Jordan14 Posted December 3, 2004 Share Posted December 3, 2004 Spurred by other posts I was thinking the doesn't quantum entanglement, the links between the electron and the positron, defy relivity. Because can't entanglement provide an instaneous form of communication across the whole universe. Link to comment Share on other sites More sharing options...
swansont Posted December 4, 2004 Share Posted December 4, 2004 Spurred by other posts I was thinking the doesn't quantum entanglement, the links between the electron and the positron, defy relivity. Because can't entanglement provide an instaneous form of communication across the whole universe. No. You always need a classical channel of communication, which is limited by c. There have been other threads on this; I suggest you go read them. Link to comment Share on other sites More sharing options...
Jordan14 Posted December 4, 2004 Author Share Posted December 4, 2004 Sorry about that Link to comment Share on other sites More sharing options...
5614 Posted December 4, 2004 Share Posted December 4, 2004 normally lasers are used.... i think one day radio waves could be used as they can go longer distances and can be used via existing satelites... but that last part is my opinion. Link to comment Share on other sites More sharing options...
swansont Posted December 4, 2004 Share Posted December 4, 2004 normally lasers are used.... i think one day radio waves could be used as they can go longer distances and can be used via existing satelites... but that last part is my opinion. Why do you say that radio waves can go further than lasers? Link to comment Share on other sites More sharing options...
5614 Posted December 4, 2004 Share Posted December 4, 2004 well, i dont know i spose they must be better than light for transmitting data purely because radios, phones and other methods of communication are all radio waves (with a tiny bit of microwaves) and sure we have fibre optic cables, but i cant remember the last time someone talked over the phone using light in a satelite, for starters there'd be too much interference (i think) from all the light on this world. ok, so there isnt actually a distance thing, but light isnt suitbale for send up to satelites and back. (or not as suitable as radio/micro waves) Link to comment Share on other sites More sharing options...
swansont Posted December 5, 2004 Share Posted December 5, 2004 well' date=' i dont know i spose they must be better than light for transmitting data purely because radios, phones and other methods of communication are all radio waves (with a tiny bit of microwaves) and sure we have fibre optic cables, but i cant remember the last time someone talked over the phone using light in a satelite, for starters there'd be too much interference (i think) from all the light on this world. ok, so there isnt actually a distance thing, but light isnt suitbale for send up to satelites and back. (or not as suitable as radio/micro waves)[/quote'] OK, I see your point. Clouds would tend to get in the way of visible light. But you could still have a fiber-optic network on the earth. You aren't required to use a satellite. Link to comment Share on other sites More sharing options...
5614 Posted December 5, 2004 Share Posted December 5, 2004 going via satelites is easier than installing mega fibre-optic cables globaly!!! fibre-optic cables are quite expensive and you'd need several, i mean, you cant have one cable for all quantum internet traffic between e.g. america and the UK! i mean, you'd need almost one per connection as you cant really have several light beams going down the same wire, the end computer would get confused! satelites, whilst slower due to the extra journey length, would probably be more suitbale than a global fibre optic network. Link to comment Share on other sites More sharing options...
swansont Posted December 5, 2004 Share Posted December 5, 2004 i mean' date=' you'd need almost one per connection as you cant really have several light beams going down the same wire, the end computer would get confused![/quote'] We do this already - multiplex many light signals on the same fiber. You need to be separate the wavelengths/frequencies far enough to tell them apart (i.e. no crosstalk), but at telecom (~1550nm) you can do this with 0.4 nm or better spacing (~50 GHz). Fiber is good for a range of many nm, so you can currently get up to 32 signals on a single fiber. Research is ongoing to improve this, of course. DWDM - dense wavelength division multiplexing edit to add: they are trying to get to 10-20 GHz spacing as the next step; that's from a conference I went to 18 months ago. Then you go to having ~100 signals on a fiber. Link to comment Share on other sites More sharing options...
5614 Posted December 5, 2004 Share Posted December 5, 2004 still, 32 or even approx 100 is not really enough for all of the USA --> UK communications. we'd still need many of these and one satelite would be easier and probably cheaper. all the same, interesting data there... thanks. Link to comment Share on other sites More sharing options...
Guest Thangalin Posted January 30, 2005 Share Posted January 30, 2005 Hey, There's a QE page that tells about how it works, from first principles, without math. http://www.joot.com/dave/writings/articles/entanglement/ Ciao! T Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now