Horizontal vs vertical

You ever stop think that the only time you hear about vertical space travel is at lift-off?!

I was in Mandeville on Sunday when it hit me....... why does all the space travel motion take place in a horizontal plane? Why is the universe expanding horizontally and not vertically? If it came from a big bang from a central point of infinitesimal pressure why did it conveniently explode and expand in the X and Z planes? Why does the USS Enterprise only travel outwards horizontally unless they get sucked into a worm hole stretching from North to South?

Light a firecracker and watch it explode and fragments go in all directions X Y and Z. Yet our reality expands in X and Z...ONLY.... with Y constant for each celestial body? That don't make sense to me!

On the surface of any celestial body everything looks as if it is above us, but that is because light rays are being bent around that body. This has really go me going!!!

I really need to know now!!!! I wonder why this never occured to me before!!!