Trouton–Rankine experiment

With the Trouton - Rankine experiment (1908 ) was to determine whether the length contraction can be measured by a moving observer, whereby a relative motion to the ether (ether wind) would be proved. The experiment went from negative and thus represented a further confirmation of the principle of relativity and the theory of special relativity (see, tests of special relativity ).

History

The famous Michelson - Morley experiment of 1887 showed that modified the hitherto accepted hypothesis ether or ever has to be abandoned. George Francis FitzGerald (1889 ) and Hendrik Antoon Lorentz (1892 ) therefore designed the contraction hypothesis that a moving body is shortened relative to the ether.

Around 1908 now said the current theories of electrodynamics, namely the Lorentz ether theory ( LET, now obsolete ) and special relativity (SRT, which without an ether got along ) that the length contraction in a comoving laboratory system can not be measured, also by the experiments of Rayleigh and Brace (1902, 1904) has been confirmed. Frederick Thomas Trouton, however, who had previously tried in vain with the Trouton -Noble experiment to measure the ether wind, went out not by these theories. Instead, he used his own ideas on the airwaves and the electrodynamics and therefore applied for the continuous Maxwell's equations and Ohm's Law - with the result that a measurable effect would occur in the laboratory system. Now, together with Alexander Oliver Rankine he tried to measure this.

The experiment

Trouton Rankine and attempted to measure the change in the resistance of a coil when it changes its orientation or the direction of movement to the ether. They applied to four identical coils in a configuration in terms of a Wheatstone bridge, which allowed for a precise measurement of a change in resistance. The assembly was then rotated about its own axis at an angle of 90 °, when the resistance is measured. Because the length of contraction is occurring only in the direction of movement, the length of the coil depends on the angle with respect to the etheric speed. Therefore, believed Trouton and Rankine that the resistance has to change if the assembly is rotated. However, their careful measurements showed no change in resistance. This therefore suggests that if the length contraction exists, it can not be measured by a moving observer, as it corresponds to the principle of relativity.