Poetry of Physics and the Physics of Poetry

140 The Poetry of Physics and The Physics of Poetry

as a gravitational force. Think of how you have been thrown forward
when the bus driver suddenly slammed on the brakes.
Einstein exploited this fact and claimed that the effects of the
accelerated motion are equivalent to those of a gravitational force. In
order to make this assertion, he noted that because the gravitational and
inertial masses are the same, objects will accelerate at exactly the same
rate in both a gravitational field and in an accelerating frame of the
reference. He therefore concluded that accelerated motion and the action
of a gravitational field are equivalent.
In order to illustrate this, let us consider the two elevator cars in
Fig. 15.1. One elevator car is sitting at rest on the surface of the Earth.
The other elevator car is situated in outer space completely removed
from the effects of any gravitational field. The elevator car, however, is
being accelerated upwards with a constant acceleration, g, equal to the
acceleration of the particle falling near the surface of the Earth. We claim
that an observer in one of these cars would not be able to determine in
which car she was situated because her experiences in both cars would be
identical. She would experience a gravitational pull towards the floor of
the elevator in both cars.

134 The Poetry of Physics and The Physics of Poetry

the bus driver suddenly slammed on the brakes.

Einstein exploited this fact and claimed that the effects of the

accelerated motion are equivalent to those of a gravitational force. In

order to make this assertion, he noted that because the gravitational and

inertial masses are the same, objects will accelerate at exactly the same

rate in both a gravitational field and in an accelerating frame of the

reference. He therefore concluded that accelerated motion and the action

of a gravitational field are equivalent.

In order to illustrate this, let us consider the two elevator cars in Fig

15.1. One elevator car is sitting at rest on the surface of the Earth. The

other elevator car is situated in outer space completely removed from the

effects of any gravitational field. The elevator car, however, is being

accelerated upwards with a constant acceleration, g, equal to the

acceleration of the particle falling near the surface of the Earth. We claim

that an observer in one of these cars would not be able to determine in

which car she was situated because her experiences in both cars would be

identical. She would experience a gravitational pull towards the floor of

the elevator in both cars.

Fig 15.1

Fig. 15.1