This is something i've observed a long time ago, and i never really got an answer to that (never really looked for one, just thinked about). But, when you have a light source behind you, and right in front of you there is an object (doesn't matte what it is), if you position your hand, arm, whatever, so that your shadow is close to the object's shadow, when you get really close, the shadows "unite", even if both you and the object are not touching at all.
Sorry if this is not the place to ask, but doesn't hurt to ask! Thanks


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