it was the capability of wiring them at will that gave Unix such flexibility.
Not just that - if you connected programs together with pipes they could run as parallel tasks. It was an easy way for even novice users to make full use of powerful machines.
This is why all users should learn the Unix command line.
Can you explain exactly what the point of XML is ?
XML is a standard way to mark up information. It is derived from SGML, but designed to be simple for people to read and for developers to write parsers for.
Before XML it was (and still is) common to devise specialised ASCII and binary formats which make no sense unless you have the documentation for the format.
An example I used to work with was chemical data, in which it was common to use position in a line to indicate meaning. In the middle of a large file you might find the line:
H 1.234 10.657 20.1234 902
What are the numbers? It may be sensible to assume they are co-ordinates, but what units? What is the number on the end?
A sensible markup will include information about meaning:
<atom><type>H</type><x unit="nm">1.234</x> etc.
This looks verbose, but is very amenable to compression.
Another important aspect to XML is extensibility. An XML document can have new tags added without breaking previously organised parsing.
XML may be verbose, and is often slow to parse, but its an excellent way for different software and organisations to exchange and store information in a documented format that won't lose meaning because it is a standard.
Ok... This is fun. You will have to bear in mind that although I am strong on the philosophy of QM, I'm very poor at the math, but here goes.
What do you mean by nothing is spinning ? What does it mean to be spinning ?
Spin is the act of rotating. A specific identifiable subset of an object undergoes a continuous displacement so as to change its angular position relative to other identifiable subsets.
This is simply because we do not teach quantum mechanics in kindergarten.
Heh. Sometimes I think it would be good if we tried - we might then get enough kids saying 'why?' and 'What does that mean?' to force us to question what we think.
Now classical rotation corresponds precisely to quantum spin.
From the Georgia State University Physics website: "The property called electron spin must be considered to be a quantum concept without detailed classical analogy".
My point is that you can start at very small with quantum notion of spin and then as you increase the number of particles in your system you will gradually reach the situation where classical notions of spin are a *very* good approximation.
And this is a very good point. I think its wrong, but I can't yet say why! If I think I can, I'll post some more.
Must confess I am being pedantic here, so I may be annoying, but....
Usual 3 dimensional spin is characterized by speed (revolutions per second) and the axis the object is spinning about.
Yes, but with quantum mechanical particles, nothing is spinning. There is not one part of an electron that is rotating about another. (see my warning about 'pedantic' above!)
Flipping spin means reversing the axis - i.e. changing the direction of rotation.
But with quantum mechanical particles, there is no real 'direction' - its a relative property, and direction is meaningless when there are only limited states.
Its a metaphor, an analogy, and that is all. We have absolutely no idea what is 'really' happening at the 'electron' level. All we have is some math that gives answers. I strongly believe that using terms like 'spin' gives a false impression of understanding. Eventually terms like 'spin' and 'orbit' are so frequently used they crowd out alternative metaphors.
I don't think Linux will ever be able to touch Windows on the desktop, people have a hard enough time running Windows, much less a sometimes finicky Linux flavor.
I think that Linux will severely impact Windows on the corporate desktop. In this situation you usually want a very stable platform that provides a standard, but relatively small, number of services. At a company I support, we have moved all but two desktops to Linux. One is a Mac, for DTP and the other is Windows to run an accounts package.
Linux makes sense - there are no forced upgrades; few if any virus problems; its easy to manage remotely without down-time for users, and its free.
There was an amusing series of articles in the UK New Scientist about daft units, like 'That was the weight of 12 blue whales' or 'the force of 5 steam trains'.
You see electron spin space is a two dimensional complex space.
I think this illustrates my point well! What mere mortals think of as 'spin' isn't two dimensional, complex, or a space.
Why not follow the suggested of a learned old physicist (was it Rutherford?) and pick a word from poetry that has less meaning in 'the real world', like 'Gyre'?
They should call it "the property that looks a lot like angular momentum, even though it technically isn't rotating, but we'll pretend it is because the math works out well that way and helps us make a lot of useful (and accurate) predictions" Doesn't really roll off the tongue though, does it?
Heh. Well why not pick some daft word that has no meaning, as was done with 'quark'?
I don't mind the 'colors' and 'flavors' of quarks as these terms are silly enough that no-one assumes they are famililar physical properties.
Spin is the intrinsic angular momentum of a particle
In layman's terms: even Dirac hated the idea of angular momentum as electrons are either point charges, or small enough that the angular momentum would imply that the 'surface' of the electron would be travelling faster than light.
More precisely: there is no 'spin' at all, simply a directional property of the particle.
I don't mind the 'colors' and 'flavors' of quarks (I'm sure the physicists will be grateful for my approval), as these terms are silly enough that no-one assumes they are famililar physical properties.
I wish physicists would be more cautious in their use of language.
In the article it states: "The UCLA team succeeded in flipping a single electron spin upside down."
Considering that the term 'spin' is just a metaphor for a quantum-mechanical property that has no equivalent in our everyday experience, it makes no sense to talk about 'flipping' it, or the spin being 'upside down'.
After all, the day may come when Windows is NOT more common OS.
Good point. But anyway, since when was the point of education to learn what is the most common? Are there literature courses that abandon all but tabloid papers as they are 99% of what people read? Are there cookery courses that have given up and present lessons in how to order a burger?
When I used to teach 'computing' I never taught Word or Excel, I taught Word Processing and Spreadsheets; I explained the differences between different systems, and the students ended up with 'Transferrable Skills'. There is no point showing them all only Win2000, and expecting them to cope when Longhorn comes out.
Well it shows that Sun's architecture is not true SMP, and it has similar tradeoffs as SGI's large multiprocessor systems,
Firstly, I would argue that the linux kernel itself implies you are wrong about Sun's architecture. From 2.0 the kernel has support for "Sun SMP". Support for NUMA was only introduced into the main kernel source in 2.4.
I can't see how it has similar tradeoffs, as the architecture is quite different. I also can't see how latency and bandwith figures would look similar or favour SGI as it's well-established that SGI-style NUMA is a compromise, working where true SMP would be hard to implement. Also, using that large NUMA system is hard work: the Linux kernel provides routines to allocate threads and memory resources to nodes. On an SMP (like Sun), you don't bother - you make your program scalable by making it fine-grained enought in terms of threads, and you can use random memory.
Funny. You'd better tell Sun that, because their architecture is NUMA.
I'm not an expert on this, but companies like Oracle clearly state that Sun is SMP, as are smaller systems like Dell and HP, whereas systems like Sequent (now IBM) and SGI are NUMA.
but Linux has been able to beat practially every general purpose UNIX OS out there in fundamental things like system call, context switch, network packet, etc overhead for quite a while.
I don't mean to be annoying, but I'm skeptical. However, I'm prepared to be convinced by statistics, and I would find this very interesting. Do you have any?
Its name implies that it would shift the existance phase in a manner similar to what happened to LaForge and Ro in that one episode - effectively making it impossible for matter and antimatter to collide and explode.
Note that they did not fall through the floor, so its ok if Data hits his head on the walls, but not the floor.....
Slashdot Mirror
Wow - do you have "Loser" tattooed on your forehead, or do you let your personality announce the fact?
/. why not go outside your double-wide, and get some of those rusted-out cars towed off your front lawn.
The personality does it every time.
Instead of posting on
Because I like them there. They are artistic, and attract wildlife.
Not an original idea, I grant you, but I always thought it'd be neat to be able to take this nasty stuff and launch it into the sun.
No - let's bury it on the moon, and then when it all explodes - Space 1999, just a few years late!
it was the capability of wiring them at will that gave Unix such flexibility.
Not just that - if you connected programs together with pipes they could run as parallel tasks. It was an easy way for even novice users to make full use of powerful machines.
This is why all users should learn the Unix command line.
Yea, and your mother sucks cock without her two front teeth. What's your point bitch?
That developers in those days could (like my mother apparently) do a hell of a lot with few resources.
Amazingly, it ran without an embedded browser and media player.
that soon IE isn't going to become the preferred browser.
This may be just a little optimistic as IE is pre-installed on every copy of Windows.
Can you explain exactly what the point of XML is ?
XML is a standard way to mark up information. It is derived from SGML, but designed to be simple for people to read and for developers to write parsers for.
Before XML it was (and still is) common to devise specialised ASCII and binary formats which make no sense unless you have the documentation for the format.
An example I used to work with was chemical data, in which it was common to use position in a line to indicate meaning. In the middle of a large file you might find the line:
H 1.234 10.657 20.1234 902
What are the numbers? It may be sensible to assume they are co-ordinates, but what units? What is the number on the end?
A sensible markup will include information about meaning:
<atom><type>H</type><x unit="nm">1.234</x> etc.
This looks verbose, but is very amenable to compression.
Another important aspect to XML is extensibility. An XML document can have new tags added without breaking previously organised parsing.
XML may be verbose, and is often slow to parse, but its an excellent way for different software and organisations to exchange and store information in a documented format that won't lose meaning because it is a standard.
Is there any record of the unauthorized use of artificial satellites to bounce signals?
It worked both ways too. Rejected Star Wars titles included:
Star Wars: Generations (would have made sense)
Star Wars: Name Of Sith
Star Wars: The One Tower (did you notice the Jedi HQ?)
It is really quite beautiful
I totally agree. Far from being dry, I think it is astonishing and very deep.
There is something called "geometrical quantization" which actually shows that quantum spin *is* the right analog of classical spin.
I'm getting concerned that this is moving towards one of those 'I am wrong' situations.
I'm getting out of my depth here, but I'm going to ask anyway...
what do you mean by 'analog': Do you mean that electrons are actually rotating? Even Feynman had doubts about this.
Analagous is not the same as 'same as'.
Ok... This is fun. You will have to bear in mind that although I am strong on the philosophy of QM, I'm very poor at the math, but here goes.
What do you mean by nothing is spinning ? What does it mean to be spinning ?
Spin is the act of rotating. A specific identifiable subset of an object undergoes a continuous displacement so as to change its angular position relative to other identifiable subsets.
This is simply because we do not teach quantum mechanics in kindergarten.
Heh. Sometimes I think it would be good if we tried - we might then get enough kids saying 'why?' and 'What does that mean?' to force us to question what we think.
Now classical rotation corresponds precisely to quantum spin.
From the Georgia State University Physics website: "The property called electron spin must be considered to be a quantum concept without detailed classical analogy".
My point is that you can start at very small with quantum notion of spin and then as you increase the number of particles in your system you will gradually reach the situation where classical notions of spin are a *very* good approximation.
And this is a very good point. I think its wrong, but I can't yet say why! If I think I can, I'll post some more.
Must confess I am being pedantic here, so I may be annoying, but....
Usual 3 dimensional spin is characterized by speed (revolutions per second) and the axis the object is spinning about.
Yes, but with quantum mechanical particles, nothing is spinning. There is not one part of an electron that is rotating about another. (see my warning about 'pedantic' above!)
Flipping spin means reversing the axis - i.e. changing the direction of rotation.
But with quantum mechanical particles, there is no real 'direction' - its a relative property, and direction is meaningless when there are only limited states.
Its a metaphor, an analogy, and that is all. We have absolutely no idea what is 'really' happening at the 'electron' level. All we have is some math that gives answers. I strongly believe that using terms like 'spin' gives a false impression of understanding. Eventually terms like 'spin' and 'orbit' are so frequently used they crowd out alternative metaphors.
I don't think Linux will ever be able to touch Windows on the desktop, people have a hard enough time running Windows, much less a sometimes finicky Linux flavor.
I think that Linux will severely impact Windows on the corporate desktop. In this situation you usually want a very stable platform that provides a standard, but relatively small, number of services. At a company I support, we have moved all but two desktops to Linux. One is a Mac, for DTP and the other is Windows to run an accounts package.
Linux makes sense - there are no forced upgrades; few if any virus problems; its easy to manage remotely without down-time for users, and its free.
That's also where the crazy units come in...
There was an amusing series of articles in the UK New Scientist about daft units, like 'That was the weight of 12 blue whales' or 'the force of 5 steam trains'.
You see electron spin space is a two dimensional complex space.
I think this illustrates my point well! What mere mortals think of as 'spin' isn't two dimensional, complex, or a space.
Why not follow the suggested of a learned old physicist (was it Rutherford?) and pick a word from poetry that has less meaning in 'the real world', like 'Gyre'?
They should call it "the property that looks a lot like angular momentum, even though it technically isn't rotating, but we'll pretend it is because the math works out well that way and helps us make a lot of useful (and accurate) predictions" Doesn't really roll off the tongue though, does it?
Heh. Well why not pick some daft word that has no meaning, as was done with 'quark'?
I don't mind the 'colors' and 'flavors' of quarks as these terms are silly enough that no-one assumes they are famililar physical properties.
Spin is the intrinsic angular momentum of a particle
In layman's terms: even Dirac hated the idea of angular momentum as electrons are either point charges, or small enough that the angular momentum would imply that the 'surface' of the electron would be travelling faster than light.
More precisely: there is no 'spin' at all, simply a directional property of the particle.
I don't mind the 'colors' and 'flavors' of quarks (I'm sure the physicists will be grateful for my approval), as these terms are silly enough that no-one assumes they are famililar physical properties.
I wish physicists would be more cautious in their use of language.
In the article it states: "The UCLA team succeeded in flipping a single electron spin upside down."
Considering that the term 'spin' is just a metaphor for a quantum-mechanical property that has no equivalent in our everyday experience, it makes no sense to talk about 'flipping' it, or the spin being 'upside down'.
Neat achievement though....
I don't believe 2.7 will ever happen. In a move guaranteed to improve the acceptance of Linux by CEOs and PHBs, it will surely be...
Linux 3000 Xtreme Professional Plus (codename: BiggerHorn) - based on NT (New Tux) technology.
After all, the day may come when Windows is NOT more common OS.
Good point. But anyway, since when was the point of education to learn what is the most common? Are there literature courses that abandon all but tabloid papers as they are 99% of what people read? Are there cookery courses that have given up and present lessons in how to order a burger?
When I used to teach 'computing' I never taught Word or Excel, I taught Word Processing and Spreadsheets; I explained the differences between different systems, and the students ended up with 'Transferrable Skills'. There is no point showing them all only Win2000, and expecting them to cope when Longhorn comes out.
Yes, you can. You just can't modify it and call it java.
You can modify it and call it Java if it passes the compatibility tests.
Well it shows that Sun's architecture is not true SMP, and it has similar tradeoffs as SGI's large multiprocessor systems,
Firstly, I would argue that the linux kernel itself implies you are wrong about Sun's architecture. From 2.0 the kernel has support for "Sun SMP". Support for NUMA was only introduced into the main kernel source in 2.4.
I can't see how it has similar tradeoffs, as the architecture is quite different. I also can't see how latency and bandwith figures would look similar or favour SGI as it's well-established that SGI-style NUMA is a compromise, working where true SMP would be hard to implement. Also, using that large NUMA system is hard work: the Linux kernel provides routines to allocate threads and memory resources to nodes. On an SMP (like Sun), you don't bother - you make your program scalable by making it fine-grained enought in terms of threads, and you can use random memory.
Funny. You'd better tell Sun that, because their architecture is NUMA.
I'm not an expert on this, but companies like Oracle clearly state that Sun is SMP, as are smaller systems like Dell and HP, whereas systems like Sequent (now IBM) and SGI are NUMA.
but Linux has been able to beat practially every general purpose UNIX OS out there in fundamental things like system call, context switch, network packet, etc overhead for quite a while.
I don't mean to be annoying, but I'm skeptical. However, I'm prepared to be convinced by statistics, and I would find this very interesting. Do you have any?
Its name implies that it would shift the existance phase in a manner similar to what happened to LaForge and Ro in that one episode - effectively making it impossible for matter and antimatter to collide and explode.
Note that they did not fall through the floor, so its ok if Data hits his head on the walls, but not the floor.....