It is not important if the MWI is standard, or what certain physicists feel about it. Indeed for the question at hand it's not even important if it correctly describes reality. It's only important that it exists and is consistent with all known facts.
And about the empirical evidence: The same is true for the standard Kopenhagen interpretation. The fact that no empirical evidence can distinguish between MWI and Kopenhagen doesn't affect just one of the interpretations, it affects both in the same way. Which of them you prefer is a purely philosophical question. If you don't want that, you must go with the "shut up and calculate" interpretation, i.e. don't ask at all what all this might mean, but just accept that the equations give the right result. But then you cannot speak about if there's FTL communication involved in those correlations either, because there's no FTL communication in the observable results, and everything going beyond can't be empirically decided.
Well, we can tell by sending a lot of equally prepared electrons through the apparatus (since they are identically prepared, they all are in the same state) and making various measurements. Let's say the incoming electrons are prepared to be spin up in x direction, while the Stern-Gerlach apparatus is set up to separate spin in z-direction.
The first measurement you can do is that indeed the electrons coming out of the "spin up exit" have spin up in z direction. That can be done e.g. by putting a second Stern-Gerlach apparatus behind that exit and noting that all the electrons which get into that second Stern-Gerlach apparatus indeed leave through its spin up exit again, which is exactly the case for spin up electrons. The same test can of course be done at the spin-down hole.
The next thing you can do is to check that the electrons coming out of each exit are not all spin up in x direction (i.e. what came in). That can done by applying a Stern-Gerlach apparatus in x direction, in which case you'll observe half of the electrons to come out of the spin up exit and the other half comping out of the spin down exit, which would be the expected behaviour for electrons polarized in positive or negative z direction, but wouldn't be the case if the electrons still had spin up in x direction.
Ok, up to now the data would be consistent with the assumption that the SG apparatus just randomly selects spin up or spin down in z direction and sends the electrons to the corresponding exit. Thus the next thing we would prove is that the positive x spin is indeed still "stored" in the electrons, despite not being found either in the electrons coming out of the spin up exit nor of the spin down exit. For that, we simply put a second SG apparatus in reverse, so that spin up electrons enter through the spin up "exit" and spin down electrons enter through the spin down "exit". Which causes the electron beams to be reunited, so that at the "entry" you get only one electron beam (the which way information is gone). Now you can again put an SG apparatus in x direction behind it, and you'll indeed find that all electrons have spin up in x direction. Thus the information was indeed preserved. Since it was neither in the upper nor in the lower path alone (you can re-check that by blocking one of the paths), it is clear that both paths contribute. Thus you know that the polarization was entangled with the position.
Of course Open Office wasn't just written as OSS from scratch, but it came from opening up Star Office. According to Wikipedia, the development of Star Writer already started in 1984. I know for sure that I got Star Writer preinstalled on the PC I bought in 1995. Given its long history, I'd say it's not really a clone of MS office (I'm not sure if MS already had MS Word as early as 1984, but it certainly wasn't dominant at that time).
And BTW, KDE came first; Gnome was started because at that time there were licensing issues with KDE (Qt did only come with a GPL-incompatible license back then). I'm sure Gnome wouldn't have been started if the KDE licensing issues had not been there.
"Observed" basically means that information about it is present in some other system. So you don't need a human to notice it; a detector completely suffices. About what observes all the particle around you when you're not looking: The environment does (by simply interacting with them). That's what is called decoherence.
CUrrently we lack an ability to select an electron based on spin without entangling it with another electron and thus breaking other entanglements. However, is this an issue with our technology or with the science behind it?
No, we don't lack the ability to measure electron spin without entangling it with another electron spin. The Stern-Gerlach experiment is the standard experiment to measure electron spin, and there's no other electron involved (well, actually there are a lot of electrons involved to make the magnetic field, but those don't get entangled). Spin up electrons just come out of one exit, and spin down electrons come out of the other exit. However that means the electron's spin is now entangled with the electron's position. Especially we still don't know what the spin originally was (unless we know for sure it was either spin up or spin down in the corresponding direction). There are only two exits, and all electrons coming out of the first exit are spin-up in the direction of the Stern-Gerlach apparatus, and all electrons coming out of the other one are spin-down, even if the incoming electrons are neither, but have their spin in a completely different direction or even are unpolarized due to entanglement.
Suppose we look at photons with entangled polarities instead. At least in theory we ought to be able to use birefringence to select photons based on known polarity properties. Thus we ought to be able to know what the polarity was supposed to be before we rotate it. Thus the noncommunication theorem might be a mere technological limitaton as opposed to a fundamental principle. We will have to see.
It's the same as with the Stern-Gerlach apparatus: There are two polarizations (horizontal and vertical relative to a direction determined by the crystal). The horizontally polarized photons come out at one place, and the vertically polarized photons come out at another place. All photons coming out at the first place are horizontally polarized, and all photons coming out at the second place are vertically polarized, even if the input photons are e.g. diagonally polarized. Again, for such cases the photon polarization is entangled with their position.
If I hypothesize that "spooky action at a distance" is evidence of an objective reference frame, can you come up with an experiment to prove that it is not?
No. What I have to come up with to counter that claim is an explanation of the evidence which works without an objective reference frame, thus disproving that it's evidence for an objective reference frame. Fortunately such an explanation exists: the Many Worlds Interpretation and its relatives. Thus the evidence isn't evidence for an objective reference frame.
True. It's been a while since I've thought deeply about quantum entanglement so I sort-of crafted the post "off-the-cuff" before I realized the mistake I had made. However, this leads to a bigger question. Even when the measurement was made, just after that time, neither earth nor mars yet know what the measurement was. So what if we hide the results of that measurement for a bit, or delay the measurement results to earth and mars? If the pre-measured entangled photons actually arrive first, then a post-measurement is made, then we later "open" the delayed pre-measurement results and view them, what happens?
The entanglement gets destroyed by the measurement itself, not by the people on Earth or Mars knowing about the result. Therefore if you measure, but hide the results, the photons which arrive are not pre-measured and not entangled. The results will not be different from what you get if the measurement results are transmitted to earth and mars first.
Indeed, "measurement" by the environment (i.e. information leakage to the environment) is the cause of decoherence, which is one of the main obstacles in building a quantum computer.
And more to the point here. Why can we not just simply generate a "preset polarized - entangled pair" of photons?
Because being entangled and being polarized are mutually exclusive. Well, actually you can create states which are a bit entangled and a bit polarized. However, even that won't help you to do FTL communication.
Most experiments "collapse" the wave function because they first measure one or the other to find the state of the other. But if we could just generate a set of polarized entangled photons with alrealy known polarizations we could just use a setup similar to the one I described right?
No. As I already wrote, entanglement does not mean that manipulations of one photon are "transmitted" to the other photon. If you change the polarization of a photon, then only that photon is affected, entanglement or no entanglement. It's only measurement ("wavefunction collapse") which is special in this respect.
It seems that photon polarization can't be controlled.
Well, polarization can be controlled quite well. You can rotate it, you can convert between linear, circular and elliptic polarization, whatever you want. However controlling polarization of course assumes there is polarization to begin with. Fully entangled states are locally unpolarized, and the only way to make them polarized is to measure them.
But this was exactly the state of affairs that I was trying to setup with my thought experiment. It simply can't be that measuring the value of one destroys the entanglement, because we could throw that measurement away without ever using it, and the photons from the outside of the apparatus would still be entangled.
Wrong. It doesn't matter if we know the measurement results. It only matters that the measurement occurs. There are certain ways to "unmeasure" (quantum erasure), but those include destruction of the measured information once and for all, so there's not even in principle a chance to ever find out what was measured. It's as if the measurement never took place. Just throwing the result away is not sufficient.
Otherwise the photon entanglement would immediately be destroyed upon interaction with just about any kind of matter, such as air molecules in the way, or mirrors used to to perform the experiment.
The entanglement is destroyed whenever the system interacts in a way that depends on the entangled observable. A mirror doesn't destroy the polarization entanglement, because the reflection at the mirror is independent of the polarization (the mirror reflects all sorts of photons alike). If you send your photon through a birefringent material, polarization entanglement is destroyed (the pol
We're dealing with the law of unintended consequences here. It doesn't help to complain at the people who are choosing the only option they have to get the result they're looking for.
Still bloated. The ultimate non-bloated program is usually found under/bin/true. Now, even there bloated versions are around, but the minimal version can be created with just the following commands (assuming/bin/true doesn't yet exist):
1. Place an entangled photon generator exactly half way between earth and mars. 2. Do not aim the photon outputs (beams) at earth and mars, but aim the beam at a 90 degree angle to earth and mars. 3. Immediately measure the polarization of one of the photons so that then, both photon polarizations are known.
Ok. Since now you measured the photon polarization, the photons cease to be entangled. Therefore you just have generated a photon of random spin (well, actually one randomly selected of two spins, where the two spins you select from are determined by your measurement device).
4. Now, transmit the "known" polarization (as binary data) on another channel, an out of band beam, at the speed of light to both earth and mars. 5. Having sent the "known" polarization of the entangled photons, now reflect (with mirrors) the entangled photons (which have now traveled for some distance from the source) to both earth and mars. One photon reflects to mars, the other the earth. 6. On earth, we first receive the polarization data from the out of band light beam, which mars also receives at the same time. 7. Now since we know what the polarization will be when the entangled photon arrives, we then make an "adjustment" to its polarization.
First, the photons are no longer entangled. Second, even if they were still entangled, the adjustment wouldn't affect anything observable on the other end. Only a measurement collapses the wave function. For example, say the entangled state says both photons are polarized the same way. Now you rotate one of the polarizations to make them polarized the opposite way it was before the manipulation. That means now the photons are still entangled, but in a way that now you always measure the opposite polarization on each side. That is, the polarization of the other photon was not changed the same way (it's hard to imagine the undefined polarization to be changed to another undefined polarization, but it's only the absolute polarization which is undefined; the relative polarization is well defined, and that is what is changed).
8. The mars receiver then sees that the polarization of the entangled photon it was supposed to get, isn't actually what is measured.
No. See above.
The other minor thing I don't understand about quantum mechanics is why such a big deal is made about the dual slit experiment.
Because it shows quite clearly that neither classical particles not classical waves can completely describe the quantum mechanical observations.
The dual slit experiment is in my opinion not the biggest mystery. The bigger mystery is why does a light beam diffract around "an edge" to begin with.
That's not mysterious if you describe light as classical waves. Basically it's the Huygens principle: Each point of a wave front is origin of a new spherical wave. For an infinitely extended plane wave the "sideways" parts cancel out, but if there's an edge, on the "dark side" there's no light waves which could cancel them out (because those light waves are blocked).
It seems rather "obvious" to me that if a light beam passes a single edge of a razor blade and "diffracts", generating a wavelike pattern on the detector, then having two slits will obviously generate the famous wave pattern in the dual slit experiment.
Yes, if it were only the interference pattern alone, there would be nothing mysterious about it. Interference of light was long known, and was used as the "final proof" that light consists of waves. The mysterious is that at the same time, photons hit the screen one by one, which means they also show behaviour we expect from particles. Waves don't make discrete, localized spots. On the other hand, particles don't interfere. That is, if you view light as classical particles, you cannot explain the interference pattern (the photon sho
If you can measure the spin, then you can measure that it has changed yes?
No. To detect a change, you'd have to know the state before it was measured, and then would have to have a measurement result which is incompatible with that state. But with entangled particles, the observable you're measuring is undefined before your first measurement (that means, your first measurement cannot measure a change), and after the measurement, the particles are not entangled any more.
So if you could change one particles spin, which causes the other entangled particles spin to also change, what's stopping you from communicating via number of spin changes in some time frame?
The fact that changing the one's particle's spin will not at all affect the other particle's spin. Only a measurement will (at least from the view of the one doing the measurement).
So the 1's and 0's are a sort of 'change' or 'no change'. (I ask with ignorance of how measuring affects the particle).
Measuring forces them into an eigenstate of the measured observable, i.e. into a state where the quantity you measure has a defined value. That defined value is what you get as measurement result.
It interests me that the effect can travel faster than light, but the conclusion about the effect can not, yet I've never seen a physicist discuss this. The discussion always goes entanglement, faster than light, spooky, bada bing.
Well, look harder. This effect is at the heart of a lot of interpretations of quantum mechanics.
In my preferred interpretation, the Many Minds Interpretation, there's nothing going at the speed of light. The fact that you'll find that the other one has measured the opposite of what you measured, despite it not be predetermined, is in MMI not any more surprising than the fact that a star which was several light years on your left is now several light years on the right after you turn around, despite the fact that there wasn't enough time for it to travel with light speed from several light years to your left to the same distance on the right. It's your turning around that "moved" the star without actually affecting it, and it's your measurement (which means becoming yourself entangled with the object), that is which "changed" the remote particle without actually affecting it. The price this comes with is to accept that there's a "parallel you" which got the exact opposite result, and with whom you'll never get contact. And that the observed facts are indeed only defined relative to the observer.
It's possible that the entanglement effect doesn't resolve itself until information about the two experimental measurements (which converges in obedience with the speed of light) actually meets up. Perhaps the disentanglement takes place only *after* the results of the two experiments meets up. That would involve the experiment (and experimenters) having become entangled in the experiment. Weird? In the realm of the very tiny, that's never stopped mother nature before.
Indeed, in the MMI, the entanglement never gets resolved. It only seems resolved to you because you yourself get entangled with the observed system, and therefore you observe only part of the complete state (your "branch" of reality). According to MMI, this is what gives the apparent (but not real) collapse of the quantum state.
On a related point, I've never seen a physicist comment on whether it is possible to take two particles of unknown histories and prove they are not entangled.
It is not. You cannot prove entanglement on a single system, ever. That's because you cannot measure the unknown state of any single quantum system. This of course includes the entanglement. You need a set of identically prepared quantum systems to do that. It's not hard to see that: Imagine you get a spin-1/2-particle, measure its z-spin, and get that it's spin up. That may be because it was spin up before you measured. But equally well, it could have been polarized in x or y direction (in which case you had a chance of 1/2 to measure z-spin up). Or it could have been one particle of a bell pair. Or maybe it was polarized almost in positive z-direction (in which case it was very probable, but not sure that you'll measure z-spin up). But also maybe it was polarized almost in negative z direction. In which case it was unlikely, but not impossible to get z-spin up on your measurement. You see, there are plenty of possibilities. Unfortunately you cannot just get more information by making another measurement on the same electron, because your first measurement destroyed the original state, whatever it was. You need a second, independent electron to get more information about it. And indeed, you'll need quite a lot of identically prepared electrons to get a good notion of its state. That includes entanglement.
If there is no physical demonstration that two particles *are not* entangled, on what basis could you answer "no"?
If you have a preparation procedure, then you can produce as many copies of the same state as you want. And with as many c
I have yet to see Lynx actually render any images. As such, the time it takes to do so is infinite. Well, maybe someone should integrate aalib into lynx.
Users are not interested in how their refrigerators work, either, but they work reliably for years. Computers should be able to work without users needing to learn all manner of ever-changing and imperfect rules for how to tell a phishing web site from a bank web site (and by the time they are looking at a web page it's too late anyway). Usually refrigerators are not linked to worldwide networks, and also the possibilities of misuse are rather limited. A private Windows computer not connected to the internet is quite secure. It will never be part of a botnet, you'll get no viruses through mail on them (you may get an old-fashioned virus on disk or USB stick, though), nor will you get phishing mails. And even if your computer is virus-infected, you'll usually not directly affect very many people (basically those using that computer, and those you are swapping data with). That's already close to the refrigerator example.
A closer analogy to the internet-connected computer would be the car. If you want to drive a car, you have to obtain a driving license. To get that, you not only have to learn how to drive a car, but also a lot of rules needed so that you don't negatively affect others. There are rules about how fast you may drive at different road types, there are rules on behaviour at crossroads, etc. Also there are things on your car the usage of which you must learn, which are not really related to driving itself, but are only there to make sure you don't endanger yourself and others. For example, why do you need to learn how to use the direction indicator? Your car will perfectly turn left or right without it. It's not there to make the task of driving possible or easier, it's just there for safety. You'll have to learn those things despite them strictly speaking not being necessary for the act of driving.
Ok, one thing which differs from cars is that the threats of the network are changing. But that's not a fault of computers or the net, but that's because there's malice behind it. The same is true everywhere where malice is at work, be it investment fraud, selling overpriced crap, etc. It's not limited to computers or the net, but it's just a fact of life.
The functional block is about as easy to understand, once you know FP:)
I disagree: The functional code is easier to understand. And no, I'm not a die-hard functional programmer; most of the code I've written is imperative.
Re:No You Dim Witted Troll
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Why Myths Persist
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· Score: 2, Informative
1 + 1 = 2 is a fundamental piece.
Yes. And we know for sure that this is the case, because that's how we define 2. The only meaning of "2" is that it's the integer following 1, i.e. 1+1. There's no independent definition of what "2" means, according to which you could prove or disprove the statement that 1+1=2. Therefore it's not a matter of faith either.
I fail to see the fuss, both formats suck and really have no place as a desktop publishing format. They are crappy WYSIWYG data dumps that are heavily tied to rendering algorithms of their respective editor and really are not archival safe.
I can take 20 year old TeX documents and render them just fine.
As much as I like TeX, it is also tied a the special rendering algorithms of a certain program, in this case the TeX processor. If several vendors wrote their own, independent TeX processors, I'm sure you'd get the same sort of incompatibilities.
But you give me even a 10 year old WYSIWYG file and there is a good chance I won't be able to do anything with the file.
That's completely unrelated to WYSIWYG. It's because unlike TeX, the word processors haven't stabilized their file formats. TeX gives consistent results because there's basically just one implementation, and that one's more or less frozen.
A WYSIWYG word processor can be just as stable as a non-WYSIWYG one (and vice versa). If a file from ten years ago doesn't render exactly the same today, that's because either the rendering algorithms have substantially changed, or the format was too much tied to the platform. Both are completely unrelated to WYSIWYG and are only due to bad decisions made by the program writers.
To answer the question in the comment title: If a committee can remove a whole planet from our solar system (we used to have nine of them, now we only have eight), I don't see a reason why they couldn't stop the rotation of the Earth.:-)
BTW name one "evil" thing this technology allows, which isn't allowed in theory by the 3G phones. Justifying all those nasty fingerprints on the display.:-)
Why not put in systems that measure, based on statistical sampling at some representative routers, a rough idea of the number of copies of content item x,y, or z that are making their way across the net at any given moment, then average that out over a week, say, and use that figure to determine the weekly share of the copyright tax.
That would make spam really lucrative: Write copyrighted text, register it with the system, and then send it by mail to everyone. This guarantees that you'll get hits on every router, and a great share of copyright tax goes to you.
Slashdot Mirror
It is not important if the MWI is standard, or what certain physicists feel about it. Indeed for the question at hand it's not even important if it correctly describes reality. It's only important that it exists and is consistent with all known facts.
And about the empirical evidence: The same is true for the standard Kopenhagen interpretation. The fact that no empirical evidence can distinguish between MWI and Kopenhagen doesn't affect just one of the interpretations, it affects both in the same way. Which of them you prefer is a purely philosophical question. If you don't want that, you must go with the "shut up and calculate" interpretation, i.e. don't ask at all what all this might mean, but just accept that the equations give the right result. But then you cannot speak about if there's FTL communication involved in those correlations either, because there's no FTL communication in the observable results, and everything going beyond can't be empirically decided.
Well, we can tell by sending a lot of equally prepared electrons through the apparatus (since they are identically prepared, they all are in the same state) and making various measurements. Let's say the incoming electrons are prepared to be spin up in x direction, while the Stern-Gerlach apparatus is set up to separate spin in z-direction.
The first measurement you can do is that indeed the electrons coming out of the "spin up exit" have spin up in z direction. That can be done e.g. by putting a second Stern-Gerlach apparatus behind that exit and noting that all the electrons which get into that second Stern-Gerlach apparatus indeed leave through its spin up exit again, which is exactly the case for spin up electrons. The same test can of course be done at the spin-down hole.
The next thing you can do is to check that the electrons coming out of each exit are not all spin up in x direction (i.e. what came in). That can done by applying a Stern-Gerlach apparatus in x direction, in which case you'll observe half of the electrons to come out of the spin up exit and the other half comping out of the spin down exit, which would be the expected behaviour for electrons polarized in positive or negative z direction, but wouldn't be the case if the electrons still had spin up in x direction.
Ok, up to now the data would be consistent with the assumption that the SG apparatus just randomly selects spin up or spin down in z direction and sends the electrons to the corresponding exit. Thus the next thing we would prove is that the positive x spin is indeed still "stored" in the electrons, despite not being found either in the electrons coming out of the spin up exit nor of the spin down exit. For that, we simply put a second SG apparatus in reverse, so that spin up electrons enter through the spin up "exit" and spin down electrons enter through the spin down "exit". Which causes the electron beams to be reunited, so that at the "entry" you get only one electron beam (the which way information is gone). Now you can again put an SG apparatus in x direction behind it, and you'll indeed find that all electrons have spin up in x direction. Thus the information was indeed preserved. Since it was neither in the upper nor in the lower path alone (you can re-check that by blocking one of the paths), it is clear that both paths contribute. Thus you know that the polarization was entangled with the position.
Of course Open Office wasn't just written as OSS from scratch, but it came from opening up Star Office. According to Wikipedia, the development of Star Writer already started in 1984. I know for sure that I got Star Writer preinstalled on the PC I bought in 1995. Given its long history, I'd say it's not really a clone of MS office (I'm not sure if MS already had MS Word as early as 1984, but it certainly wasn't dominant at that time).
And BTW, KDE came first; Gnome was started because at that time there were licensing issues with KDE (Qt did only come with a GPL-incompatible license back then). I'm sure Gnome wouldn't have been started if the KDE licensing issues had not been there.
"Observed" basically means that information about it is present in some other system. So you don't need a human to notice it; a detector completely suffices.
About what observes all the particle around you when you're not looking: The environment does (by simply interacting with them). That's what is called decoherence.
No, we don't lack the ability to measure electron spin without entangling it with another electron spin. The Stern-Gerlach experiment is the standard experiment to measure electron spin, and there's no other electron involved (well, actually there are a lot of electrons involved to make the magnetic field, but those don't get entangled). Spin up electrons just come out of one exit, and spin down electrons come out of the other exit. However that means the electron's spin is now entangled with the electron's position. Especially we still don't know what the spin originally was (unless we know for sure it was either spin up or spin down in the corresponding direction). There are only two exits, and all electrons coming out of the first exit are spin-up in the direction of the Stern-Gerlach apparatus, and all electrons coming out of the other one are spin-down, even if the incoming electrons are neither, but have their spin in a completely different direction or even are unpolarized due to entanglement.
It's the same as with the Stern-Gerlach apparatus: There are two polarizations (horizontal and vertical relative to a direction determined by the crystal). The horizontally polarized photons come out at one place, and the vertically polarized photons come out at another place. All photons coming out at the first place are horizontally polarized, and all photons coming out at the second place are vertically polarized, even if the input photons are e.g. diagonally polarized. Again, for such cases the photon polarization is entangled with their position.
No. What I have to come up with to counter that claim is an explanation of the evidence which works without an objective reference frame, thus disproving that it's evidence for an objective reference frame. Fortunately such an explanation exists: the Many Worlds Interpretation and its relatives. Thus the evidence isn't evidence for an objective reference frame.
The entanglement gets destroyed by the measurement itself, not by the people on Earth or Mars knowing about the result. Therefore if you measure, but hide the results, the photons which arrive are not pre-measured and not entangled. The results will not be different from what you get if the measurement results are transmitted to earth and mars first.
Indeed, "measurement" by the environment (i.e. information leakage to the environment) is the cause of decoherence, which is one of the main obstacles in building a quantum computer.
Because being entangled and being polarized are mutually exclusive. Well, actually you can create states which are a bit entangled and a bit polarized. However, even that won't help you to do FTL communication.
No. As I already wrote, entanglement does not mean that manipulations of one photon are "transmitted" to the other photon. If you change the polarization of a photon, then only that photon is affected, entanglement or no entanglement. It's only measurement ("wavefunction collapse") which is special in this respect.
Well, polarization can be controlled quite well. You can rotate it, you can convert between linear, circular and elliptic polarization, whatever you want. However controlling polarization of course assumes there is polarization to begin with. Fully entangled states are locally unpolarized, and the only way to make them polarized is to measure them.
Wrong. It doesn't matter if we know the measurement results. It only matters that the measurement occurs. There are certain ways to "unmeasure" (quantum erasure), but those include destruction of the measured information once and for all, so there's not even in principle a chance to ever find out what was measured. It's as if the measurement never took place. Just throwing the result away is not sufficient.
The entanglement is destroyed whenever the system interacts in a way that depends on the entangled observable. A mirror doesn't destroy the polarization entanglement, because the reflection at the mirror is independent of the polarization (the mirror reflects all sorts of photons alike). If you send your photon through a birefringent material, polarization entanglement is destroyed (the pol
There's still the "underrated" option.
Ok. Since now you measured the photon polarization, the photons cease to be entangled. Therefore you just have generated a photon of random spin (well, actually one randomly selected of two spins, where the two spins you select from are determined by your measurement device).
First, the photons are no longer entangled. Second, even if they were still entangled, the adjustment wouldn't affect anything observable on the other end. Only a measurement collapses the wave function. For example, say the entangled state says both photons are polarized the same way. Now you rotate one of the polarizations to make them polarized the opposite way it was before the manipulation. That means now the photons are still entangled, but in a way that now you always measure the opposite polarization on each side. That is, the polarization of the other photon was not changed the same way (it's hard to imagine the undefined polarization to be changed to another undefined polarization, but it's only the absolute polarization which is undefined; the relative polarization is well defined, and that is what is changed).
No. See above.
Because it shows quite clearly that neither classical particles not classical waves can completely describe the quantum mechanical observations.
That's not mysterious if you describe light as classical waves. Basically it's the Huygens principle: Each point of a wave front is origin of a new spherical wave. For an infinitely extended plane wave the "sideways" parts cancel out, but if there's an edge, on the "dark side" there's no light waves which could cancel them out (because those light waves are blocked).
Yes, if it were only the interference pattern alone, there would be nothing mysterious about it. Interference of light was long known, and was used as the "final proof" that light consists of waves. The mysterious is that at the same time, photons hit the screen one by one, which means they also show behaviour we expect from particles. Waves don't make discrete, localized spots. On the other hand, particles don't interfere. That is, if you view light as classical particles, you cannot explain the interference pattern (the photon sho
No. To detect a change, you'd have to know the state before it was measured, and then would have to have a measurement result which is incompatible with that state. But with entangled particles, the observable you're measuring is undefined before your first measurement (that means, your first measurement cannot measure a change), and after the measurement, the particles are not entangled any more.
The fact that changing the one's particle's spin will not at all affect the other particle's spin. Only a measurement will (at least from the view of the one doing the measurement).
Measuring forces them into an eigenstate of the measured observable, i.e. into a state where the quantity you measure has a defined value. That defined value is what you get as measurement result.
Well, look harder. This effect is at the heart of a lot of interpretations of quantum mechanics.
In my preferred interpretation, the Many Minds Interpretation, there's nothing going at the speed of light. The fact that you'll find that the other one has measured the opposite of what you measured, despite it not be predetermined, is in MMI not any more surprising than the fact that a star which was several light years on your left is now several light years on the right after you turn around, despite the fact that there wasn't enough time for it to travel with light speed from several light years to your left to the same distance on the right. It's your turning around that "moved" the star without actually affecting it, and it's your measurement (which means becoming yourself entangled with the object), that is which "changed" the remote particle without actually affecting it. The price this comes with is to accept that there's a "parallel you" which got the exact opposite result, and with whom you'll never get contact. And that the observed facts are indeed only defined relative to the observer.
Indeed, in the MMI, the entanglement never gets resolved. It only seems resolved to you because you yourself get entangled with the observed system, and therefore you observe only part of the complete state (your "branch" of reality). According to MMI, this is what gives the apparent (but not real) collapse of the quantum state.
It is not. You cannot prove entanglement on a single system, ever. That's because you cannot measure the unknown state of any single quantum system. This of course includes the entanglement. You need a set of identically prepared quantum systems to do that. It's not hard to see that: Imagine you get a spin-1/2-particle, measure its z-spin, and get that it's spin up. That may be because it was spin up before you measured. But equally well, it could have been polarized in x or y direction (in which case you had a chance of 1/2 to measure z-spin up). Or it could have been one particle of a bell pair. Or maybe it was polarized almost in positive z-direction (in which case it was very probable, but not sure that you'll measure z-spin up). But also maybe it was polarized almost in negative z direction. In which case it was unlikely, but not impossible to get z-spin up on your measurement. You see, there are plenty of possibilities. Unfortunately you cannot just get more information by making another measurement on the same electron, because your first measurement destroyed the original state, whatever it was. You need a second, independent electron to get more information about it. And indeed, you'll need quite a lot of identically prepared electrons to get a good notion of its state. That includes entanglement.
If you have a preparation procedure, then you can produce as many copies of the same state as you want. And with as many c
A private Windows computer not connected to the internet is quite secure. It will never be part of a botnet, you'll get no viruses through mail on them (you may get an old-fashioned virus on disk or USB stick, though), nor will you get phishing mails. And even if your computer is virus-infected, you'll usually not directly affect very many people (basically those using that computer, and those you are swapping data with). That's already close to the refrigerator example.
A closer analogy to the internet-connected computer would be the car. If you want to drive a car, you have to obtain a driving license. To get that, you not only have to learn how to drive a car, but also a lot of rules needed so that you don't negatively affect others. There are rules about how fast you may drive at different road types, there are rules on behaviour at crossroads, etc. Also there are things on your car the usage of which you must learn, which are not really related to driving itself, but are only there to make sure you don't endanger yourself and others. For example, why do you need to learn how to use the direction indicator? Your car will perfectly turn left or right without it. It's not there to make the task of driving possible or easier, it's just there for safety. You'll have to learn those things despite them strictly speaking not being necessary for the act of driving.
Ok, one thing which differs from cars is that the threats of the network are changing. But that's not a fault of computers or the net, but that's because there's malice behind it. The same is true everywhere where malice is at work, be it investment fraud, selling overpriced crap, etc. It's not limited to computers or the net, but it's just a fact of life.
I disagree: The functional code is easier to understand.
And no, I'm not a die-hard functional programmer; most of the code I've written is imperative.
Yes. And we know for sure that this is the case, because that's how we define 2. The only meaning of "2" is that it's the integer following 1, i.e. 1+1. There's no independent definition of what "2" means, according to which you could prove or disprove the statement that 1+1=2. Therefore it's not a matter of faith either.
As much as I like TeX, it is also tied a the special rendering algorithms of a certain program, in this case the TeX processor. If several vendors wrote their own, independent TeX processors, I'm sure you'd get the same sort of incompatibilities.
That's completely unrelated to WYSIWYG. It's because unlike TeX, the word processors haven't stabilized their file formats. TeX gives consistent results because there's basically just one implementation, and that one's more or less frozen.
A WYSIWYG word processor can be just as stable as a non-WYSIWYG one (and vice versa). If a file from ten years ago doesn't render exactly the same today, that's because either the rendering algorithms have substantially changed, or the format was too much tied to the platform. Both are completely unrelated to WYSIWYG and are only due to bad decisions made by the program writers.
To answer the question in the comment title: If a committee can remove a whole planet from our solar system (we used to have nine of them, now we only have eight), I don't see a reason why they couldn't stop the rotation of the Earth. :-)
Let me repeat this
Early DOS versions didn't have the "Fail" option at all, that was a later addition.
And I still remember the jokes about viruses in email messages ... Remember the signature virus?
Metric is standard.
That would make spam really lucrative: Write copyrighted text, register it with the system, and then send it by mail to everyone. This guarantees that you'll get hits on every router, and a great share of copyright tax goes to you.
Ok, so now instead of getting charged for sending encrypted content, you're charged for the copyrighted material you hid it inside! :-)