Ritva, energy forms like matter which are only or primarily black or "dark" just means that they can absorbe ALL of the wavelength associated with visible light...

IMHO, all other propertities and laws are still the same...

What creates these dark energy forms can be analyzed to some extent by looking at the BLACK matter forms here on Earth!

White light is split into the main sub-colors like with a rainbow or crystal, but, there is no such thing as black light!!!

eom