What makes atoms bosonic versus fermionic? Just whether or not they follow the Pauli exclusion principle?
No, obedience or non-obedience of the Pauli exclusion principle does not define what is a fermion or a boson. It is just a property of fermions that they obey the Pauli principle, and a property of bosons that they do not.
So what's the definition of a fermion or a boson, and in this specific case, of a fermionic or bosonic nucleus?
Bosons have integer spin, and fermions have half-integer (n+1/2, where n is a nonnegative integer) spin. The spins of the individual quarks in nucleons (protons and neutrons) always add up to a half-integer, so nucleons are fermions. The quarks themselves are too. The spins of the nucleons in a nucleus can add up in different ways, depending on the number of each kind (proton and neutron) present. When the spins add to become an integer, the nucleus is bosonic. When the spins add to a half-integer, the nucleus is fermionic.
If a given nucleus is fermionic, then identical nuclei of that type obey the Pauli exclusion principle. If the nucleus is bosonic, then the Pauli exclusion principle does not apply to it, and the possibility of a collection of that kind of nucleus forming a BEC exists.
Slap together some old but interesting IP, flash 10 second ad of a new burger (or in how to ask for a particular burger a certain way to save 50 cents), for say Burger King and see what happens.
Release it on one of these sites and swear up and down not to prosecute anyone so long as the ad stays intact. The trickle effect should be noticeable for weeks...Conditions include for distribution and private viewing only, not for public display (perhaps roll that across the screen every 10 minutes)
Actually, the Fox show Arrested Development had a very similar idea used for humorous ends. On the show, the character Tobias is an actor. He took some acting lessons from Carl Weathers, who played Apollo in the first few Rocky movies.
Here's the relevant dialogue:
Narrator: And Tobias met with Carl Weathers at Burger King.
Carl Weathers: Thanks for meeting me down here at Burger King. I'm trying to get them to underwrite a new TV project I'm working on. Get some money in exchange for setting a scene here at Burger King.
Tobias: Well, as long as you don't draw attention to it.
The two talk a bit about Carl's project. The scene ends as follows:
Carl Weathers: I'm gonna go get a new soda. Hey, you know that you can get a refill on any drink you want here, and it's free? (Laughs)
Tobias: (Laughs) It's a wonderful restaurant. Mmm!
If everything of any significant complexity was deliberately created, who created the creator?
From there, it's turtles all the way down!;-)
But seriously, that question is as ill-defined as "what happened before the Big Bang" (time is only definable after the Big Bang) or "what's outside the edge of the universe" (space is only defined within the universe).
I don't like the way these people are putting wild-ass conjecture supported by faith on the same level as a theory that is testable and disprovable, and that has so far been verified in numerous independent observations. But there are undefined and ill-posed questions in both the scientific (testable, disprovable, and well-supported) theory and in the non-disprovable conjecture supported only by faith.
I've been led to believe there's a problem with this scheme.
The bank where I have my account right now is Bradesco, the largest non-government bank in Brazil. I'm told Bradesco had the fifth internet banking site in the world, the first in Latin America, and as of a couple of years ago, it was the third largest internet banking site in terms of transaction volume, trailing only two banks in the USA.
To get into my account in Bradesco's internet banking site, I have to type a secret phrase (minimum 12 characters) and type in a 4-digit code using a graphical numerical keypad where the position of the keys is random. Also, to verify each transaction, I get a confirmation screen and confirm by typing in a six-digit code using a graphical numerical keypad with the keys in random positions.
The problem, I'm told, is that some clever but nasty people have made applications like keyloggers that take "snapshots" of the region immediately surrounding the mouse pointer when the button is clicked. If that's true, it seems to me it would indeed defeat the purpose of the graphical keypads with randomly placed keys.
I have no way to verify this, but it scares the crap out of me. I use Firefox, and I sweep my machine daily with an antivirus program that is updated daily. I also sweep it daily with an anti-spyware program and occasionally with a second one. I also have a personal firewall. Still, I just don't feel all that safe. I know that in theory, using a credit card on the internet can be safer than using one in a gas station or restaurant, but given the many security holes in Windows and the industry of identity stealers, crackers, phishers, and such that has sprung up, I worry about a keylogger (or keylogger "plus") somehow getting into my machine.
The parent post was modded as funny (and it is), but I consider it insightful too. What was so cool about The Force in the original movies was that it was basically magic. Lightsabers too. When reading about King Arthur, I didn't have any questions about how Excalibur was forged. I don't care how the magic used by Gandalf and Saruman in LOtR works. It just does.
That's why, to me, the biggest offense of Episode I wasn't Jar Jar or the stupid and ridiculously prolonged fish-eat-fish scene. It was less than a minute of stupid technobabble dialogue about chlamydians or whatever (OK, I know it's midi-clorians, but I get a chuckle out of this alternate name). In that brief bit of dialogue, the magic of The Force was ruined and reduced to a mere blood condition. Seriously... could a simple shot of penicillin have avoided the whole Darth Vader situation, and with it the Galactic Empire?
I prefer The Force as it was in the original trilogy. It was magic! In Star Wars Han Solo even disparaged The Force as a "hokey religion" and lightsabers as "ancient weapons," saying that the combination was no match for a good blaster at your side. I wasn't as cynical about The Force as Han (and even Han changed his view, wishing "May the Force be with you" to Luke before leaving the Yavin IV base before the attack on the Death Star). I thought it was pretty cool. But I really never wanted to know the nuts and bolts of how it worked. Jeeze, if I wanted ridiculous technobabble "explanations" of how things work, I'd watch ST:tNG reruns and and get my fill of tetrions and subatomic bacteria and such.
Actually hearing about midi-clorians ruined the magic of The Force for me. I don't see how Jar Jar can "ruin" people's memories of the original series, because one has nothing to do with the other. But the babble about the chlamydians did ruin The Force.
It really surprises me people complain so much about Jar Jar and so little about the midi-clorians.
OK, I RTFA, and there's something I don't get.
TFA says
But if the light was a single photon beam, others in the room could not see it, and the two friends would also know instantly if it had been intercepted.
How? What keeps a third party between the two friends from receiving the photons transmitted by one friend and retransmitting exactly the same sequence of photons to the other while keeping a record, and therefore, a copy of the message?
I'm pretty sure there's more to it than appeared in TFA, and that there is a way to be sure there isn't an eavesdropper between the two friends, but I don't know what it is.
Seriously, can you imagine how well this would work to teach difficult concepts to people who are otherwise not entirely technical?
I'm not sure if you really think this is a good idea or not, but I can tell you it worked in this case.
I sent the link to a bunch of people. My mother, who is 63, wrote this after watching it:
THAT is amazing. I was glued, and I understood it.
And it was pretty and fun. I'll be sending it along.
So Hitachi's clip was good enough to keep a 63 year old woman who couldn't care less about the inner workings of her hard drive "glued," and she actually ended up learning from it.
There's one more thing: it's fun to watch, like the Schoolhouse Rock clips that at least partially inspired it. The horizontal bit that learns it has to go vertical looks a lot like the bill that was sitting on Capitol Hill on Saturday mornings when I was a kid. The tune is catchy enough that I didn't get tired of it, and I got a kick out of the bit backup singers with afros. I think this is the single coolest technology announcement I've ever seen. I've seen cooler technologies announced, and I've seen tech announcements with more detailed info, but this was the coolest announcement.
I find it amazing that somebody made all this effort, and made something this cool, to announce a technological advance that isn't even a product yet.
Somebody enlighten me. Is there any use in knowing Pi to 2 billion decimal places (or even just a few hundred!) Do we hope to find a hidden message, or make the world's most accurate circle, or is it just because we can calculate it? And how do you check for errors?
Well, on the question of hoping to find a hidden message, TFA says:
They wonder whether the digits contain a hidden rule, an as yet unseen architecture, close to the mind of God.
Aside: this reminded me a lot of the movie Pi. I have to wonder if this article was part of the inspiration for that movie.
As for the question of how to check for errors, there are other mathematical methods. After a few dozen digits, you exceed our capacity for measurement precision. But/pi shows up all over the place in math, for example in complex analysis. One way to see how/pi would show up in complex analysis is this: complex numbers are made up of two parts: a real part and an "imaginary" part ("imaginary" numbers are multiples of i, a square root of -1). Complex numbers can therefore be represented as positions on the "complex plane," where the horizontal (x) position represents the real component and the vertical position represents the imaginary component. That is, a complex number z can be written x+iy, and the x and y can be plotted as coördinates. But there's another convenient way to represent points in a plane: polar coördinates/rho and/theta. Rho is the distance from the origin (the square root of the sum x^2+y^2, using good ol' Pythagoras's theorem), and/theta is the angle made by the line representing rho with the x axis (measured counter-clockwise). For the angles, it's convenient to use radians. There are 350 in a circle, but there are 2 pi radians. That way, the angle in radians tells you how far in terms of distance around a circle of radius 1 (circumference 2 pi) a given angle would take you.
Some interesting and surprising things involving pi come up in very basic complex analysis. For example, i raised to the i power has a finite real value, and that value involves pi {it's e^(-pi/2)}.
One (unity, the number 1) is of course e^0 (any nonzero real number raised to the zero power is 1). But negative 1 (-1) is e^(i pi). And i is e^(i pi/2) and -i is e^(-i pi/2).
I digress. This is all just an example of how pi shows up in places where you might not expect it in mathematics. There are more advanced examples, but I think this one serves to make the point.
As for the principal question, why one would need to know pi so accurately, well, for some it's just the challenge. According to TFA, the Chudnovskys were hoping to find a pattern. But just going further than anyone else has its own value. Would you have asked Edmund Hillary why he needed to climb Everest?
Was there ever a female Doctor? That might be cool.
Well, you can't promote Rose to be the Doctor (they're two different beings!), but a friend (who I didn't even know was a fan of Dr. Who) told me Ace, my favorite Dr. Who assistant of all time (no, I'm not forgetting Romana), became the first human Time Lord in some of the novels and stuff. Rose could apparently become a Time Lord, but I'm not sure if that fits her character, having only seen her in one episode (in which she was pretty clueless about everything going on, as one would expect when a person first meets the Doctor and starts to learn about the larger universe).
The previous Brazilian president's health minister, José Serra (currently mayor of São Paulo), did several really important things when he held that office. He set up a modern organ donation system (cutting down significantly on the black market for organs that existed previously). He pushed for the law making generic medications possible. He created an anti-AIDS policy that is a model studied by governments from all over the world. And part of that AIDS policy involved the government giving medications to AIDS patients.
The success of Brazil's anti-AIDS policy had convinced many that it was well designed and should continue as it had. But as the multinational pharmaceutical companies jacked up the prices of AIDS treatment medications, it got to the point where continuing the otherwise successful policy would be beyond the government's financial limits. Serra went to the pharmaceutical companies (there were two main ones making AIDS treatment meds) and told them that a clause in the Brazilian constitution allowed him, in the case of a crisis (and AIDS would have been accepted by the courts as a crisis), to break the patents and allow Brazilian companies to manufacture the drugs without paying a cent to the patent holders. He made it clear that he did not want to do that, and that he just wanted the companies to stop jacking up the prices. One company agreed immediately. The other decided to call Serra's bluff. He moved forward with the actions he had to take to break the patents, and the other company gave in.
Brazil's successful anti-AIDS policy continues to work, even after a change of governments (Serra lost the presidential election of 2002 to Luis Inácio Lula da Silva, one of the founders of the Brazilian labor movement). I do have some questions about where to draw the line between a crisis and a non-crisis, and I worry about what else the government could just take in the name of averting a "crisis," but this is an example where the end result was pretty positive. The pharmaceutical companies didn't get to do as much price gouging as they had hoped, but since their usual argument is that drugs have to be expensive because of the high cost of developing new drugs, there was little reason to keep elevating the price of drugs that had been on the market for some time. In terms of public health, it was a big win, as Brazil's policy continues to limit the spread of AIDS.
firstly it was a genuine problem with many back-end financial (and other) systems...
So, for most people's point of view it was a lot of fuss about nothing, because they never saw the real problem, which could have caused serious problems, and only saw the hyped, non problem.
It's true that Y2K problems on personal computers (at least home ones) probably wouldn't have been very severe, even without preventive fixes. But it is also true that there were some systems where Y2K and similar problems could have caused serious havoc.
I think one example of systems that could have had problems and could have caused serious trouble were the avionics and other systems in airplanes (and air traffic control). I recall reading articles about the hard work the Y2K teams did, digging into these systems looking for any component that might have a 2-digit year or other similar problem.
I also recall reading that the Chinese government found a very good way of making sure Chinese airlines would be safe: Chinese airline officials (executives?) were required to be in passenger planes in the air as 1999 ended and 2000 began.
If you were paying attention, you'd have noted that not only is MSFT developing it's on AV tool but they also plan their own spyware scanner/remover.
Yeah... of course, they didn't forget "step 3" in the business model this time:
1) Integrate browser into OS so browser vulnerabilities are OS vulnerabilities
2) Halt development of browser for all platforms except Longhorn, and make some browser security patches available only to XP SP2 users
3) Make antivirus and anti-spyware software, and charge for it
4) Profit!
I believe tinfoil will filter all frequencies that we presently use for radio communication (mostly because I can't see through it).
You can't see through it because it reflects or absorbs (more reflecting than absorbing, I'd say) most visible light. I'm not so sure about radio frequencies.
It certainly can't filter gamma waves
I doubt the device inside my mother's transpass can receive and transmit gammas.
Still, having two frequencies on which the device can respond, one filtered by the bag and the other not, is definitely a plausible explanation (why didn't I think of it?!) for the behavior my mother observed.
I think I'll tell my mom to wrap the transpass in aluminum foil and see what happens. I wonder if they'd notice if some car were scanned (with the transpass in the bag, so it wouldn't be charged) getting on the highway and then never appeared getting off the highway, or vice-versa. It'd be interesting to see if "they" (the highway authorities) monitor that kind of thing and look for cars that might have gone off the road.
Different how? All I've ever seen tollbooths do is say "EZ Pass. $x.xx. OK" and then raise the barrier. Did start to raise the barrier, hesitate, bring it back down and then say "Um. yeah. no ezpass. wink wink"?
Not all that far off. The tollbooth gave some message that meant that it had detected the Transpass (I don't remember the details of the message), but did not charge the trip to the transpass, and my mother had to pay in order to get through.
actually, shoplifters have been using this method (wrapping in tinfoil) for a while now. same kind of concept.
Can anyone confirm if this really works?
My mother has one of those electronic passes for the toll highway she takes to work and back. The pass comes with a metallized plastic bag into which the user is supposed to place it when she does not want the toll booth to automatically detect and charge (as in money) the pass.
I am not sure if that device uses RFID, but the basic principle is similar. The tollbooth (or store stocking, security, and possibly checkout systems, or the government's Big Brother-style citizen tracking infrastructure) detects the device at a distance and takes some action upon doing so. For various different reasons, people might want to block detection of these devices, and I'd like to know which blocking schemes work and how well.
Mom did a few experiments with her highway pass. She noticed that the way the tollbooths (both entering and leaving the highway) responded differently when she had the pass in the bag than when there was no pass in the car. So even though putting the pass into the bag did keep it from being used for that particular trip, it did not keep the highway authorities from knowing the bag was there and tracking the user's movements.
I'd really like to see reports of some tests of RFIDs and similar technologies with different shielding schemes. Does a layer of tinfoil work? Two layers? Three layers? etc. (Anything beyond 5 layers starts to get to be difficult). What other schemes work, and how well?
Of course, the DMCA might complicate this, because while I see blocking schemes as a means to protect privacy, others see it as a way to shoplift, and the RFID companies and US government will almost certainly see them as "circumvention."
Maybe somebody in Europe could do some tests...
I found this article in Wired (referenced by most of the first 60 hits in Google), but the article contains exactly what I was thinking:
Privacy activists at the workshop also said the companies promoting the new standard for using RFID tags, called the Electronic Product Code, are exaggerating RFID's limitations in order to assuage consumers' privacy concerns.
Mandelbrot _discovered_ fractals he did not invent them.
No, he did not discover them either. The work of the other mathematicians I mentioned predated Mandelbrot's work. The concepts of fractals already existed, and the Hausdorff Dimension already existed and had been calculated for some fractal sets.
Also, I did not "discredit" Mandelbrot. I simply pointed out that he is a shameless self-promoter who tries to claim credit for inventing or discovering things that others had discovered before. If you'd read my whole post, you'd have noticed that after retelling the joke about Mandelbrot's work, which I think does a good job of showing that the general opinion among serious scientists in the 1980s was that Mandelbrot's main talent is for self-promotion, I did point out that he made some contributions of value. I'll even do it again. He was the first to plot the Julia Sets and the "M set" that divides Julia Sets into connected and disconnected sets. Those are interesting and worthwhile contributions.
I personally don't think that applying the word "fractal" to the work of other mathematicians constitutes anything of great value. That doesn't mean unifying the work of others couldn't be a major contribution. Maxwell started out by comparing the work of other physicists and unifying it, and ended up creating a unified theory of electricity and magnetism.
Mandelbrot borrowed from the work of others, made some interesting but incremental gains and applied the word "fractal" to the sets. He did not come up with any kind of unifying theory of fractals.
It's worth noting that many scientists and mathematicians have complained that Mandelbrot was a bit stingy in his citation of previous works. Others have used harsher terms; I'm happy to just leave it as I just put it. Mandelbrot did at least acknowledge that his "M Set" work was based on the Julia Sets.
I'm not sure why the Anonymous Coward troll can't accept the idea of Mandelbrot not being the great pioneer he claims to be. Maybe it's because the view of Mandelbrot as an overrated self-promoter (once again, that doesn't mean he didn't do something of value, just that he over-promotes what he did) doesn't jibe with what one finds in popular literature books that tend to swallow Mandelbrot's self-promotion hook, line, and sinker and then pass it undigested it to their audience.
As for my peer-reviewed work, it appears in physics journals and not mathematical journals (one is "both:" a paper in J. Math. Phys.). None of my research has constituted a major breakthrough. But that's not relevant, because unlike Mandelbrot, I haven't claimed to be the creator of the fields in which I have published works. Unlike Mandelbrot, I recognize that my work represents incremental gains for science, starting from the work of others, and not earth-shaking breakthroughs.
Mandelbrot's contribution was interesting and worthwhile, but nowhere near as impressive as the work of Julia. Julia did more with less. But Mandelbrot claims to have created the field of fractals with his "amazing discoveries," which really are nothing more than incremental gains starting from the work of others like Julia. I want to make it clear that I believe there's nothing at all "wrong" with one's work constituting incremental gains. Most of science advances by incremental gains, and major breakthroughs and scientific "revolutions" tend to be very few and far between. Some of the physicists I most respect didn't do anything revolutionary, but have pushed back the boundaries of knowledge by incremental steps, building on the work of predecessors and colleagues. I do, however, take issue with people like Mandelbrot, who make these kinds of incremental steps and then try to claim credit for all the advances made from the beginning, including the work of predecessors.
Mandelbrot is not the inventor of fractals!
Three people whose work on fractals predated Mandelbrot's by some time, and IMNSHO was infinitely more impressive because it was done without the help of computers, are Felix Hausdorff, inventor of the Hausdorff dimension, Georg Cantor, inventor of the fractal Cantor "middle thirds" Set, and Gaston Julia, who discovered/invented the Julia Set, to which the Mandelbrot Set is closely related.
Think about how amazing the work of these three mathematicians was, given that they, unlike Mandelbrot, didn't have computers to iterate maps or visualize sets, and yet they were able to characterize these sets, including their fractal nature. I find Julia's accomplishment especially impressive.
Mandelbrot is better than these three at self-promotion. When he fiddled a bit with the Julia Set and produced a new set from it, he called it the "M Set" in his work, and waited for somebody else to fill in the remaining 9 letters after "M."
There was a joke among physicists messing around with fractal stuff in the late 1980s that while the most common letter in the English language is "e," the most common letter in Mandelbrot's work was either "I" or "M" (the probable winner, given that "me," "my," "mine," and "Mandelbrot" all begin with "M").
That said, Mandelbrot's work was interesting, and he did acknowledge Julia's work in his own. After all, the Mandelbrot Set is a map where each point on the complex plane represents a Julia Set, where the points inside the Mandelbrot Set represent connected Julia Sets and the points outside represent disconnected Julia Sets. And Mandelbrot took advantage of the computer technology available to him to plot some of these sets, giving us visual representations of these things. But to give him credit for inventing fractals is unfair to the great mathematicians who worked on fractals long before Mandelbrot.
The real news is that they actually found an interesting use for those "pages of a scientific journal."
There was a joke among physicists - I first heard it in the early 1990s- that said that a certain physics journal (I believe it was Physical Review Letters, or "PRL") was growing so quickly that its expansion was actually faster than the speed of light. There was, however, no violation of relativity, because no information was being conveyed.
The original intent was to have the House more subject to the "whims" of the voters, all its members having to face election every other year, while Senators, with six-year terms, would be a bit safer from having to shift according to how the political "winds" were blowing. The Senate would then be able to take a longer-term view and offset some of the volatility of the House.
Ironically, despite having to face the voters three times as often as Senators, House members are now "safer" than Senators, because incumbents win (significantly) more frequently in the House than in the Senate. How can this be? Through the magic of gerrymandering. A Senator must face all the voters in his state. A member of the House need only face the voters in his own district, which in many cases was created to give his party an advantage there (whether his own party set it up to give him a safe seat or whether the other party set it up to concentrate his voters in one district and keep his party from winning two districts).
An interesting article on this subject appeared in The New Yorker late last year. The piece is sympathetic to the Dems in Texas who got squeezed by the unusual redistricting orchestrated there by Tom DeLay last year, but I think even Republican partisans might find the parts about the software available for gerrymandering and how fiendishly effective it is pretty interesting (especially since both parties have done their share of gerrymandering).
I personally see gerrymandering as a problem peculiar to two-party political systems. I also think it's one of the biggest problems in the US political system, but it is largely ignored by the media and most voters.
This page makes a fairly convincing argument that 256 bit CPUs should be enough (basically, there would be no way to exhaust the amount of memory a 256 bit CPU could access, because the number of memory locations is about the same as the number of atoms in the universe).
Great post. Unfortunately, my response is very late because I only got to see your post when metamodding.
The parent's detailed knowledge of some major issues in the USA (of which many UnitedStatesians, I'm ashamed to admit, are not as aware) reminds me of something I saw in a documentary in the early-to-mid 1990s. An expert on certain labor issues was giving a talk in Europe. A person in the audience (IIRC, he was Dutch) started asking some questions. At first, they were fairly general, like audience questions often are. But they got more and more detailed and complex. It got to the point where the fellow giving the talk was only able to respond to the questions because he happened to have done some research on specific cases being raised by the questioner from the audience. The speaker finally asked the person from the audience how he knew so much about the subject. The questioner said he saw a thing on TV about it. This, of course, left the speaker completely stunned. He couldn't imagine that somebody could learn so much about a subject from TV.
The questioner then said something to the effect of "oh yeah... I also saw a thing on TV about how in the USA, all your media are controlled by a handful of corporations, and this keeps you from getting any detailed information about issues from your mass media outlets."
But the parent didn't mention this issue explicitly, despite getting very close to it a few times. So I'd say that another "core issue" with which the USA must deal is the problem of control of the mass media by a few corporations. This goes along with the "Make it harder for politicians to be bribed" and "Improve education" issues cited in the parent post, but it is separate and just as important.
I can say, as a UnitedStatesian expat in Brazil, that even though there is a scary corporate media giant here (Globo, subject of the British documentary "Beyond Citizen Kane"), and even though some of the large media companies seem to follow the US media (e.g., in the week after Sept. 11, 2001, the covers of two major news magazines were basically exact copies of the cover of either Time or Newsweek from the same time), we do get to see a lot of news that nobody seems to get from the USian mass media.
This sounds to me like a more advanced classical mechanics text. In my second year in college (physics major), we used Marion & Thornton's Classical Dynamics of Particles and Systems, which seems to be one of the standard texts at that level. I believe Symon's Mechanics is another book at about the same level.
In my first year in grad school, I took a great classical mechanics course taught by a guy who uses classical mechanics in his research on planetary systems. His name is Stanton Peale. He got semi-famous by publishing a paper just before Voyager arrived near Jupiter, saying that Io might be volcanic. He would have published it a lot sooner, but he didn't notice that orbital data on the Galilean moons are, for historical reasons, recorded differently than those for other moons in the solar system. He had therefore mistakenly calculated that none of the Galileans would be volcanic. By chance (if such a thing exists:D), he was working on another problem and noticed this. He then repeated his calculations and saw that tidal stresses on Io might be strong enough to give it a liquid interior. He had trouble getting the paper published in the short time before pictures started coming back from Voyager, but managed. As he told me, anyone can write a paper explaining why a moon is volcanic after the discovery of vulcanism on the moon, but he wanted to publish the prediction before the pictures came back.
But I digress... in Peale's class, we used the standard graduate text on Classical Mechanics, which is Goldstein's Classical Mechanics.
Both the Goldstein book and the Marion & Thornton book cover Lagrangian and Hamiltonian mechanics. Goldstein goes into more details about things like Poisson Brackets and canonical transformations.
The Landau & Lifshitz book Mechanics, the first volume of the "Course of Theoretical Physics," covers much of the same material, but is quite concise. For that reason, like most of the Landau/Lifshitz (and Lifshitz/Pitaevskii, after Landau died) books, it is pretty dense.
I'm not sure if Oliver intended to bring these things to folks other than physics majors, but who other than physics majors (and maybe the occasional math major or other science/engineering major) has enough interest in the subject to wade through the math? The math isn't all that complicated (for a physics or math major), but it's complicated enough to deter anyone not really interested in the subject. Peale's classical mechanics class was not quite a weed-out course, but it was one that a significant number of people dropped in their first year and were taking for the second time when I took it. I worked really hard in that class and ended up learning a lot. And it wasn't just the math that made it tough. But the point is that this material can be taught at a level that's challenging for grad students...
Say again how a book with a title (and subtitle) like that is objective?
Uh... maybe the title was chosen after the research had been done and it became clear that Brazil's electronic voting machines are extremely vulnerable to fraud and present no means of independent verification or auditing of results...
Slashdot Mirror
So what's the definition of a fermion or a boson, and in this specific case, of a fermionic or bosonic nucleus?
Bosons have integer spin, and fermions have half-integer (n+1/2, where n is a nonnegative integer) spin. The spins of the individual quarks in nucleons (protons and neutrons) always add up to a half-integer, so nucleons are fermions. The quarks themselves are too. The spins of the nucleons in a nucleus can add up in different ways, depending on the number of each kind (proton and neutron) present. When the spins add to become an integer, the nucleus is bosonic. When the spins add to a half-integer, the nucleus is fermionic.
If a given nucleus is fermionic, then identical nuclei of that type obey the Pauli exclusion principle. If the nucleus is bosonic, then the Pauli exclusion principle does not apply to it, and the possibility of a collection of that kind of nucleus forming a BEC exists.
Here's the relevant dialogue: The two talk a bit about Carl's project. The scene ends as follows:
But seriously, that question is as ill-defined as "what happened before the Big Bang" (time is only definable after the Big Bang) or "what's outside the edge of the universe" (space is only defined within the universe).
I don't like the way these people are putting wild-ass conjecture supported by faith on the same level as a theory that is testable and disprovable, and that has so far been verified in numerous independent observations. But there are undefined and ill-posed questions in both the scientific (testable, disprovable, and well-supported) theory and in the non-disprovable conjecture supported only by faith.
I've been led to believe there's a problem with this scheme.
The bank where I have my account right now is Bradesco, the largest non-government bank in Brazil. I'm told Bradesco had the fifth internet banking site in the world, the first in Latin America, and as of a couple of years ago, it was the third largest internet banking site in terms of transaction volume, trailing only two banks in the USA.
To get into my account in Bradesco's internet banking site, I have to type a secret phrase (minimum 12 characters) and type in a 4-digit code using a graphical numerical keypad where the position of the keys is random. Also, to verify each transaction, I get a confirmation screen and confirm by typing in a six-digit code using a graphical numerical keypad with the keys in random positions.
The problem, I'm told, is that some clever but nasty people have made applications like keyloggers that take "snapshots" of the region immediately surrounding the mouse pointer when the button is clicked. If that's true, it seems to me it would indeed defeat the purpose of the graphical keypads with randomly placed keys.
I have no way to verify this, but it scares the crap out of me. I use Firefox, and I sweep my machine daily with an antivirus program that is updated daily. I also sweep it daily with an anti-spyware program and occasionally with a second one. I also have a personal firewall. Still, I just don't feel all that safe. I know that in theory, using a credit card on the internet can be safer than using one in a gas station or restaurant, but given the many security holes in Windows and the industry of identity stealers, crackers, phishers, and such that has sprung up, I worry about a keylogger (or keylogger "plus") somehow getting into my machine.
Exactly.
The parent post was modded as funny (and it is), but I consider it insightful too. What was so cool about The Force in the original movies was that it was basically magic. Lightsabers too. When reading about King Arthur, I didn't have any questions about how Excalibur was forged. I don't care how the magic used by Gandalf and Saruman in LOtR works. It just does.
That's why, to me, the biggest offense of Episode I wasn't Jar Jar or the stupid and ridiculously prolonged fish-eat-fish scene. It was less than a minute of stupid technobabble dialogue about chlamydians or whatever (OK, I know it's midi-clorians, but I get a chuckle out of this alternate name). In that brief bit of dialogue, the magic of The Force was ruined and reduced to a mere blood condition. Seriously... could a simple shot of penicillin have avoided the whole Darth Vader situation, and with it the Galactic Empire?
I prefer The Force as it was in the original trilogy. It was magic! In Star Wars Han Solo even disparaged The Force as a "hokey religion" and lightsabers as "ancient weapons," saying that the combination was no match for a good blaster at your side. I wasn't as cynical about The Force as Han (and even Han changed his view, wishing "May the Force be with you" to Luke before leaving the Yavin IV base before the attack on the Death Star). I thought it was pretty cool. But I really never wanted to know the nuts and bolts of how it worked. Jeeze, if I wanted ridiculous technobabble "explanations" of how things work, I'd watch ST:tNG reruns and and get my fill of tetrions and subatomic bacteria and such.
Actually hearing about midi-clorians ruined the magic of The Force for me. I don't see how Jar Jar can "ruin" people's memories of the original series, because one has nothing to do with the other. But the babble about the chlamydians did ruin The Force.
It really surprises me people complain so much about Jar Jar and so little about the midi-clorians.
TFA says How? What keeps a third party between the two friends from receiving the photons transmitted by one friend and retransmitting exactly the same sequence of photons to the other while keeping a record, and therefore, a copy of the message?
I'm pretty sure there's more to it than appeared in TFA, and that there is a way to be sure there isn't an eavesdropper between the two friends, but I don't know what it is.
The people responsible for mirroring the site have been sacked.
I sent the link to a bunch of people. My mother, who is 63, wrote this after watching it: So Hitachi's clip was good enough to keep a 63 year old woman who couldn't care less about the inner workings of her hard drive "glued," and she actually ended up learning from it.
There's one more thing: it's fun to watch, like the Schoolhouse Rock clips that at least partially inspired it. The horizontal bit that learns it has to go vertical looks a lot like the bill that was sitting on Capitol Hill on Saturday mornings when I was a kid. The tune is catchy enough that I didn't get tired of it, and I got a kick out of the bit backup singers with afros. I think this is the single coolest technology announcement I've ever seen. I've seen cooler technologies announced, and I've seen tech announcements with more detailed info, but this was the coolest announcement.
I find it amazing that somebody made all this effort, and made something this cool, to announce a technological advance that isn't even a product yet.
As for the question of how to check for errors, there are other mathematical methods. After a few dozen digits, you exceed our capacity for measurement precision. But
Some interesting and surprising things involving pi come up in very basic complex analysis. For example, i raised to the i power has a finite real value, and that value involves pi {it's e^(-pi/2)}.
One (unity, the number 1) is of course e^0 (any nonzero real number raised to the zero power is 1). But negative 1 (-1) is e^(i pi). And i is e^(i pi/2) and -i is e^(-i pi/2).
I digress. This is all just an example of how pi shows up in places where you might not expect it in mathematics. There are more advanced examples, but I think this one serves to make the point.
As for the principal question, why one would need to know pi so accurately, well, for some it's just the challenge. According to TFA, the Chudnovskys were hoping to find a pattern. But just going further than anyone else has its own value. Would you have asked Edmund Hillary why he needed to climb Everest?
The previous Brazilian president's health minister, José Serra (currently mayor of São Paulo), did several really important things when he held that office. He set up a modern organ donation system (cutting down significantly on the black market for organs that existed previously). He pushed for the law making generic medications possible. He created an anti-AIDS policy that is a model studied by governments from all over the world. And part of that AIDS policy involved the government giving medications to AIDS patients.
The success of Brazil's anti-AIDS policy had convinced many that it was well designed and should continue as it had. But as the multinational pharmaceutical companies jacked up the prices of AIDS treatment medications, it got to the point where continuing the otherwise successful policy would be beyond the government's financial limits. Serra went to the pharmaceutical companies (there were two main ones making AIDS treatment meds) and told them that a clause in the Brazilian constitution allowed him, in the case of a crisis (and AIDS would have been accepted by the courts as a crisis), to break the patents and allow Brazilian companies to manufacture the drugs without paying a cent to the patent holders. He made it clear that he did not want to do that, and that he just wanted the companies to stop jacking up the prices. One company agreed immediately. The other decided to call Serra's bluff. He moved forward with the actions he had to take to break the patents, and the other company gave in.
Brazil's successful anti-AIDS policy continues to work, even after a change of governments (Serra lost the presidential election of 2002 to Luis Inácio Lula da Silva, one of the founders of the Brazilian labor movement). I do have some questions about where to draw the line between a crisis and a non-crisis, and I worry about what else the government could just take in the name of averting a "crisis," but this is an example where the end result was pretty positive. The pharmaceutical companies didn't get to do as much price gouging as they had hoped, but since their usual argument is that drugs have to be expensive because of the high cost of developing new drugs, there was little reason to keep elevating the price of drugs that had been on the market for some time. In terms of public health, it was a big win, as Brazil's policy continues to limit the spread of AIDS.
I think one example of systems that could have had problems and could have caused serious trouble were the avionics and other systems in airplanes (and air traffic control). I recall reading articles about the hard work the Y2K teams did, digging into these systems looking for any component that might have a 2-digit year or other similar problem.
I also recall reading that the Chinese government found a very good way of making sure Chinese airlines would be safe: Chinese airline officials (executives?) were required to be in passenger planes in the air as 1999 ended and 2000 began.
1) Integrate browser into OS so browser vulnerabilities are OS vulnerabilities
2) Halt development of browser for all platforms except Longhorn, and make some browser security patches available only to XP SP2 users
3) Make antivirus and anti-spyware software, and charge for it
4) Profit!
Still, having two frequencies on which the device can respond, one filtered by the bag and the other not, is definitely a plausible explanation (why didn't I think of it?!) for the behavior my mother observed.
I think I'll tell my mom to wrap the transpass in aluminum foil and see what happens. I wonder if they'd notice if some car were scanned (with the transpass in the bag, so it wouldn't be charged) getting on the highway and then never appeared getting off the highway, or vice-versa. It'd be interesting to see if "they" (the highway authorities) monitor that kind of thing and look for cars that might have gone off the road.
--Mark
My mother has one of those electronic passes for the toll highway she takes to work and back. The pass comes with a metallized plastic bag into which the user is supposed to place it when she does not want the toll booth to automatically detect and charge (as in money) the pass.
I am not sure if that device uses RFID, but the basic principle is similar. The tollbooth (or store stocking, security, and possibly checkout systems, or the government's Big Brother-style citizen tracking infrastructure) detects the device at a distance and takes some action upon doing so. For various different reasons, people might want to block detection of these devices, and I'd like to know which blocking schemes work and how well.
Mom did a few experiments with her highway pass. She noticed that the way the tollbooths (both entering and leaving the highway) responded differently when she had the pass in the bag than when there was no pass in the car. So even though putting the pass into the bag did keep it from being used for that particular trip, it did not keep the highway authorities from knowing the bag was there and tracking the user's movements.
I'd really like to see reports of some tests of RFIDs and similar technologies with different shielding schemes. Does a layer of tinfoil work? Two layers? Three layers? etc. (Anything beyond 5 layers starts to get to be difficult). What other schemes work, and how well?
Of course, the DMCA might complicate this, because while I see blocking schemes as a means to protect privacy, others see it as a way to shoplift, and the RFID companies and US government will almost certainly see them as "circumvention."
Maybe somebody in Europe could do some tests...
I found this article in Wired (referenced by most of the first 60 hits in Google), but the article contains exactly what I was thinking: So... anybody know of reliable tests?
--Mark
Also, I did not "discredit" Mandelbrot. I simply pointed out that he is a shameless self-promoter who tries to claim credit for inventing or discovering things that others had discovered before. If you'd read my whole post, you'd have noticed that after retelling the joke about Mandelbrot's work, which I think does a good job of showing that the general opinion among serious scientists in the 1980s was that Mandelbrot's main talent is for self-promotion, I did point out that he made some contributions of value. I'll even do it again. He was the first to plot the Julia Sets and the "M set" that divides Julia Sets into connected and disconnected sets. Those are interesting and worthwhile contributions.
I personally don't think that applying the word "fractal" to the work of other mathematicians constitutes anything of great value. That doesn't mean unifying the work of others couldn't be a major contribution. Maxwell started out by comparing the work of other physicists and unifying it, and ended up creating a unified theory of electricity and magnetism.
Mandelbrot borrowed from the work of others, made some interesting but incremental gains and applied the word "fractal" to the sets. He did not come up with any kind of unifying theory of fractals.
It's worth noting that many scientists and mathematicians have complained that Mandelbrot was a bit stingy in his citation of previous works. Others have used harsher terms; I'm happy to just leave it as I just put it. Mandelbrot did at least acknowledge that his "M Set" work was based on the Julia Sets.
I'm not sure why the Anonymous Coward troll can't accept the idea of Mandelbrot not being the great pioneer he claims to be. Maybe it's because the view of Mandelbrot as an overrated self-promoter (once again, that doesn't mean he didn't do something of value, just that he over-promotes what he did) doesn't jibe with what one finds in popular literature books that tend to swallow Mandelbrot's self-promotion hook, line, and sinker and then pass it undigested it to their audience.
As for my peer-reviewed work, it appears in physics journals and not mathematical journals (one is "both:" a paper in J. Math. Phys.). None of my research has constituted a major breakthrough. But that's not relevant, because unlike Mandelbrot, I haven't claimed to be the creator of the fields in which I have published works. Unlike Mandelbrot, I recognize that my work represents incremental gains for science, starting from the work of others, and not earth-shaking breakthroughs.
Mandelbrot's contribution was interesting and worthwhile, but nowhere near as impressive as the work of Julia. Julia did more with less. But Mandelbrot claims to have created the field of fractals with his "amazing discoveries," which really are nothing more than incremental gains starting from the work of others like Julia. I want to make it clear that I believe there's nothing at all "wrong" with one's work constituting incremental gains. Most of science advances by incremental gains, and major breakthroughs and scientific "revolutions" tend to be very few and far between. Some of the physicists I most respect didn't do anything revolutionary, but have pushed back the boundaries of knowledge by incremental steps, building on the work of predecessors and colleagues. I do, however, take issue with people like Mandelbrot, who make these kinds of incremental steps and then try to claim credit for all the advances made from the beginning, including the work of predecessors.
--Mark
Mandelbrot is not the inventor of fractals!
Three people whose work on fractals predated Mandelbrot's by some time, and IMNSHO was infinitely more impressive because it was done without the help of computers, are Felix Hausdorff, inventor of the Hausdorff dimension, Georg Cantor, inventor of the fractal Cantor "middle thirds" Set, and Gaston Julia, who discovered/invented the Julia Set, to which the Mandelbrot Set is closely related.
Think about how amazing the work of these three mathematicians was, given that they, unlike Mandelbrot, didn't have computers to iterate maps or visualize sets, and yet they were able to characterize these sets, including their fractal nature. I find Julia's accomplishment especially impressive.
Mandelbrot is better than these three at self-promotion. When he fiddled a bit with the Julia Set and produced a new set from it, he called it the "M Set" in his work, and waited for somebody else to fill in the remaining 9 letters after "M."
There was a joke among physicists messing around with fractal stuff in the late 1980s that while the most common letter in the English language is "e," the most common letter in Mandelbrot's work was either "I" or "M" (the probable winner, given that "me," "my," "mine," and "Mandelbrot" all begin with "M").
That said, Mandelbrot's work was interesting, and he did acknowledge Julia's work in his own. After all, the Mandelbrot Set is a map where each point on the complex plane represents a Julia Set, where the points inside the Mandelbrot Set represent connected Julia Sets and the points outside represent disconnected Julia Sets. And Mandelbrot took advantage of the computer technology available to him to plot some of these sets, giving us visual representations of these things. But to give him credit for inventing fractals is unfair to the great mathematicians who worked on fractals long before Mandelbrot.
--Mark
--Mark
The original intent was to have the House more subject to the "whims" of the voters, all its members having to face election every other year, while Senators, with six-year terms, would be a bit safer from having to shift according to how the political "winds" were blowing. The Senate would then be able to take a longer-term view and offset some of the volatility of the House.
Ironically, despite having to face the voters three times as often as Senators, House members are now "safer" than Senators, because incumbents win (significantly) more frequently in the House than in the Senate. How can this be? Through the magic of gerrymandering. A Senator must face all the voters in his state. A member of the House need only face the voters in his own district, which in many cases was created to give his party an advantage there (whether his own party set it up to give him a safe seat or whether the other party set it up to concentrate his voters in one district and keep his party from winning two districts).
An interesting article on this subject appeared in The New Yorker late last year. The piece is sympathetic to the Dems in Texas who got squeezed by the unusual redistricting orchestrated there by Tom DeLay last year, but I think even Republican partisans might find the parts about the software available for gerrymandering and how fiendishly effective it is pretty interesting (especially since both parties have done their share of gerrymandering).
I personally see gerrymandering as a problem peculiar to two-party political systems. I also think it's one of the biggest problems in the US political system, but it is largely ignored by the media and most voters.
--Mark
This page makes a fairly convincing argument that 256 bit CPUs should be enough (basically, there would be no way to exhaust the amount of memory a 256 bit CPU could access, because the number of memory locations is about the same as the number of atoms in the universe).
--Mark
Great post. Unfortunately, my response is very late because I only got to see your post when metamodding.
The parent's detailed knowledge of some major issues in the USA (of which many UnitedStatesians, I'm ashamed to admit, are not as aware) reminds me of something I saw in a documentary in the early-to-mid 1990s. An expert on certain labor issues was giving a talk in Europe. A person in the audience (IIRC, he was Dutch) started asking some questions. At first, they were fairly general, like audience questions often are. But they got more and more detailed and complex. It got to the point where the fellow giving the talk was only able to respond to the questions because he happened to have done some research on specific cases being raised by the questioner from the audience. The speaker finally asked the person from the audience how he knew so much about the subject. The questioner said he saw a thing on TV about it. This, of course, left the speaker completely stunned. He couldn't imagine that somebody could learn so much about a subject from TV.
The questioner then said something to the effect of "oh yeah... I also saw a thing on TV about how in the USA, all your media are controlled by a handful of corporations, and this keeps you from getting any detailed information about issues from your mass media outlets."
But the parent didn't mention this issue explicitly, despite getting very close to it a few times. So I'd say that another "core issue" with which the USA must deal is the problem of control of the mass media by a few corporations. This goes along with the "Make it harder for politicians to be bribed" and "Improve education" issues cited in the parent post, but it is separate and just as important.
I can say, as a UnitedStatesian expat in Brazil, that even though there is a scary corporate media giant here (Globo, subject of the British documentary "Beyond Citizen Kane"), and even though some of the large media companies seem to follow the US media (e.g., in the week after Sept. 11, 2001, the covers of two major news magazines were basically exact copies of the cover of either Time or Newsweek from the same time), we do get to see a lot of news that nobody seems to get from the USian mass media.
--Mark
--Mark
This sounds to me like a more advanced classical mechanics text. In my second year in college (physics major), we used Marion & Thornton's Classical Dynamics of Particles and Systems, which seems to be one of the standard texts at that level. I believe Symon's Mechanics is another book at about the same level. :D), he was working on another problem and noticed this. He then repeated his calculations and saw that tidal stresses on Io might be strong enough to give it a liquid interior. He had trouble getting the paper published in the short time before pictures started coming back from Voyager, but managed. As he told me, anyone can write a paper explaining why a moon is volcanic after the discovery of vulcanism on the moon, but he wanted to publish the prediction before the pictures came back.
In my first year in grad school, I took a great classical mechanics course taught by a guy who uses classical mechanics in his research on planetary systems. His name is Stanton Peale. He got semi-famous by publishing a paper just before Voyager arrived near Jupiter, saying that Io might be volcanic. He would have published it a lot sooner, but he didn't notice that orbital data on the Galilean moons are, for historical reasons, recorded differently than those for other moons in the solar system. He had therefore mistakenly calculated that none of the Galileans would be volcanic. By chance (if such a thing exists
But I digress... in Peale's class, we used the standard graduate text on Classical Mechanics, which is Goldstein's Classical Mechanics.
Both the Goldstein book and the Marion & Thornton book cover Lagrangian and Hamiltonian mechanics. Goldstein goes into more details about things like Poisson Brackets and canonical transformations.
The Landau & Lifshitz book Mechanics, the first volume of the "Course of Theoretical Physics," covers much of the same material, but is quite concise. For that reason, like most of the Landau/Lifshitz (and Lifshitz/Pitaevskii, after Landau died) books, it is pretty dense.
I'm not sure if Oliver intended to bring these things to folks other than physics majors, but who other than physics majors (and maybe the occasional math major or other science/engineering major) has enough interest in the subject to wade through the math? The math isn't all that complicated (for a physics or math major), but it's complicated enough to deter anyone not really interested in the subject. Peale's classical mechanics class was not quite a weed-out course, but it was one that a significant number of people dropped in their first year and were taking for the second time when I took it. I worked really hard in that class and ended up learning a lot. And it wasn't just the math that made it tough. But the point is that this material can be taught at a level that's challenging for grad students...
--Mark
--Mark