# Was Einstein the first person to think of the equivalence of a ball drop in an accelerated elevator and a ball drop on Earth?

Consider the following figure taken from Wikipedia.

Was Einstein the first person to think of the equivalence of a ball drop in an elevator with acceleration of $g$ and a ball drop on Earth?

To be honest, I was also thinking of it before I learned relativity in high school.

• I don't know enough of the history to write a definitive answer, but certainly people knew long before Einstein that fictitious forces could mimic gravity. That's very different from saying that gravity is just a fictitious force, which is what the equivalence principle says. If you accept the e.p., then it's just a few short logical steps to gravitational time dilation, which certainly nobody thought of before relativity.
– user466
Sep 18 '15 at 19:54
• I would just note that it's relatively common for people in the current time-period to independently re-discover ideas, philosophies, principles, etc. that would have been practically unthinkable before their initial discovery. All those original ideas have come to permeate our society in so many ways that we're handed all the clues necessary to connect the dots. It's fun when it happens and then later you learn it was a major discovery and think OMG I thought of that when I was 16! Jul 15 '16 at 8:26