For instance,\n// playing Ping-Pong on the train, one would find that\n// the ball obeyed Newton’s laws just like a ball on a table by the track.\n// So there is no way to tell whether it is the train or the earth that is moving.
The laws of science\n// should be the same for all freely moving observers,\n// no matter what their speed. This was true for Netwon’s laws of motion,\n// but now the idea was extended to include Maxwell’s theory. All observers\n// should measure the same speed of light, no matter how fast they are moving.
Gravity is not a force\n// like other forces, but is a consequence of the\n// fact that space-time is curved by the distribution of mass and energy in it.
\n// An object in a gravitational field experiences the same effects as if it were\n// accelerating at a rate proportional to the strength of that gravitational field.