Andromeda and Milky Way Collide?

Andromeda is our nearest proper galaxy, two and a half million light years away. The force of gravity between and Andromeda and the milky way is greater than the force caused by the expansion of the universe. Alpabida says what kind of fuel will be will be best to use for strath for space travel. If an alien who travels across galaxies would laugh at these primitive little monkeys using chemical rockets - i speculate.