They use Gold partially because it doesn't react with anything - they know that there will no peturbations from Gold Oxide contaminants for instance.
They don't use a whole lot of Gold, if you're worried :0)
Thanks for your reply. I do know that gold is inert - but how does making inert substances collide at super high speeds simulate the big bang? What we know of the big bang arises from observations after the event. We don't know what conditions led to that event arising, do we? Therefore, isn't this experiment artificial, in more ways than one?