Shivans could use the power provided by their cap ship/fighter to live. I like this "subspace tap" idea very much but I`m gonna change it slightly.
What if a shivan has an internal subspace signal reciver that can accept a low subspace signal emenated from their ships internal structure or fighter cockpit. The signal carries the energy required to power a shivan.
They use this energy to charge a battery for emergency power if seperated and the subspace charge powers their weapons.
this would explain why
a)Shivans do not use ground troops, they bombard planets from their ships hence them not being interested in planets
b)why terrans are able to have captured shiavn specimen. they could have captured shivans from a ship so damaged that it could not generate the power signal. the shivans, living off emergency power, could not use weapons and so could be captured easily. They could be kept alive by the terrans feeding them low power from fusion reactors ect.
This also explains why their ships use gas miners to collect fuel. they need it to power the reactors of the ship from which they feed from the subspace signal.
Feeding off subspace would make their ships not need the use of gas ect as they could take power from subspace reactors...
Hang on... What if they just use the various gas particles to make ships?? I mean the terrans needed Argon (I think) to build the prometheus S cannon. Shivans do not live on planets or even seem interested in their resources.
So a shivan internal tap taking subspace or fusion, M/AM reactor energy is probably the best idea....
Unless they use Matter/Antimatter reactions themselves. A tiny reactor (the size of a matchbox) of that size that could power a single shivan with the energy also fro a plasma cannon ect. A bigger one could generate power for shivan cruisers. Again though, they need gas particles to run it.
Signal is probably quarkion or gluon in nature (well some high powered particle present in subspace)
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