Jennifer Doudna and her colleagues found an enzyme in bacteria that makes editing DNA in animal cells much easier. Cailey Cotner/UC Berkeley hide caption

itoggle caption Cailey Cotner/UC Berkeley

All of our scientific tools have limits. These limits ensure that we will never see the whole picture. We can never have complete knowledge of the universe. Above, the ESO's APEX radio telescope probes the heavens from its lonely perch on Chile's Chajnantor plateau. Gordon Gillet/ESO hide caption

itoggle caption Gordon Gillet/ESO