It had been thought until this time that shadows were merely the absence of light; but an innovative research team from the University of Lower Sodbury has ruined that perfectly good theory by discovering a new wavelength of light -- that responsible for shadows.
Doctor Bob Wigglebottom, head of the research team, explains the accidental discovery that instigated the research:
"While fiddling around one day with a couple of uwave fluxometers and a jug of Bozleys Best Bitter, I noticed a peculiar thing. But it went away again when I stopped moving my head. Anyway, after that I noticed that when the fluxometers were waved in the shadow of the beer, there were some slight, unexpected fluctuations in the readings on the U.W.F. I tried it again, only sober this time, and noted the same effect. I began thinking about the possible cause...".
After 2 years of painstaking research and extra-long lunch breaks, the Sodbury team have gathered enough data to reveal their discovery -- the fascinating world of Shadowlight.
Shadowlight is a form of light which exists at very small wavelengths, far beyond the visible spectrum. It has a smaller wavelength even than microwaves, enabling it to propagate through solid objects (without exciting their molecules and making them explode, as luck would have it). As it passes through solids, shadowlight excites the dark particles lying within them, causing a current* of dark in the same direction. Thus, dark can be seen flowing out of the side of objects facing away from the light source. Transparent objects contain a much lower dark density, and thus produce weaker shadows.
[A related discovery of the team explains the danger of standing under a levitated piano: Should the dark inside slip, it can be propelled towards the ground by shadowlight at very high velocity, and if it hits a person, it can supersaturate their eyes and brain with dark so that they are temporarily blinded and fall unconscious. (Often the piano will also be sucked down by the vortex created by the sudden movement of dark, which can cause great damage and may get blood on the piano.)]
It is thought that if Newton was aware of the way in which solar Shadowlight accelerates dark, which in turn applies a downward force to solid objects, our concept of gravity would be quite different.
This phenomenon is also responsible for the movement of rivers: as solar shadowlight reflects down from snowcapped mountains, it drives deep into the river, pushing the dark downhill. The slight friction between dark particles and water particles pushes the water. This moving water in turn pushes the water that lies further down out of sight of the mountains, until it flows out into the sea.
Although the emitted dark is carried out of the solid by the shadowlight, it tends to spread out slightly as it leaves the object, resulting in a fuzzy edge (the shadow penumbra). Test this for yourself - as you move an object further from its shadow, the shadow spreads out and gets fuzzier and fainter. This is because the cone-shaped flow of dark is being spread out over a larger area, and is therefore diluted by more light.
Postulating that objects 'recharge' by absorbing dark during the night, the team set up an experiment where objects were continuously exposed to a 100 watt dark sucker. After 3 months the observed shadows had not weakened, and it was then that an able young student realized that the dark sucker had been running on 50 Hz AC power, and that dark was able to leak back into the objects between AC cycles. Experiments are planned to use a second bulb with a 90 degree phase-lag to provide a more constant dark vacuum, as soon as the funding for the extra bulb comes through from the University Senate.
Doctor Wigglebottom is now collaborating with Bell Laboratories on research into the potential uses of solar shadowlight in driving dark through power-generating turbines.
* Dark current is measured with an SI unit based upon the number of negative candelas of light (or positive candelas of dark) emitted from an appropriately excited black-body object (such as a Nubian woman's brazier, heated to body temperature, and folded to make a roughly spherical shape), the 'candelabra'.