Stuff in the Way can Help with Perception

Perception is a hot topic in philosophy.  Do we directly perceive objects in the world, or only the images of objects on our retinas?  Does the answer change when we see something reflected by a mirror or refracted through a lens?  As anyone who needs glasses knows, sometimes putting something between your eye and an object can help you to see it better.  Surprisingly, sometimes the most useful ‘lens’ is made of solid matter.

Solid matter can help us see distant objects by bending spacetime. It may sound far-fetched, but physicists routinely rely on this effect to see distant stars and galaxies that would otherwise be