If I understand holography and what they're doing correctly (and I DID work as a tech in Emmett Leith's lab so I have some clue), they're transforming the information.
When did you work in Emmett's lab? I worked with him between 2002 and 2005, and I was a co-author on his last paper (published in 2006).
\citeauthor{kunstprosa2} devotes his second appendix of {\em Die Antike Kunstprosa} to the subject,\footnote{\citealt*[Anhang 2: pp. 909--960]{kunstprosa2}.} and de Groot analyzes Greek prose rhythm and traces the lineage into Roman {\em numerus} in his {\em Handbook of Antique Prose-Rhythm}\footnote{\citealt*{GrootHandbook1}, see especially the seventh lecture, pp. 119--131.}
At the very least, you should probably define a macro for \footnote{\citealt*[optional]{required}}, and maybe some more sematic macros to italicize (or otherwise format) titles and foreign words. Yes, it take a little bit of effort up front, but it will probably save you quite a bit of effort in the long run, and the end result would be a more readable source document with reasonable separation of formatting and content.
UM has lost focus of the spirit of the event. This is a race, but it's not a race to a finish line. It's a race to learn as much as you can in the limited time you have as an undergraduate in a club activity.
Michigan wants so badly to win that they realize needlessly risky designs to pursue fleetingly small perceived advantages. Gaming the race framework and then blaming the outcome of borderline engineering on others is bad form and is representative of the poor sportsmanship that has given the team such a bad reputation in the solar car racing community.
On the flip side, there is a lot of pressure on any given Michigan solar car team to win the (N)ASC because of the team's reputation and tradition of winning, so they have to pursue winning designs over innovative designs. (Michigan tried an ambitious two-passenger, four-wheel-steering design in 2003, and it is quite telling that some consider that car to be an embarrassment.) Add to that the pressure of trying to catch the Dutch Nuon team which, as I understand it, has even more technological and logistical support than Michigan. My $0.02.
speaking of trucks. Dont they got a lot of space on the trailers to load up on solar cells! Would a trailer covered completely with pv cells be enough juice to run the truck? This could make the shipping system in the country cheaper in the long run?
Assuming 100% coverage of the top surface of a trailer 102 inches wide and 28.5 feet long, the solar power available would be (2.6 m)*(8.7 m)*(1400 W/m^2) = 31.67 kW = 42.5 horsepower. This is even before considering the fact that the best solar cells are only about 25% efficient, or the cost of the solar cells (which runs into the hundreds of thousands of dollars for solar cars, which are much smaller than a semi trailer), or the size and weight of the battery pack you would want to use to store the solar energy.
I think you're somehow confusing the North American Solar Challenge (which Carnegie Mellon has never entered, to my knowledge) with the DARPA Grand Challenges, where Carnegie Mellon has usually been the favorite and has traditionally done quite well (an upset by Stanford in 2005 notwithstanding). They are very different races requiring different expertise, although it would be interesting to apply machine learning techniques to solar racing strategy.
Stipulate that the vehicles must charge their batteries using solar power and utilize only the power they have derived from the sun. This would allow high-performance electric cars to be showcased doing their sports-car killing speed runs whilst whining by like a flying saucer.
This is essentially the existing rule in the North American Solar Challenge (and I'm pretty sure in the other solar challenges, like the upcoming South African Solar Challenge and the 2009 World Solar Challenge), and the operating principle behind every competing solar car. No one powers their car directly from the solar array--they all use rechargable batteries and use the solar array to charge those batteries. They're fast, too--the current University of Michigan solar car has been tested at more than 80 mph on the racetrack, and the past two World Solar Challenge-winning cars from the Dutch Nuon team had comparable top speeds.
Ugh...out of the 3 submissions regarding the NASC, the least-accurate and least-timely one is the one that gets promoted to the front page. Sasha Zbrozek, the team lead for Stanford's next solar car, submitted a much better write-up a few days ago when the NASC started.
Indeed, everybody knows that the standard unit for small distances in science news reporting is (human hair width)^-1. Why they didn't use this standard unit escapes me.
Your standard unit of distance has units of inverse distance. You might want to fix that.:-p
True, but right now any real applications are still vaporware, or as I like to say, imaginary light.
Ironically, the word "evanescent" is used in optics to describe imaginary light (i.e. light where the imaginary component of the wavevector is nonzero).
According to TFA, the stimulated emission of light actually takes place in an indium phosphide (InP) laser diode. The laser diode is bonded to a silicon waveguide, which acts like a miniature optical fiber to guide the laser light around the chip. The "evanescence" is because the laser light is evanescently coupled from the laser diode into the waveguide. A proper description of evanescent coupling requires a pretty sophisticated understanding of electromagnetism, but the short version is that if you shine a laser beam parallel and adjacent (within a few microns) of a waveguide or optical fiber, some of the laser light will hop over and start propagating down the waveguide or fiber. In particular, by placing the actual laser parallel to and near a carefully-designed waveguide, you can have almost all of the laser light emitted into the waveguide, even though the constituent atoms of the waveguide are not emitting any light at all! For this reason, I think the name "silicon evanescent laser" is misleading since the silicon isn't emitting any light, and Roland Piquepaille's description of evanescent lasers is just flat out wrong. Getting silicon to emit light remains an extremely difficult task, and as far I know, no one has succeeded yet in getting silicon to convert electricity directly into laser light.
If anyone wants to read the Optics Express paper referenced in TFA, it's available online at http://www.opticsexpress.org/abstract.cfm?id=14097 3. However, that paper doesn't really define the term "evanescent laser" anywhere, so I had to go back to one of the research group's earlier papers to find a decent description of an evanescent laser and understand the physics of the device.
The blogger is about as knowledgeable about particle accelerator design as the average Slashdotter.:-p Interestingly enough, no one at the American Physical Society's 48th Annual Meeting of the Division of Plasma Physics seems to have issues with the use of the units "electron volts per meter".
The point is that these wakefield-accelerator designers are interested in the energy that they can impart onto an electron, normalized by the interaction length. To that end, electron volts per meter are a perfectly reasonable unit to use. The Slashdot blurb is not the only case of this--if you read the abstract for this paper or any of the other wakefield accelerator abstracts for the 48th Annual Meeting of the Division of Plasma Physics, you see them using units of electron volts per meter. I agree that it's sloppy dimensional analysis, but I understand why those units are convenient in that specific discipline.
Particle physics has nothing to do with it, it's just straight old electrodynamics (E&M). Your assumption is correct, they specically say it's the electric field, and the slashdot blurb incorrectly inserts the word 'electron' there.
The electric field is merely the negative gradient of the scalar potential (ie, voltage)*. So in SI it will have units of Volts/Meter.
Since the electric field is interacting with electrons, it is actually reasonable to use units of electron volts per meter. The quantity described by these units is no longer the electric field strength, but rather the strength of the interaction between this electric field and an electron. This is probably a very useful quantity to someone who designs a particle accelerator based on the strength of the interaction between an intense electric field and an electron.
The article is about the US, Japan and a whole swack of European countries (presuming that I can include Turkey as European). Okay, but what about the rest of the world?
I tracked down the Science article as well, and I had that same question. It would be more interesting (and possibly more persuasive from a policy standpoint) to compare acceptance of evolution in Canada and in the United States than to try to claim that Europe represents 32 uncorrelated sample populations...
Whenever Slashdot discusses science, I find that I'm a lot happier if I skip the linked article and track down the original papers. I don't usually read the original paper carefully, but I get a better sense of what the research is actually about from skimming the original paper than from reading a watered-down description of the original paper. And I woke up two hours earlier than I needed to today, so yeah, I have some extra time on my hands.:-)
He's no longer creating an interference pattern with the living.
I think that statement would have given Prof. Leith a good laugh. He had a cartoon on his office door illustrating the difference between classical and quantum barriers. In the classical case, this guy is making faces at a lion on the other side of the barrier because the lion cannot penetrate the barrier. In the quantum case, the guy is running for his life because the lion has tunneled through the barrier...
Slashdot Mirror
Woohoo!
When did you work in Emmett's lab? I worked with him between 2002 and 2005, and I was a co-author on his last paper (published in 2006).
Many of the standard introductory undergraduate and graduate physics textbooks have been mentioned by other posters, but I'm surprised that no one has mentioned Michael Spivak's Elementary Mechanics from a Mathematician's Viewpoint , which is based on his Pathway Lectures at Keio University.
For anyone who wants to read the actual paper: http://arxiv.org/abs/0805.2781
At the very least, you should probably define a macro for \footnote{\citealt*[optional]{required}}, and maybe some more sematic macros to italicize (or otherwise format) titles and foreign words. Yes, it take a little bit of effort up front, but it will probably save you quite a bit of effort in the long run, and the end result would be a more readable source document with reasonable separation of formatting and content.
This is somewhat off topic, but Murray Sargent, whose blog you linked to, is one smart guy. How many people can simultaneously claim to be a theoretical laser physicist and a software engineer?
On the flip side, there is a lot of pressure on any given Michigan solar car team to win the (N)ASC because of the team's reputation and tradition of winning, so they have to pursue winning designs over innovative designs. (Michigan tried an ambitious two-passenger, four-wheel-steering design in 2003, and it is quite telling that some consider that car to be an embarrassment.) Add to that the pressure of trying to catch the Dutch Nuon team which, as I understand it, has even more technological and logistical support than Michigan. My $0.02.
Assuming 100% coverage of the top surface of a trailer 102 inches wide and 28.5 feet long, the solar power available would be (2.6 m)*(8.7 m)*(1400 W/m^2) = 31.67 kW = 42.5 horsepower. This is even before considering the fact that the best solar cells are only about 25% efficient, or the cost of the solar cells (which runs into the hundreds of thousands of dollars for solar cars, which are much smaller than a semi trailer), or the size and weight of the battery pack you would want to use to store the solar energy.
I think you're somehow confusing the North American Solar Challenge (which Carnegie Mellon has never entered, to my knowledge) with the DARPA Grand Challenges, where Carnegie Mellon has usually been the favorite and has traditionally done quite well (an upset by Stanford in 2005 notwithstanding). They are very different races requiring different expertise, although it would be interesting to apply machine learning techniques to solar racing strategy.
This is essentially the existing rule in the North American Solar Challenge (and I'm pretty sure in the other solar challenges, like the upcoming South African Solar Challenge and the 2009 World Solar Challenge), and the operating principle behind every competing solar car. No one powers their car directly from the solar array--they all use rechargable batteries and use the solar array to charge those batteries. They're fast, too--the current University of Michigan solar car has been tested at more than 80 mph on the racetrack, and the past two World Solar Challenge-winning cars from the Dutch Nuon team had comparable top speeds.
Ugh...out of the 3 submissions regarding the NASC, the least-accurate and least-timely one is the one that gets promoted to the front page. Sasha Zbrozek, the team lead for Stanford's next solar car, submitted a much better write-up a few days ago when the NASC started.
According to TFA, the stimulated emission of light actually takes place in an indium phosphide (InP) laser diode. The laser diode is bonded to a silicon waveguide, which acts like a miniature optical fiber to guide the laser light around the chip. The "evanescence" is because the laser light is evanescently coupled from the laser diode into the waveguide. A proper description of evanescent coupling requires a pretty sophisticated understanding of electromagnetism, but the short version is that if you shine a laser beam parallel and adjacent (within a few microns) of a waveguide or optical fiber, some of the laser light will hop over and start propagating down the waveguide or fiber. In particular, by placing the actual laser parallel to and near a carefully-designed waveguide, you can have almost all of the laser light emitted into the waveguide, even though the constituent atoms of the waveguide are not emitting any light at all! For this reason, I think the name "silicon evanescent laser" is misleading since the silicon isn't emitting any light, and Roland Piquepaille's description of evanescent lasers is just flat out wrong. Getting silicon to emit light remains an extremely difficult task, and as far I know, no one has succeeded yet in getting silicon to convert electricity directly into laser light.
7 3. However, that paper doesn't really define the term "evanescent laser" anywhere, so I had to go back to one of the research group's earlier papers to find a decent description of an evanescent laser and understand the physics of the device.
If anyone wants to read the Optics Express paper referenced in TFA, it's available online at http://www.opticsexpress.org/abstract.cfm?id=1409
The blogger is about as knowledgeable about particle accelerator design as the average Slashdotter. :-p Interestingly enough, no one at the American Physical Society's 48th Annual Meeting of the Division of Plasma Physics seems to have issues with the use of the units "electron volts per meter".
The point is that these wakefield-accelerator designers are interested in the energy that they can impart onto an electron, normalized by the interaction length. To that end, electron volts per meter are a perfectly reasonable unit to use. The Slashdot blurb is not the only case of this--if you read the abstract for this paper or any of the other wakefield accelerator abstracts for the 48th Annual Meeting of the Division of Plasma Physics, you see them using units of electron volts per meter. I agree that it's sloppy dimensional analysis, but I understand why those units are convenient in that specific discipline.
Yeah, it's kinda annoying that TFA didn't have a link to the arXiv preprint. Thanks for making up for my laziness and looking it up. :-)
Whenever Slashdot discusses science, I find that I'm a lot happier if I skip the linked article and track down the original papers. I don't usually read the original paper carefully, but I get a better sense of what the research is actually about from skimming the original paper than from reading a watered-down description of the original paper. And I woke up two hours earlier than I needed to today, so yeah, I have some extra time on my hands. :-)