In optics, a caustic is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light.
A piece of milled plexiglass acting as a projecting lens; via the Computer Graphics and Geometry Lab at the École Polytechnique Fédérale de Lausanne
New milling techniques applied to glass and plexiglass panels could be used to “create windows that are also cryptic projectors, summoning ghostly images from sunlight.”
[Pauly and Bompas] hope that the technique will be used in architectural design, to create windows that mould sunlight and throw images or patterns onto walls or floors,” which, if timed, milled, and manipulated just right, could produce a slowly animated sequence of images being projected by an otherwise empty window during different times of day.
To control the shape of a caustic pattern generated by a specular or refractive surface, we need to solve the inverse problem: how can we change the surface geometry, such that incident light is redirected to produce a desired caustic image?
In this sense, trust is a polarizing strategy, and it's one that is important to apply early on in the relationship before someone becomes important to you. If you trust someone excessively and it goes badly, but they don't matter to you, you can just kick them to the curb. In general, trusting someone at a level that seems slightly excessive for their level of importance to you will help you sort people in your life who you want to be more important to you than they are from those who you want to be less important than they are.
And it does need to be excessive. It needs to be trust beyond reason. Not beyond all reason, but somewhat beyond what currently seems reasonable. If it is not, then unless they are prepared to take the first move, you will never find the signs you need to move to a higher level of mutual trust.
Sometimes this will go badly, but you need to be able to try bad things.