I know that it took approximately 3 minutes for lights to travel from sun to earth. Let say the sun is gone now. Like erased, click-n-drag out of the universe in an instant! So until 3 minutes later, no one on earth would realize it, because nothing travel faster than light! But, could I argue that at the instance the sun is gone, we wont feel the gravity of the sun anymore, which surely could be detected by some sort, and so we know that the sun is gone!