Nuclear physics

Lore & Background

In the years that followed, radioactivity was extensively investigated, notably by Marie Curie, Pierre Curie, Ernest Rutherford, and others. By the turn of the century, physicists had discovered three types of radiation: alpha, beta, and gamma. The plum pudding model had predicted that the alpha particles should come out with trajectories at most slightly bent, but a few particles were scattered through large angles, even completely backwards.

Reader's Guide

Nuclear physics is significant because it revealed the structure of matter at its most fundamental level, the atomic nucleus, and provided the basis for numerous technologies. The discovery of radioactivity by Becquerel and the subsequent work of the Curies and Rutherford opened the door to understanding nuclear transformations. Rutherford's discovery of the nucleus overturned the plum pudding model and established the modern picture of the atom. The discovery of the neutron by Chadwick solved the problem of nuclear spin and allowed scientists to calculate nuclear binding energies, confirming Einstein's mass-energy equivalence. Yukawa's theory of the strong force explained nuclear stability and led to the prediction of mesons. These developments enabled applications ranging from nuclear power and weapons to medical imaging and radiocarbon dating. Nuclear physics also gave rise to particle physics and nuclear astrophysics, which explains the inner workings of stars and the origin of the chemical elements.

Did You Know?

• Ernest Rutherford likened the discovery of the atomic nucleus to firing a bullet at tissue paper and having it bounce off.