Trouton-Rankine experiment

from Wikipedia, the free encyclopedia

With the Trouton-Rankine experiment (1908) it should be determined whether the length contraction can be measured by a moving observer, whereby a relative movement to the ether (ether wind) would be proven. The experiment had a negative outcome and thus represented a further confirmation of the principle of relativity and the special theory of relativity (cf. tests of the special theory of relativity ).

history

The famous Michelson-Morley experiment of 1887 showed that the ether hypothesis that had been accepted until then had to be modified or even given up. George Francis FitzGerald (1889) and Hendrik Antoon Lorentz (1892) therefore drafted the contraction hypothesis , according to which a moving body is shortened relative to the ether.

Around 1908 the current theories of electrodynamics, namely the Lorentzian ether theory (LET, now outdated) and the special relativity theory (SRT, which managed without an ether), said that the length contraction in a moving laboratory system cannot be measured, which is also possible with the Experiments by Rayleigh and Brace (1902, 1904) have been confirmed. Frederick Thomas Trouton, on the other hand, who had previously tried in vain to measure the ether wind with the Trouton Noble experiment , did not start from these theories. Instead he used his own ideas about the ether and electrodynamics and applied Maxwell's equations and Ohm's law in connection with this - with the result that a measurable effect would have to occur in the laboratory system. Together with Alexander Oliver Rankine he now tried to measure this.

The experiment

Trouton and Rankine tried to measure the change in resistance of a coil when it changes its orientation or the direction of movement towards the ether. They brought four identical coils into a configuration in the sense of a Wheatstone bridge , which enabled a precise measurement of a change in resistance. The assembly was then rotated 90 ° around its own axis when the resistance is measured. Because the length contraction only occurs in the direction of movement, the length of the coils depends on the angle in relation to the aether speed. Because of this, Trouton and Rankine believed that when the assembly is rotated, the resistance must change. However, their careful measurements showed no change in resistance. So this suggests that if the length contraction exists, it cannot be measured by a moving observer, as it corresponds to the relativity principle.

See also

Individual evidence

  1. ^ Trouton FT, Rankine A. On the electrical resistance of moving matter . In: Proc. Roy. Soc. . 80, No. 420, 1908. doi : 10.1098 / rspa.1908.0037 .
  2. ↑ Laub, Jakob: About the experimental foundations of the principle of relativity . In: Yearbook of radioactivity and electronics . 7, 1910, pp. 460-461.