Final answer:
Scientists find the age of rocks and fossils using radiometric dating, which measures radioactive decay, or relative dating, which sequences events based on rock layers.
Step-by-step explanation:
Scientists attempt to find the age of rocks and fossils through a process called radiometric dating or relative dating. Radiometric dating is a technique that involves using radioactive isotopes to determine the exact age of a rock or a fossil, based on the known decay rate of radioactive materials.
In contrast, relative dating is a method that allows scientists to determine the sequence of events and which fossils are older or younger by their location in rock layers, but does not give an exact age in years.
For instance, when using radiometric dating, scientists might measure how much of a radioactive isotope like carbon-14 has decayed in a fossil to estimate its age. With relative dating, they might look at the sequence of rock layers and use stratigraphy to understand the order in which different organisms lived, but cannot specify the exact number of years ago each organism existed.