Chapter 3
The Physical Elements of the Special
Theory of Relativity
In 1905 Einstein [14, 15] in his paper, ‘On the electrodynamics of moving bodies’,
managed to explain all those curious effects that were connected to the propagation
of light. This paper was the foundation of Einstein’s Special Theory of Relativity,
which itself was then the basis for the following theoretical physics. Starting out
from a single basic postulate, the Einsteinian principle of relativity, all those curious
effects that were observed in the propagation of light were deducible. This paper
therefore implicitly contains the answer about the ether without however explicitly
discussing it, cf. Einstein [14, 15]. Here, we will now sketch out using a purely
empirical approach the relatively simple contents of Special Relativity.
1
The negative outcome of all the ether experiments should for the present be formulated with utmost caution.
There is no instrument of measurement capable of responding to the ether.
This statement is reason enough for us to make our instruments of measurement, our
measuring-rods and clocks themselves the objects of our observation. The questions
concerning the reference system for our observations which defines the framework
will be discussed in the next chapter. The following statement will have to suffice for
the moment: Our reference system is the laboratory in which the laws of Newtonian
mechanics are valid. This is a so-called inertial system.
Our measurements now lead us into making two exciting discoveries. All clocks
and measuring-rods a physicist can build show the following properties:
1 Today, we could actually follow this path. At the beginning of the century, the necessary experiments could not be carried out with the required precision. In those days, one was forced on to
the thin ice of conclusions deduced from a bold theory. In 1905, Einstein achieved this with his
paper. One should not however forget that other outstanding theoreticians also tried the same thing,
but failed or could not bring their thoughts to a conclusive end. E. Mach, H. A. Lorentz and
H. Poincaré still stand as the pioneers of the Special Theory of Relativity. We refer here to the
historical depiction of all the facts and developments in A. Pais’ [71] book.
© The Editor(s) (if applicable) and The Author(s), under exclusive
license to Springer Nature Singapore Pte Ltd. 2020
H. Günther, Elementary Approach to Special Relativity,
https://doi.org/10.1007/978-981-15-3168-2_3
13
The Physical Elements of the Special
Theory of Relativity
In 1905 Einstein [14, 15] in his paper, ‘On the electrodynamics of moving bodies’,
managed to explain all those curious effects that were connected to the propagation
of light. This paper was the foundation of Einstein’s Special Theory of Relativity,
which itself was then the basis for the following theoretical physics. Starting out
from a single basic postulate, the Einsteinian principle of relativity, all those curious
effects that were observed in the propagation of light were deducible. This paper
therefore implicitly contains the answer about the ether without however explicitly
discussing it, cf. Einstein [14, 15]. Here, we will now sketch out using a purely
empirical approach the relatively simple contents of Special Relativity.
1
The negative outcome of all the ether experiments should for the present be formulated with utmost caution.
There is no instrument of measurement capable of responding to the ether.
This statement is reason enough for us to make our instruments of measurement, our
measuring-rods and clocks themselves the objects of our observation. The questions
concerning the reference system for our observations which defines the framework
will be discussed in the next chapter. The following statement will have to suffice for
the moment: Our reference system is the laboratory in which the laws of Newtonian
mechanics are valid. This is a so-called inertial system.
Our measurements now lead us into making two exciting discoveries. All clocks
and measuring-rods a physicist can build show the following properties:
1 Today, we could actually follow this path. At the beginning of the century, the necessary experiments could not be carried out with the required precision. In those days, one was forced on to
the thin ice of conclusions deduced from a bold theory. In 1905, Einstein achieved this with his
paper. One should not however forget that other outstanding theoreticians also tried the same thing,
but failed or could not bring their thoughts to a conclusive end. E. Mach, H. A. Lorentz and
H. Poincaré still stand as the pioneers of the Special Theory of Relativity. We refer here to the
historical depiction of all the facts and developments in A. Pais’ [71] book.
© The Editor(s) (if applicable) and The Author(s), under exclusive
license to Springer Nature Singapore Pte Ltd. 2020
H. Günther, Elementary Approach to Special Relativity,
https://doi.org/10.1007/978-981-15-3168-2_3
13