Albert Einstein signed with inscription E = MC2 Photograph. Albert Einstein’s Big Idea E = MC2. It’s the world’s most famous equation, it can be quoted by scientists and non-scientists alike, but what does it really mean? Energy equals mass times the speed of light squared. On the most basic level, the equation says that energy and mass (matter) are interchangeable; they are different forms of the same thing. This item has been professionally custom matted and framed and comes with a letter of authenticity issued by a reputable 3rd-party authenticator. At least 10 positive reviews.