Ives–Stilwell experiment

The Ives - Stilwell experiment was the first experiment that the transverse Doppler effect and thus the following from the special theory of relativity time dilation could be detected directly. Together with the Michelson - Morley experiment and the Kennedy - Thorndike experiment, it is one of the fundamental experiments of special relativity, from which the whole theory can be derived. Similar experiments to measure the relativistic Doppler effect, the Mössbauer rotor experiments and modern Ives - Stilwell experiments in storage rings. Another method is to measure the dilation of moving particles. ( see also Tests of special relativity ).

• 2.1 Relativistic Doppler Effect
• 2.2 isotropy of the speed of light

• 3.1 Fast moving clocks
• 3.2 Slowly moving clocks

Ives - Stilwell experiment

History

Joseph Larmor ( 1900) and Hendrik Antoon Lorentz (1904 ) presented to the Lorentz transformation, to explain the Undetectability of a stationary ether. Here Larmor noticed that the altered time coordinate can be understood as processes run slower moving objects in the ether. Albert Einstein ( 1905) showed that this effect is a necessary consequence of the inferred from the principle of relativity and the constancy of the speed of light, relativity of time, and has nothing to do with an ether. Leads to time dilation Einstein to a modification of the longitudinal Doppler effect, and in addition, an effect occurs in the transverse direction. 1907 Einstein proposed an experiment with the help of light emitted by canal rays light in order to demonstrate this effect.

Only in 1938 could the associated technical problems by Herbert E. Ives and GR Stilwell be overcome. There now arose a positive effect, which corresponded to the prediction of special relativity. In 1941, she leads the experiment with greater accuracy through again. ( Ives itself, incidentally, was an opponent of the theory of relativity and referred to the confirmation of the " ether of Larmor and Lorentz ." This theory, however, is conceptually obsolete compared to special relativity and is no longer considered. ) Experiments of this kind in partly modified form today repeated. For example, Otting (1939 ), almond Berg, et al. (1962),

While in this test, the transverse Doppler effect from the longitudinal was filtered out, so to speak, was in 1979 a " purely transverse " test be performed.

Implementation

Ives refrained from the time dilation caused by the transverse Doppler effect

Observed at right angle to the movement direction of the canal rays as a longitudinal effect of the Doppler effect was hardly be excluded. Therefore, he developed a method to observe the transverse Doppler effect in the longitudinal direction of propagation of the canal rays. Three beams of light are compared, which originate from non-moving, approaching, and receding canal rays.

According to classical Doppler effect, the frequency of in - and opposite to the direction of motion propagating light would be shifted by where c is the speed of light and v is the velocity of the canal rays. If this is transferred to the wavelengths yields the classical Doppler effect red - and blue-shifted wavelengths with the values ​​and. If all three wavelengths ( red-shifted, blue-shifted, unchanged ) are marked on a linear scale, would these wavelengths to be found according to the classical theory in a completely equal intervals.

However, considering the time dilation would have the two outer marks may be shifted slightly (relative to the stationary central mark). This shift would have to exactly match that which would occur also in the transverse direction. Ives and Stilwell actually found a significant shift of the centroid of the three markers, in accordance with the relativistic Doppler effect with a maximum deviation of 10-2.

Mössbauer rotor experiment

Relativistic Doppler effect

A detailed analysis is the relativistic Doppler effect was achieved in the 1960s with the Moessbauer rotor experiments. From a source mounted in the center of a rotating disc, gamma rays are transmitted to a receiver at the edge (the game types which were also placed upside down ). Due to the rotation speed of the receiver, the absorption rate decreases when a transverse Doppler effect is present. Indeed, such an effect could be detected using the Mössbauer effect. The maximum deviation was 10-5, while she was still at the Ives - Stilwell experiments at 10-2. Such experiments were performed by Hay et al. (1960), Champeney et al. (1963, 1965), and Kundig (1963) is performed.

Isotropy of the speed of light

Moessbauer rotor experiments were also used in order to determine a possible anisotropy of the speed of light or an ether wind within the meaning of the Michelson -Morley experiment. This is due to the fact that the ether wind would have a disruptive influence on the absorption frequency. There was - as in all other aether drift experiments - a negative result, the accuracy allowed a maximum aether drift of 3-4 m / s. These include the experiments of Champeney and Moon (1961 ), Champeney et al. (1963) and Turner & Hill ( 1964).

Modern experiments

Fast moving clocks

With modern experimental setups, which have a certain similarity with the Ives - Stilwell experiments, a far greater accuracy. Here, for example, lithium ions whose emitted frequencies are accurately determined and thus act as an optical atomic clocks, in heavy-ion storage rings such as the Test Storage Ring at the Max Planck Institute for Nuclear Physics ( MPIK ), accelerated to 3-6 % of the speed of light. The thereby occurring Doppler effect is evaluated, for which saturation spectroscopy is applied.

Slowly moving clocks

Meanwhile, it has been possible to demonstrate the time dilation of optical atomic clocks even at everyday speeds. Chou et al. (2010) used for aluminum ions that have been back and forth moves in a 75 m long, phase-stabilized optical fiber, and signals of a particular frequency transmitted, the accuracy of these watches was ~ 10-17. This allowed at speeds under 36 km / h ( <10 m / s) occurring shift of ~ 10-16 according to the relativistic time dilation, by comparing the frequency of moving and stationary ions are measured.