I'm writing an essay for a contest and I'm about half way done. I want to know how accurate my information is. It should be self explanatory as we are supposed to write it for the general non-physics person who might have no clue about the subject. The asterisks are places where I'll have to insert a footnote to briefly explain the concept, similarly to the way I explained the Doppler effect. After this I will start talking about dark matter/energy. Thanks for reading.