I think the idea of every kid having there only laptop is great - I know I would have loved one and learnt a lot from one when I was a kid - but I dont think having a laptop for every child should be getting the kind of attention it seems to be getting...
Basic computer skills are good for any kid to have and the analytical skills built through programming are also very valuable but before you can develop any of these skills you need a good grounding in the basics - basic mathematics/literacy and so on... I think every kid having a computer will add to the basic learning process or distract from it - flashy graphics might help kids learn certain things more easily but by that reasoning CNN should be a much better news resource then any static web page, and we all know thats not true, dont we?
Im not entirely sure but if you look at the title of the paper at the science.com site:
Low (Sub-1-Volt) Halfwave Voltage Polymeric Electro-optic Modulators Achieved by Controlling Chromophore Shape
The paper itself is'nt available without a subscription but from that it looks more like modulation then the reverse.... that said you should never judge a book by its cover (or a paper by its title;-)....
From what I can see your right about the computers running faster but I think it will make the pipes bigger, the reason being that at the moment most optical systems use either mach-zender type modulator (which are pretty slow) or they actually change the current biasing the laser to modulate it.... The problem with that is that if you modulate the biasing of a laser it also tends to modulate its wavelength (theres a lot of research gone into changing a lasers output power while maintaing its wavelength stability but they are all far, far from perfect).... With this new system though you could leavethe laser pumping continuously at one wavelength and modulate it with this stuff.... That means the wavelength wont move around so much which means you can have more lasers pumping into the same fiber at closer spaced intervals which means you can have bigger bandwidths....
The real beauty is that you can use the existing fiber that already been laid and the fiber ampifier that are already there and just invest in new modulator/demodulator pairs at either end and get a much bigger bandwidth....
Some of the cool stuff some researchers are doing is integrating a laser onto a normal ASIC.... That means that the connection from the chip to the rest of the world is optical rather then the usual bondwires and (relatively) slow electrical ones.... That means that if you have a chip with a 1GHz internal clock the whole system can move data around at the same speed - stick a few of the lasers in parallel on the same chip and youve got a 1GB/s connection with the rest of your system...
Now all we need is a way of producing RAM and peripherals that keep match with the speed.... StormChaser
I mean, why don't they just pick up a Celeron or two (or a "Celeron 2":-), toss on an embedded Linux or Windows CE, and BANG!
Okay - I agree going open source with the software would have been a good move, but using a Celeron or any Intel/AMD chip would have been a step backwards... Quite rightly Sony have figured that if they're going to make a games machine then they should make a games machine, not a general purpose computer configured that way but an elegantly designed piece of machinery that has been engineered from day one with its eventual use in mind.
...that a lot of countries would leave trade disputes up to the WTO
How would an action by the EU against a corporation (Microsoft) be consisdered a trade dispute - unless your suggesting that Microsoft is a country in its own right or that America and Microsoft should be considered as one and the same thing abroad (something I shudder to think of).....
As your wave travels down this ideal transmission line, the charge distribution within the line changes in such a way as to keep the wave intact. Without this, there would be no transmission.
Which is carrying the signal then - the EM field which travels at the speed of light or the electrons (most of which will not have moved as much as a millimeter by the time your signal has reached its destination)....
Thus, I submit that in waveguides, the electrons are indeed carrying the information - in _conjunction_ with the fields. Fields alone would just radiate, not propagate down the line.
Not true..... Take a cylindrical waveguide (cylindrical conductor which streches to infinity in either direction and is a small number of wavelengths wide (for arguments sake))..... An EM wave propogated down this will be reflected by the conductive walls and will create a standing wave. This standing wave can then be modulated to send a signal. The electrons in the waveguide will be affected by this (after all its the free electrons in the conductor which enable it reflect the wave) but its the EM wave that is doing the work of transmitting the signal.
I dont really want to go into the ins and out of the theory of waveguides here.... All I want to make clear is that the magnetic field surrounding the conductor is at least as important if not more important than what the electrons are doing - this is true of all transmission line situation be it at microwave frequencies or even at 50 Hz over the power grid (or whatever the frequency is in you country of choice).... Also referring to you first post - electrons do not travel inside a conductor - if you go through Maxwells laws you will see that thats not possible at all in the ideal case and is unlikely execept under special circumstances down to a skin depth of a small fraction of a millimeter in real life.
something about sending signals through the magnetic field around the power cable. Call me a skeptic, but
Of course it was around the the conductor - all electronic signals are transmitted as changes in the magnetic/electric fields around a conductor - thats basic physics.....
There was a current affairs program on English TV recently (Channel 4) which described how one of the English secret service divisions had erected a tower in the middle of the microwave link between England and Ireland and had beeen routinely monitoring all calls between the two countries. The stated reason for this was to prevent terrorism from the IRA (which I completely agree with) but it had also been used to get information valuable from an economic perspective. It only came to light because with the increased use of fiber optics the microwave link wasnt being used and the relevant tower was up for sale.... My point is though, that if the English government thought it was a good idea to spend a whole lot of money spying on Irish calls (and we were very much a second world nation at that time) why wouldnt the american government decide a similar operation would be justified on all incoming european traffic, especially if they have a large surveillance network already in place??? (Of course they probably do already, but theres no need to be so blatant about it:-] )
Its might well just be a nuisance for most americans but speaking as a non-american (Im European) I dont want a foreign nation spying on every mail I send or transaction I have and Im sure a lot of businesses would be very concerned about the possibilites from state sponsered industrial espionage . Look at it this way a lot of transatlantic cables ground themselves at or near the Irish coast - how would you like it if we listened in on every conversation you had to Europe? Its just going to mean that Americas going to cut itself off, to a certain extent, from the rest of the world...
DWDW is centered around 1550nm - in the infra-red region, but the main reason for that is that the fibre has a dip in its attenuation right about there (it can be engineered up and down a bit but its centered around 1550). However since there not using fibre they may have decided to go with some other freqs... That said with the amount of money invested in infra-red comms lasers its doubtful theyve switched to something totally different.
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I think the idea of every kid having there only laptop is great - I know I would have loved one and learnt a lot from one when I was a kid - but I dont think having a laptop for every child should be getting the kind of attention it seems to be getting...
Basic computer skills are good for any kid to have and the analytical skills built through programming are also very valuable but before you can develop any of these skills you need a good grounding in the basics - basic mathematics/literacy and so on... I think every kid having a computer will add to the basic learning process or distract from it - flashy graphics might help kids learn certain things more easily but by that reasoning CNN should be a much better news resource then any static web page, and we all know thats not true, dont we?
StormChaser
Im not entirely sure but if you look at the title of the paper at the science.com site:
;-)....
Low (Sub-1-Volt) Halfwave Voltage Polymeric Electro-optic Modulators Achieved by Controlling Chromophore Shape
The paper itself is'nt available without a subscription but from that it looks more like modulation then the reverse.... that said you should never judge a book by its cover (or a paper by its title
StormChaser
From what I can see your right about the computers running faster but I think it will make the pipes bigger, the reason being that at the moment most optical systems use either mach-zender type modulator (which are pretty slow) or they actually change the current biasing the laser to modulate it.... The problem with that is that if you modulate the biasing of a laser it also tends to modulate its wavelength (theres a lot of research gone into changing a lasers output power while maintaing its wavelength stability but they are all far, far from perfect).... With this new system though you could leavethe laser pumping continuously at one wavelength and modulate it with this stuff.... That means the wavelength wont move around so much which means you can have more lasers pumping into the same fiber at closer spaced intervals which means you can have bigger bandwidths....
The real beauty is that you can use the existing fiber that already been laid and the fiber ampifier that are already there and just invest in new modulator/demodulator pairs at either end and get a much bigger bandwidth....
StormChaser
Some of the cool stuff some researchers are doing is integrating a laser onto a normal ASIC.... That means that the connection from the chip to the rest of the world is optical rather then the usual bondwires and (relatively) slow electrical ones.... That means that if you have a chip with a 1GHz internal clock the whole system can move data around at the same speed - stick a few of the lasers in parallel on the same chip and youve got a 1GB/s connection with the rest of your system...
Now all we need is a way of producing RAM and peripherals that keep match with the speed....
StormChaser
I mean, why don't they just pick up a Celeron or two (or a "Celeron 2" :-), toss on an embedded Linux or Windows CE, and BANG!
Okay - I agree going open source with the software would have been a good move, but using a Celeron or any Intel/AMD chip would have been a step backwards... Quite rightly Sony have figured that if they're going to make a games machine then they should make a games machine, not a general purpose computer configured that way but an elegantly designed piece of machinery that has been engineered from day one with its eventual use in mind.
StormChaser
...that a lot of countries would leave trade disputes up to the WTO
How would an action by the EU against a corporation (Microsoft) be consisdered a trade dispute - unless your suggesting that Microsoft is a country in its own right or that America and Microsoft should be considered as one and the same thing abroad (something I shudder to think of).....
I have a final in data communications tomorrow.
Good Luck!
As your wave travels down this ideal transmission line, the charge distribution within the line changes in such a way as to keep the wave intact. Without this, there would be no transmission.
Which is carrying the signal then - the EM field which travels at the speed of light or the electrons (most of which will not have moved as much as a millimeter by the time your signal has reached its destination)....
Thus, I submit that in waveguides, the electrons are indeed carrying the information - in _conjunction_ with the fields. Fields alone would just radiate, not propagate down the line.
Not true..... Take a cylindrical waveguide (cylindrical conductor which streches to infinity in either direction and is a small number of wavelengths wide (for arguments sake))..... An EM wave propogated down this will be reflected by the conductive walls and will create a standing wave. This standing wave can then be modulated to send a signal. The electrons in the waveguide will be affected by this (after all its the free electrons in the conductor which enable it reflect the wave) but its the EM wave that is doing the work of transmitting the signal.
I dont really want to go into the ins and out of the theory of waveguides here.... All I want to make clear is that the magnetic field surrounding the conductor is at least as important if not more important than what the electrons are doing - this is true of all transmission line situation be it at microwave frequencies or even at 50 Hz over the power grid (or whatever the frequency is in you country of choice).... Also referring to you first post - electrons do not travel inside a conductor - if you go through Maxwells laws you will see that thats not possible at all in the ideal case and is unlikely execept under special circumstances down to a skin depth of a small fraction of a millimeter in real life.
something about sending signals through the magnetic field around the power cable. Call me a skeptic, but
Of course it was around the the conductor - all electronic signals are transmitted as changes in the magnetic/electric fields around a conductor - thats basic physics.....
There was a current affairs program on English TV recently (Channel 4) which described how one of the English secret service divisions had erected a tower in the middle of the microwave link between England and Ireland and had beeen routinely monitoring all calls between the two countries. The stated reason for this was to prevent terrorism from the IRA (which I completely agree with) but it had also been used to get information valuable from an economic perspective. It only came to light because with the increased use of fiber optics the microwave link wasnt being used and the relevant tower was up for sale.... My point is though, that if the English government thought it was a good idea to spend a whole lot of money spying on Irish calls (and we were very much a second world nation at that time) why wouldnt the american government decide a similar operation would be justified on all incoming european traffic, especially if they have a large surveillance network already in place??? (Of course they probably do already, but theres no need to be so blatant about it :-] )
Its might well just be a nuisance for most americans but speaking as a non-american (Im European) I dont want a foreign nation spying on every mail I send or transaction I have and Im sure a lot of businesses would be very concerned about the possibilites from state sponsered industrial espionage . Look at it this way a lot of transatlantic cables ground themselves at or near the Irish coast - how would you like it if we listened in on every conversation you had to Europe? Its just going to mean that Americas going to cut itself off, to a certain extent, from the rest of the world...
DWDW is centered around 1550nm - in the infra-red region, but the main reason for that is that the fibre has a dip in its attenuation right about there (it can be engineered up and down a bit but its centered around 1550). However since there not using fibre they may have decided to go with some other freqs... That said with the amount of money invested in infra-red comms lasers its doubtful theyve switched to something totally different.