What was the above piece trying to draw attention to?

If you chip a tooth, most likely you will go to the dentist to have the missing material filled in. currently the material used to fill in teeth is a polymer that is flexible when put in, yet is hardened to the strength of a tooth after irradiation with blue light at a wavelength of 461 nm. what is the energy in joules for a photon of light at this wavelength?

How do dying stars contribute to the formation of planets

How many grams of iron can be made from 16.5 grams of fe2o3