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Re: starship-design: Re: The Size of the Problem

To Kevin and Kelly,

>> However, why is a substructure necessary? It is already known that quarks
>> can change flavour under influence of the weak force. Take for example:
>> n -> p + e- where a down-quark is changed in an up-quark
>                                             _
>Okay, but how do you change a d quark into a d quark for example.  My
(again, limited)
>understanding was that not enough of the right type of quarks are in a sample
>of matter to allow one to create a sample of anit-matter.  I would be happy to
>learn that I am wrong on this.

I'm not sure what you mean with the right type of quarks, but in ordinary
matter you only have normal (non-anti) quarks. In fact from the six normal
quarks only the 2 with the lowest energy are in ordinary matter, namely the
up and down quarks.
To change quarks to anti-quarks one needs theoretical particles called
Lepto-quarks. The theories that predict these particles are not proofed and
of course these particles are not found yet.
Clearly these particles are not everywhere around us, unless they are
somehow savely locked away (maybe we could unlock them?).
The latter is the only thing that would be really useful, one could almost
call it Zero point energy (ZPE).

>What are the quark triplets needed for:

Quark triplets are present in: Protons, Neutrons, Anti-Protons,
Anti-Neutrons, these are called "Baryons".
Electrons and Anti-Electrons are "Leptons" and have no know substructure,
they  do not react to the strong force (which glues quarks together).

How to make the weak-force? I'm not sure, to me it's of the strangest
forces, since it actually can change particles, unlik other forces that
mainly do some gluing or repelling.
One thing is sure, the weak force is doing some real work in making an
unstable nucleus stable (beta decay, see the equation above). So in general
making unstable "normal" particles will invoke the weak force, or the
electromagnetic force (gamma-rays).
However keep in mind that it can only change quark flavour (up, down etc.),
not change quarks into anti-quarks.

>> That roughly means 48 weeks of robot creation. However, those robot should
>> create their own power supplies, so that would mean they could use no more
>> than about 100 to 400 Watt (pretty efficient machines!!)
>The main jobs of the Robots would be gathering material, and putting pieces
>together.  The job of converting raw material into refined stocks would be 
>the job of a central machine, (which would be fed by several tens of m^2 of
>solar panels.  This is why I think that there might be some lower limit to
>the number of Robots needed to start a new colony

But how much power would be needed to lift all that mass from the Moon or
Mercury? On Earth making solar panels is a rather expensive procedure,
essentially because so much high grade silicium is needed. I'm not sure what
makes it expensive; energy or processing-time. I hope for you it is the latter.