Colonies Close Around the Sun
Colonizing the sun. Sure, why not? Smash Mouth sang something about walking there.
Maybe fusion reactors are never practical to commercially use for power generation. The sun is an already established fusion reactor. Plenty of energy and heatb can be harnessed from around the sun. About three million kilometers from the sun's surface the pull of gravity is similar to Earth's. At that distance photons can be reflected and most heat can be radiated away. The Sun has a huge magnetic field which Mars and Venus don't have.
After the 21 minute point is when the video gets really interesting. I like the idea of turning the sun into a natural laser, known as a "stellaser". Not to be confused with a solar-pumped laser.
Large diameter mirrors facing each other are strategically placed in the Sun's corona. Ions that are already excited act as the lasing material. The emitted radiation from the excited ions is bounced back and forth between the mirrors and an almost coherent beam at a certain frequency is amplified. You can use it to beam power directionally at a far away colony or use it to slow down approaching spacecraft so the craft doesn't need to use fuel for deceleration.