Long and short, narrow and wide, I shorten the gap, ignoring the tide

I have keys but open no doors, I hold a space but no room, I can return though I never leave.

I am used to create and destroy, but I am not used to be gentle. You can find me in Maxwell's hand.

Sometimes I have five digits, sometimes none. I can grab things, yet I have no bones of my own.

You measure my life in hours and I serve you by expiring. I’m quick when I’m thin and slow when I’m fat. The wind is my enemy