Stephanie did the research, and now has written an article about Why physics teachers should read blogs for The Physics Teacher, and here’s a link to the director’s cut in which she says a few nice things about me, and has several links, and links to links (but AFAICT no links to links about links, or links to links about lynx)
Will it Go ‘Round in Circles?
Building The Amazing Steam Candle
This is a variant of the pop-pop engine — if you point the tubes parallel rater than in opposite directions, you’ll get linear propulsion.
At first glance you might think this couldn’t work. Once you hit steady-state, the rate at which water enters and exits the tube has to be equal. Inside the tubes, that means that the momenta must be equal in magnitude, but opposite in direction, meaning no net momentum for the water, and no propulsion for the boat. The effect is a little more subtle — one has to consider what happens at the entrance to the tube. The water exiting will have its velocity vector along the direction of the tube. But the incoming water is drawn from different directions; it only has to have a component of its velocity in the direction of the tube, meaning the ejected water exerts a greater force.
Plasma inside the sun blazes at millions of degrees, but much of the matter between the stars is also plasma, in a colder form. In the lab, cold plasmas have always been made from ionized atoms, but a team reports in the 14 November Physical Review Letters that molecules can also be turned into an ultracold plasma. They created the molecular plasma by cooling a beam of nitric oxide molecules and then hitting it with lasers. They say the technique can work for any molecule that can be vaporized. Ultracold molecular plasmas probably don’t exist in nature, yet they share characteristics with very dense plasmas in the centers of some stars and gaseous planets. On Earth they may be used to explore more complex plasma dynamics, or help researchers create even colder atomic plasmas.
How to make water bounce.
Using a high-speed camera setup in the lab, GE scientists captured details of water droplets dancing on amazing superhydrophobic surfaces developed in GE Global Research’s Nanotechnology lab.
Cramming isn’t effective as a long-term learning method. Wow, you could knock me over with a big, fat history book.
So is cramming effective or not? A new study by UC–San Diego psychologists confirms what you may suspect deep down: The answer is no. Hurried memorization is a hopeless approach for retaining information. But it’s not all bad news. The team offers a precise formula for better study habits, and it doesn’t necessarily entail dogged discipline and routine.
If only I were Michael J. Fox, a letter I would send back in time.
I see that you were funded throughout your career by the National Science Foundation. So while some researchers at well funded schools have access to your paper, the amusing thing is that the people who paid for your work, also known as tax payers, don’t have access to your work. A public good that’s no longer public, because somehow the academic community has decided to let a company charge way too much for work they did not perform.
Each proton (or neutron) is made of three quarks – but the individual masses of these quarks only add up to about 1% of the proton’s mass. So what accounts for the rest of it?
Theory says it is created by the force that binds quarks together, called the strong nuclear force. In quantum terms, the strong force is carried by a field of virtual particles called gluons, randomly popping into existence and disappearing again. The energy of these vacuum fluctuations has to be included in the total mass of the proton and neutron.
Ab Initio Determination of Light Hadron Masses
Dürr, et al. Science 21 November 2008:Vol. 322. no. 5905, pp. 1224 – 1227
(h/t to Martin)
Oh, well, That’s Life
How much does it cost?
I only have a dime.
Oh, well, That’s Life
(OK, “Who’s on first” is much better, but off the topic here)
Helical (angled-tooth) gears. Witchcraft, because they’re made of wood.
More at the maker’s site
Everyone expects the U.S. president to know the difference between Sunni and Shiite, or understand the causes of the financial meltdown. But in today’s high-tech world, many critical issues have more to do with electrons than economics. Here are five short physics lessons for President-elect Obama from the author of Physics for Future Presidents.
The article does a decent job of pointing out the gaps between conventional wisdom and the actual science, especially nuggets like
It’s true that after 300 years, nuclear waste is still about 100 times more radioactive than the original uranium that was removed from the earth. But even this isn’t as scary as it sounds. If the waste is stored underground in such a way that there’s only a 10 percent chance that 10 percent of it will leak—which should be more than doable—the risk will be no worse than if we had never mined the uranium in the first place.
Regarding space —
Explain to the public that putting humans in space is not only very dangerous; it usually slows the advance of science. If the public just wants the adventure, then let them know that that is the real purpose.
I think there is value in the adventure, and the engagement of kids in getting them interested in science. The “wow” factor when the shuttle astronauts dropped by for a visit was significant. It’s a question of whether it’s worth the expense, and in the reality of finite budgets, what’s more important. Alka-Seltzer tablet reactions in zero-g are cool, but are they billion-dollar cool? No, probably not.
I think the article glosses over the connection between global warming and energy independence, though — there are certainly initiatives that can attack both at once — and the global warming section flirts with a “tu quoque” fallacy.
Yes, it is true that the United States is responsible for one fourth of past global warming. However, U.S. emissions are growing relatively slowly today.
So why are we so worried? It’s the rapidly growing greenhouse gas emissions of the developing world.
Is slowly growing emissions good enough, from the perspective of either reversing warming or setting an example? I don’t thinks so. I’m not sure how well a do-as-I-say-not-as-I-do policy plays out. Reduced dependence on foreign oil and a reduction in carbon dioxide emissions are both achievable, and needs to be done in parallel with getting developing nations to follow suit.