All-optical networking Was: [Re: Notes on the Internet for Bell Heads]
Vadim Antonov
avg at exigengroup.com
Sat Jul 13 00:36:41 UTC 2002
The discussion is certainly entertaining, but --
1) All-optical networking is a bunch of nonsense until optical processing
ability includes complete set of logic and storage elements - i.e.
achieving fully blown optical computing.
Rationale for the statement: telecom is fundamentally a multiplexing
game, and w/o stochastical multiplexing a network won't be able to
achieve price/performance comparable to that of stochastically muxed
network. Stochastical multiplexing requires logic and storage.
The current opcial gates are all electrically-controlled, and either
mechanical (and wear rather quickly, too, so you can't switch them
per-packet or whatever), or iherently slow (liquid crystals), or
potentially fast (poled LiNbO3 structures, for example) but requiring
tens of kV per mm, making it slow to charge/discharge.
Besides, your truly years ago invented a practical way to achieve
nearly infinite switching capacity in electronics. Too bad, Pluris didn't
survive the WorldCom scandal, as some investors suddenly got cold feet.
2) Wiretapping does not require storage of the entire traffic stream; and
filtering for the target sessions can be done relatively easily at wire
speed.
3) Nitpicking:
> I think you may be thinking about quantum-entangled pairs. That
> phenomena is better suited to cryptography than general networking.
>
> In an entangled system, both recipients would know pretty quickly that they
> did not receive their photons as there would be an early 'measurement' on
> one end, and a missing photon on the other.
You cannot detect "measurement" per se. What you get is skewed
statistics; the entangled pairs obey Bell inequalities, which no
classical system can. This gives an opportunity to detect insertion of
anyting destroying entanglement of the pair - but only statistically.
You need to send enough pairs to distinguish normal noise from intrusion
reliably.
Besides, quantum entanglement cannot be used to send any information at
all. What it gives is the ability to get co-ordinated sets of
measurements at the ends, but the actual results of those measurements
are random. I.e. you can generate identical vectors of random bits at the
ends, but cannot send any useful message across using only
entanglement.
Therefore quantum entanglement (aka Einstein-Podolsky-Rosen paradox)
does not violate the central postulate of the special relativity theory (that
no kind of entity can propagate faster than the speed of light in
vacuum, in any non-accelerating reference frame).
--vadim
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