Riddle Me Slow

I'd booked in for the Trinity Writer's Festival. The timing proved to be a little unfortunate. Last year, I left frazzled in a good way. This year, I was equally frazzled at the end, but in a bad way. The flow is very slow at the moment.

The only thing I left with was this ...

Sitting alone at the head of my column,
I move through the world unseen,
making no difference, taking no responsibility,
the lightest kind of nothingness
that isn't explosive.

What am I?