Einstein’s happiest thought (1907): “For an observer falling freely from
the roof of a house, the gravitational field does not exist” (left).
Conversely (right), an observer in a closed box — such as an elevator or
spaceship — cannot tell whether his weight is due to gravity or acceleration (einstein.stanford.edu)
the roof of a house, the gravitational field does not exist” (left).
Conversely (right), an observer in a closed box — such as an elevator or
spaceship — cannot tell whether his weight is due to gravity or acceleration (einstein.stanford.edu)
