Questions on faster than light

On Aug 22, 8:00*am, "Dr. Mary Ruwart" wrote:
You stated that:

"And of course spacecraft traveling at 0.99999c --
or anything faster than about 0.10 c, it turns out --
verge on the ridiculous. *Even 0.10 c requires a vastly
better rocket (a theoreticalboron-hydrogen fusion affair)
than we have now. *Such a spacecraft might shave a year
or two off a round trip lasting two centuries to a system
10 lightyears distant. "

The best systems for thrust-to-weight ratio and minimal fuel storage
and using say, the 'easier' Helium-3 fusion, might be able to reach
0.1c. But now what happens if you run across a rock floating in space
at that speed? Not only do you have to get to that speed, you also
have to plan for what you do when something goes wrong. The part I
like the best is what you are going to do at your destination. You
must slow back down to non-relavistic velocities. What if there's
nothing for you to use at your destination to help you? (like oxygen
to breathe, or water to drink, or a place to live easily) You now must
get back up to 0.1c and go somewhere else.



Don't forget antimatter:

Interstellar travel is just an antimatter of time.
Energy from particle annihilation could cut voyages by light years.
Keay Davidson, Chronicle Science Writer
Sunday, August 8, 2004
"Matter/antimatter annihilation represents the 'ultimate' source of
stored energy for space propulsion," says a November 2002 report from
NASA's Marshall Space Flight Center in Alabama.
"Today's rockets use chemical fuel, which is too weak and heavy to
support an interstellar mission. The nearest stars are more than 20
trillion miles away; a trip by chemical rocket would take thousands of
years.
"By contrast, antimatter engines would accelerate so fast that the
mission would be much shorter. Howe and his colleagues have calculated
that with 17 grams of antimatter -- barely enough to hold in your hand
-- a robotic space probe could get to Alpha Centauri in 40 years. To
get there in a decade, the rocket would need at least four times as
much antimatter.
"Interstellar flight requires quantities of antiprotons that we can't
even imagine producing at this point," acknowledges Howe, whose firm
is largely funded by the NASA Institute of Advanced Concepts. But time
might change everything; he notes that in the early 1940s, there were
only "micrograms of enriched uranium (for nuclear bombs) available to
the world.
"At that time, if you said you'd need a ton of it, it would have
seemed impossible. But nowadays, we have so many tons of it, we've
quit making it."
http://www.sfgate.com/cgi-bin/articl...NG0984OM41.DTL


Considering the pace at which phyiscs is advancing I believe we will
know how to produce and store antimatter in large amounts within just
a few decades.


Bob Clark