This is a joke about Einstein’s form of the Equivalence Principle:
Thanks. Let’s see:
The weak equivalence principle, also known as the universality of free fall or the Galilean equivalence principle can be stated in many ways.
And
“… in a uniform gravitational field all objects, regardless of their composition, fall with precisely the same acceleration.” “The weak equivalence principle implicitly assumes that the falling objects are bound by non-gravitational forces.”[11]
I’m just beginning to understand. I’m not there yet.
If you are standing in a closed box, there is no experiment you can make that tells you whether that box is standing on earth, or is on a rocket in space accelerating at 9.81m/s²
This has a bunch of interesting implications about the nature of spacetime
