... has an answer to "Why is the sky blue?". It's mostly right, without being informative at all. Of course, I saw that with Firefox, so maybe it'd have been a lot better of an answer if I'd used IE 6+.
I haven't yet looked at the video, so I can't say for sure. I was speaking of the quote on this page: http://arxivblog.com/?p=401 which says, "At one point they divide their cell into nine smaller ones and the liquid in each cell rotates in exactly the same way."
The fact that the rotation goes one way and then another says that the rotational symmetry is broken spatially, and temporally, so *something* is not in steady-state (despite their claims). Something isn't consistent (it may just be an error in the slashdot submission -- heaven knows THAT's never happened before), especially as it says, "The puzzle is this: the electric fields are static, so what's driving the motor?". The paper at http://arxiv.org/abs/0902.3733 doesn't especially address it, and, in fact, a claim that _static_ fields (carrying no angular momentum) can lead to this sort of rotation stinks of kookiness. Either I'm missing something big (it's entirely possible) or this *really* needs to be looked into (as I suspect will happen).
I'd love to know how they got stable films, showing thin-film optical interference, of thicknesses on the order of several millimeters (stated a couple of times in the paper). They specifically call it a "suspended liquid film" and say that the z-boundaries are considered "free", so I don't think these films are sitting in a little box with just the top open.
Exactly. Additionally, I just skimmed their paper, and if the external fields are truly static, then I don't see any way to break the symmetry about the z-axis (their rotational axis). Since all of their little film-cells rotate in the same direction, this says to me that there is an unaccounted-for field which is breaking the symmetry and starting the effect. Alternatively, they could have shown a subtle coupling in which one cell starts its rotation one way, and through interactions with the other cells, they all start going in the same direction.
And, as someone else has already noted, frictional effects are important here. It would be interesting for them to measure the current needed to feed their electrodes in the steady state, since, if there is work being done w/in the cells, the fields have to supply the driving power.
I suspect that the sonoluminescence experiment (not to mention the Bell's inequality one) might be a little over-the-top for a first-year set of students. There are a lot of subtleties to them that would probably get lost unless the students really understand the basics about the principles.
However, one often doesn't need a fancy setup for the sono experiments: I saw a talk several years ago where a student did the experiment extremely cheaply, and got fantastic results (and, I believe, the optics used to catch the results are probably quite informative in their own way). The technique is termed the "drop tube" method, and you don't need a transducer to trap/excite the bubbles. The abstract of the talk:
Drop tube generates 10-W flashes of sonoluminescence (A)
Brian A. Kappus, Avic Chakravarty, and Seth J. Putterman
Phys. Dept., UCLA, 1-129 Knudsen Hall, Los Angeles, CA 90095
Use of a low vapor pressure liquid such as phosphoric acid, with dissolved xenon in a vertically exited tube, generates ~200-ns flashes of sonoluminescence with a peak power of 10 W. We are in the process of characterizing the bubble motion by use of backlighting, stroboscopic, and streak photography. We will also broach the topic of disequilibrium between atom and electron temperatures. [Research funded by DARPA. We thank Carlos Camara and Shahzad Khalid for valuable discussions.] a)Deceased.
It could be one day possible to create a kind of device that harmonizes human beings early on in childhood development, increasing their awareness and understandings.
Set a pendulum in motion and you'll inevitably give it an ellipsoidal motion, which naturally tends to precess.
I suspect the point is that the summary is somewhat poor, in that it's incomplete or just plain wrong. Why would an elliptical motion given to a pendulum tend to precess, even in the absence of a rotating reference frame? A "natural" precession (termed so in the summary) doesn't come about unless the axial symmetry of the Hamiltonian is broken. Even for a pendulum in which torsional modes and swinging modes are coupled, or for one in which a ratchet allows for elliptical motion in one angular direction, etc., there is no precession.
The Golden Ratio -- or some other book on the same constant -- which goes into things like sunflowers and nautilus shells IIRC.
I do hope (I have not read The Golden Ratio) that this isn't one of those popular mathematics books which presents a lot of very intriguing factoids as though they're actually true. There are some very good pop maths books (The Story of I comes to mind), and this may be one of them. However, I'm pretty leery of the "fact" that the golden ratio describes a lot of things in nature (like the chambered nautilus shell's structure): this is a pretty painful falsehood if you actually superimpose onto a nautilus shell a logarithmic spiral.
Slashdot Mirror
... has an answer to "Why is the sky blue?". It's mostly right, without being informative at all. Of course, I saw that with Firefox, so maybe it'd have been a lot better of an answer if I'd used IE 6+.
I hope you were drinking milk. Actually, I kinda don't.
You score with your wife based on dice rolls? Awesome. Careful with snake-eyes, though. That's when the whimpering starts.
Pffft. There are already synthetic boobies.
Aim lower.
Synthetic boobies for really old ladies?
I haven't yet looked at the video, so I can't say for sure. I was speaking of the quote on this page: http://arxivblog.com/?p=401 which says, "At one point they divide their cell into nine smaller ones and the liquid in each cell rotates in exactly the same way."
The fact that the rotation goes one way and then another says that the rotational symmetry is broken spatially, and temporally, so *something* is not in steady-state (despite their claims). Something isn't consistent (it may just be an error in the slashdot submission -- heaven knows THAT's never happened before), especially as it says, "The puzzle is this: the electric fields are static, so what's driving the motor?". The paper at http://arxiv.org/abs/0902.3733 doesn't especially address it, and, in fact, a claim that _static_ fields (carrying no angular momentum) can lead to this sort of rotation stinks of kookiness. Either I'm missing something big (it's entirely possible) or this *really* needs to be looked into (as I suspect will happen).
I'd love to know how they got stable films, showing thin-film optical interference, of thicknesses on the order of several millimeters (stated a couple of times in the paper). They specifically call it a "suspended liquid film" and say that the z-boundaries are considered "free", so I don't think these films are sitting in a little box with just the top open.
Exactly. Additionally, I just skimmed their paper, and if the external fields are truly static, then I don't see any way to break the symmetry about the z-axis (their rotational axis). Since all of their little film-cells rotate in the same direction, this says to me that there is an unaccounted-for field which is breaking the symmetry and starting the effect. Alternatively, they could have shown a subtle coupling in which one cell starts its rotation one way, and through interactions with the other cells, they all start going in the same direction.
And, as someone else has already noted, frictional effects are important here. It would be interesting for them to measure the current needed to feed their electrodes in the steady state, since, if there is work being done w/in the cells, the fields have to supply the driving power.
Actually, I very much hope to be alive for the next perigee of Halley's.
It's my own word, to be pronounced just the same as antegnostication.
Too bad the /. posting is a day late.
They didn't put in parentheses for order-of-operations:
LinuxNew = 325x(costLinuxOld - performanceLinuxOld)
and
WindowsNew = 325x(costWindowsOld - performanceWindowsOld)
There.
[...] journalistic integrity requires a writer in this situation [...]
Hahahahaha... *gasp* wait, wait, .... HAHAHAHAHAHHAHA!
Andy Schlafly, is that you?
They're just verbing their nouns, thereby incentivizing efficiency.
That is why I named my son hjretgwjsdfk. I was sure he would be the only one. I heard that his friends call him John. Don't understand why...
The 'r' is obviously silent.
I suspect that the sonoluminescence experiment (not to mention the Bell's inequality one) might be a little over-the-top for a first-year set of students. There are a lot of subtleties to them that would probably get lost unless the students really understand the basics about the principles.
However, one often doesn't need a fancy setup for the sono experiments: I saw a talk several years ago where a student did the experiment extremely cheaply, and got fantastic results (and, I believe, the optics used to catch the results are probably quite informative in their own way). The technique is termed the "drop tube" method, and you don't need a transducer to trap/excite the bubbles. The abstract of the talk:
Drop tube generates 10-W flashes of sonoluminescence (A)
Brian A. Kappus, Avic Chakravarty, and Seth J. Putterman
Phys. Dept., UCLA, 1-129 Knudsen Hall, Los Angeles, CA 90095
Use of a low vapor pressure liquid such as phosphoric acid, with dissolved xenon in a vertically exited tube, generates ~200-ns flashes of sonoluminescence with a peak power of 10 W. We are in the process of characterizing the bubble motion by use of backlighting, stroboscopic, and streak photography. We will also broach the topic of disequilibrium between atom and electron temperatures. [Research funded by DARPA. We thank Carlos Camara and Shahzad Khalid for valuable discussions.] a)Deceased.
and Putterman's webpage: http://www.physics.ucla.edu/research/putterman/gallery/index1.htm
Do ya put your weeeeeeeeeeeeeeeed in there?
Starring Adam Sandler
It could be one day possible to create a kind of device that harmonizes human beings early on in childhood development, increasing their awareness and understandings.
Beer.
If you mean total solar eclipses, maybe. Partials are a dime-a-dozen.
Don't you have a naval to gaze at?
Some people just can't keep their ship together.
Set a pendulum in motion and you'll inevitably give it an ellipsoidal motion, which naturally tends to precess.
I suspect the point is that the summary is somewhat poor, in that it's incomplete or just plain wrong. Why would an elliptical motion given to a pendulum tend to precess, even in the absence of a rotating reference frame? A "natural" precession (termed so in the summary) doesn't come about unless the axial symmetry of the Hamiltonian is broken. Even for a pendulum in which torsional modes and swinging modes are coupled, or for one in which a ratchet allows for elliptical motion in one angular direction, etc., there is no precession.
The date on the announcement is from August 8, 2009.
Eek! The Large Hadron Collider's effects have started leaking to other slashdot dimensions!
Good idea! Additionally, there are some very good lectures out there which bright highschoolers can easily understand, such as this one: http://www.learnerstv.com/video/video.php?video=674&cat=Physics
The Golden Ratio -- or some other book on the same constant -- which goes into things like sunflowers and nautilus shells IIRC.
I do hope (I have not read The Golden Ratio) that this isn't one of those popular mathematics books which presents a lot of very intriguing factoids as though they're actually true. There are some very good pop maths books (The Story of I comes to mind), and this may be one of them. However, I'm pretty leery of the "fact" that the golden ratio describes a lot of things in nature (like the chambered nautilus shell's structure): this is a pretty painful falsehood if you actually superimpose onto a nautilus shell a logarithmic spiral.
http://www.laputanlogic.com/articles/2005/04/14-1647-4601.html