What's the highest you've ever counted to in your head? What's the largest amount of anything you've ever counted? How many pieces of paper do you think you could count before making a mistake?
Um...don't you need sunlight to grow (almost) anything? How exactly do you propose to get enough sunlight by going vertical! I suppose maybe some crops can get enough sunlight near sunrise and sunset...
After trying Vista, I have to say that I like it. I think the new GUI is really slick (yes, I know it was a total rip off of Mac. I don't care). The widgets on the desktop are really cool too.
Of course, I did get it for free (legally too!), and I would never drop the $200+ for a copy.
Any multiple test score is always imprecise at some level. Even if you subtract so guessing averages out to no difference, there can still be wide variations in there that average out to zero. It doesn't mean the test is meaningless.
What a worthless post. He gave one situation where guessing is more important than knowledge, but didn't at all address the specifics of the tests he was talking about. A typical vapid blog that for some reason gets posted to/.
That comment's not insightful at all. Regardless of how poor these watch lists may be implemented, some real terrorist threats will make their way on them. And those people will then be prevented from legally traveling without the government knowing about it. Now of course the privacy issues (not to mention the freedom issues--what if a relative dies/is dying and I need to leave NOW) make this a bad idea, and of course not every potential terrorist will be on the watch list, but that doesn't mean this would be completely ineffective.
This shit is useful for catching Cat Stevens, providing a false sense of security, more power to the police state, and not a damn thing else.
For the most part, I agree with you. Of course this is why treating terrorism as a law enforcement issue is not a good idea.
No, you would not see any interference pattern in Cramer's experiment. The reason is because of the lens that, in a paraphrase of Cramer, images the same position of the first photon on the second screen, because of the momentum entanglement (going through a lens is the same as taking the Fourier transform, or looking at the momentum of the photon). This means that you can measure which slit the second photon went through to get "which way" information. I'm not sure how Cramer is planning on reconstructing the interference pattern, since I don't see how his setup would act as a quantum eraser. Although Cramer seems to think he will actually see an interference pattern without looking at coincidence so I don't think he really understands how a quantum eraser works anyway.
Speed is constant between reference frames, at least in this case. You and the cop would have disagreed on the speed you threw the beer can from your window though.
After inserting the QWPs, no interference pattern is visible. The only way to see an interference pattern is to selectively look at the photons that are correlated to the other photon either getting through the polarizer or not.
Essentially what the second polarizer is doing is measuring whether or not the other photon got through a slit. By doing this, it destroys the information about which slit the first photon went through. So in order to see the interference pattern, you need to only look at events where you saw a photon at both detectors, which is called a coincidence. The coincidence chamber just tells you when both detectors triggered at the same time.
Disclaimer: I am a physicist working in a quantum information group, and have taken a graduate level physics course on quantum information.
This won't work. The article doesn't give details, but by googling the scientist, I found this proposal, and immediately recognized the flaw in the experiment. He's trying to use a quantum eraser (wiki of quantum eraser, and link to good article on them) to change the image of the downconverted photons on a camera, but that simply cannot be done. The image on a screen can be changed using a nonlocal eraser, but only when you look at conincidences of the two photons. This is a common proposal for FTL communication, I just can't believe no one ever told this guy why it wouldn't work.
The quantum eraser (linked above) can be pretty tough to get your head around. It combines interference, entanglement, and nonlocality, all tough nonclassical phenomena. Feel free to ask if you read the article and don't understand something.
This is one of the weirdest things to explain about quantum mechanics but I'll give it a shot. Each particle is described by a wavefunction, which describes the probability density*, sort of describing how it is "spread out". This is why you can't describe exactly where a particle is or exactly what it's momentum is. When two particles get close, their wavefunctions overlap, and it is impossible (and really nonsensical!) to describe them separately. In fact, since wavefunctions generally decay exponentially and never go to zero, every electron everywhere overlaps with every other electron, and they all need to be described simultaneously! In practice, of course this amount of overlap can be determined to be infintesimal and can be ignored.
It's hard stuff to understand without studying it for a few months (or more)...
*Actually it's the square of the wavefunction that describes the probability density.
This does not imply that two human beings assembled out of particles in the same state are the same person.
Yes it does. Any object can, in principle, be exactly described if the exact quantum state can be determined. I am not suggesting this is likely, or even possible, for something as big and complex as a human.
And furthermore "according to quantum mechanics" does not help your argument.
Why? Do you know of a better theory?
Would you argue that two particles in the same state at different points in time are the "same" particle?
Difficult to say. I'd say it depends on whether or not you consider time as a parameter describing a state. If you do, then an electron sitting alone does not remain the same particle.
Quantum cryptography (or more accurately, quantum key distribution) is immune to man in the middle attack, assuming that you have a verifiable (but not necessarily secure!) classical communication channel (which should be pretty easy).
No. According to quantum mechanics, two particles in the same state are the same. There is no way of "marking" an electron as electron A, and then following that one. The state describes everything about a particle.
The state that is being teleported can only be reconstructed by sending some amount of classical information, which must be sent at (or slower than) the speed of light. So there is no information moving "faster than light".
Slashdot Mirror
Like the other poster said, I think your warehouse analogy only works for closed source voting machines.
What's the highest you've ever counted to in your head? What's the largest amount of anything you've ever counted? How many pieces of paper do you think you could count before making a mistake?
Turning vast amounts of society's resources into a project to get a handful of humans onto Mars is a waste of my money.
Turning vast amounts of society's resources into a project to get a handful of humans to sail west from Spain to Asia is a waste of money.
While this is an improvement, it is not peer review. Allowing public comments is different than requesting recommendations from experts in the field.
No, this is like choosing to pay for hurricane insurance in the middle of Missouri.
Um...don't you need sunlight to grow (almost) anything? How exactly do you propose to get enough sunlight by going vertical! I suppose maybe some crops can get enough sunlight near sunrise and sunset...
After trying Vista, I have to say that I like it. I think the new GUI is really slick (yes, I know it was a total rip off of Mac. I don't care). The widgets on the desktop are really cool too.
Of course, I did get it for free (legally too!), and I would never drop the $200+ for a copy.
Any multiple test score is always imprecise at some level. Even if you subtract so guessing averages out to no difference, there can still be wide variations in there that average out to zero. It doesn't mean the test is meaningless.
What a worthless post. He gave one situation where guessing is more important than knowledge, but didn't at all address the specifics of the tests he was talking about. A typical vapid blog that for some reason gets posted to /.
Yep. Don't ask a global warming alarmist though, they'll tell you all the science is settled and the models can't be wrong.
That comment's not insightful at all. Regardless of how poor these watch lists may be implemented, some real terrorist threats will make their way on them. And those people will then be prevented from legally traveling without the government knowing about it. Now of course the privacy issues (not to mention the freedom issues--what if a relative dies/is dying and I need to leave NOW) make this a bad idea, and of course not every potential terrorist will be on the watch list, but that doesn't mean this would be completely ineffective.
This shit is useful for catching Cat Stevens, providing a false sense of security, more power to the police state, and not a damn thing else.
For the most part, I agree with you. Of course this is why treating terrorism as a law enforcement issue is not a good idea.
No, you would not see any interference pattern in Cramer's experiment. The reason is because of the lens that, in a paraphrase of Cramer, images the same position of the first photon on the second screen, because of the momentum entanglement (going through a lens is the same as taking the Fourier transform, or looking at the momentum of the photon). This means that you can measure which slit the second photon went through to get "which way" information. I'm not sure how Cramer is planning on reconstructing the interference pattern, since I don't see how his setup would act as a quantum eraser. Although Cramer seems to think he will actually see an interference pattern without looking at coincidence so I don't think he really understands how a quantum eraser works anyway.
So the one place where greenhouse gas emissions don't matter uses renewable energy? :P
Speed is constant between reference frames, at least in this case. You and the cop would have disagreed on the speed you threw the beer can from your window though.
After inserting the QWPs, no interference pattern is visible. The only way to see an interference pattern is to selectively look at the photons that are correlated to the other photon either getting through the polarizer or not.
Essentially what the second polarizer is doing is measuring whether or not the other photon got through a slit. By doing this, it destroys the information about which slit the first photon went through. So in order to see the interference pattern, you need to only look at events where you saw a photon at both detectors, which is called a coincidence. The coincidence chamber just tells you when both detectors triggered at the same time.
Disclaimer: I am a physicist working in a quantum information group, and have taken a graduate level physics course on quantum information.
This won't work. The article doesn't give details, but by googling the scientist, I found this proposal, and immediately recognized the flaw in the experiment. He's trying to use a quantum eraser (wiki of quantum eraser, and link to good article on them) to change the image of the downconverted photons on a camera, but that simply cannot be done. The image on a screen can be changed using a nonlocal eraser, but only when you look at conincidences of the two photons. This is a common proposal for FTL communication, I just can't believe no one ever told this guy why it wouldn't work.
The quantum eraser (linked above) can be pretty tough to get your head around. It combines interference, entanglement, and nonlocality, all tough nonclassical phenomena. Feel free to ask if you read the article and don't understand something.
Yes, it does seem obvious--it's also not true!
This is one of the weirdest things to explain about quantum mechanics but I'll give it a shot. Each particle is described by a wavefunction, which describes the probability density*, sort of describing how it is "spread out". This is why you can't describe exactly where a particle is or exactly what it's momentum is. When two particles get close, their wavefunctions overlap, and it is impossible (and really nonsensical!) to describe them separately. In fact, since wavefunctions generally decay exponentially and never go to zero, every electron everywhere overlaps with every other electron, and they all need to be described simultaneously! In practice, of course this amount of overlap can be determined to be infintesimal and can be ignored.
It's hard stuff to understand without studying it for a few months (or more)...
*Actually it's the square of the wavefunction that describes the probability density.
No. The fact that they are completely indistinguishable is what gives rise to Bose-Einstein statistics.
This does not imply that two human beings assembled out of particles in the same state are the same person.
Yes it does. Any object can, in principle, be exactly described if the exact quantum state can be determined. I am not suggesting this is likely, or even possible, for something as big and complex as a human.
And furthermore "according to quantum mechanics" does not help your argument.
Why? Do you know of a better theory?
Would you argue that two particles in the same state at different points in time are the "same" particle?
Difficult to say. I'd say it depends on whether or not you consider time as a parameter describing a state. If you do, then an electron sitting alone does not remain the same particle.
Quantum cryptography (or more accurately, quantum key distribution) is immune to man in the middle attack, assuming that you have a verifiable (but not necessarily secure!) classical communication channel (which should be pretty easy).
No. According to quantum mechanics, two particles in the same state are the same. There is no way of "marking" an electron as electron A, and then following that one. The state describes everything about a particle.
The state that is being teleported can only be reconstructed by sending some amount of classical information, which must be sent at (or slower than) the speed of light. So there is no information moving "faster than light".
Oh, and news flash: wood is not a fossil fuel.
What difference does it make? The EPA considers carbon dioxide a pollutant now anyway.
Nope. It's not "increasingly" the case, it always has been.