At some of the greatest distances probed by telescopes, where many ordinary galaxies are too dim to be seen, we find the brilliant centers of galaxies, glowing with the light of an extraordinarily energetic process. These brilliant galaxy centers are known as ___.

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.