From: Eugen Leitl (eugen@leitl.org)
Date: Mon Sep 09 2002 - 04:37:23 MDT
On Mon, 9 Sep 2002 CurtAdams@aol.com wrote:
> Indeed. Vacuum tubes actually work! How can anybody be sure a
> technology that may not even work be able to withstand phenomenal
> radiation loads? *If* drextech is possible, it will have an error
The density of interstellar gas is about 1 particle / cm^3. Intergalactic
medium is much thinner, approaching 1 particle / m^3. Bulk of it is
hydrogen, the rest of it is helium. Number of impacts is directly
proportional to your speed of travel. Relativistic effects begin to take
hold at roughly 0.9 c. In terms of impact/s, there is not much difference
between 0.9 c and 0.99 c, it's the impact energy which goes up
asymptotically. Protons at 80% c is 590 MeV.
In terms of star-star hops it doesn't matter whether you travel at 10, 30,
50 or 90% of c. The bad mojo only starts after that. Depending on the
impact energy you can try to shield (hiding in the shadow of a tungsten
rod). Notice that you're being pulled by a carbon cloth sail heated to
white indescandescence. The microwave beam propelling you will both
vaporise dust and clean the path, minimizing the speck hazard.
A redundant dry system doesn't suffer damage by diffusible radicals. The
damage path is linear, and well defined (at high energies the tungsten rod
becomes a liability, you would probably do lots better with a light,
shallow target. Unless you get hit by a pebble in transit, you are
accreting incremental damage in the molecular circuitry. You can repair
that incrementally, or you can just make new systems from scratch in
transit. Make a block, copy state from old block to new, recycle old
block. If there's material activation (I doubt it, not at these energies),
you can use isotope separation to get rid of hot nuclei.
> correction limit, and even if it's remarkably better than wetware
> nanotech, it could still fall far short of .95c travel.
Yes, it could. But intuitively, the ceiling is pretty high. I think if you
ask a particle physicist who understands proton-target interaction at
similiar luminosities and energies he will agree that damage is low
density, limited to tracks (with the notable effect of high-energy
secondaries), and the rate of lattice defects is tolerable, given that
we're not sticking a petri dish into a cyclotron beam but a handful of
bucytronics.
Which brings us to an experiment: stick said handful of buckies into a
beam of appropriate energy and luminosity, and irradiate for a day. Remove
the target, and estimate the amount of broken bonds. Do the same with
heavy shielding (1000 mm of tungsten), etc.
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:16:52 MST