Why would the person who doesn't measure care anymore? He's already sent the message.
no he didn't send a message.
There are three steps to a teleportation protocol:
distributing the entangled state: this happens at less than speed of light and doesn't send a message (it just means the two parties (call them A and B) share a predetermined state).
A performs a measurement (either on his state alone or on his state and an additional "message state" in a teleportation protocol): this doesn't send a message either: not from B to A since B cannot influence at all what A will measure, nor from A to B since the state of B's system (as far as B can determine) is unchanged by A's operation: no matter whether he did a measurement or not and no matter what the result, B's state is the same.[1]
A sends a classical message with his result to B: this sends a message, but it can't happen faster than speed of light. Once B receives the message, he knows more about his state: if A performed a teleportation scheme, he now knows his state to be a (unitarily transformed) copy of A's message state; if A just measured his part of the entangled system, B learns what his state is.
for speed of gravity, see
Kopeikin et al, on www.arxiv.org (eg. gr-qc/0310065 and references therein); note that there has been criticism of this paper, I can't judge who's right.
But it seems that John Baez is convinced by Kopeikin's result, and I'd trust Baez' word on this.
I don't know of any measurements of the speed of the strong and weak force. This is certainly extremely difficult, since they are short-range interactions (acting within nuclei only, 10^-15m and shorter, see here ).
I'm not aware of any problems with the standard model: the particles mediating the weak interaction (W+,W-,Z) are massive, hence the speed of the weak force should be smaller than c. The force between quarks is mediated by "gluons" which are predicted to be massless, hence the speed shoud be c.
17 years or instantaneously? Neither?
instantaneously. Pay no attention to those who do not accept this.
sorry, but that's not accurate: the state changes "instantaneously" for the one who performs the measurement (and, yes, a QND measurement first prepares an entangled state between two systems and then measures one of them to determine the state of the other)
But to send a message the state for the party who doesn't measure (and presumably is light years away) must change. However, her state is still a random mixture of
|0><0| and |1><1|
and only a message containing A's result changes that.
Well, wouldn't it be possible to relay information by defining the state (or lack thereof) it was sent in as 0 and the altered state as 1?
There's no "lack of state". Both before A has measured and after the measurement (but before the result is known) the state of B is described by the *same* mathematical object, which is the random mixture of the two states "0" and "1". This randomness (of each single system considered by itself) is a necessary consequence of the overall system being entangled.
Thus if B makes any kind of measurement (and even if there are many identically prepared systems to start from) there is no way of distinguishing the two cases. No matter what measurements B does, they yield (randomly and with equal probability) one of the two possible results.
The "spooky action at a distance" makes sure that the random results that A and B get are *correlated* (if they do the same measurements). However, since the results are random (and cannot be controlled by A or B) they can't send information this way. [They could "coordinate" instantaneously, e.g., perform some synchronous swimming in two different galaxies - but it would of course take a signal at lightspeed or less to ascertain that they are indeed synchronous;-]
And wouldn't it be possible to have some kind of "ping" for determining the message speed?
I.e. get two pairs far enough away from each other to get measurable values, tie a machine to one half that "flicks" the other bit once the first bit is "flicked", then measure the time difference between flicking the first bit and receiving the flick of the second?
i'm not sure i understand this correctly: you start out in a state with the property that each particle has a 50% probability to be found in "0" (and 50% chance to be found in "1"). Measurement at A gives a *random* result (outside the control of the experimenter) and forces the other particle to now have 100% probability to be found in the same state. But since B doesn't know what "the same" is, for him it is still 50:50, i.e unchanged to before the measurement. therefore there is no "message".
As for checking the "speed of correlation": people have seen that it is larger than c. Even if A and B perform their measurement at exactly the same time, the correlation between the results is exact. But that is hardly surprising, as the two parties had essentially communicated before (to set up the entangled state). As someone explained before: A could throw a coin and take a picture of it (without looking if it's head or tails) and send the picture to B. Now they share a "classically-correlated state" (both picture and coin show heads or tails with 50% probability). Once one of them looks at his object he instantly knows the state of the other object as well. But no information is transmitted by looking at the picture.
[The cool thing about the entangled quantum state is that there is more than just the "head-or-tails" property. This is why the quantum-correlated state can be used to send (at signal speed) quantum states or shared secret bits.
This is really quite vague, quantum entangle two particles (how is this done?),
you have to make them interact, hence it will take at least 17 years to entangle two particles 17 lightyears apart (unless there were prior entanglement)
stick one at a point 17 light years distant and twiddle the other, when does the one 17 light years away "change".
17 years or instantaneously? Neither?
both;-) For the observer doing the measurement, it changes (nearly) instantaneously and indeoendent of the separation of the two particles. For the other one it does only change after a message (travelling at speed of light) has informed him about the outcome of the measurement.
Look at it this way: the quantum state describes what is known about the quantum system. We start in a situation, when both parties A and B (the one on Earth and the one 17 lightyears away) know the two particles to be in a state Psi (which is entangled). [That's why it took 17 years to set up the experiment;-]
If the observer on the earth now does his measurement, he knows "instantaneously" the state of his and the other particle. But the observer 17ly away does at best know that a measurement has been performed (say they had synchronized their clocks and agreed that A would mesure at a certain time). Since B does not know the result of the measurement, his particle is still in a completely undetermined state - indistinguishable from the one before the measurement! Only after he receives the message containing the measurement result (which takes another 17 years) does he learn what state his particle is in (which some describe as his state "collapsing" into the state corresponding to the measurement result.
The curious thing is, that instead of waiting for the message from A, B could himself perform a measurement. This would be guaranteed to yield the same result as the one obtained by A [for the appropriate entangled state and if both measure the same observable].
Thus A and B can turn their "quantum correlation" (entanglement) into classical correlations instantaneously. But since the results obtained are completely random and out of their control, it is not possible to transmit information without further classical messages, slowing everything down to the speed of light.
[note that I am not talking about "teleportation" here, in which case any measurement by B will destroy the quantum state that A tries to send]
I'm curious as there appears to be a lack of clarity on this particular issue, if it is in fact "absolutely instantly" does that really mean you can setup a 0ms latency link between say the Earth and Mars by exploiting Quantum entanglement as a communications channel?
So just to be utterly and entirely certain about this, quantum entanglement requires an electromagnetic link of some description between the two entangled items and is thus limited to lightspeed also?
for all we know: yes. To create entanglement between two particles they have to interact either directly or indirectly. In the former case, we are clearly limited by the speed of light; the second case is, e.g., what has been called "entanglement swapping": create two entangled pairs and perform a joint measerement on two particles (one from each pair). Once the result of this measurement is known at the locations of the remaining particles -- which requires a signal of some kind which again limits the speed --, they are in a useful entangled state. One can build a recursive protocol, chaining together ever more separate entangled pairs. Checking the math, one sees that it will take at least 1 year to create entanglement between to particles on lightyear apart. (Similarly, to use the entanglement to teleport a signal over this distance will again take at least one year.)
(BTW: the link needs not be electromagnetic, of course. Any interaction/signal will do, but light is usually the best.)
If the particles are entangled, and it observe one of the observer ones, isn't that going to change all of them because they are still entangled?
yes, any observation on a set of entangled particles changes the state of the whole set. However, if you do it appropriately it does change it in such a way, that (a) your measurement tells you nothing about the unknown state and (b) the unknown state is still encoded in the state of the unmeasured particles.
or do you unentangle them before you observe them?
not before - but the act of measurement disentangles the measured particle from the rest.
It may lead to *all* particle being disentangled (e.g., if they were in a state |00000>+|11111> and you measure in the basis {|0>,|1>}) or it may leave the unmeasured particles entangled (e.g., if you measure in the basis {|+>=|0>+|1>, |->=|0>-|1>}).
Can you unentangle particles without changing their state?
no, since the state they are in is either entangled or not, disentangling them implies changing their state. However, the 5-qubit state may be a *redundant* encoding of another state Psi (of fewer qubits). Then it is possible to change the overall state (either by measurements or normal time-evolution) such that one ends up with a single qubit in the state Psi.
This can be useful, since it may allow to if something has happened to the state encoded *without* learning anything about the state. This is the essential idea of quantum error correction: encode in a big (say 2^5-dimensional) space the state of a two-dimensional system. Detect, whether the state has moved out of this subspace (i.e. an error has occurred) but do it such that you do nott distinguish the two states in the subspace (thus leaving it untouched).
Red Dawn
(for its absurd story and poor acting)
and
The Lord of the Rings I
(for how awfully it underachieved compared to the book which it was based on; from all I've heard II and III are even worse, but I haven't seent them)
6 digits! Did Microsft buy a few licences or something? I doubt the EV1 deal can bring 6 digits, and there isn't really anything else they can count as SCOSource revenue. As reported on Groklaw they are thinking of bundling SCOsource with their UNIX-offerings. That way, the customer just pays for UNIX but SCO can book part of the revenue as SCOsource to make shareholders happy.
As long as it resolves to ones and zeros, it can be broken. Perhaps not easily, but it can be, if it is based on any arithmatic. In the end, it may prove that traditional crypto is more secure, using huge keys.
wrong and right! The Vernam cipher or one-time pad is a provably secure encryption method. But is indeed a classical method that involves a key which is as long as the message. Quantum ethods only come in as a method (the only known one) for provably securely distributing such keys.
I was under the impression that quantum computing might bring the power needed (factoring) to give people the ability to brute force RSA, 3DES, etc...
RSA and other public-key cryptosystems relying on the (presumed) difficulty of things like factoring, finding solutions of the Pell Equation or computing Gauss sums are compromised by a quantum computer.
DES, on the other hand, is a block cipher key and AFAIK there is no specific quantum-enhanced attack on it.
So wouldn't that make the secure transfer of
the keys somewhat pointless?
no, since the ultimate encryption algorithm - which is unbreakable by both quantum and classical computers) just needs a secret random string of the same length as the message ("Vernam cipher") -- and this is just what "quantum cryptography" (quantum key distribution) allows to generate.
distributing keys is only made pointless by a QC if you want to use them in a sub-par way, sending a message much longer than the key.
Frodo and Bilbo were both of the same age, but Frodo had had the Ring for 17 years. Thus he looked like "a robust hobbit just out of his tweens" while Bilbo (at the time he set out with the dwarfs) would have looked somewhat less youthful (or should i say childlike?)
For $86 million Microsoft has created an enourmous amount of chaos.
granted the chaos, but they also generated a huge amount of publicity -- much more than RHAT, NOVL, OSDL etc. could have generated on their own. And since the quality of argumentation has been so onesided, this whole thing may have helped Linux more than it hurt.
Bandwidth is effectively a "commons". As such, unless there is some economic disincentive to prevent every user from utilizing just as much bandwidth as they can, it is subject to the problem of "The Tragedy of the Commons."
In Lawrence Lessig's book "The future of ideas" this very point is discussed: novel methods of using the electromagnetic spectrum (essentially using packets and hopping in frequency) can provide essentially limitless bandwith. (References to these methods can be found in Lessig's book). This would pevent the "Tragedy".
There are other means to reach the same goal:one could make only part of the spectrum a commons, one could still sell licenses but regulate their use (like the use of AT&T's phone lines was regulated).
No... I think what they are trying to say is that *after* a patch is released and a description of the exploit is given, mal-ware writers then run off and use this description to write mal-ware to take advantage of folks who haven't applied the provided patches.
exactly, so MS shouldn't patch any holes in the first place, then no malware would be written and everyone would live happily ever after
This kind of knee-jerk ostricization of bright people with ideas is just plain wrong. Maybe he's wrong about the idea, but you don't smack a guy down just for writing his ideas down, you correct where wrong if you want to be helpful or ignore if you don't. Being rude just isn't called for.
I agree that one should be open to new ideas, but you might admit that coming forward with thousand of pages mixing well-known and original stuff and proposing this as the New Kind of Science is also meant to provoke the "old scientists". Moreover, most people who out of the blue come up with the New Big Theory are wrong (or not even wrong). Typically, that has been practiced by entrenched organizations like churches for thousands of years is the first-line defense against critique (see Crackpot Index, item 32).
I haven't read the whole book since what read in it and about it gave me the impression that it is not worth the time (for me). I found this review interesting, since it pointed out (among other things) a (possibly fundamental) flaw in Wolfram's reasoning (his model of computation is classical, and seems to be in contradiction with the experimentally verified violation of Bell's inequality).
Is Penrose still blathering about how human minds are somehow magically transcendant due to quantum bogodynamic handwaving, and therefore not
subject to any form of simulation?
Actually, in his second book (Shadows of the Mind) he (as far as I can tell) claims to prove that the human mind does things a universal Turing machine cannot and must therefore be based on different physics. Please correct me if I remember this wrong.
While I do not buy Penrose's argument, it is also not entirely clear to me, where it fails. The gist seemed to be: "In any formal system of logic there are statements that can be proven to be undecidable; however, we can see that they must be true, since if they were not, there would be a counterexample, which would make them decidable. Hence human reasoning is different from just following formal logic (which is what, supposedly, a computer following the laws of classical or quantum mechanics would do). Consequently the human brain must follow different laws - and quantum gravity seemed to be the [only|obvious] place left to look for them.
I really just couldn't hold any respect for him after reading The Emperor's New Mind, which is too bad since it's one of those "tour de force" books ala hofstadter
I think it is a great book, even though I disagree with his point on AI.
I don't think he should lose respect because of the ideas he has put forward, especially since he now tries to think up experiments on how to test his hypothesis.
I do enjoy those laymans science books. Any you might recommend?
I enjoyed reading Deutsch "The Fabric of Reality" (although it is in places very speculative and I do not agree with several points) and Greene "The Elegant Universe" (cf. also the BBC tv series).
Prof. Moglen's article demonstrates that the only two code
segments that SCO has been specific about are not copyright
infringements at all, so it makes no difference whether SCO's Linux
kernel contained them or not.
Thanks for your response. I am aware of this and from what I've seen here, at Groklaw and
elsewhere, SCO's case is ridiculously weak. But even if they had a
case it might be best for them to hide the evidence until they
have to show it in court. FUD is much greater this way than if 10
specific violations are pointed out and quickly removed by the Linux
community. Moreover, as McBride said explicitly, they are happy to let
the "infringements" continue to collect larger amounts of money later
on.
My question concerning Moglen's argument is: how strong are the
conclusions that can be drawn from SCO's distribution of a GPL'd
Linux? Is the kernel (by and large) always the same or can there be significant differences between different
distributions? In the former case, Moglen's argument holds, but in the latter case I don't see that SCO distribution some kernel
already implies that they have distributed the "infringing code" themselves
and revealed the "trade secrets".
there was a positive report in Barron's magazine by, guess who, a Deutsche Bank anal-yst indicating that SCO stock might be worth 185$ (-20% for Boies) if they succeed (see CBS Marketwatch, the original article is unaccessible w/o paid registration)
They probably mention that the stock could go to zero as well, but for a trader that doesn't matter, he can probably make big bucks just surfing the ups and downs.
SCO's legal situation contains an inherent contradiction. SCO claims [...] that the Linux program contains material over which SCO holds copyright. It also has brought trade secret claims against IBM, alleging that IBM contributed material covered by non-disclosure licenses or agreements to the Linux kernel. But it has distributed and continues to distribute Linux under GPL. It has therefore published its supposed trade secrets and copyrighted material, under a license that gives everyone permission to copy, modify, and redistribute.
I am not sure I follow this argument: Is it obvious (or known) that the code that SCO has distributed contains everything that, say, a RHAT distribution contains? Or could it (in principle) be that SCO's distro (old and unkempt as it is;-) does not contain the "infringing" pieces while other distributions do?
Similarly, has SCO distributed all of IBM's contributions to Linux (thus necessarily including the alleged trade secrets)?
To the contrary: I think todays decision is cause for joy, and the parlamentarians are to be commended for not having followed the commission and big business.
As discussed in the Heise article cited on the update of the original/.-posting today's decision does scale back the initial proposal strongly. Pure software patents are not allowed. There must be a relation to technology and the use of natural forces. One cannot use patents to inhibit the writing of data-conversion programs.
In fact, it seems that most demands of small/mid-sized businesses and open-source initiatives have been heeded while MSFT and its ilk express "disappointment".
Complete rejection of the initiative might have been more harmful, since it would leave the field to national patent offices, some of which like to patent software. So the new rule would unify and restrict the SWPAT-practice in the EU.
However, this was not the final vote! Now the amended proposal goes back to the European commission (which favored a more US-style law) and then has to be submitted to the parliament again.
Since "grassroots lobbying" seems to have had much to do with today's success we need to stay alert! Let your representatives in the EU parliament know what you think of their vote today!
Slashdot Mirror
no he didn't send a message.
There are three steps to a teleportation protocol:
- distributing the entangled state:
- A performs a measurement (either on his state alone or on his state and an additional "message state" in a teleportation protocol):
- A sends a classical message with his result to B: this sends a message, but it can't happen faster than speed of light.
[1] namely an equal mixture ofthis happens at less than speed of light and doesn't send a message (it just means the two parties (call them A and B) share a predetermined state).
this doesn't send a message either: not from B to A since B cannot influence at all what A will measure, nor from A to B since the state of B's system (as far as B can determine) is unchanged by A's operation: no matter whether he did a measurement or not and no matter what the result, B's state is the same.[1]
Once B receives the message, he knows more about his state: if A performed a teleportation scheme, he now knows his state to be a (unitarily transformed) copy of A's message state; if A just measured his part of the entangled system, B learns what his state is.
for speed of gravity, see Kopeikin et al, on www.arxiv.org (eg. gr-qc/0310065 and references therein); note that there has been criticism of this paper, I can't judge who's right.
But it seems that John Baez is convinced by Kopeikin's result, and I'd trust Baez' word on this.
I don't know of any measurements of the speed of the strong and weak force. This is certainly extremely difficult, since they are short-range interactions (acting within nuclei only, 10^-15m and shorter, see here ).
I'm not aware of any problems with the standard model: the particles mediating the weak interaction (W+,W-,Z) are massive, hence the speed of the weak force should be smaller than c. The force between quarks is mediated by "gluons" which are predicted to be massless, hence the speed shoud be c.
exactly, when you measure[1] one member of an entangled pair, the two particles are no longer entangled
[1] "perform a complete measurement on" (for the pedantic)sorry, but that's not accurate: the state changes "instantaneously" for the one who performs the measurement (and, yes, a QND measurement first prepares an entangled state between two systems and then measures one of them to determine the state of the other)
and only a message containing A's result changes that.But to send a message the state for the party who doesn't measure (and presumably is light years away) must change. However, her state is still a random mixture of
There's no "lack of state". Both before A has measured and after the measurement (but before the result is known) the state of B is described by the *same* mathematical object, which is the random mixture of the two states "0" and "1". This randomness (of each single system considered by itself) is a necessary consequence of the overall system being entangled. ;-]
And wouldn't it be possible to have some kind of "ping" for determining the message speed? I.e. get two pairs far enough away from each other to get measurable values, tie a machine to one half that "flicks" the other bit once the first bit is "flicked", then measure the time difference between flicking the first bit and receiving the flick of the second?Thus if B makes any kind of measurement (and even if there are many identically prepared systems to start from) there is no way of distinguishing the two cases. No matter what measurements B does, they yield (randomly and with equal probability) one of the two possible results.
The "spooky action at a distance" makes sure that the random results that A and B get are *correlated* (if they do the same measurements). However, since the results are random (and cannot be controlled by A or B) they can't send information this way. [They could "coordinate" instantaneously, e.g., perform some synchronous swimming in two different galaxies - but it would of course take a signal at lightspeed or less to ascertain that they are indeed synchronous
i'm not sure i understand this correctly: you start out in a state with the property that each particle has a 50% probability to be found in "0" (and 50% chance to be found in "1"). Measurement at A gives a *random* result (outside the control of the experimenter) and forces the other particle to now have 100% probability to be found in the same state. But since B doesn't know what "the same" is, for him it is still 50:50, i.e unchanged to before the measurement. therefore there is no "message".
As for checking the "speed of correlation": people have seen that it is larger than c. Even if A and B perform their measurement at exactly the same time, the correlation between the results is exact. But that is hardly surprising, as the two parties had essentially communicated before (to set up the entangled state). As someone explained before: A could throw a coin and take a picture of it (without looking if it's head or tails) and send the picture to B. Now they share a "classically-correlated state" (both picture and coin show heads or tails with 50% probability). Once one of them looks at his object he instantly knows the state of the other object as well. But no information is transmitted by looking at the picture.
[The cool thing about the entangled quantum state is that there is more than just the "head-or-tails" property. This is why the quantum-correlated state can be used to send (at signal speed) quantum states or shared secret bits.
you have to make them interact, hence it will take at least 17 years to entangle two particles 17 lightyears apart (unless there were prior entanglement)
stick one at a point 17 light years distant and twiddle the other, when does the one 17 light years away "change". 17 years or instantaneously? Neither?both ;-) For the observer doing the measurement, it changes (nearly) instantaneously and indeoendent of the separation of the two particles. For the other one it does only change after a message (travelling at speed of light) has informed him about the outcome of the measurement.
Look at it this way: the quantum state describes what is known about the quantum system. We start in a situation, when both parties A and B (the one on Earth and the one 17 lightyears away) know the two particles to be in a state Psi (which is entangled). [That's why it took 17 years to set up the experiment;-]
If the observer on the earth now does his measurement, he knows "instantaneously" the state of his and the other particle. But the observer 17ly away does at best know that a measurement has been performed (say they had synchronized their clocks and agreed that A would mesure at a certain time). Since B does not know the result of the measurement, his particle is still in a completely undetermined state - indistinguishable from the one before the measurement! Only after he receives the message containing the measurement result (which takes another 17 years) does he learn what state his particle is in (which some describe as his state "collapsing" into the state corresponding to the measurement result.
The curious thing is, that instead of waiting for the message from A, B could himself perform a measurement. This would be guaranteed to yield the same result as the one obtained by A [for the appropriate entangled state and if both measure the same observable].
Thus A and B can turn their "quantum correlation" (entanglement) into classical correlations instantaneously. But since the results obtained are completely random and out of their control, it is not possible to transmit information without further classical messages, slowing everything down to the speed of light.
[note that I am not talking about "teleportation" here, in which case any measurement by B will destroy the quantum state that A tries to send]
I'm curious as there appears to be a lack of clarity on this particular issue, if it is in fact "absolutely instantly" does that really mean you can setup a 0ms latency link between say the Earth and Mars by exploiting Quantum entanglement as a communications channel?no
for all we know: yes. To create entanglement between two particles they have to interact either directly or indirectly. In the former case, we are clearly limited by the speed of light; the second case is, e.g., what has been called "entanglement swapping": create two entangled pairs and perform a joint measerement on two particles (one from each pair). Once the result of this measurement is known at the locations of the remaining particles -- which requires a signal of some kind which again limits the speed --, they are in a useful entangled state. One can build a recursive protocol, chaining together ever more separate entangled pairs. Checking the math, one sees that it will take at least 1 year to create entanglement between to particles on lightyear apart. (Similarly, to use the entanglement to teleport a signal over this distance will again take at least one year.)
(BTW: the link needs not be electromagnetic, of course. Any interaction/signal will do, but light is usually the best.)yes, any observation on a set of entangled particles changes the state of the whole set.
or do you unentangle them before you observe them?However, if you do it appropriately it does change it in such a way, that (a) your measurement tells you nothing about the unknown state and (b) the unknown state is still encoded in the state of the unmeasured particles.
not before - but the act of measurement disentangles the measured particle from the rest. It may lead to *all* particle being disentangled (e.g., if they were in a state |00000>+|11111> and you measure in the basis {|0>,|1>}) or it may leave the unmeasured particles entangled (e.g., if you measure in the basis {|+>=|0>+|1>, |->=|0>-|1>}).
Can you unentangle particles without changing their state?no, since the state they are in is either entangled or not, disentangling them implies changing their state.
However, the 5-qubit state may be a *redundant* encoding of another state Psi (of fewer qubits). Then it is possible to change the overall state (either by measurements or normal time-evolution) such that one ends up with a single qubit in the state Psi.
This can be useful, since it may allow to if something has happened to the state encoded *without* learning anything about the state. This is the essential idea of quantum error correction: encode in a big (say 2^5-dimensional) space the state of a two-dimensional system. Detect, whether the state has moved out of this subspace (i.e. an error has occurred) but do it such that you do nott distinguish the two states in the subspace (thus leaving it untouched).
Red Dawn
(for its absurd story and poor acting)
and
The Lord of the Rings I
(for how awfully it underachieved compared to the book which it was based on;
from all I've heard II and III are even worse, but I haven't seent them)
6 digits! Did Microsft buy a few licences or something? I doubt the EV1 deal can bring 6 digits, and there isn't really anything else they can count as SCOSource revenue.
As reported on Groklaw they are thinking of bundling SCOsource with their UNIX-offerings. That way, the customer just pays for UNIX but SCO can book part of the revenue as SCOsource to make shareholders happy.
they don't have to change the name again - for this they now have the Firesomething extension
wrong and right! The Vernam cipher or one-time pad is a provably secure encryption method. But is indeed a classical method that involves a key which is as long as the message. Quantum ethods only come in as a method (the only known one) for provably securely distributing such keys.
RSA and other public-key cryptosystems relying on the (presumed) difficulty of things like factoring, finding solutions of the Pell Equation or computing Gauss sums are compromised by a quantum computer. DES, on the other hand, is a block cipher key and AFAIK there is no specific quantum-enhanced attack on it.
So wouldn't that make the secure transfer of the keys somewhat pointless?
no, since the ultimate encryption algorithm - which is unbreakable by both quantum and classical computers) just needs a secret random string of the same length as the message ("Vernam cipher") -- and this is just what "quantum cryptography" (quantum key distribution) allows to generate.
distributing keys is only made pointless by a QC if you want to use them in a sub-par way, sending a message much longer than the key.
Frodo and Bilbo were both of the same age, but Frodo had had the Ring for 17 years. Thus he looked like "a robust hobbit just out of his tweens" while Bilbo (at the time he set out with the dwarfs) would have looked somewhat less youthful (or should i say childlike?)
granted the chaos, but they also generated a huge amount of publicity -- much more than RHAT, NOVL, OSDL etc. could have generated on their own. And since the quality of argumentation has been so onesided, this whole thing may have helped Linux more than it hurt.
In Lawrence Lessig's book "The future of ideas" this very point is discussed: novel methods of using the electromagnetic spectrum (essentially using packets and hopping in frequency) can provide essentially limitless bandwith. (References to these methods can be found in Lessig's book). This would pevent the "Tragedy".
There are other means to reach the same goal:one could make only part of the spectrum a commons, one could still sell licenses but regulate their use (like the use of AT&T's phone lines was regulated).
exactly, so MS shouldn't patch any holes in the first place, then no malware would be written and everyone would live happily ever after
I agree that one should be open to new ideas, but you might admit that coming forward with thousand of pages mixing well-known and original stuff and proposing this as the New Kind of Science is also meant to provoke the "old scientists".
Moreover, most people who out of the blue come up with the New Big Theory are wrong (or not even wrong). Typically, that has been practiced by entrenched organizations like churches for thousands of years is the first-line defense against critique (see Crackpot Index, item 32).
I haven't read the whole book since what read in it and about it gave me the impression that it is not worth the time (for me). I found this review interesting, since it pointed out (among other things) a (possibly fundamental) flaw in Wolfram's reasoning (his model of computation is classical, and seems to be in contradiction with the experimentally verified violation of Bell's inequality).
Actually, in his second book (Shadows of the Mind) he (as far as I can tell) claims to prove that the human mind does things a universal Turing machine cannot and must therefore be based on different physics. Please correct me if I remember this wrong.
While I do not buy Penrose's argument, it is also not entirely clear to me, where it fails. The gist seemed to be: "In any formal system of logic there are statements that can be proven to be undecidable; however, we can see that they must be true, since if they were not, there would be a counterexample, which would make them decidable. Hence human reasoning is different from just following formal logic (which is what, supposedly, a computer following the laws of classical or quantum mechanics would do). Consequently the human brain must follow different laws - and quantum gravity seemed to be the [only|obvious] place left to look for them.
I really just couldn't hold any respect for him after reading The Emperor's New Mind, which is too bad since it's one of those "tour de force" books ala hofstadter
I think it is a great book, even though I disagree with his point on AI.
I don't think he should lose respect because of the ideas he has put forward, especially since he now tries to think up experiments on how to test his hypothesis.
I do enjoy those laymans science books. Any you might recommend?
I enjoyed reading Deutsch "The Fabric of Reality" (although it is in places very speculative and I do not agree with several points) and Greene "The Elegant Universe" (cf. also the BBC tv series).
Thanks for your response. I am aware of this and from what I've seen here, at Groklaw and elsewhere, SCO's case is ridiculously weak. But even if they had a case it might be best for them to hide the evidence until they have to show it in court. FUD is much greater this way than if 10 specific violations are pointed out and quickly removed by the Linux community. Moreover, as McBride said explicitly, they are happy to let the "infringements" continue to collect larger amounts of money later on.
My question concerning Moglen's argument is: how strong are the conclusions that can be drawn from SCO's distribution of a GPL'd Linux? Is the kernel (by and large) always the same or can there be significant differences between different distributions? In the former case, Moglen's argument holds, but in the latter case I don't see that SCO distribution some kernel already implies that they have distributed the "infringing code" themselves and revealed the "trade secrets".there was a positive report in Barron's magazine by, guess who, a Deutsche Bank anal-yst indicating that SCO stock might be worth 185$ (-20% for Boies) if they succeed (see CBS Marketwatch, the original article is unaccessible w/o paid registration) They probably mention that the stock could go to zero as well, but for a trader that doesn't matter, he can probably make big bucks just surfing the ups and downs.
I am not sure I follow this argument: Is it obvious (or known) that the code that SCO has distributed contains everything that, say, a RHAT distribution contains? Or could it (in principle) be that SCO's distro (old and unkempt as it is ;-) does not contain the "infringing" pieces while other distributions do?
Thanks.Similarly, has SCO distributed all of IBM's contributions to Linux (thus necessarily including the alleged trade secrets)?
more prosaic physicists call it the bottom quark. ;-)
But I am happy to see that Beauty and Truth are still in use
To the contrary: I think todays decision is cause for joy, and the parlamentarians are to be commended for not having followed the commission and big business.
As discussed in the Heise article cited on the update of the original /.-posting today's decision does scale back the initial proposal strongly. Pure software patents are not allowed. There must be a relation to technology and the use of natural forces. One cannot use patents to inhibit the writing of data-conversion programs.
In fact, it seems that most demands of small/mid-sized businesses and open-source initiatives have been heeded while MSFT and its ilk express "disappointment".
Complete rejection of the initiative might have been more harmful, since it would leave the field to national patent offices, some of which like to patent software. So the new rule would unify and restrict the SWPAT-practice in the EU.
However, this was not the final vote! Now the amended proposal goes back to the European commission (which favored a more US-style law) and then has to be submitted to the parliament again.
Since "grassroots lobbying" seems to have had much to do with today's success we need to stay alert! Let your representatives in the EU parliament know what you think of their vote today!