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Vint Cerf Plugs Android Into Interplanetary Net
Several readers sent in an update on DTN, the interplanetary Internet protocol that Vint Cerf has been working on for many years (and we have been discussing for nearly as long). The news now is that Cerf has added a DTN stack to the open source Android code, seeing uses in mobile applications for a protocol that does not assume a continuous connection.
You miss the point. They're not adding DTN to the mobile for extraterrestrial communication - they're adding it to the mobile for better terrestrial communication.
The situations this protocol is designed to deal with - intermittent connection with variable (and potentially high) latency - are things that apply very much to mobile devices.
Well, yes and no.
The effective speed of light changes in different medium, but only because of the refractive index. The light is still travelling at the same constant speed but because of the refractive index, it's not travelling in a straight line so it only appears to travel slower.
What you refer to is the speed of propogation of light through various transparent medium. The light is delayed due to absorbtion and re-emission, but is not slowed down.
Even experiments to slow and completely stop a beam of light (say, in a Bose-Einstein Condensate) are really just affecting it's effective speed, effectively capturing it with "tiny mirrors" but the absolute speed of the light is unaffected.
"Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves
Several readers sent in an update on DTN, the interplanetary Internet protocol ...
Please stop screwing up the meaning of DTN. Not just /., but everyone writing article about Vint Cerf and "his" interplanetary internet. The acronym stands for Delay Tolerant Network, and is a type of network in which connectivity is ephemeral and a contemporaneous path between two points often doesn't exist at any point in time, necessitating any communication to be tolerant to delay (and/or disruption).
A DTN protocol is one that takes advantage of the ephemeral connectivity of DTNs, usually along the lines of employing the store, carry, and forward approach to getting data from A to B via a time-varying path; e.g. a path exists, just not at any point in time.
What Cerf has done has create a bundle forwarding protocol stack for the Android. It's not as "out there" as you'd think- someone send you data, you carry it, then forward it later. Lots of questions/issues in between as you might imagine.
I think some people like Kevin Fall need to get more credit for their contribution to this area of research.
Disclaimer: I am NOT Kevin Fall but I am a network researcher, specifically in the area of DTNs. No, not the algorithm.
http://mailman.ccsds.org/pipermail/sis-dtn/2008-July/000038.html
tomorrow who's gonna fuss