Hi. In light of that ridiculous Ham / Nye debate I have someone trying to explain away the red shift of light from galaxies by suggesting it could be due to the photons interacting with electrons or other subatomic particles en-route, thereby loosing energy and increasing their wavelength. Can anyone explain to me why this isn't a reasonable explanation for the red shift? (Please use small words without formulas if possible!) As a supplementary question, can you explain why light is able to pass through glass but not opaque matter? Thank you.