Though we cannot see beyond the CMB, we can still probe the earlier epochs of our universe by using different techniques. Which of the following is not a valid technique for this? Primary Metal Dousing Rods. These allow us to pick up "Ghost Fields" that were around prior to the CMB. Particle Accelerators, where we can simulate earlier eras of the universe through "Little Bangs". Gravity Wave Telescopes, where if the sensitivity becomes good enough we can detect gravitational waves the predate the CMB. (Future Method) Particle Ray Telescopes. Neutrinos and other early particles that predate the CMB may still be around