How do physical scientists know that the universe is expanding, how old it is, how the stars create energy, how chemical elements are formed, how far the earth is from the sun, planets and other stars, and what is the mass of the earth and the other planets? Without getting “too technical,” we will answer these and many other questions about how physical scientists know what they know by describing the various methods scientists have used to discover some of the important laws of nature.

Moderator: Jim Rauf, BA physics, Thomas More College, BME mechanical engineering, Univ. of Detroit. Retired from GE Aviation where he was a manager and principal engineer in the Commercial Engines Product Support Group.