[ExI] Star Harvesting

Stuart LaForge avant at sollegro.com
Mon Jul 2 01:26:33 UTC 2018

Sorry about the accidental misattribution in the previous copy of this
sent out to the list. Because Yahoo has not been playing well with the
list server, I sometimes have to do weird things between my various email

John Clark wrote:

>​> ​Considering that red dwarfs make up something like 75% of the stars we
>> survey, colliding them together to make hotter stars that can accelerate
>> faster seems like a more efficient use of available energy.
> I think it would be better to break up a large star and make several
> small stars out of it because small stars are actually more efficient
> than large stars. Small stars transport the energy produced in their core
> to the surface largely by convection so there is constant mixing of
> material into and out of the core, so eventually all the hydrogen fuel in
> the star finds its way into the core and gets burned up. But with large
> stars the energy transport in mainly by radiation so there is far less
> mixing and most of the hydrogen never gets anywhere near to the core.
> When a large star comes to the end of its life it still has most of the
> hydrogen fuel it was born with but its useless because its not in the
> core where its needed. Small stars don't waste any hydrogen they'll
> eventually burn it all up but it might take more than a trillion years.
> Large stars go supernova and blast up to 90%(in the very largest stars)
> of the hydrogen fuel in them into space.

Of course this is correct, but how would you propose this could be

An advanced civilization of about Kardashev 2.5 could conceivably move
stars around using a swarm of angled reflectors to vector photons and
stellar wind into directional thrust as Spike, Keith, Bradbury, et. al.
have discussed on this list. Being able to move stars entails being able
to crash them together and fuse them into larger stars because gravity is
working in your favor.

But it would be orders of magnitude harder to fission a large star into
several smaller ones and the EROI is probably not thermodynamically worth
it. Also the relatively short lifespan of hot massive stars means that you
would not have much time in which to do it.

Stuart LaForge 

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