Re: Solar engineering
Just hypothetically if we possessed the technology to create fusion reactions to form new stars could we postpone the heat death of the universe?
No. To perform "work" you need an energy differential. Heat death is when the energy is the same across the entire Universe. You couldn't avoid heat death by building a reactor as you wouldn't be able to get the energy to build the reactor.
Slightly shorter term, could the same technology create a new sun in our solar system? What size object would be needed to create a similar sized sun a similar distance from Earth? E.g. if we sacrifice Pluto as 'kindling' for our new sun would it be bigger than Sol is now?
According to hypertextbook.com/facts/2001/KellyMaurelus.shtml, you need something about 80 times bigger than Jupiter to form a star. And that's assuming the proto-star has the right composition for nuclear fusion. Main sequence stars, such as Sol, "burn" Hydrogen to form Helium, etc. Pluto is a rocky planet, so not much Hydrogen to burn.