The Theory of Relativity

When you throw a ball across a train
the ball moves with its own speed,
but if you watch from the ground
the ball travels at greater speed,
for it moves with the train
and sums two velocities.
Velocities are added depending upon
the observer’s reference-frame,
and all is as expected
until light enters the foray,
for the speed of light
on the ground
or the train
never seems to change.
But if the speed of light is constant
something else must give.
Could it be that space and time
are not definite?
To preserve D=RT
Einstein says they’re relative.
Scientific experiments have confirmed
time and time again
that space contracts
and time dilates
when you measure them.
The Theory of Relativity
holds true
for as long as light has been.