Katie Bouman's PhD thesis begins with the following paragraph:
Watching a raindrop fall into a puddle of water, causing a ring of expanding ripples, may seem mundane. However, behind this commonplace phenomenon is a complex process governed by fluid dynamics and its interaction with light. By understanding these connections we realize that the water's temperature is encoded in subtle speed differences of the expanding ripples and the size of the falling water droplet [12]. With the proper models and analysis techniques, we may be able to extract this seemingly invisible signal and turn a regular camera into a visual thermometer, without ever interacting with the fluid.
I was wondering if this was purely a thought experiment to illustrate a point, or has anyone ever calculated the physics of it and devised an actual measurement device to measure temperature based on a video. (Citation 12 does not answer this question, it seems to be a generic reference on fluid dynamics.)
