Hmm, building on the previous post: Let's assume high-bandwidth mesh links are via lasers to tiny base stations built into most surroundings. Your equipment has a power of one milliwatt, which is -30 dBW and hence your optimal bandwidth is about 1 Tb/s. So a full ego can be transmitted in minutes (especially if egos only encompass the difference from a standard brain and these are decently small; I have my doubts about that, but there are issues of compressibility of neural connectivity too). Note that figure 4 in the above paper assumes a 1 km link (in vacuum): you have a decent range, although air, dust and so on decreases it a bit. Now, what happens when a team tries to escape the Imminent Doom? (which kindly enough doesn't interfere with communications... I am much more fond of Imminent Dooms that also jam communications ;-) ) In this case there will be several milliwatt sources shining away, adding noise light, but this is likely (if I understood the paper right - I am *not* a signals guy!) not a problem with the right kind of detectors. The real problem is available spectrum: each signal has a bandwth which is limited by its coherence bandwidth, which in turn is dependent on delay spread. If we assume people in a 1 km area the delay spread will be 300,000 Hz, and you can transmit a huge number of egos (since the frequencies are on the order of 10^14 Hz). But if the people are crammed into a room, with distances measured in meters, then the delay spread will be 300 million Hz. Still more than enough for a few people, but now the spectrum can only handle a few hundred thousand - and this was *theory*, using perfect sensors and equipment, no people getting in the way of the lasers, no back-scattering and so on. It is at this point the evil GM gleam comes into my eye and I start drawing slowly advancing progress bars in the air...

NewtonPulsifer wrote:

Your mit.edu link is getting "Page not Found" so I couldn't read it.

Hmm, the page seems to have disappeared recently. The paper is behind a paywall at http://www.opticsinfobase.org/jocn/abstract.cfm?uri=jon-4-8-501 Nice to know the MIT estimates were rather conservative.

OneTrikPony wrote:

NewtonPulsifer wrote:

OAM link has a spectral efficiency of 95.7 bits per hertz

I forgot about that other thread. Thanks for bringing up OAM again. Orbital Angular Momentum only works if you assume everyone using it is wearing a rather large spiral reflector hat to transmit. LOL Regardless; you still have the issue of bandwidth between your transceiver and the spiral reflector antenna that gives your signal its angular momentum. Sure, you might speculate that, in the future, someone has figured out how to do OAM without the big spiral reflector but that's a hard bit of physics to handwave.

Here they've done it holographically in silicon: http://www.ncbi.nlm.nih.gov/pubmed/23232408 Plus the Alan E. Willner experiment above did *not* use a spiral reflector either. Is there a thread where someone gave you the idea that taking the garden shears to a satellite dish antenna is the only way OAM will work? It's not - its just the cheapest/easiest with off the shelf components if you wished to do it right now. One thing about EP, is they have mind-bogglingly powerful *optical* computers. It follows that the exact same optical tricks they use inside their optical computers will work in long distance communications. Simply put in EP bandwidth will scale with computing power.

Without touching the science part of this, i feel uploading a backup should take an hour or two at minimum. Swapping the cordical stack for a new one is of course the fastest way, but that means physical delivery...and risks associated with that (which of course is a positive thing as far as the gaming experience is considered). EP:s intro story features some sort of emergency neutrino farcaster implanted in a morph that can send the ego out in an instant, but i feel gadgets like those should be the exception to the rule. I feel that players should instead get creative; Start recording LD audio/video after every backup, and implant emotional responses as metadata in the video's timeline. Should the player's find themselves in a pinch you described, just upload that file in the cloud and retrieve it later for analysis.

Good Link! Thanks. It's pretty rare these days that I don't google myself into a paywall. I do not have a suspension of disbelief issue. I don't really see how the mesh *isn't* using a large investment of infrastructure either. If I had a suspension of disbelief problem it would be with the mesh as presented in the core. In EP there is no privately owned mesh infrastructure, no American Tower Corp. no AT&T. Right? The mesh is publicly owned in the sense that every one who uses the mesh actually caries a piece of it in their skull. That's all the mesh is; an ad-hock network built of participating nodes. Those participating nodes are inserts and public spimes. Don't blame me, I didn't write it. :) It's a eutopian concept. I like it because, in EP, I wouldn't have to pay AT&T $100 a month to tell me how much of American Towers capacity I *Can't* use. On the otherhand your entire communications infrastructure has to fit inside the skulls of the people who use it. That's a situation that makes me Extremely skeptical that use of the term "unlimited bandwidth" actually means unlimited. I have no problem with the way the mesh works and is used as described in the setting. I hope it's actually possible some day. My suspension of disbelief issues and skepticism are with the ideas that the mesh is capable of carrying real-time (or even frequent) wireless backup traffic. Perhaps the paper you just led me to will help with that skepticism.

The players in my group have a simple mechanic. When you perform a backup take a snapshot of your character sheet. This can be done w cell phone cams or even a GM digital cam for archiving your character's backups. This is effectively keeping track of your latest brainprint. Most backup insurance policies perform the backup every six months. You can pay more for nonstandard backups but typically even then this process is only done every month. For those who are less tech savvy or camera deprived you can also keep a Rez Log which tracks expenditures and changes to the character in question. The only other method(despite what real-world science indicates) is to pay for the highly cherished Neutrino Farcaster. This will allow you to escape that impending doom if you're within the Sol solar system. Any other methods to "backup" a character on the fly i.e. the mesh is just a pc workaround to avoid rez loss and shouldn't be considered as it takes away from the spirit of Eclipse Phase. Yes you will die and sometimes even under the best of circumstances you lose time and character advancement(rez expenditures). Hopefully this helps.

NewtonPulsifier has it. Transferring a stored ego from a file, or from a cyberbrain, is fast and easy. HOWEVER, you're limited by radio range and wireless link quality. Not quite to the level some folks posit above -- but I could see even a smart protocol needing several actions over a poor link. I think radio ranges are given in the gear section. ALSO, you're limited by how accessible the backup is. Someone in a synthmorph can send their ego right away -- but people in biomorphs and pods usually _don't_ have access to their cortical stack (this is a security measure, so that if their personal mesh is compromised it can't be used to wipe, corrupt, or copy their stack). So, if you're in a biomorph or a pod you don't have a backup to send. (Note that the device in the story that radios stack contents back has two modes: Normally, it regularly transmits a copy of your stack /when in radio contact/ with a nearby storage facility. Once, it can use a tiny bit of antimatter to send a neutrino burst anywhere in the solar system, but the process of generating the energy needed fries the morph. Costly, but it's there for exactly the type of situation your characters are in.) Making a backup takes ten minutes for a biomorph, and of course you can save a copy every time you resleeve anyway. I'd say it depends on the situation -- some people might be paranoid enough to make daily backups, others might do it less often.