There are a couple of things that I don't understand about this discussion.
Firstly, we are talking about the expansion of intelligence after a
singularity, outwards from this solar system. There is a discussion of EM vs
matter. How is it possible to expand as EM? There's no receiver, no way to
kickstart a replicator at the other end. So are we (I'll be there) not
entirely limited to *initial* transmission using matter? Damien asked the
same question on list a while back, actually, and I don't remember anyone
answering "you can use em as so ...."
(There is a possible answer to that, of course; you send out an SI seed
blueprint in a form that a low-tech civilisation could intercept and use.
Very dodgy in many ways, though: Is there life out there to receive it?
Who's going to receive it; low tech friend or scary higher tech SI gobbling
foe? etc etc)
So it seems that sending modulated EM is not useful, except as follow up
signals to an initial spread of spores. Except that Robert tells us it is
too wasteful.
My second point is, given that you've already got matter out there in some
form, you've had time to put a bunch of relay stations *out there*, ready to
relay your signal. A big long (long!) line of them could take a signal from
one star to the next, without anywhere near the losses or a super death ray,
could it not? What they are powered with is an interesting problem (the
energy they receive?), but in principle it seems that you could create a
string of relay stations between one star and the next, which should overall
use less energy in communicating at (damned near) C than blasting a wave
directly from one end to the other.
My third point (I've a disordered mind) is that the cost of EM communication
might be high, but the speed may justify the cost. Information is important
to us; maybe it'll be important to giant spaceborn brains? Timelines often
makes the difference between information and noise. Waiting for your sub-c
message-in-a-bottle may not be an option, if others are communicating at
light speed.
Emlyn
My candle burneth at both ends, it shall not last the night. But ah my foes,
and oh my friends, it casts a lovely light
(possibly close to a poem by Emily Dickinson)
Emlyn James O'Regan - Managing Director
Wizards of AU
http://www.WizardsOfAU.com
emlyn@WizardsOfAU.com
"Australian IT Wizards - US Technology Leaders
Pure International Teleworking in the Global Economy"
----- Original Message -----
From: "Robert J. Bradbury" <bradbury@aeiveos.com>
To: <extropians@extropy.org>
Sent: Friday, March 16, 2001 2:07 PM
Subject: Interstellar Information Transmission, was Re: Kurzweil's ...
>
>
> On Thu, 15 Mar 2001, Zero Powers wrote:
>
> I said:
> > >The only way you send information is by encoding it in matter
> > >and send the matter. You can't send matter at the "speed-of-light"
> > >because its infinitely expensive to send it at that velocity.
> >
> > I'll admit to having little knowledge and no expertise in this area.
But
> > can't you encode information using only EM waves? Isn't that what fiber
> > optics is about? Isn't that how we communicate with satelites?
>
> Zero, always feel free to smack me in the side of the head when
> I have jumped one too many tracks (I often don't realize I may
> have done it).
>
> This derives from conversations that Spike and I had about the
> equivalence of matter and energy due to Einstein's (E = mc^2).
> Using this you can assign a real "cost" to losing energy
> (due to photon spreading due the inverse square law affecting
> the strength of signals being transmitted -- photons you can't
> receive with your "detector" are lost energy/matter) and the actual
> "matter" lost due to ablation by interstellar particles during
> interstellar transit at high velocities.
>
> You *can* encode the information on EM waves, but you lose
> the value (read matter or energy) of that depending on the
> transmission distance. The further the distance, the more
> of your investment you lose (unless you can guarantee
> that the receiver is of sufficient size to capture all of
> the photons you are transmitting -- across light-year
> distances, that gets *really* big).
>
> Now, of course, you can confine the information preventing
> it from spreading (by internal reflection) and that *is* what
> fiber optics *is* all about. It works great for the connection
> of your brain to the NET (a few dozen meters perhaps). It works
> less great over a few hundred km (but the clever fiber people
> have found ways of pumping up erbium atoms with excess laser
> energy and then using this to amplify the actual signals
> without converting the optical information stream to electrical
> information and back to optical (which gets expensive, causes
> losses, etc.) However, a fiber optic cable spanning a few light
> years has serious problems (which I'm sure you can imagine).
>
> We do communicate with satellites, but it isn't with fiber
> optic cables. It is with directional microwave transmissions
> (all those radio-satellite dishes you see on the top of
> television stations). They can effectively transmit to
> the satellite or receive and focus data from the satellite
> sufficiently to provide reliable transmission or reception
> of signals. However the question typically "unexplored"
> is how much of the energy that is radiated by the transmitters
> goes unreceived by the receivers??? Another way to think
> about the question is -- how much of the transmission energy that
> is radiated by your local cell-phone transmission tower (or your
> local television broadcast antenna) is *NEVER* usefully received?
>
> My post was simply a commentary on the fact that if you
> transmit your information as a "probe" (read tape/CD/letter)
> it doesn't "spread" across interstellar distances. It may
> suffer from erosion, but if you send it moderately slowly
> you can minimize this. On the other hand if you attempt
> to transmit data (as EM wave) at the speed of light, your
> information spreads, and unless the receiver has really big
> antennas a large fraction of this gets lost.
>
> It all comes down to the fundamental question in communication --
> How do you tell someone something at a minimal cost to yourself
> and guarantee that they receive all of what you are sending them
> (nothing more and nothing less).
>
> Going back to my comment, you cannot send a "letter/tale/CD"
> at the "speed-of-light" because it requires an infinite amount
> of energy to accelerate it to that speed (this is a consequence
> of the relativity equations). So you send information as "matter"
> (slowly), or you send information as EM wave (but lose most
> of your investment). I've got a spreadsheet that does the
> tradeoffs and for the amount of information present in advanced
> civilizations (e.g. MBrains) you would rarely use EM waves as your
> data information carrier across interstellar distances. Its like
> trying funnel the flow from a fire hose into a hypodermic needle.
>
> Robert
>
>
>
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:59:41 MDT