Or they can just be dust: dust that reflects an off-focus image from the flash of a camera. It's probably a good idea to consult a camera specialist, but the explanation has something to do with the shortened focal length between the camera lens and the chip that records the digital picture. The focal point will be in focus, but other points (dust) brightened by the flash will be out of focus, causing the orb effect.
I can handle this information however primitive and poorly understood. However, after seeing all those orbs in the photographs of Yoga classes on winter days shortly after we opened at PH Balance, I'm inclined to think I might need to clean the place thoroughly--dust, vacuum, clean blinds.
Which, of course, makes me prefer the mystical explanation much more.
So I write all this to say that if we are created from the dust as stated by the Yahwist writer, who is the oldest reference in the Torah (Genesis 2:7), who's to say whether or not a bright flash of light can bring momentary life to a speck of dust, liberating whatever wave energies might be bound in that particle? Who's to say that ashes to ashes, dust to dust is just a mere explanation of the time we experience in relativity and that quantumly speaking, our ashes and dust have a whole other experience?