How do you move the selection in photoshop (marching ants) without moveing any part(pixels) of the selected layer?
In addition to Carl's answer.. you can choose
Select > Transform Selection from the menu after you've created a selection.
By (re-)selecting the selection tool. You will only move pixels if you drag a selection with the move tool (V) active. When dragging a selection with the selection tool (M) active, you'll leave the pixels alone.
While dragging out your marquee selection, hold down the spacebar and that should allow you to do as described.
Note: Both must be held down at the same time.
it only can be done with the "new selection" option active,, when you press key M, it will display a bar with some options... select the first one and then you are now able to move the marching ants without moving any pixels