First of all, let’s review how ghosts appear to us ( See Introduction). To say the least, their appearance is ghostly:
In a dim light ghosts often appear as shadows. And, in general, ghosts have a somewhat limited Visibility: people may not see them at all, but cameras do. And so do animals (dogs, cats). Ghosts also can be seen as 2D reflections in mirrors and in 3D in fog or Smoke. Finally, ghosts can appear to us and then disappear within one occurrence, sort of “dissolve' into thin air. What does this means from the standpoint of physics?
Yet, what makes ghosts sort of vary in their spectral appearance and disappear after all? We are not there yet. If the latter assumption is correct, this means that ghosts carry thermal signatures. Thermal is a key word here, ghost temperature must somehow define their optical properties.
Those thermal signatures might not be as Strong as ones of living beings, but nevertheless they ought to be strong enough for detection. And this fact is corroborated by chilling of air in ghostly presence. In order to appear before the observer ghost needs to absorb thermal energy from the environment (air). So from that I would dare to assume that ghosts are likely acting as black bodies (that is physics term) and hence absorb heat (and therefore lower ambient temperatures in their presence), absorb light and re-emit heat (light) in near IR region of a spectrum. Their spectral appearance hence becomes a function of their thermal energy and hence, as a result of energy fluctuation, their spectral appearance Call change even within the short time frame of a single encounter. So a ghost can become visible and then, as its energy is emitted and depleted, invisible again. (To note: I would rather use term gray body instead of black body, because I don't have in front of me a graph of a spectral signature of a ghost. Yet, as far as this discussion is concerned, there is no difference.)
If you are not too familiar with physics, think about ambers in a fire (an example of a gray body). When ambers are hot, they radiate bright white light. When fire gets weaker, ambers radiation changes from white light to red. When fire dies out (i.e. gives up its thermal energy), the ambers may remain warm, but they become gray in appearance or turn black. In a dark, moonless night you may not see them at all: the black ambers become invisible. The ghosts act pretty much in the same manner as ambers in a fire, although their thermal energy is changing in a less dramatic way (or range).
Conclusions: Ghosts act as gray (black) bodies, their spectral characteristics are defined by their thermal energy, which they absorb from the environment (air). And since their thermal energy changes in time (say, it can be lost due to radiation) ghosts spectral appearance shifts towards near infrared region, and hence to us, with our limited spectral range of vision, ghosts disappear right in front of our eyes.
Question: If all that is so (black body, near IR) how come we can see sometimes ghosts reflected in mirrors, while we cannot see them directly?
to be continued
#Ghosts and Spirits; #Metaphysics and Mysticism; #Paranormal and Supernatural