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Messages - Bo

#1
The statistaical nature of QM indeed never gets lost, until you do the very measurement. QM can never tell you what whould happen to a single electron. It can only tell you what could happen.
What decoherence does for you is changing the quantum probability (which includes entanglement, so cats being alive and dead at the same time), to a 'normal' statistical state (cats being either alive or dead).

Bo
#2
Quote from: LMNO on August 28, 2007, 03:01:15 PM
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17. Decoherence
"The mechanisms of decoherence are different from (though related to) those responsible for the approach of thermal equilibrium. In fact, decoherence precedes dissipation in being effective on a much faster timescale, while it requires initial conditions which are essentially the same as those responsible for the thermodynamic arrow of time." E. Joos, in the Introduction to "Decoherence and the Appearance of a Classical World in Quantum Theory" 2nd Ed.,by D. Giuliani, E. Joos, C. Kiefer, J. Kupsch, I.-O. Stamatescu, and H.D. Zeh, Springer, Berlin 2003. This is a technical monograph, but parts should be comprehensible to non-specialists.

Well it's still only a footnote :) (but that's a footnote more then in my QM books...)

Bo
#3
Quote from: LMNO on August 24, 2007, 02:41:45 PM
And generally speaking there's more of a consensus agreement around the Copenhagen Interpretation than the Multiverse theory, so wha'cha gonna do?

The copenhagen interpretation itself is also still 'under  construction'. A big puzzle in this interpretation is what causes the so called collapse of the wave function, meaning: what changes a quantum statistical probability to a physical thingie. In the original interpretation there was this thing called an 'observer' that causes the collapse, however nobody could interpret what properties this observer should have. (To solve this so called measurement-problem people even considered religion, or psychic stuff).
However nowadayas there is a pretty good and quite generally accepted solution to this problem called decoherence. (unfortunately, decoherence is hardly covered in standard QM courses/books and thus not well known). The main idea of decoherence is that apart from the system (the thing you measure) and the observer (the thing that measures), there is always a background. The background consists basically of those thing you don't/can't measure, but that are there; in other words: the system feels the background, but the observer cannot see it. now it turns out that if the background is 'large' enough, the quantum nature of the system effectively dissappears. so e.g. if we look at a single electron in vacuum (almost no background), we see all the quantum stuff. If we look at the electric field (which is caused by electrons) of a radio (so a large background) we don't see the quantum stuff. In my opinion decoherence gives by far the best description of the transition betweeb quantum and 'classical' behavior.

Bo
#4
Or Kill Me / Re: steam rolling
April 12, 2007, 05:25:12 PM
Quote from: triple zero on April 12, 2007, 05:18:57 PM
maybe i should have been more clear, i think there are certain parts of this boundary that are unknowable, so the entire boundary is impossible to determine.

mwkay i can accept that, but still I would like to hear the good reasons you have for this statement :)

#5
Or Kill Me / Re: steam rolling
April 12, 2007, 05:08:31 PM
Quote from: triple zero on April 12, 2007, 04:30:44 PM
i have good reason to believe that these boundaries themselves are part of the unknowable, so they cannot be determined.
So what are these good reasons? :)
In principle I could keep asking questions (like 'why?' or  'how?'). As long as I can answer these questions, I have not reached the boundary, as soon as I can't answer them (or I fail to ask a new question), I have reached the boundary.
The only problem arises if the number of questions is infinite, but that is imo equivalent to saying that there is no boundary.
#6
Or Kill Me / Re: Phake Fizzics
April 12, 2007, 04:56:26 PM
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shit, is that really true? also in other fields of research besides physics? i never really noticed that pressure, but maybe i'm not paying enough attention. also, either way, i should get working, whether i want to be/get to be a professor or not :)

yes it's true. I don't really know how it is in other fields. Biology, chemistry and medicine appear to be comparable.  I don't know how it is in social studies
#7
Or Kill Me / Re: Phake Fizzics
April 12, 2007, 02:29:38 PM
Quote from: LMNO on April 12, 2007, 02:22:18 PM
Payne, just a bit of info:  Yes, a physicist has managed to slow light down (http://www.hno.harvard.edu/gazette/1999/02.18/light.html).  However, Einstien didn't say that light couldn't be slowed, he said that nothing can go faster.  He posited ight as a "constant" merley because the numbers worked out that way.  So far, faster-than-light travel has not been shown to be possible (never mind what those QUIP junkies say).  Slower-than-light travel, however, happens all the time.
The constant speed of light of einstein is always referring to the speed of light in vacuum. There the speed (according to him) is really constant. and the maximum speed. These experiments of slowing light down, are all related to slowing light in a cerain medium. (and it goes completely according to the rules)
#8
Or Kill Me / Re: Phake Fizzics
April 12, 2007, 02:20:25 PM
Quote from: Cain on April 12, 2007, 01:48:07 PM
Has it become more complex though?  Well, obviously, to a degree it has, but too complex for a gifted individual to understand and be able to work in several fields?  I don't think so.
In a sense you're right; I certainly think it has become more difficult, but if you're smart enough...
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What has happened is that Universities in the 18th and 19th century moved away from education and became suppliers for the management class of capitalism, specializing the needs of all major fields in such a way that comprehensive knowledge itself became a monopoly held by the governing elite.  Call it a reaction to the Enlightenment and the last Renaissance men, if you will.  Knowledge monopolies are one thing capitalism refuses to acknowledge the existence of, because its one of the main mechanisms of hidden power among its elite.
very true, but i don't realy see how it is related to the above..

Another thing that certainly is important is the pressure on researchers to publish. If you persue a scientiffic career (in physics, biology, chemestry, medicine...) you must publish articles. and if you want to have any hope of becoming a (assistant) professor, you mst publish articles that are cited by many people. So many young researchers are almost desperately trying to write this article that will make them famous (enough) (You usually get 1-2 years to achieve this).   In other words: each hour you spend not working on your area of expertise, will diminish your chances of becoming a professor.
#9
Or Kill Me / Re: Phake Fizzics
April 12, 2007, 01:36:10 PM
Quote from: Payne on April 12, 2007, 04:49:33 AM
I do not profess to have any real understanding of quantum physics, string theory, or any of the new areas of research in Physics. The only contribution I can make to any discussion of this right now is this: Until the late nineteenth century, as I understand my history, many of the leading physicists were actually more philosophical than scientific.
You are right here in one aspect and wrong in another. You are right in the sense that something like the homo universalis (people like da vinci, descartes, pascal) does not exist anymore. the simple reason is that the material has become to complex to be an expert in many fields.
However (theoretical) physics itself has become more philosophical. The reason is that until 1900, physicists did experiments and then tried to understand them. With the advance of quantum theory and general relativity, the strange situation has appeared that theoretical physics is more advanced then experimental physics. this automatically makes physics more philosophical then before. moreover, nowadays we get closer and closer to using physics to answer the prime philosophical questions of say the 18th century like: what is space? what is time? how did the universe begin? etc. the language in which physicists talk about these problems is mathematics, but the discusion is philosophical. (Of course on could wonder if mathematics is the right language for this purpose)

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One final example. I read somewhere a few years back that a couple of guys had used one of these more philosophical branches of 'New Physics' to prove that Einstein could be wrong with E=MC2, by showing that light can travel at different speeds, and is not constant, at least at all times and all places. I haven't heard anything more about it, so I'm assuming it was all bullshit, maybe one of you has?
First of all: there are many people who claim einstein was wrong, just for the sake of it. most of these people have no idea what they're talking about (it gives you 10 points; http://math.ucr.edu/home/baez/crackpot.html )
There are some more serious people who have worked with variable speed of light theories (moffat and others). however evidence for this approach is completely absent and as far as I can judge no one except moffat himself takes this idea very seriously. (but it got him a lot of media attention)

#10
Or Kill Me / Re: of the internet and intelligence
April 11, 2007, 05:00:09 PM
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So the follow-up questions are-

At what point can we fairly say the internet is a conscious entity? What behaviors would it have to display to be considered conscious, by our definition?
I don't think we would ever notice it if the internet became 'conscious' (whatever that may mean). In the same way that your neurons would never realize that they make up our consciousness. Consciousness is imho almost by definition a property that becomes only visible on macro-scales.

A shot for a definition of consciousness:
A conscious being:
1) has thoughts and/or perceptions
2) Is aware that these thoughts/perceptions belong to him

I'm not to happy with this definitio, but I don't know how to alter it. the ability to act, or to have free will doesn't seem crucial to me. As for the internet: it certainly obeys 1), (in the form of information) but obeying 2) seems difficult..

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if the logic is that complexity breeds consciousness, what level of complexity is necessary? Complexity is a human perception, and I also think consciousness is a human perception. Arguably, cities and weather are also complex systems which display properties similar to consciousness. Is it fair to say they're alive too?
If you mean by alive: 'evolving according to complex patterns' (or something like that) I would say yes.
#11
Quote from: triple zero on March 22, 2007, 10:34:55 PM
btw unpredictability, order and "entropy" (not the physical entropy, but the statistical one, how much information does a message carry) are tricky subjects.
on the one hand, white noise carries the theoretical maximum of information and is completely unpredictable, yet it is boring as fuck and not very creative.
and this is where CHAOS ties in, because for something to be "interesting" you need the right balance between order and disorder. just being completely random, or just being ridigly ordered is not enough.
It also depends on how you look at it. From the Fourier (look it up) point  of view white noise is the most ordered state you can have. So perhaps something is interesting if it has disorder in any representation?
but your right that it is not just the amount of information that is important; it is the unpredictability of the information.
#12
You could also talk about disorder as the number of degrees of freedom your system has. (and a degree of freedom is then defined as 'a property that can change over time') The more freedom, the more disorder in general. (this is somewhat like an enthropy).
#13
Quote from: Cain on March 22, 2007, 01:40:38 PM
True.  I do feel the time aspect of disorder and order has been really overlooked, however.  Its totally essential, since disorder and order are not static properties but are bound in time and subject to change.  I'm not sure how to build on that, however.
I think order and disorder are not even welldefined without a notion of time, for indeed the are inherent dynamical properties. For example if I have a photograph of a collection dots nicely ordered in a grid. this however does not tell me that the system is ordered, since all dots could be flying in different directions at different speeds. Order and disorder are defined by the predictability of a system both over space and time.
#14
Quote from: LMNO on March 22, 2007, 12:20:01 PM
Is it the product of changing one thing into another?  That is, I can "create" a pastrami sandwich, but is that being "creative"?  I'd tend to think that most people would say there's a difference between how those two uses of "create" are being used.

Based on the discussion so far I think a definition of creativity must include:
- The creation process is conscious and/or intentional  (to rule out accidental creations, which can be fun, but don't seem creative to me)
- The creation must include more then just an application of the methodology would imply (to rule out the pastrami sandwich, unless you do something special with it)
#15
Quote from: Cain on March 22, 2007, 09:16:52 AM
Does creation count as creation if it is done within the methodology of a previous system or school of thought?  Or is just application of previous ideas to materials and objects not considered before?  Does this mean that creativity comes from creating new forms and methods of style, not in the actual content of what is made?
You might have an important point here. If you're really not adding anything to the methodology, you're doing nothing else then applying the rules. (it takes some talent or insight though to apply the rules in a good way). I think however in practice it is difficult not to add something to a method.
for example: early (say mozart-age) sonata's follow strict rules. At that time there where a lot of composers who just applied these rules and are therefore completely forgotten. only those who added something extra (like mozart himself) are remembered. It is tempting to say that these forgotten composers where much less creative then the remembered ones.