The atom was an unknowable mystery in the early 20th century when pioneers such as Niels Bohr began to pin down its nature. Scientists first “split the atom” in 1917 and realized that it had constituent parts of its own. Bohr was the first to suggest that the electrons, carriers of the negative charge in the atom, circle the positively charged nucleus in different orbits called “energy levels” and gain or lose energy by jumping from one level to another. Although modern quantum theory—which Bohr himself helped develop—has shown that the orbits associated with energy levels are more metaphoric than literal, this “Bohr model” of the atom is still essentially accurate.

Bohr’s grandson Vilhelm Bohr will discuss his forebear’s life and legacy during a public lecture tonight, Wednesday, June 3 at 7 P.M. Eastern time that will be broadcast live here on this page. The talk, “Niels Bohr: Life behind the Physics,” is part of the public lecture series at the Perimeter Institute for Theoretical Physics in Ontario presented by Sun Life Financial. Vilhelm Bohr is a department chair at the National Institute on Aging at the National Institutes of Health in Baltimore and chairs the Niels Bohr Archive in Copenhagen.

During the live Webcast a panel of Perimeter Institute physicists will answer questions and provide commentary in the chat window below the video player. The panel will also be available for 30 minutes after the talk finishes to answer further questions. Online viewers can also pose questions to Bohr by tweeting to @Perimeter and using the #piLIVE hashtag.