As explained in the gravity assist link the body has to be rotating/moving faster than the spaceship speed for the assist to work.
I dont think so , orac.
2 x U + V does not rerquire that V be lower than U
it only states that the initial V will be increased by 2 x U
An interstellar slingshot using the Sun is conceivable, involving for example an object coming from elsewhere in our galaxy and swinging past the Sun to boost its galactic travel. The energy and angular momentum would then come from the Sun's orbit around the Milky Way.
you were wrong about the rotation.
you were wrong about the speed requirements.
you were wrong about you being smart.
so obviously the rest of your post was also wrong as usual.
so if a spaceship were traveling at the speed of light
as it approached our sun it would accelerate.
when it accelerates it will be traveling faster than
the speed of light.
so the astronaut would get younger.