sentence meticulously. After the talk, there was a question-and-answer session. Someone raised his hand and said, “Professor Dirac, I do not understand how you derived the formula on the top left side of the blackboard.”
“This is not a question,” Dirac curtly responded. “It is a statement. Next question, please.”
Dirac’s rigidity in conversation contrasted with his extraordinary brilliance and creativity in discerning the properties of the universe. In the early days of quantum mechanics, his agile mathematical mind rapidly encompassed radical new ways of interpreting physics. He developed theories and ideas so fantastic, such as a negative energy sea that fills all of space, that they knocked the breath out of his colleagues. This concept relates to arguably his most important contribution to physics, the Dirac equation, proposed in 1928. The Dirac equation offered a quantum, relativistic description of an electron, encompassing properties such as its mass, charge, and spin. It predicted the existence of positively charged counterparts to electrons. Known as positrons, they were first experimentally detected in 1932. For his pivotal scientific contributions, Dirac was awarded a Nobel Prize the following year.
In 1937, Dirac applied his prodigious talents in an attempt to explain an astonishing physical coincidence in cosmology. Comparing the strength of the electrical and gravitational forces acting between the proton and electron in a hydrogen atom, he noticed that the ratio is an immense number, approximately 1040 (one followed by 40 zeros). The fact that this value is so large is related to what is now known as the “hierarchy problem.” Curiously, Dirac found that the present age of the universe as expressed in atomic units (the time for a light particle to trek across a hydrogen atom) is roughly the same size. In what is known as the Large Numbers Hypothesis (LNH), Dirac suggested that the two numbers are in fact equal.
Sometimes apparent coincidences mask fundamental truths. For example, when physicist Murray Gell-Mann discovered that he could