You can feel free to go ahead and explain decoherence to all of the people at/. I am not able to speak truthfully and understandably to both a general audience and to the specialists on this subject.
Wave collapse is obviously not true in the ultimate sense just because of relativity.
But since you are obviously in the know. Decoherence is not sufficient to solve the problem of measurement.
that's not a definition, and there's nothing in the equations of QM that makes any distinction between micro and macro- anything, or that can be interpreted as measurement.
There are large differences, namely with the density matrix of the different systems. Classical systems have a very localized density matrix.
MWI was invented well before people discovered and understod quantum field theory (which is more fundamental than quantum mechanics).
It is my belief that if you took a student completely ignorant of MWI; taught them quantum mechanics and quantum field theory to the point that they understood it well; and then presented them with MWI that they would laugh at it.
I think the only reason it survives is because it's a really neat idea that anyone can latch onto. Simple and interesting ideas have a way of surviving. Aether is still around and Branes will probably be here for a very long time.
(It should be noted that MWI's old time competitor isn't really perfect either and to accept one to reject the other is a serious mistake)
Honestly I don't think I could rigorously define measurement off of the top of my head, but I can very easily answer your question.
Measurement is a physical process. Despite what many people have said in the past it, has nothing to do with what you are aware of. If you detected a photon, then you did something physical to collapse the wave function. So it doesn't matter if you throw the data away or not, the physical interaction still occured.
So in other words, if you are familiar with Shroedinger's cat paradox: The cat in the box will start to rot and stink or it won't. (given food, air, water...) It doesn't matter if you don't check the cat, because the physical process between the macroscopic measuring device and the quantum state has already occured.
If I had to make a definition, I would say that measurement is a physical process between a macroscopic "classical" system and a quantum superposition of states. The interaction is in such a way that the superposition is collapsed to a single state and triggers the macroscopic measuring device into giving us a certain result - that result corresponding to what state the quantum system was collapsed to. All this with the addendum that the measuring device should be "fair" and give us a probabilities that are not modified by the measuring.
Measurement is not well understood by everyone in the community. This is probably because measurement as performed mathematically is retartedly simple. But that is a gross oversimplification of how measurement really occurs in nature. When you do the calculation for a measurement you don't even consider the interaction between the device and the system, you just assume it all works perfectly.
And even for the best among us, measurement isn't completely understood. There are serious issues with measurement dealing with time and relativity. Somebody might know these answers, but it isn't me.
That's not the many worlds theory- the splitting happens whether or not a measurement is made in the MWI.
Maybe in your MWI theory, maybe even in most MWI theories. That is not true for all MWI proponents. I qualified my statement with an "if". I then justified the very reasoning you support.
I basically said: if MWI then MWI_A. You say: MWI_A == MWI
Now I am going to say, it wasn't always the case that things were so clear. And some people are still to dumb to realize what is so obvious to you and I.
Are you nuts? Unsplitting is implicit in the double slit experiment- the fact that the photon went through two different slits in two different universes, before the universes joined is the whole point. MWI inevitably has joining.
I am nuts, but unsplitting is not implicit in MWI. How do you unsplit a living and dead cat. In that case there are two different universes that cannot be unsplit.
So now you either have to admit that unsplitting doesn't always happen or you have to explain why the cat doesn't really split in the first place.
Every argument I have seen for the latter has been based on complexity and is really bad/nonrigorous/ill-defined.
> P.S. We also don't understand why quantum mechanics rules apply at > very small scales, but very different rules apply at larger scales. > (A photon can seem to go through two slits at once, but you won't get > a baseball to do that trick, or even a really tiny speck of dust.)
That is not true at all. You can easily derive F=ma from QM. This is done in every good QM book.
The reason a bat doesn't diffract is because the bat is very massive and big.
Just calculate the deBroglie wave length for anything to see how wave-like it is. (compare the wavelength to the size of the object)
wave length = plank's constant / momentum = 6.6E-34 Js / ( ~5kg v ) = ~1E-34 m^2/s / v as compared to a meter
planks constant is very small and the bat's momentum is very large. Even if the bat were traveling at continental drift speeds (1E-10 m/s), that would be waaaay too fast to diffract.
To put it shortly, you can't use the law of averages when dealing with multiple universes.
It is improbable that all of my molecules are lined up in such a way that I will tunnel through my floor. It could happen, but it is improbable.
However, if there are multiple universes then there will be a universe where improbable things happen. There will be a universe where I tunnel right through my floor into the basement. In most universes I won't, but in some I will.
This experiment seems to be some attempt to reduce the number of universes you exist in by forcing an improbable event to occur in the universe you survive in.
That is the classical argument that was mostly pushed by people object to QM. It is a pretty good justification but it isn't good enough to be used in other situations when you really have to do QM to get the right answer.
Just to give perspective, I am a physicist who thinks that the Many Worlds interpretation (along with other things like the anthropic principle) is not only incorrect but is bad science.
It fills in a small interpretational gap but creates much larger (unanswered) questions and confusion.
If you think universe splitting occurs whenever a measurement is made, then I believe that you have a very poor understanding of what measurement is. First of all collapse is not some special/magical process and secondly you can't arbitrarily seperate the universe into observed and observer. If you are going to have splitting, it's got to happen always/everywhere and with every state basis. I would say that a preferred splitting is far more egocentric than only wanting to have 1 universe.
And assuming there is no unsplitting/suicide (and maybe even if there is) then there will universes with no measurable physics, or even worse - measurements that give a false physics. And there is no reason for us to not be in one of those universes, other than probability. Of course this could (improbable) happen here, but the point is that according to MWI it does happen somewhere. Infact, Everett proved that the crazy universes will have zero norm on the Hilbert space only if infinite measurements are taken.
No, according to the Bible, works ("living a good life" in your words) don't count, no matter how great and wonderful you think you're being. Faith, and only faith gets the job done. It's an incredibly simple requirement: profess your faith in Jesus as your savior, accept the gift of redemption offered by his death (and proven valid by his resurrection). That's it. Nothing else to it. It's in black and white in the Bible. You'd have to actually read it to know that, though.
So if I am raised by wolves (and thus don't know who Jesus is) but I otherwise live a good life and am a good person, then I automatically go to hell?
In physics UNIX usage is much higher and Apple usage is slightly higher than normal. Alphas are almost not used anymore and now we are in a transition from Sun to Linux. (Historically it's gone Alpha, Sparc, and now Linux on x86)
As far as clustering though, MS and Apple are insignificant. Though at least now there are Apple clusters. (The majority of Windows clusters I've seen are donated) And as far as desktops, UNIX and Apple are in the same league. Though the trend in grad students is an increasing number of Linux users.
In mathematics Apple use is very high (comparatively). I can't say anything about computational work in math as I never see those people.
And just incase you didn't know, many physicists and mathematicians are just as computer illiterate as everyone else.
Expensive shot: Gravity in the presence of delocalization. One can, in principle, convert huge amounts of mass-energy (gigagrams) into photons, and diffract those photons over large distances (hundreds of meters). GR predicts that those photons will create a substantial gravity field, one that is "trivially" measurable with a spatial resolution of meters. GR does not predict the values of those measurements. Ergo, GR does not describe the universe. It is easy to devise other quantized systems for which GR predicts a particular average result, but makes no predictions about the distribution of results.
Did you use classical gravity with the expectation value of the stress-momentum tensor, or did you use semiclassical gravity to make this calculation.
It's not fair to mix classical with quantum in any manner.
Yes indeed. The founders of Intel worked under Shockley at his company. Shockly was one of the inventors of the transistor. He was also racist and a terrible boss. The "Traitorous 8" left Shockley to found Fairchild Semiconductors. 2 of those 8 later founded Intel. One of those 2 is More of More's law.
Re:Your familiar has been slain!
on
D&D Is 30
·
· Score: 1
Well I am Lawful Evil.
Re:Your familiar has been slain!
on
D&D Is 30
·
· Score: 2, Informative
You also cannot get another familiar for a year unless you raise dead.
I have the core D6 rule book. D6 is sweet untill you realise that it is nearly vacuous.
D6 is great for "role play/story/interaction" oriented games like Vampire, when you don't want the rules to get in the way of the game and you don't want alot of technical diversity in your characters.
But for games that involve lots of dungeon crawling or stats/numbers like Star Wars and DC Comics it does a really bad job.
The D6 version of the DC Superheroes was particularly bad, almost to the point of being unplayable.
However that said, D6 did a wonderful job at getting kids who are bad at math into RPG's.
DCH had a log scale AND a 3x3 matrix for your character attributes - that was the cartesian product of type (physical, spiritual, mental) and function (accuracy/speed, power, resistance/capacity) - and therefore it had a single task resolution that encompassed magic and combat.
The system had to be good because it had to work for every character in the DC universe. It was soo good that when Mayfair (the creator) and DC killed it off, the system (sans the superheroes) was licensed by an upstart company.
Try finding some solutions to a transcendental equation like the solutions to a finite square well potential.
solve for k k = -c tan(a k) or k = c cot(a k)
Graphing k against c tan(a k), visually inspecting the intersections, and then numerically calculating the intersections is the easiest way to do this.
I agree that people need to learn the hard way first, but we don't all have to be ascetic math monks.
In a not so incredible plot twist amnesia guy finds out that he was the former evil boss. All the strange dreams and questionable Jedi training now makes sense.
Amnesia guy has to question who he is now that he has been given a second chance at life.
Amnesia guy decides to continue special mission. Some companions don't trust him, some do.
In an incredible plot twist amnesia guy reveals that he really is evil to the core and has been pretending to be good all this time. All the strange things he has done now make sense.
He reactivates his former assassin droid, murders the young handsome soldier, turns two companion Jedi to the darkside and kills the other, takes revenge on backstabing former evil sub boss/current boss and rules the Universe as a Sith Lord with fallen Jedi Mistress at his side.
But better than any of that - ohh the joy of murdering that annoying Twl'lek girl and her frustrated Wookie companion not being able to do anything because he owes you a life debt. That was like killing all of the Ewoks, Annakin, and Jar Jar.
Slashdot Mirror
You can feel free to go ahead and explain decoherence to all of the people at /. I am not able to speak truthfully and understandably to both a general audience and to the specialists on this subject.
Wave collapse is obviously not true in the ultimate sense just because of relativity.
But since you are obviously in the know. Decoherence is not sufficient to solve the problem of measurement.
that's not a definition, and there's nothing in the equations of QM that makes any distinction between micro and macro- anything, or that can be interpreted as measurement.
There are large differences, namely with the density matrix of the different systems. Classical systems have a very localized density matrix.
MWI was invented well before people discovered and understod quantum field theory (which is more fundamental than quantum mechanics).
It is my belief that if you took a student completely ignorant of MWI; taught them quantum mechanics and quantum field theory to the point that they understood it well; and then presented them with MWI that they would laugh at it.
I think the only reason it survives is because it's a really neat idea that anyone can latch onto. Simple and interesting ideas have a way of surviving. Aether is still around and Branes will probably be here for a very long time.
(It should be noted that MWI's old time competitor isn't really perfect either and to accept one to reject the other is a serious mistake)
Honestly I don't think I could rigorously define measurement off of the top of my head, but I can very easily answer your question.
...) It doesn't matter if you don't check the cat, because the physical process between the macroscopic measuring device and the quantum state has already occured.
Measurement is a physical process. Despite what many people have said in the past it, has nothing to do with what you are aware of. If you detected a photon, then you did something physical to collapse the wave function. So it doesn't matter if you throw the data away or not, the physical interaction still occured.
So in other words, if you are familiar with Shroedinger's cat paradox: The cat in the box will start to rot and stink or it won't. (given food, air, water
If I had to make a definition, I would say that measurement is a physical process between a macroscopic "classical" system and a quantum superposition of states. The interaction is in such a way that the superposition is collapsed to a single state and triggers the macroscopic measuring device into giving us a certain result - that result corresponding to what state the quantum system was collapsed to. All this with the addendum that the measuring device should be "fair" and give us a probabilities that are not modified by the measuring.
Measurement is not well understood by everyone in the community. This is probably because measurement as performed mathematically is retartedly simple. But that is a gross oversimplification of how measurement really occurs in nature. When you do the calculation for a measurement you don't even consider the interaction between the device and the system, you just assume it all works perfectly.
And even for the best among us, measurement isn't completely understood. There are serious issues with measurement dealing with time and relativity. Somebody might know these answers, but it isn't me.
That's not the many worlds theory- the splitting happens whether or not a measurement is made in the MWI.
Maybe in your MWI theory, maybe even in most MWI theories. That is not true for all MWI proponents. I qualified my statement with an "if". I then justified the very reasoning you support.
I basically said: if MWI then MWI_A.
You say: MWI_A == MWI
Now I am going to say, it wasn't always the case that things were so clear. And some people are still to dumb to realize what is so obvious to you and I.
Are you nuts? Unsplitting is implicit in the double slit experiment- the fact that the photon went through two different slits in two different universes, before the universes joined is the whole point. MWI inevitably has joining.
I am nuts, but unsplitting is not implicit in MWI. How do you unsplit a living and dead cat. In that case there are two different universes that cannot be unsplit.
So now you either have to admit that unsplitting doesn't always happen or you have to explain why the cat doesn't really split in the first place.
Every argument I have seen for the latter has been based on complexity and is really bad/nonrigorous/ill-defined.
> P.S. We also don't understand why quantum mechanics rules apply at
> very small scales, but very different rules apply at larger scales.
> (A photon can seem to go through two slits at once, but you won't get
> a baseball to do that trick, or even a really tiny speck of dust.)
That is not true at all. You can easily derive F=ma from QM. This is done in every good QM book.
The reason a bat doesn't diffract is because the bat is very massive and big.
Just calculate the deBroglie wave length for anything to see how wave-like it is. (compare the wavelength to the size of the object)
wave length = plank's constant / momentum
= 6.6E-34 Js / ( ~5kg v )
= ~1E-34 m^2/s / v
as compared to a meter
planks constant is very small and the bat's momentum is very large. Even if the bat were traveling at continental drift speeds (1E-10 m/s), that would be waaaay too fast to diffract.
To put it shortly, you can't use the law of averages when dealing with multiple universes.
It is improbable that all of my molecules are lined up in such a way that I will tunnel through my floor. It could happen, but it is improbable.
However, if there are multiple universes then there will be a universe where improbable things happen. There will be a universe where I tunnel right through my floor into the basement. In most universes I won't, but in some I will.
This experiment seems to be some attempt to reduce the number of universes you exist in by forcing an improbable event to occur in the universe you survive in.
That is the classical argument that was mostly pushed by people object to QM. It is a pretty good justification but it isn't good enough to be used in other situations when you really have to do QM to get the right answer.
Just to give perspective, I am a physicist who thinks that the Many Worlds interpretation (along with other things like the anthropic principle) is not only incorrect but is bad science.
It fills in a small interpretational gap but creates much larger (unanswered) questions and confusion.
If you think universe splitting occurs whenever a measurement is made, then I believe that you have a very poor understanding of what measurement is. First of all collapse is not some special/magical process and secondly you can't arbitrarily seperate the universe into observed and observer. If you are going to have splitting, it's got to happen always/everywhere and with every state basis. I would say that a preferred splitting is far more egocentric than only wanting to have 1 universe.
And assuming there is no unsplitting/suicide (and maybe even if there is) then there will universes with no measurable physics, or even worse - measurements that give a false physics. And there is no reason for us to not be in one of those universes, other than probability. Of course this could (improbable) happen here, but the point is that according to MWI it does happen somewhere. Infact, Everett proved that the crazy universes will have zero norm on the Hilbert space only if infinite measurements are taken.
But enough of my rambling, just go here for some information against MWI
No, according to the Bible, works ("living a good life" in your words) don't count, no matter how great and wonderful you think you're being. Faith, and only faith gets the job done. It's an incredibly simple requirement: profess your faith in Jesus as your savior, accept the gift of redemption offered by his death (and proven valid by his resurrection). That's it. Nothing else to it. It's in black and white in the Bible. You'd have to actually read it to know that, though.
So if I am raised by wolves (and thus don't know who Jesus is) but I otherwise live a good life and am a good person, then I automatically go to hell?
In physics UNIX usage is much higher and Apple usage is slightly higher than normal. Alphas are almost not used anymore and now we are in a transition from Sun to Linux. (Historically it's gone Alpha, Sparc, and now Linux on x86)
As far as clustering though, MS and Apple are insignificant. Though at least now there are Apple clusters. (The majority of Windows clusters I've seen are donated) And as far as desktops, UNIX and Apple are in the same league. Though the trend in grad students is an increasing number of Linux users.
In mathematics Apple use is very high (comparatively). I can't say anything about computational work in math as I never see those people.
And just incase you didn't know, many physicists and mathematicians are just as computer illiterate as everyone else.
The batteries is a hybrid have nothing to do with lower emissions, that is all managed by computerized engine controls and catalytic converters.
The engine turns off when you are waiting at stop lights.
The decaying light theory introduces a dozen new flaws for every existing flaw it fixes.
Expensive shot: Gravity in the presence of delocalization. One can, in principle, convert huge amounts of mass-energy (gigagrams) into photons, and diffract those photons over large distances (hundreds of meters). GR predicts that those photons will create a substantial gravity field, one that is "trivially" measurable with a spatial resolution of meters. GR does not predict the values of those measurements. Ergo, GR does not describe the universe. It is easy to devise other quantized systems for which GR predicts a particular average result, but makes no predictions about the distribution of results.
Did you use classical gravity with the expectation value of the stress-momentum tensor, or did you use semiclassical gravity to make this calculation.
It's not fair to mix classical with quantum in any manner.
I think the answer to the dark matter problem and the quantum theory of gravity is one in the same. Our description of gravity is wrong.
Do you realise that you can couple a theory of exotic mater or energy together with our current theory of gravity?
What you are saying could be analogous to "GR can't explain accretion, therefore GR is wrong". (You have to add E&M to the mix)
Toying with the stress-energy-momentum tensor and the cosmological constant would not really be changing the theory of GR.
Yes indeed. The founders of Intel worked under Shockley at his company. Shockly was one of the inventors of the transistor. He was also racist and a terrible boss. The "Traitorous 8" left Shockley to found Fairchild Semiconductors. 2 of those 8 later founded Intel. One of those 2 is More of More's law.
Well I am Lawful Evil.
You also cannot get another familiar for a year unless you raise dead.
A year and a day.
That was fixed in 3.5
I have the core D6 rule book. D6 is sweet untill you realise that it is nearly vacuous.
D6 is great for "role play/story/interaction" oriented games like Vampire, when you don't want the rules to get in the way of the game and you don't want alot of technical diversity in your characters.
But for games that involve lots of dungeon crawling or stats/numbers like Star Wars and DC Comics it does a really bad job.
The D6 version of the DC Superheroes was particularly bad, almost to the point of being unplayable.
However that said, D6 did a wonderful job at getting kids who are bad at math into RPG's.
TORG was sweet but DC Heroes trumped it.
DCH had a log scale AND a 3x3 matrix for your character attributes - that was the cartesian product of type (physical, spiritual, mental) and function (accuracy/speed, power, resistance/capacity) - and therefore it had a single task resolution that encompassed magic and combat.
The system had to be good because it had to work for every character in the DC universe. It was soo good that when Mayfair (the creator) and DC killed it off, the system (sans the superheroes) was licensed by an upstart company.
Here is the current incarnation of it.
Peh that poison was only DC 12.
Only the Elven Wizard would complain.
Yes we can name it "The People's Republic of Chin... er UN"
Try finding some solutions to a transcendental equation like the solutions to a finite square well potential.
solve for k
k = -c tan(a k)
or
k = c cot(a k)
Graphing k against c tan(a k), visually inspecting the intersections, and then numerically calculating the intersections is the easiest way to do this.
I agree that people need to learn the hard way first, but we don't all have to be ascetic math monks.
The plot was just excelent:
Amnesia guy fights the baddies.
Jedi Mistress escorts him on special mission.
In a not so incredible plot twist amnesia guy finds out that he was the former evil boss. All the strange dreams and questionable Jedi training now makes sense.
Amnesia guy has to question who he is now that he has been given a second chance at life.
Amnesia guy decides to continue special mission. Some companions don't trust him, some do.
In an incredible plot twist amnesia guy reveals that he really is evil to the core and has been pretending to be good all this time. All the strange things he has done now make sense.
He reactivates his former assassin droid, murders the young handsome soldier, turns two companion Jedi to the darkside and kills the other, takes revenge on backstabing former evil sub boss/current boss and rules the Universe as a Sith Lord with fallen Jedi Mistress at his side.
But better than any of that - ohh the joy of murdering that annoying Twl'lek girl and her frustrated Wookie companion not being able to do anything because he owes you a life debt. That was like killing all of the Ewoks, Annakin, and Jar Jar.
That alone was worth $10.