## Einstein's theory of special relativity

is not so difficult as you are told. Physics of fields and forces is difficult, but these topics are
usually not meant, and relativity imprints here only a simple but strict receipt of writing the equations.
It is kinematics which shows so curious, odd and unfamiliar properties. The relativistic kinematics, however,
is only geometry, more specific, the geometry on a registration strip called space-time.

The registration strip is represented here as a rouleau which keep the trace of a train moving on the curtain rail.
At some instance, a light signal is started in the center of the train, and it traces its propagation
to the front an rear ends, where it is reflected. Since the speed of light does not change in composition with other velocities,
the reflection events are simultaneous for the train, but not for the roulaeu. Simultaneity is relative.

The registration is the instrument to ban the time and the motion on the paper strip in order to permit a
geometrical analysis, which uses the strategies of the familiar geomotry. The difference lies in the
construction of a reflection. Since the registration strip indicates space and time, the compass looses its
force and its function. Reflections are now defined by Einstein's axiom, that the speed of light
cannot be changed even by moving mirrors. The figure of the white traces on the rouleau is symmetric
with respect to the trace of the center of the train.

It is my personal long-time experience that the presentation in geometric form of the kinematics of special relativity
is the only remedy against the ubiquitous **misinterpretation of formulas**.

The leading topis are

the *twin paradox*

,
the *a² - b² = c²* on the space-time strip,

the **symmetry of time dilation**,

the **length contraction**,

the famous *E = mc²*,

and the **Michelson experiment**.

Figures and movies of different lectures are found starting with the **special-relativity** chapter