[extropy-chat] FW: The Drake Equation and Spatial Proximity

Eugen Leitl eugen at leitl.org
Wed Oct 25 19:45:31 UTC 2006

On Wed, Oct 25, 2006 at 04:29:17PM +0100, John Heritage wrote:

> I did some googling around, but couldn't find any information on the pellet streams you mentioned.

It's an old device: never underestimate the bandwidth of a station
wagon filled with tape cartridges. The usual comeback is that the
latency would suck, but that argument goes away with relativistic
matter streams.
> I'd take a guess that perhaps you mean encoding information on single atoms (perhaps in their electron spin state) and then sending collections of them as packets in pellet form.

No, just encode things as lattice defects (with error coding, even
if punch a hole through interstellar vacuum there will be some
proton and heavy ion radiance from the background). You encode
them on one end, accelerate them, and catch them on the other end.
> But I'm not sure how this idea could better the theoretically infinite bandwidth of the EM spectrum.

If you look at deep space antenna network, you'll see that they're using
giant antennas to catch a few photons, resulting in a very low data rate
close to the noise background. Lasers are much better, but what is your beam
divergence to Alpha Centauri, and how many channels can you resolve spatially,
even if senders/emitters are lightminutes apart? It's certainly a channel,
but for an advanced culture it's a terribly narrow pipe. DNA stores, how
much? 1 bit/nm^3, which is about 10^9 bits for a micron-sized dust 

> Of coarse, we don't have infinite coverage of the EM band with practical lasers, but it's definitly not a static area - we're developing x-ray lasers in my electronics department... I think.

Right now WAN (allright, vacuum is lots more transparent than glass,
but still) is 40 GBit/s, and we're already in touching distance
of the physical limits in the laboratory (not yet in the field).

Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
ICBM: 48.07100, 11.36820            http://www.ativel.com
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