You can even pick them up from behind, lift them, and drop them, and they might tip over. This can be done by making them fall through a portal, or dropping something on them and making them tip over. To defeat these turrets, all you really need to do is make them fall over. There are small, immobile turrets in this room that will shoot at you if they see you.
Test Chamber 04 - Reaching Far Off Places.Test Chamber 02 - Get the Blue Portal Gun.
