From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sat Apr 26 2003 - 11:57:48 MDT
On 26 Apr 2003, Alejandro Dubrovsky wrote:
> On Sat, 2003-04-26 at 05:58, Robert J. Bradbury wrote:
> >
> > Previously I had thought this would be impossible. An exabyte
> > is 10^18 bytes which is a zettabit (10^21 bits). To even begin
> > thinking about this one has to learn how to modulate a carrier
> > of X-rays (10^18 Hz) to Gamma-rays (10^20 Hz) to carry a zettabit.
> > That did not look like an easy task to do in a short period
> > of time (SciFi authors get to ignore some of these more complicated
> > details with a little hand-waving).
> >
> I don't think there's a need for such high frequencies. You don't have
> to carry the whole thing in one band. Just parallelise, and use a 100 x
> 100 array of your off-the-shelf terabit/second transmitters (nicely
> spaced apart on a 10km on a side square so that they can be resolved
> individually on the other side by the huge parabollic space mirror) and
> you can do the whole thing in about 15 minutes (btw, you mangled the
> conversion. 1 exabyte = 10^18 bytes < 10^19 bits (i think you were
> thinking in powers of 2))
Alejandro is right, I botched the math. So a body is ~10 exabits.
That bumps my other numbers down by about 2 orders of magnitude
making things a little more interesting -- body teleportation in
~7 hrs using 1 fs pulses and 2-4 days using 10fs pulses (today's tech).
I have no problem with the array transmission idea -- its actually
a requirement to fork civilizations. Advanced civilizations probably
have 10^50+ bits at their disposal and there is no way you are going
to send even a fraction of that via spaceship or even a large array
of lasers across interstellar distances (too much power required &
too much beam spread). You are only going to be able to pull it
off using large arrays when a developed civilization (e.g. MBrain)
comes into contact with a suitable undeveloped solar system, e.g.
one where the nanorobots can rapidly construct an array of receiving
mirrors/telescopes and sufficient memory capacity to hold the incoming
data.
That is why I think the "diaspora" takes place very slowly -- it
depends not on space ships expanding outward at 0.1c but on close
encounters between star systems. Those are either very infrequent
or very expensive to "arrange".
Robert
This archive was generated by hypermail 2.1.5 : Sat Apr 26 2003 - 12:06:45 MDT