There's book smarts and there's applied intelligence.
NASA is ALL about applied intelligence. Additionally they still have a number of theorists working for them as well.
Anyway, your tired quote about teachers not being able to 'do' isn't accurate at all. University professors only spend a minority of their time 'teaching', at least in the sciences at real research universities. The majority of their efforts go towards research, and that success is based upon their publications, and more importantly, how often their publications are referenced by others. The smartest 'professors' i referred to in my original post are quite successful in this regard.
The smartest people are in the private sector, why not use their skills and efficiencies to benefit the race to the stars?
That's not really true, so I'll take it you haven't worked with NASA much at all. I've worked with NASA scientists on several projects and the scientists/engineers there are typically top-notch. Much more knowledgeable than most engineers I've dealt with from the private sector. NASA's problems primarily stem from its bureaucracy and red-tape, not from shortcomings of its engineers.
And to take your skepticism further, the smartest people I've encountered to date have been university professors (at least in physics). Usually more likely to collaborate w/ NASA than with the private sector, too.
Would it be cheaper than NASA developing the same things in-house?
I used to work on a DARPA-funded project, and I can tell you - almost certainly.
There has been a push w/ governmental agencies, including NASA, to use COTS (Commercial Off-The-Shelf) products. A private company researches and develops a certain product product (which NASA could do as well), but can then sell the products to a variety of outlets for profit (which NASA is forbidden to do). So NASA buying a one-off of a COTS component pays only a fraction of the R&D cost that the company spent making it.
As an example, I know of a group that needed a very linear high-bandwidth op-amp for a project. Such an op-amp within their specs didn't exist, so they began the intensive effort of designing one themselves. Halftway through the process another company (maybe Burr-Brown? I forget) put a device on the market that did meet their specs. Although they spent time/money on the research, they still saved out in the end because they just bought and used that op-amp without wasting further development efforts.
The big win for COTS comes from the fact that NASA and other governmental agencies and labs CANNOT sell products for profit, but private companies CAN. For example, the lab I worked in (not my group, though) did alot of radar research. After proving new radar concepts would work, companies like Lockheed-Martin or Raytheon would go and build many of them, making millions of $$$ for themselves. Such is the life of research;-)
Spin is perhaps better explained through it's nomenclature often used by physicists - intrinsic angular momentum
That's basically it. Spin is a kind of angular momentum that just exists in the various particles. Electrons, neutrons, photons, etc all have spin.
Now to get a better idea, you have to understand how angular momentum works in quantum mechanics. Actually, it's quite complicated, and alot of group theory has come around to describe it succintly.
Angular momentum is 'quantized'. A spinning top can spin at any rotational velocity (including two directions - clockwise/counterclockwise). For any given particle, the spin only comes in discrete steps of h-bar, the Plank constant.
The angular momentum must also be centered around 'zero', so this means there are two types of particles. THose with integer spin (having values of -2,-1,0,1,2,etc) or half-integer spin (having values of -3/2, -1/2, 1/2, 3/2, etc). The former are called Bosons and the latter called Fermions. The properties between these two differ vastly (mostly due to QED theory that describes symmetric vs antisymmetric wavefunction upon particle interchange. This gives a 'Pauli-exclusion' law for fermions with no such law for bosons.)
Okay, I don't know if anybody bothered to read this far, but things get more complicated. Each particle has a total spin (photons are spin 1, and electrons are spin 1/2, for instance). But one really doesn't know the 'direction' of the spin, so one can look at the projection of the spin on the z-axis, which has to be quantized. So a spin-1 photon can have a z-projection of -1,0,1. And an electron can be +1/2 or -1/2. If you remember your high-school chemistry and quantum numbers one of them was the spin. This is why each set of n,l,m has two allowed values for the electron spin. But beyond this, one cannot know exactly which direction the spin points because, in quantum mechanics terms, the x, y, and z spin projection operators don't commute. So there's an inherent uncertainty there.
Now to get even more complicated, there's orbital angular momentum (for atoms) and the spin. So this gives the total angular momentum. But adding angular momentum must be done properly within the mathematical confines of group-theory, it's not simple vector-addition at all. So it gets pretty crazy, because you cannot simultaneously know both the total spins z-components of two particles (in specific cases you can, but not in general). So you have things like Clebsch-Gordon coefficients, etc. Anyway, the l and m quantum numbers from chemistry basically come from the orbital angular momentum.
To answer your question about measuring spin, remember it's quantized. But in any interaction the z-component of the spin must be conserved. So if a photon is emitted, that subtracts the total spin by one. So spin of the resulting system must change appropriately (remember the differnece between total spin and z-component of spin). So in a way, torque can be applied by bombarding something w/ particles, but the change in angular momentum must be quantized by units of hbar.
No "information" is exchanged in the "teleportation" it is just that one can "copy" a quantum mechanical state from one place to another
Not quite.
You're correct that quantum teleportation will transfer a quantum wavefunction from one point to another. But it cannot 'copy' the wavefunction. In order to send the wavefunction, the original wavefunction must be destroyed during the process.
Sorry, fanout is strictly prohibited in quantum computing.
Wow, 2 quantum computation articles on/. within two days.
I mentioned this yesterday as well, but for an idea of what qubits are you can take a look at my currently unfinished Java Quantum Computation applet. As of now one can only do single-qubit operations, but eventually I hope to have a demo of quantum teleportation (teleportation of a single qubit, or spinor, that is).
This applet will give you an idea of what qubits are. Essentially they're a 'spinor' which in quantum-mechanical terms is a 2-element discrete wavefunction. In lay terms, this just means a set of two complex numbers (properly normalized). They are also displayed in a more visible representation, called the 'Bloch Sphere'.
This applet will let you take any input qubit, and operate on it with 6 different single-qubit quantum gates, and see the resulting qubit.
Look at the two qubits represented on the Bloch sphere. The yellow vector represents the qubits. The red dot indicates a classical 'zero' and the blue dot indicates classical 'one'. In classical computing any bit can only point exactly to the red or blue dots. In quantum computation a qubit can point anywhere on that sphere.
[For the mathematically curious, a qubit is 2 complex numbers, which would be 4 independent parameters. However, the sum of the modulus squared of each complex number must be unity, so that constraint leaves only 3 free parameters. Secondly, the entire qubit can be multiplied by any arbitrary phase constant (e^i*gamma) which changes the spinor but not its relative values. Hence, there are only two parameters for each qubit that really matter, so it can be expressed in 2D, mapped nicely to the sphere.]
In classical computing there are only 2 single-bit gates - Not and Buffer (actually, I never formally studied computer science, so someone please correct me if this isn't true). 'not' flips the bit, 'buffer' keeps the bit unchanged. In quantum computing there are infinitely many single-bit gates, some of the common ones are demonstrated in the applet. Basically, these gates can control how relatively 'one' or 'zero' the bit is by the superposition, as well as change the relative phase.
Anyway, I should be adding in two-qubit operations soon (like the infamous controlled-not) and hopefully get to something worthwhile.
So this applet isn't very useful for actual simulation of quantum computation yet, but it will you give an idea of what qubits are and how they can be represented.
I am working on a quantum computing simulation in Java as well, and it's been up for a few months now. So far I only have single-qubit operations, which are useful only in explaining how qubits act and how they differ from classical bits. The meat of quantum computation doesn't really kick in until you can have multiple qubits entangled.
Anyone interested can try it out here . You can take any valid input qubit, operate on it with any of six different single-qubit operators, and then see the output qubit. Qubits are represented as both complex spinors and on the Bloch sphere.
Next up is to add two-qubit operations, then work to having a controllable demo of quantum teleportation. I'd appreciate any constructive comments, if anyone would like to add some input.
Just curious - when did you live here (Baltimore)?
I'm going on my 4th year here now, and it does really look like Baltimore is turning around. Of course there are some problems, like this email thing as well as financial incompetency problems w/ the public schools. But many other problems seem to be finally coming around.
For the first time in decades the population in Baltimore is actually increasing, and many formerly bad or sketchy areas are actually quite nice now.
There's still a bunch of problems but even in the 4 years I've been here I've seen major improvements. I think in 5-10 years Baltimore will be a pretty schweet place to be.
No one is forcing you to eat 1000+ calorie meals. You make the choice and you have to live with the consequences.
You should see the movie because that's the whole point. Personally I can't stand fast food, and lately my girlfriend and I have been cooking most of our meals, avoiding processed foods, etc.
But if you see the Supersize Me documentary, it shows you just how 'entrenched' our society is with all this fast-food and junk foods. The movie opens with a large group of little kids singing a song about pizza hut, kfc, and mcdonalds. It's more than just pop culture, fast food images are embedded into their heads through tv commercials, public school meal programs, and even summer-camp songs (as that song demonstrates).
In the movie they talk with the lobby group (i forget the name) that represents mcdonalds and all the other huge multinational fast-food and other food companies. They have tons of power, and lobby the gubmint to pass favorable legislation for them, etc.
Another point brought out by the movie is that this crappy food is so cheap that for many people it's what they depend on. And one really does have to go out of their way to avoid it completely (not just mcdonalds but all fast food and other questionable food companies like kraft, heinz, etc that load their foods w/ sugars/fats as well).
Yeah, I never really understood all those mcdonalds mascots.
You've got ronald mcdonald, a scurvy-ridden freak who's the prime representative of mcdonalds to the public. He's got major nutritional problems, besides his chalky-white face he's got bright-red hair and eye problems. Kind of like Joker when he fell into the vat of acid. Makes you want to think twice before biting into that cheeseburger, doesn't it?
Then you've got grimace, who's name is a synonym for making a face like you just ate something nasty. Actually, merriam-webster gives this definition : "a facial expression usually of disgust or disapproval" And what kind of mutant blob is he supposed to be? How many big macs did his mom eat while she was pregnant, to mutate him so much?
Fry-guys. Okay, so the french fries there don't even come from potatoes but from some obscure animal lifeform. Are they driven to extinction? Maybe they're last remaining hideout is in some corners of the Amazon rainforest. Or are they a collection of fries that, due to the toxic chemicals they're made from, suddently acquired a collective concious. Hmmm.
And the hamburgler. Yup, eating at mcdonalds makes you so addicted you resort to stealing to be able to get your next big-mac fix.
Seriously, what a bunch of weird-ass characters to represent a company. They are like their own X-Men or similar.
You can get a BA in Physics from many universities, but its worth is certainly questionable.;)
I hope that smiley means you are being sarcastic.
At my alma mater (University of Pennsylvania) all undergraduate degrees in the 'natural sciences' are awarded as BA's. So I got a BA in physics, along with all other graduating physics majors, chemistry majors, biology majors, etc.
There was no option of getting a BS in physics. The aforementioned departments are all part of the school of "Arts and Sciences" and by nature the school only offers BA's for those fields. BS's are only awarded for graduates of the engineering school.
I am curious, can anybody that has done this with either SBLibe or Delta 44 or anything higher end please respond.
I cannot imagine that the SB Live would have a decent AD converter for the audio input. I know that a good 16 or 18 bit hi-fi audio AD converter (capable of working at 44 or 48 kHz) costs about $65 just for the AD chip itself (at least as of a few years ago). Now granted Creative would be buying whatever front-end AD converters they use in bulk so it would be cheaper. But I would be surprised if they had a really quality-grade chip in there.
That said, I haven't used it so I have no actual experience with this. Has anybody recorded music via this input and can comment on its quality?
I know that there are external 'boxes' that most likely have a kickass AD converter in them, and send the digital data via USB or something similar. Anybody used any of these types of things and can comment on how good they sound?
I'm currently looking to set up a small studio to record some musical ideas bouncing around in my head. I was thinking of doing it analog, just for simplicity and coolness. but if digital wouldn't be that much more expensive, I might go for this option instead.
music today is CRAP. I don't care what my friends tell me, or what the TV tells me, there's no way around it.
Dude, get the hell out of your house and go to some live music clubs. It seems like you are limiting your definition of music to what you listen to on the big commercial radio stations.
Music definitely isn't dead, there's tons and tons of bands playing around in damn near any style you can think of. Sure, many of these bands suck, but a good number are quite talented and really rock! Go to some of your local music clubs (try smaller venues w/ like 100-200 person capacity). There's probably several local bands that you might like right under your nose that you weren't aware of. Or catch some touring bands when they come through your neck of the woods.
There's TONS of innovation and musical talent now, just as much as ever. You have to know where to go look for it (hint - not on top-20 radio stations or in Sam Goody or whatever crappy music chain is in your nearby mall).
The U.S. goverment may have supported the development of the internet, but Tim Berners-Lee develped the World Wide Web, HTML, TCP/IP, etc. and he was Brit working at CERN in Switzerland. Pretty good for the old Europe.
Why oh why do so many people here on/. get into pissing contests about their nationality contributing more to science/technology/arts/culture than another nationality? Jeezuz, this is totally ridiculous. All y'all are a bunch of bickering children.
Most of the scientists that everybody is proud to claim from their own respective countries care more about advancing humanity in general than caring about some nationalistic nitwit many years later bragging that "technology X" was developed in "Country Y".
Basically every country has contributed alot of useful stuff to the aforementioned categories. Why do some people need to either put down other countries or try to overaccentuate their own country's contributions?
Seriously, does it make one person feel more important to have been born on one side of an arbitrary border than on the other side?
Once at a bar, my friend went to the bathroom. While she was gone me and another friend talked about sending her some kind of 'souvenir' from the bar. We got the bright idea of sending one of those cardboard beer coasters. So we wrote her name and address on the coaster (we didn't even know her zip code so we left it off), put a stamp on it, and gave it to the bartender to drop in a mailbox. We were doubtful it would ever get to her, bit sure enough she got it in good condition within 1-2 days.
Since then I've mailed all kinds of fun stuff with addresses written on them, like chewing gum wrappers, tiny post-it notes, etc. I think everything has arrived intact and relatively quickly. And all for a single stamp.
So in my personal experience, USPS totally rocks.
Re:Hardcore?
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Hardcore Java
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· Score: 2, Informative
Didn't the word, or phrase originate from porn? Or was it in use before that? It certanly pre-dates assembly language.
I've heard it used in certain physics scattering models to refer to atoms with a hard core. Ie, scattering off of something with a 'soft' outer shell and a harder core. Rutherford may have used this term first w/ his gold foil experiment that determined the hard core nature of the atomic nucleus.
Also used in some basic solid-state physics transort equations, like the Drude model. But I don't know if they were used by the original discoverers or scientists that came later.
But it's possible that the usage of this hard core meaning was retroactively applied after the term existed, to refer to systems that actually have a hard core.
In my opinion, I actually prefer a notebook. I find that it's quicker and easier to jot down some notes without distracting from the trip. With a paper notebook - sure you'll spend time transcribing the notes online. With a PDA or whatever it'll take longer to write notes out, and you'll still need to 'fix them up' when you're done anyway.
Mainly, I find that during my trip I don't want to spend the time writing in my journal during my trip. But I do it anyway because it makes the post-trip memories much better. Sometimes I'm more into writing than other times, and occasionally I'm really into it and trying to write decent prose. But overall I usually write the gist of my travels, and then edit it after my trip.
I did a 2 month road trip before going to grad school, and had a small leather-bound journal that was given to me as a going away present by a coworker at my job.
For me, this journal was PERFECT for what I needed, small enough to not be a nuisance, and I could jot down whatever thoughts came through my mind. When in a hurry I'd quickly scribble a few sentences.
Call me old-fashioned, but there's a certain flavor with a handwritten journal that's lacking with electronic notes. For example I can make little sketches, draw doodles, interspersed in my writing. Or I could collect little 'souveniers'. Like receipts from cool places, a cutout of the paper menu from a cool bar, parts of a flyer for a cool music show, etc. My journal is really colorful and fun to read. Plus, there's alot of stuff in the handwriting, you can get a feel of when I'm hurried, when I'm happily lazy, when I'm annoyed, etc.
Anyway, I would imagine that ultimately any recorded journal would need to be edited after a trip. The traveller might get a hint of saving time by recording directly into a PDA, but I think the overall result would be better w/ a handwritten journal, where a few notes can be jotted down quickly without distracting much at all from the actual trip. But that's just my opinion.
In case anyone's interested, here is a link to my still unfinished travel log. The delay comes from my being in grad school and EVERYTHING ELSE having priority to finishing my journal. Ie, the bottleneck is not because I don't have my travel notes in electronic format.
I can tell who has and who has not taken some formal physics and actually studied quantum mechanics, and who is trying to remember that episode of whatever on Discovery from a few months back.
So which one do you think I am?;-)
Anyway, yeah, I responded to a different comment in this article, and basically I mentioned that I haven't really done much of the philosophizing of physics in a while.
Back in my undergrad days I dual-majored in physics and philosophy, but I have lost interest in philosophy over the years as my interest for physics has increased. Back in the olden days, science and philosophy were one and the same, physics actually being called 'natural philosophy'. The physics department at Univerity of Pennsylvania, for example, only existed for about 100 years. But they had a natural philosophy department prior to that. But these two fields have since diverged quite greatly. As on of my physics professors recently stated, "Physics is Philosophy with Integrals!"
But yes, there is alot of philosophical science drivel here on slashdot, but regardless of what the moderators think, most of us physicists can easily pull the signal from the noise.
Yes, but you can correlate the polarization of EM waves to collapsing the wavefunction of a spin-1/2 particle through various Stern-Gerlach machines. So the parent is correct in relating it to quantum processes.
Ie, the EM wave, considered classically, is really a very similar model of the two eigenstates of an electron spinor measured in a magnetic field in various directions. Actually, it's more than similarity because in the quantum realm a photon is a spin-1 particle and an electron is spin-1/2. But of the 3 spin eigenstates of a photon (m=1,0,-1) available, only the m=1 and m=-1 (right and left circular polarized) are allowed in the travelling wave. So it kind of looks like a 2-element spinor system.
. But you get the standard wave diffraction pattern built up, even if you only let through one photon at a time...
Well, yes and no. If you measure the location of the single photon, you'll basically find it only in a single place. You would get the standard wave diffraction pattern if you measured many instances of 'single photons' and formed their expectation value that way. What exists before you measure it is the quantum wave-function. It's collapsed into a single eigenstate upon measurement.
I believe the explanation for the double-slit experiment in the many-worlds interpretation of QM boils down to the photon interfering with all the corresponding photons in all the other universes...
Regarding the many-universe theory, I think of it in terms of the variety of possible values. Ie, in universe A the photon is measured as being at position 1. In univese B the same photon is measured as being at position 2. The 'expectation value' integrated over these universes as a function of position would then coincide with the expectation value of the position measurement of the wavefunction.
At least that's how I understood it. I could be wrong, I haven't thought about many universe theory since writing a paper for it for my undergraduate quantum class back in 1996 (the professor didn't like the 'pseudeoscience' of it and gave me a bad grade on the paper). Anyway, I'm a grad student in physics now, but I haven't given much thought to this philosophizing of the quantum wavefunction lately.
Slashdot Mirror
NASA is ALL about applied intelligence. Additionally they still have a number of theorists working for them as well.
Anyway, your tired quote about teachers not being able to 'do' isn't accurate at all. University professors only spend a minority of their time 'teaching', at least in the sciences at real research universities. The majority of their efforts go towards research, and that success is based upon their publications, and more importantly, how often their publications are referenced by others. The smartest 'professors' i referred to in my original post are quite successful in this regard.
That's not really true, so I'll take it you haven't worked with NASA much at all. I've worked with NASA scientists on several projects and the scientists/engineers there are typically top-notch. Much more knowledgeable than most engineers I've dealt with from the private sector. NASA's problems primarily stem from its bureaucracy and red-tape, not from shortcomings of its engineers.
And to take your skepticism further, the smartest people I've encountered to date have been university professors (at least in physics). Usually more likely to collaborate w/ NASA than with the private sector, too.
I used to work on a DARPA-funded project, and I can tell you - almost certainly.
There has been a push w/ governmental agencies, including NASA, to use COTS (Commercial Off-The-Shelf) products. A private company researches and develops a certain product product (which NASA could do as well), but can then sell the products to a variety of outlets for profit (which NASA is forbidden to do). So NASA buying a one-off of a COTS component pays only a fraction of the R&D cost that the company spent making it.
As an example, I know of a group that needed a very linear high-bandwidth op-amp for a project. Such an op-amp within their specs didn't exist, so they began the intensive effort of designing one themselves. Halftway through the process another company (maybe Burr-Brown? I forget) put a device on the market that did meet their specs. Although they spent time/money on the research, they still saved out in the end because they just bought and used that op-amp without wasting further development efforts.
The big win for COTS comes from the fact that NASA and other governmental agencies and labs CANNOT sell products for profit, but private companies CAN. For example, the lab I worked in (not my group, though) did alot of radar research. After proving new radar concepts would work, companies like Lockheed-Martin or Raytheon would go and build many of them, making millions of $$$ for themselves. Such is the life of research ;-)
I may be wrong, but I do believe NASA has subcontracted out to non-USA companies before. How this prize will fare I have no idea.
That's basically it. Spin is a kind of angular momentum that just exists in the various particles. Electrons, neutrons, photons, etc all have spin.
Now to get a better idea, you have to understand how angular momentum works in quantum mechanics. Actually, it's quite complicated, and alot of group theory has come around to describe it succintly.
Angular momentum is 'quantized'. A spinning top can spin at any rotational velocity (including two directions - clockwise/counterclockwise). For any given particle, the spin only comes in discrete steps of h-bar, the Plank constant.
The angular momentum must also be centered around 'zero', so this means there are two types of particles. THose with integer spin (having values of -2,-1,0,1,2,etc) or half-integer spin (having values of -3/2, -1/2, 1/2, 3/2, etc). The former are called Bosons and the latter called Fermions. The properties between these two differ vastly (mostly due to QED theory that describes symmetric vs antisymmetric wavefunction upon particle interchange. This gives a 'Pauli-exclusion' law for fermions with no such law for bosons.)
Okay, I don't know if anybody bothered to read this far, but things get more complicated. Each particle has a total spin (photons are spin 1, and electrons are spin 1/2, for instance). But one really doesn't know the 'direction' of the spin, so one can look at the projection of the spin on the z-axis, which has to be quantized. So a spin-1 photon can have a z-projection of -1,0,1. And an electron can be +1/2 or -1/2. If you remember your high-school chemistry and quantum numbers one of them was the spin. This is why each set of n,l,m has two allowed values for the electron spin. But beyond this, one cannot know exactly which direction the spin points because, in quantum mechanics terms, the x, y, and z spin projection operators don't commute. So there's an inherent uncertainty there.
Now to get even more complicated, there's orbital angular momentum (for atoms) and the spin. So this gives the total angular momentum. But adding angular momentum must be done properly within the mathematical confines of group-theory, it's not simple vector-addition at all. So it gets pretty crazy, because you cannot simultaneously know both the total spins z-components of two particles (in specific cases you can, but not in general). So you have things like Clebsch-Gordon coefficients, etc. Anyway, the l and m quantum numbers from chemistry basically come from the orbital angular momentum.
To answer your question about measuring spin, remember it's quantized. But in any interaction the z-component of the spin must be conserved. So if a photon is emitted, that subtracts the total spin by one. So spin of the resulting system must change appropriately (remember the differnece between total spin and z-component of spin). So in a way, torque can be applied by bombarding something w/ particles, but the change in angular momentum must be quantized by units of hbar.
Not quite.
You're correct that quantum teleportation will transfer a quantum wavefunction from one point to another. But it cannot 'copy' the wavefunction. In order to send the wavefunction, the original wavefunction must be destroyed during the process.
Sorry, fanout is strictly prohibited in quantum computing.
I mentioned this yesterday as well, but for an idea of what qubits are you can take a look at my currently unfinished Java Quantum Computation applet. As of now one can only do single-qubit operations, but eventually I hope to have a demo of quantum teleportation (teleportation of a single qubit, or spinor, that is).
This applet will give you an idea of what qubits are. Essentially they're a 'spinor' which in quantum-mechanical terms is a 2-element discrete wavefunction. In lay terms, this just means a set of two complex numbers (properly normalized). They are also displayed in a more visible representation, called the 'Bloch Sphere'.
This applet will let you take any input qubit, and operate on it with 6 different single-qubit quantum gates, and see the resulting qubit.
Look at the two qubits represented on the Bloch sphere. The yellow vector represents the qubits. The red dot indicates a classical 'zero' and the blue dot indicates classical 'one'. In classical computing any bit can only point exactly to the red or blue dots. In quantum computation a qubit can point anywhere on that sphere.
[For the mathematically curious, a qubit is 2 complex numbers, which would be 4 independent parameters. However, the sum of the modulus squared of each complex number must be unity, so that constraint leaves only 3 free parameters. Secondly, the entire qubit can be multiplied by any arbitrary phase constant (e^i*gamma) which changes the spinor but not its relative values. Hence, there are only two parameters for each qubit that really matter, so it can be expressed in 2D, mapped nicely to the sphere.]
In classical computing there are only 2 single-bit gates - Not and Buffer (actually, I never formally studied computer science, so someone please correct me if this isn't true). 'not' flips the bit, 'buffer' keeps the bit unchanged. In quantum computing there are infinitely many single-bit gates, some of the common ones are demonstrated in the applet. Basically, these gates can control how relatively 'one' or 'zero' the bit is by the superposition, as well as change the relative phase.
Anyway, I should be adding in two-qubit operations soon (like the infamous controlled-not) and hopefully get to something worthwhile.
So this applet isn't very useful for actual simulation of quantum computation yet, but it will you give an idea of what qubits are and how they can be represented.
Anyone interested can try it out here . You can take any valid input qubit, operate on it with any of six different single-qubit operators, and then see the output qubit. Qubits are represented as both complex spinors and on the Bloch sphere.
Next up is to add two-qubit operations, then work to having a controllable demo of quantum teleportation. I'd appreciate any constructive comments, if anyone would like to add some input.
Ah, Berkeley. Famous for ?SD.
Well, what chemical in the beef was he allergic to? Chances are all the processing mcdonalds does could have denatured said chemical.
I'm going on my 4th year here now, and it does really look like Baltimore is turning around. Of course there are some problems, like this email thing as well as financial incompetency problems w/ the public schools. But many other problems seem to be finally coming around.
For the first time in decades the population in Baltimore is actually increasing, and many formerly bad or sketchy areas are actually quite nice now.
There's still a bunch of problems but even in the 4 years I've been here I've seen major improvements. I think in 5-10 years Baltimore will be a pretty schweet place to be.
(from that Simpson's episode where Bart gets Stampy the Elephant)
DJ3000: Those clowns in Congress did it again. What a bunch of clowns.
Bill: How does it keep up with the news like that?
You should see the movie because that's the whole point. Personally I can't stand fast food, and lately my girlfriend and I have been cooking most of our meals, avoiding processed foods, etc.
But if you see the Supersize Me documentary, it shows you just how 'entrenched' our society is with all this fast-food and junk foods. The movie opens with a large group of little kids singing a song about pizza hut, kfc, and mcdonalds. It's more than just pop culture, fast food images are embedded into their heads through tv commercials, public school meal programs, and even summer-camp songs (as that song demonstrates).
In the movie they talk with the lobby group (i forget the name) that represents mcdonalds and all the other huge multinational fast-food and other food companies. They have tons of power, and lobby the gubmint to pass favorable legislation for them, etc.
Another point brought out by the movie is that this crappy food is so cheap that for many people it's what they depend on. And one really does have to go out of their way to avoid it completely (not just mcdonalds but all fast food and other questionable food companies like kraft, heinz, etc that load their foods w/ sugars/fats as well).
You've got ronald mcdonald, a scurvy-ridden freak who's the prime representative of mcdonalds to the public. He's got major nutritional problems, besides his chalky-white face he's got bright-red hair and eye problems. Kind of like Joker when he fell into the vat of acid. Makes you want to think twice before biting into that cheeseburger, doesn't it?
Then you've got grimace, who's name is a synonym for making a face like you just ate something nasty. Actually, merriam-webster gives this definition : "a facial expression usually of disgust or disapproval" And what kind of mutant blob is he supposed to be? How many big macs did his mom eat while she was pregnant, to mutate him so much?
Fry-guys. Okay, so the french fries there don't even come from potatoes but from some obscure animal lifeform. Are they driven to extinction? Maybe they're last remaining hideout is in some corners of the Amazon rainforest. Or are they a collection of fries that, due to the toxic chemicals they're made from, suddently acquired a collective concious. Hmmm.
And the hamburgler. Yup, eating at mcdonalds makes you so addicted you resort to stealing to be able to get your next big-mac fix.
Seriously, what a bunch of weird-ass characters to represent a company. They are like their own X-Men or similar.
I hope that smiley means you are being sarcastic.
At my alma mater (University of Pennsylvania) all undergraduate degrees in the 'natural sciences' are awarded as BA's. So I got a BA in physics, along with all other graduating physics majors, chemistry majors, biology majors, etc.
There was no option of getting a BS in physics. The aforementioned departments are all part of the school of "Arts and Sciences" and by nature the school only offers BA's for those fields. BS's are only awarded for graduates of the engineering school.
I cannot imagine that the SB Live would have a decent AD converter for the audio input. I know that a good 16 or 18 bit hi-fi audio AD converter (capable of working at 44 or 48 kHz) costs about $65 just for the AD chip itself (at least as of a few years ago). Now granted Creative would be buying whatever front-end AD converters they use in bulk so it would be cheaper. But I would be surprised if they had a really quality-grade chip in there.
That said, I haven't used it so I have no actual experience with this. Has anybody recorded music via this input and can comment on its quality?
I know that there are external 'boxes' that most likely have a kickass AD converter in them, and send the digital data via USB or something similar. Anybody used any of these types of things and can comment on how good they sound?
I'm currently looking to set up a small studio to record some musical ideas bouncing around in my head. I was thinking of doing it analog, just for simplicity and coolness. but if digital wouldn't be that much more expensive, I might go for this option instead.
Dude, get the hell out of your house and go to some live music clubs. It seems like you are limiting your definition of music to what you listen to on the big commercial radio stations.
Music definitely isn't dead, there's tons and tons of bands playing around in damn near any style you can think of. Sure, many of these bands suck, but a good number are quite talented and really rock! Go to some of your local music clubs (try smaller venues w/ like 100-200 person capacity). There's probably several local bands that you might like right under your nose that you weren't aware of. Or catch some touring bands when they come through your neck of the woods.
There's TONS of innovation and musical talent now, just as much as ever. You have to know where to go look for it (hint - not on top-20 radio stations or in Sam Goody or whatever crappy music chain is in your nearby mall).
One of my friends even drove by that place every day for years and never even thought about it perversely.
Why oh why do so many people here on /. get into pissing contests about their nationality contributing more to science/technology/arts/culture than another nationality? Jeezuz, this is totally ridiculous. All y'all are a bunch of bickering children.
Most of the scientists that everybody is proud to claim from their own respective countries care more about advancing humanity in general than caring about some nationalistic nitwit many years later bragging that "technology X" was developed in "Country Y".
Basically every country has contributed alot of useful stuff to the aforementioned categories. Why do some people need to either put down other countries or try to overaccentuate their own country's contributions?
Seriously, does it make one person feel more important to have been born on one side of an arbitrary border than on the other side?
Once at a bar, my friend went to the bathroom. While she was gone me and another friend talked about sending her some kind of 'souvenir' from the bar. We got the bright idea of sending one of those cardboard beer coasters. So we wrote her name and address on the coaster (we didn't even know her zip code so we left it off), put a stamp on it, and gave it to the bartender to drop in a mailbox. We were doubtful it would ever get to her, bit sure enough she got it in good condition within 1-2 days.
Since then I've mailed all kinds of fun stuff with addresses written on them, like chewing gum wrappers, tiny post-it notes, etc. I think everything has arrived intact and relatively quickly. And all for a single stamp.
So in my personal experience, USPS totally rocks.
I've heard it used in certain physics scattering models to refer to atoms with a hard core. Ie, scattering off of something with a 'soft' outer shell and a harder core. Rutherford may have used this term first w/ his gold foil experiment that determined the hard core nature of the atomic nucleus.
Also used in some basic solid-state physics transort equations, like the Drude model. But I don't know if they were used by the original discoverers or scientists that came later.
But it's possible that the usage of this hard core meaning was retroactively applied after the term existed, to refer to systems that actually have a hard core.
Mainly, I find that during my trip I don't want to spend the time writing in my journal during my trip. But I do it anyway because it makes the post-trip memories much better. Sometimes I'm more into writing than other times, and occasionally I'm really into it and trying to write decent prose. But overall I usually write the gist of my travels, and then edit it after my trip.
I did a 2 month road trip before going to grad school, and had a small leather-bound journal that was given to me as a going away present by a coworker at my job. For me, this journal was PERFECT for what I needed, small enough to not be a nuisance, and I could jot down whatever thoughts came through my mind. When in a hurry I'd quickly scribble a few sentences.
Call me old-fashioned, but there's a certain flavor with a handwritten journal that's lacking with electronic notes. For example I can make little sketches, draw doodles, interspersed in my writing. Or I could collect little 'souveniers'. Like receipts from cool places, a cutout of the paper menu from a cool bar, parts of a flyer for a cool music show, etc. My journal is really colorful and fun to read. Plus, there's alot of stuff in the handwriting, you can get a feel of when I'm hurried, when I'm happily lazy, when I'm annoyed, etc.
Anyway, I would imagine that ultimately any recorded journal would need to be edited after a trip. The traveller might get a hint of saving time by recording directly into a PDA, but I think the overall result would be better w/ a handwritten journal, where a few notes can be jotted down quickly without distracting much at all from the actual trip. But that's just my opinion.
In case anyone's interested, here is a link to my still unfinished travel log. The delay comes from my being in grad school and EVERYTHING ELSE having priority to finishing my journal. Ie, the bottleneck is not because I don't have my travel notes in electronic format.
So which one do you think I am? ;-)
Anyway, yeah, I responded to a different comment in this article, and basically I mentioned that I haven't really done much of the philosophizing of physics in a while.
Back in my undergrad days I dual-majored in physics and philosophy, but I have lost interest in philosophy over the years as my interest for physics has increased. Back in the olden days, science and philosophy were one and the same, physics actually being called 'natural philosophy'. The physics department at Univerity of Pennsylvania, for example, only existed for about 100 years. But they had a natural philosophy department prior to that. But these two fields have since diverged quite greatly. As on of my physics professors recently stated, "Physics is Philosophy with Integrals!"
But yes, there is alot of philosophical science drivel here on slashdot, but regardless of what the moderators think, most of us physicists can easily pull the signal from the noise.
Ie, the EM wave, considered classically, is really a very similar model of the two eigenstates of an electron spinor measured in a magnetic field in various directions. Actually, it's more than similarity because in the quantum realm a photon is a spin-1 particle and an electron is spin-1/2. But of the 3 spin eigenstates of a photon (m=1,0,-1) available, only the m=1 and m=-1 (right and left circular polarized) are allowed in the travelling wave. So it kind of looks like a 2-element spinor system.
Well, yes and no. If you measure the location of the single photon, you'll basically find it only in a single place. You would get the standard wave diffraction pattern if you measured many instances of 'single photons' and formed their expectation value that way. What exists before you measure it is the quantum wave-function. It's collapsed into a single eigenstate upon measurement.
I believe the explanation for the double-slit experiment in the many-worlds interpretation of QM boils down to the photon interfering with all the corresponding photons in all the other universes...
Regarding the many-universe theory, I think of it in terms of the variety of possible values. Ie, in universe A the photon is measured as being at position 1. In univese B the same photon is measured as being at position 2. The 'expectation value' integrated over these universes as a function of position would then coincide with the expectation value of the position measurement of the wavefunction.
At least that's how I understood it. I could be wrong, I haven't thought about many universe theory since writing a paper for it for my undergraduate quantum class back in 1996 (the professor didn't like the 'pseudeoscience' of it and gave me a bad grade on the paper). Anyway, I'm a grad student in physics now, but I haven't given much thought to this philosophizing of the quantum wavefunction lately.