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starship-design: Re: Anti-antimatter
Timothy replies to Ken:
>Could someone please re-post Timothy's 1/30 Re:
>Relativistic Electric Thrusters so I could try to read it? Thanks!
I'll sent it to you at the same time this letter is sent.
> As for the ongoing discussion on Relativistic Thrusters, I'm
>slowly getting up to speed. I checked out Timothy's Web Page and saw why
>a fusion spacecraft should limit the fuel speed to 0.1c; I didn't check
>the numbers, but it sounds reasonable.
Since Rex has done similar calculations and got the same numbers, I'm quite
confident about the results.
> So for self-powered ships, that seems to leave relativistic
>engines to the regime where you can transfer your ship mass to energy
>with a near-unity efficiency.
And even then, only if you want high (>0.9c) final velocities of the
spaceship (high velocity means more energy)
> The most obvious way to do this is with
>antimatter, of course, but here I'm a bit skeptical. Even if we're
>assuming some pretty amazing technological advances, I find it hard to
>imagine storing huge quantities of anti-matter on a ship. I don't know
>if this has been discussed already, but I would guess there would be
>some sort of theoretical minimum matter/antimatter ratio, just from
>containment considerations. Anyone want to tackle that one?
A minimum ratio? Why would do you think that?
> So, keeping this in mind, here are another two ideas for
>"antimatter-type" engines; ways to convert mass to pure energy--without
>using antimatter. These are nearly as speculative as large-scale
>antimatter containment, but I'd still argue that they're more probable.
I've thought of a flywheel before, but never mentioned it because it seemed
- Its estimated weight was too high.
- Containing/guiding a huge fly wheel that rotates with super high
velocities seemed almost infeasable.
>So already, for a 200 meter radius flywheel,
>we're talking about an energy storage of 10^10 J/Kg. We'd probably need
>at least 10^14 J/Kg to make a decent spaceship.
Actually I think that 1E16 J/kg is the absolute minimum if you want to get
into the direction of relativistic velocities.
> Idea #2: Catalyze nucleon decay using captured magnetic
The mean idea of using a monopole is probably it's heigh energy:weight
ratio. Maybe we can find other ways to store energy.
For example storing photons in a perfect mirror sphere.