the space scenes... something always makes me smile

The space scenes are awesome, but something always makes me smile in this and many other movies like this... for some reason, no gravity scenes means one move in slow motion. I never quite understand why?

Of course, one reason is that it is filmed in slow-motion and so look like slow motion-ish, but in reality why would a movie-maker think this? Cannot argue, as I bought it was perfect back then.... but still, makes me smile.