bases convert harmful UV energy to heat to prevent sun damage in the same way that sunscreen molecules protect sunbathers.
Back then, they studied only single bases floating in water. They hit the bases with a kind of UV strobe light, and saw that the energy was released as heat in less than one trillionth of a second.
Their new experiments show that the behavior of full DNA differs profoundly from that of isolated bases. When the chemists turned their strobe light on whole strands of novel DNA, the UV energy still changed to heat eventually, but the energy dissipated a thousand times more slowly.
Today I found a few links to some Geometric Algebra/Calculus resources as I was looking at some Python science modules. I first heard of Clifford algebra when I was at Immersive, but found it rather difficult to visualize properly.
I found links to David Hestenes's Oersted Medal Lecture (2002) in which he gives a wonderful, lucid, and enlightening exposition on Geometric Algebra and its applications to understanding physics.
I ordered his book New Foundations for Classical Physics. I'm really excited to see all this material be unified in a new, more geometric framework. (I've always been better at geometry than algebra.)
Intelligent Design is a good site that shows the latest Creationist tactic to destroy science education in our schools.
Here are some startling facts about global warming:
According to recent reports of the joint WMO/United Nations Environmental Panel on Climate Change, the global average surface temperature has increased around 34° since 1861. New analyses of proxy data for the Northern Hemisphere indicate that in the 21st century increases are likely to be the largest in any century over the past 1,000 years. Average global land and sea surface temperatures in May 2003 were the second highest since records began in 1880. The ten hottest years in the 143-year-old global temperature record have all been since 1990, with the three hottest being 1998, 2001 and 2002.
Of course, the Bush administration refuses to pass any legislation to reduce warming-causing pollution. (Until 2002, the administration denied that global warming was a problem.)
The 2003 Reith lectures are by Dr. Ramachandran and take the listener/reader through a number of topics in neuroscience. You can listen to the broadcasts and read the lecture transcripts from the BBC site here.
The Telegraph UK has a fascinating story about a woman who is actually two non-identical twins that merged in her mother's womb into a single individual human being. Some of the cells in her body are of one genetic type, some are of another type. Her unusual constitution was discovered when two of her three sons were found to be biologically unrelated to her. Amazing!
Here is a wonderful analysis and description of our nation's electrical grid. Neat stuff!
MSNBC has an article about canned tuna (e.g. Starkist) and its potentially hazardous amounts of mercury.
Mercury enters the environment naturally and through industrial pollution. Nearly all fish contain trace amounts of methylmercury but longer-lived, larger predator fish like shark or swordfish accumulate the highest amounts of methylmercury and pose the largest threat to people who eat them regularly.
Environmentalists say the agency bowed to pressure from fishing and packing interests when it left tuna off its do-not-eat list in 2001, but one group said it was somewhat happy with the panel?s recommendation.
?We think it?s a step forward,? said Caroline Smith DeWaal, a food-safety director at the Center for Science in the Public Interest that believes pregnant women should avoid fresh tuna steaks and children under 5 should eat no more than one or two servings of canned tuna per month.
Last night I attended a Friday night observing session at Fuertes Observatory for the first time in three or four years. It was sponsored by the Cornell Astronomical Society (of which I was once a member), and I found out about it through the listserv (which I had just recently joined).
Given that it is a Friday night in the middle of the summer, I did not expect too many people to show up. When I arrived at the observatory (9:30pm), there were at least 50 people there already. Fuertes is not a large building, and this was effectively a mob. The telescope dome room itself was packed, the classroom downstairs had a dozen or so people loitering around, and the observing deck outside the building was as packed as a dance floor.
I brought along my newly-acquired ETX-90 but put off setting it up due to the lack of space. I viewed some stuff through my binoculars but overall the first hour or so was pretty much a wash. After the crowd had thinned a bit, I talked with Jagadheep (the person who sent out the announcement email) for a while and proceeded to do some observing with my little scope.
To make a long story short, we stayed until 2am, and through the course of the night I was able to see the Andromeda Galaxy, some double stars, Mars, and the moon through my scope, and in the main scope we saw the Eagle Nebula, an open cluster in Scutum, Mars and some other nice sights. The open cluster was a real treat in the 12" refractor - I had never seen one through such a large instrument before and it really blew my mind. Everyone else there also seemed very impressed - almost every single person who looked through the eyepiece breathed a "Wow" as they saw it.
The best part of the evening, though, was getting a chance to introduce so many people to the stars. While the other two CAS members were setting up the telescope and showing sights inside, I stood on the deck and gave some sky tours to people - pointing out stars with the amazing green laser pointer, telling them about the constellations, answering their questions, hearing their stories about their childhood experiences or interests in astronomy. One girl's father got her a department-store telescope when she was a child and she managed to see a few planets in it, but hasn't looked through a scope since; another guy was in town visiting his girlfriend in a summer program here and he dropped his tough-boy gangsta persona after gazing upwards for a while and letting the beauty of it get to him; yet another girl grew up in Indiana and told us about how her family used to go camping in this open meadow that stretched as far as the eye could see, and in the summers they would lay out on tarps and be awash in starshine. (Well, those weren't her exact words.) Talking to all these people - some high schoolers, some early fall students here for the summer, some grown-ups - I was somehow very moved... and I am deeply grateful for the chance to have shared an evening under the stars with them.
It is impossible to express the simple and inexplicable joy that comes from opening someone else's eyes. A muttered "whoa", a slight gape of the mouth as their eyes register starlight from millions of light-years away - these are the same reactions I had as a child when I first laid eyes on the heavens. When someone looks at the cosmos for the first time, their reactions come from the core; stripped of the illusory artifacts and constructs of our day-to-day world, they connect with a primal sense of wonder that we all possess as children and (for many) slowly erode as we age. I could almost see us as apes on a savannah, gazing upwards in mystified wonder, faint tendrils of thought and understanding tickling our primitive minds.
Last night was very fun, wonderfully good. I look forward to helping out with more observing sessions in the future. In fact, this Sunday from 6pm-8pm there is going to be some group or organization that is visiting the observatory, and I'm going to go help out.
Here is a eurekalert article about research that shows that 9-month-old infants, when exposed to Mandarin Chinese spoken by a person, can differentiate between phonetic elements of the language, while infants exposed to DVD or audiotape recordings of the exact same sounds cannot. The findings seem to indicate that social interaction is critical to helping infants learn what is their "native" language and what sorts of sounds they should learn to pay attention to.